Ridstar Q16 Review: 20 MPH Factory, 30 MPH Unlocked

Moto-style e-bike on 16 × 4.0 fat tires · front and rear suspension · one rear hub motor printed three ways: "1500W", "1200W Motor(PEAK 1500W)" and "750 watts" · "20 MPH Factory speed" and "30 MPH Unlocking speed" on Ridstar's motor image · 48V 20Ah, 960 Wh · 64 lb, a 330 lb load and a 31.4-inch seat · our listing sold out at $976.35 · verified October 25, 2026

Quick Answer — The Ridstar Q16 is a fat-tire e-bike on 16 × 4.0 tires with a rear hub rated "1200W Motor(PEAK 1500W)" and a 48V 20Ah pack, sold out here at $976.35. Our model gives a 180 lb rider 57 miles at a steady 15 mph on the throttle over level pavement; Ridstar prints 30 in "pure electric mode".

Ridstar's own US variant is unavailable too. On October 24, 2026 ridstar.net's Q16 listing showed its US variant unavailable at $849, the store's second Q16 listing offered one variant marked "CA", at $1,499, and ridstar.com listed no Q16 at all.

Its motor image prints a "20 MPH Factory speed" beside a "30 MPH Unlocking speed", and the class section shows which of the two decides the law where you ride.

Know the maker's record before you buy either badge. The CPSC issued two stop-use warnings about Ridstar's Q20 family in 2026: 26-337 on March 19, warning that Q20 and Q20 Pro batteries and wiring can ignite, and 26-584 on June 25, that Q20 and Q20 Lite front wheels can detach.

Neither names the Q16 or the K16, and the June warning tells owners where to look: "The model number Q20 or Q20 Lite is printed on the purchase receipt." If you own a 16-inch Ridstar, read your receipt, because the record section quotes a buyer who ordered a "Q20 16’" from Amazon and received a bike marked Q16.

What this review covers

The printed figures · Two listings · Fit on the bench · Motor · Pack · Range · Brakes and lights · Frame and bench · Mercer family · UL line · Recall check · Maker's record · YVY K16 · Other Ridstars · 20 or 30 mph · Paths and trails · Flags · Verdict · Checklist · Buying from us · FAQ · Limitations · Bottom line · References

How we verified this Ridstar Q16 review

Every Q16 figure here is Ridstar's own, read on October 24, 2026 from its two ridstar.net listings with the US market selected, and each of its nine photographs was opened at full size that day.

On the same days we read the CPSC record, every statute quoted here, YVY's K16 listing, the storefronts that sell under Ridstar's name, and our own stock, checkout and cart shipping quote; stock and prices were checked once more on October 25. Each calculation is printed beside the figure it produces, and the arguments for the bike get the same scrutiny as those against it. Part of our e-bike reviews.

Written by Milad Ghobadibeygvand, BScN (Western University, 2014). Corrections: support@redtailebikes.com.

The Q16's figures, as Ridstar printed them

One Q16 listing prints three motor ratings, three top speeds, four range figures and two rider windows, and its brake line contradicts its own heading. In each row the figure you can work with comes first, followed by what ridstar.net's text, specification block, Technical Details tab and photographs print for it.

The first of Ridstar's nine Q16 photographs on ridstar.net and the only one that shows the whole bike without dimension arrows; the blue streaks on the fork and shock, and the words in the sky, are Ridstar's artwork.

The 960 Wh is 48 volts times 20 amp-hours, a figure Ridstar never prints. The drawing's wheel base and its length do not add up: two 18.5-inch wheels with axles 49.2 inches apart make a bike at least 67.7 inches long, and the same drawing prints 59.8 inches, so this page takes no measurement off it, and neither should you (the fit section shows the check).

Two listings, one machine: what the Q16 is

Ridstar sells the Q16 through two ridstar.net listings with the same title, the same nine photographs and the same text, apart from one sentence about the brakes. The first, created March 29, 2024, carries a US and a CA variant; the second, a "-copy" created August 29, 2025, carries one variant marked CA.

On October 24, 2026 both of the first listing's variants read unavailable, and the copy's CA variant read in stock at $1,499. ridstar.com, Ridstar's other storefront, listed 56 products that day and no Q16, and the Q16's photographs on ridstar.net carry the same nine file names as a Wayback capture of March 28, 2025.

The brake sentence is where the two pages part. The first listing says "The mechanical dual brakes enhance safety by cutting braking distance by 50%"; the copy says "The hydraulic dual brakes system reduces the average braking distance by 50% compared to mechanical brakes". Both sit under the same bold heading, "Full Suspension & Hydraulic Dual Brakes", and both print "Brake : Mechanical Disc Brakes" in the specification block.

Ridstar names the bike three ways on one page. The title says Q16, the specification block says "Model Number : Q16 Lite", and the Technical Details tab says "Model Name Q16" beside "Brand Bopzin" and "Manufacturer Bopzin", a name the rest of the page never uses. Neither Ridstar store lists a Q16 Lite among the 85 and 56 products their catalogs held on October 24, 2026, so this page treats the three names as one bike.

Ridstar's size drawing, the ninth Q16 photograph on ridstar.net: the only place it prints the bike's weight and its seat height, beside one of its two rider heights.

The drawing also shows the stance. The seat sits 31.4 inches up on 18.5-inch wheels, the 22.4-inch bench takes up more than a third of the 59.8-inch length, and you sit behind a caged round headlight with a phone bag on the top tube, the look Ridstar's description sells as "a unique & imaginative design".

Who the Q16 fits: two windows and a 31.4-inch bench

Seated on the Q16's 31.4-inch bench, the median rider touches the floor with both feet from 5'6" up: in the Army's ANSUR II survey, 61 in 100 riders of 5'6" sit flat-footed, and 3 in 100 of 5'2". The leg asks a different question when it pedals: by the 109% rule, a 5'8" rider of median build wants the saddle top 35.6 inches up from the pedal axle.

Ridstar prints two windows for this bike, and they meet near 5'2". Its size drawing reads "To 5'2"" over "Rider Height", and the FAQ under its description answers "Recommended height range is 5.2 to 6.0 feet". Read the tables below at your own height, and set your inseam against them before either window.

Your fit, in three steps:

1. Find your inseam: in socks, heels touching a wall, raise a hardcover book until it presses up like a saddle, and read a tape from the floor to its spine.
2. Look up your height in the bench table to see whether your feet reach the floor when you stop, and in the saddle table for the saddle height your leg wants on the pedals.
3. On the first ride, set the height with the heel method, then check that your knee keeps a 25-to-35-degree bend when that pedal sits at six o'clock.

Ridstar's Q16 pages leave out the seat-tube angle, the bench's travel, the crank length, the grip position and the bottom-bracket height, and none of them says whether the bench moves. So the model works from the single seat height Ridstar prints, 31.4 inches up to the bench top, and leaves the reach to the bars and the load on your hands uncomputed.

Will the Q16's saddle go high enough for me?

Each row gives three saddle heights for the median rider of that height, measured from the pedal axle: 109% of inseam, the figure Peveler et al. (2005) compared with the heel method, and a band from 106% to 110.4% drawn from Ferrer-Roca et al. (2012), the low end of the literature range they cite and the high end of their own equation.

The inseam column covers the middle 90% of legs at each height in the Army's ANSUR II survey. Ridstar prints no pedal height for the Q16, so the table gives what your leg asks for, and whether the bench delivers it is a question for the seller before you order.

Columns: saddle-top height above the pedal axle at 109%, 106% and 110.4% of inseam, across the central 90% of each height's ANSUR II bodies; heights with fewer than 30 bodies are left out, which drops 4'10". Without a printed crank length, the 88.3% figure LeMond measured from the crank axle has nowhere to sit on this bike.

Can I put a foot down at a stop?

Seated, the median rider's feet stop short of the floor at 5'4" and below, by 0.9 inches at 5'4" and 3.0 inches at 5'0"; at 5'6" 61 in 100 riders reach it flat-footed, and at 5'10" all of them do. Each row repeats one subtraction for every body, barefoot inseam minus the 31.4-inch seat height, and a body whose result is zero or positive sits flat-footed.

Rows run by height: the ANSUR II median inseam less the drawing's 31.4-inch seat, then the count, out of 100 riders that tall, whose inseam reaches the floor. Minus signs mark bare soles hanging clear of the floor by that many inches, before a shoe takes some of it back.

Ridstar's two windows sit either side of this table's turning point. A rider at the drawing's "To 5'2"" ceiling, about where the FAQ's window begins, starts with 1.9 inches of air under the median sole, and the 6'0" rider at the FAQ's top has 3.5 inches to spare, so a short rider on this bike stops by sliding forward off the bench and standing over the frame.

Ridstar's drawing prints no height for the frame ahead of the bench, so that standing position goes uncomputed. Ask the seller for it, and set it against your inseam before you buy.

Will you sit stretched or cramped on the Q16?

The lean from your hips to the bars is not computed: the Q16's grip position is not published, nor its stem length or seat angle. Its drawing gives the bike's total height as 41.7 inches, a height that says nothing about reach, and the 22.4-inch bench lets you sit anywhere along it; if the cockpit worries you, include your arm length when you send us your inseam.

How much weight goes through your wrists?

The share of your weight on the bars cannot be computed for this bike, because its grip position is not published and the bench gives no fixed sit point. For scale, Carahalios (2015) measured about 15% of body weight on the stem across ten road racers on the hoods, a long, low position nothing like an upright bench, so use it as a reference point and never as the Q16's figure.

How do you set the saddle when it arrives?

On the Q16 the only seat setting is whatever the bench allows, and Ridstar does not say it moves. Its text describes "a strengthened pole & hollowed-out bracket" under the saddle and gives no height range, so ask before you order whether the bench raises and how far.

If it does, set it with the heel method: crank down and in line with the seat tube, heel on the pedal, leg just straight. On a first ride, watch the knee as each pedal bottoms out: Peveler, Pounders and Bishop (2007) cite 25 to 35 degrees of bend from earlier cycling studies; Ferrer-Roca et al. (2012) set their own study's target at 30 to 40.

The fit arithmetic, step by step

All 6,068 ANSUR II bodies go through the same four steps: inseam times 1.06, 1.09 and 1.104 gives three saddle heights over the pedal axle, and inseam less 31.4 inches says, by its sign, whether both feet touch down from the bench.

Worked at 5'8" (68 inches): a median inseam of 32.6 inches gives a 109% saddle height of 35.6 inches above the pedal axle, inside a band from 34.6 to 36.0 inches; seated on the 31.4-inch bench, the same rider has 1.2 inches to spare under bare soles.

The same 2005 study put LeMond's method at 109.2 ± 0.9% of inseam, measured from the pedal, within a point of the tables' 109%; at 5'8" LeMond's 88.3% works out to 28.8 inches from the crank axle, a figure that cannot be compared without the crank length Ridstar leaves out.

Nothing is measured off the size drawing, and the reason is in the drawing. Scaled from its own 31.4-inch seat arrow, three of its other arrows land close to their labels and two do not:

Arrow lengths measured in pixels on Ridstar's 1464 × 600 drawing, scaled by its 31.4-inch seat arrow at 12.04 pixels to the inch. Where the bench sits under you, and where your hands land, is not marked at all.

Limitations names what the missing figures leave open.

One rear hub motor, rated three ways

The Q16 runs one motor in its rear hub, and Ridstar rates it three different ways on one page: "1500W" in the title, "1200W Motor(PEAK 1500W)" in the specification block and "Wattage 750 watts" in the Technical Details tab. Ridstar's parts catalog confirms where the motor sits: its "Ridstar Rear hub contains motor" listing sells a "US / Q16" option at $379.

The text adds "a torque of up to 85Nm" and says the motor "can easily conquer steep slopes with a gradient of up to 35°", while the motor image prints "30° Slope". No torque figure appears on any image, and no page says which of the three wattages is the continuous rating a regulator would read; the class section runs all three for your state.

The seventh Q16 photograph on ridstar.net, and the only place Ridstar prints a factory speed: 20 mph, with 30 mph as the "Unlocking speed". Its "65 Miles" sits over the label "Max speed" as printed.

Two speeds on one image is the Q16's defining choice. As it leaves the factory, the motor image says, it holds 20 mph; unlocked, 30; the FAQ under the description says "28+++ mph in pure electric mode (ensure a full charge)". Ridstar's pages do not describe how the unlocking is done or who does it.

For range, the three ratings barely move flat-ground figures. The model's motor is rebased to 1,200 W, and at a steady 15 mph with a 180 lb rider it gives 57.6 miles with a 750 W rating, 57.0 at 1,200 W and 55.9 at 1,500 W. Climbs are where you feel the rating: on an 8% grade at 10 mph the same rider gets 10.5, 12.4 and 13.1 miles.

The model's motor tops out where Ridstar's figures put it. Given Ridstar's 30 mph as the speed it reaches with no load, it holds 26.8 mph on flat pavement under a 180 lb rider, a speed the factory setting of 20 mph keeps out of your reach until the bike is unlocked.

One 48V pack, 20 amp-hours

The Q16 carries one removable 48V 20Ah pack, 960 watt-hours by our arithmetic, which Ridstar calls a "UL-certified battery" that "incorporates BMS security protection and power-saving capabilities". The specification block prints "Battery : 48V/20 Ah", the battery image prints "48V20AH", and no Q16 page names a watt-hour figure, a cell maker or a UL standard; the UL section reads what that claim can and cannot tell you.

The eighth Q16 photograph on ridstar.net: "Max Range 35-65 Miles" printed with no rider weight, speed or mode beside it.

Ridstar quotes "4-6 hours at 3A" to charge. Simple division gives a different figure from empty: 20 amp-hours at 3 amps is 6.7 hours, so plan on most of your evening when the pack is flat and less when it is not.

If you want a second pack, it is harder to find for this bike. Ridstar's parts catalog of October 24, 2026 sells a "US / Q16" motor, controller, display and front fork, and no battery with a Q16 option, while YVY's catalog sells a "US / K16" option on its "YVY K20/DC26/H20 48V 20AH" battery listing at $429.

Your running costs are small. The US Energy Information Administration puts August 2026's average residential price at 18.16 cents per kWh, so refilling 960 Wh costs about 17 cents, and a 1,000-mile year ridden at 15 mph on the throttle comes to about $3.06, both before the charger's own losses.

Range: 57 miles at 15 mph on the throttle, for a 180 lb rider

On flat pavement at a steady 15 mph, a 180 lb rider on the throttle alone gets 57 miles from a full Q16 charge, by our model, and 43 if a quarter of the pack stays unused as a reserve. Ridstar prints 30 miles in "pure electric mode" and 50 with pedal assist; the maker's figures below show which rides produce each.

Three steps to your own number:

1. Find your speed in the speed table, and the column for how hard you pedal.
2. Adjust for the ride: hills, your weight and load, cold air.
3. Plan on the "with 25% kept" figure, which holds back the share of the pack a measured pedelec could not use.

Every figure is computed from Ridstar's printed weight, pack and wheel size and from published physics, and the arithmetic section lists each input with its source. The model assumes steady riding, so stop-and-go streets leave you with less than each figure.

How long will the Q16's 48V 20Ah battery last?

At 10 mph the 960 Wh pack carries a 180 lb rider 79 miles on the throttle, and at 20 mph, the factory speed, 40; holding a quarter back, those become 60 and 30. The 25 mph row exists only if the bike is unlocked, and it costs 11 of the 40 miles.

Flat pavement, no wind, 77 °F, 180 lb of rider on a 64 lb bike, the throttle alone, the full 960 Wh; "with 25% kept" holds back the reserve Schmitt, Decker and Doppelbauer (2019) measured on a pedelec. The 25 mph row needs Ridstar's "Unlocking speed" setting; the factory setting stops at 20 mph.

Pedaling stretches the same charge far further, because every watt from your legs is a watt the pack does not supply. At 15 mph, easy pedaling of 75 W lifts the 57 miles to 88, and steady pedaling of 150 W to 178.

Flat pavement, 180 lb rider, full pack. The rider adds 75 W in the "Easy pedaling" column and 150 W in the "Steady pedaling" one; your legs alone, with no motor, would hold 9.2 mph and 13.3 mph on the 64 lb bike.

Do the gears or the throttle change the Q16's range?

On a rear hub motor the Shimano 7-speed changes how fast your legs turn, never how fast the motor spins: the motor turns with the wheel. So the gear that saves battery is whichever lets you pedal steadily, because pedal watts replace pack watts, as the Wh-per-mile figures below show.

Watt-hours per mile, 180 lb rider. Flat rows at 15 and 20 mph; climb rows at 12 mph on 4% and 8% grades. On the throttle alone, the 8% climb uses 77.1 Wh a mile, 4.6 times the 15 mph flat figure.

How much range does a climb cost on the Q16?

A 4% grade at 10 mph uses 40 Wh a mile on the throttle, enough to empty the pack in 24 miles, and a 10% grade uses 100 Wh a mile, about 10 miles of climbing. Plan by the height you gain: climbing 1,000 feet at 6% on the throttle uses about 144 Wh on top of the flat-ground cost of covering that distance.

10 mph on paved grades, 180 lb rider, full pack; the last column adds easy pedaling of 75 W. At 15%, the steepest row, the pack delivers about 1,498 W and 51.6 A, near the motor's printed 1,500 W peak; Ridstar prints no current rating for the Q16's controller.

Ridstar's own climbing figures, "up to 35°" in the text and "30° Slope" on its image, are angles near 58% to 70% grades, far past the 15% the table runs to, and Ridstar does not say at what speed or rider weight either was reached.

Does the rider's weight change the Q16's range?

From a 180 lb rider to Ridstar's 330 lb maximum load, the 15 mph flat ride loses 11 miles, about 3.7 for every 50 lb, and the 8% climb halves, from 12 miles to 6. On the climb every pound has to be lifted as well as rolled, so weight costs the most there.

Weights are rider and cargo, with the 64 lb bike added to each, on the throttle alone with a full pack at 77 °F. The 330 lb row is Ridstar's printed maximum load, rider and cargo together.

Range in the cold

Cold cells give up part of their energy, and cold tires roll harder. At 32 °F the model's 15 mph flat ride falls from 57 miles to 45, within a measured band of 41 to 48, and at 14 °F to 41, where the band widens to 20 to 41 because the cell data spreads.

15 mph, flat, 180 lb rider, throttle only. Pack energy against 77 °F, with the measured spread in brackets at 32 °F and 14 °F, from LG HG2 cell discharge data at temperature, since Ridstar names no cell; the tire's rolling resistance rises as it cools.

Keep the pack indoors until you ride: by the table above, the colder the cells, the less of the 960 Wh they give back.

Fat tires and the range

Ridstar prints a 16 × 4.0 tire and no tread or casing name, so for rolling resistance the model takes the middle value of ten fat tires measured on one drum by Bicycle Rolling Resistance, a coefficient of 0.0105, with the best and worst of the ten as its bracket.

15 and 20 mph, flat, 180 lb rider, throttle only. The ten tires are 26 × 4.0, measured at 12 psi; how the Q16's 16-inch wheel changes the figure was not measured, which Limitations records.

How far does Ridstar say the Q16 goes?

Ridstar prints four range figures for the Q16, and each one is reachable on the model: its 30 miles in "pure electric mode" matches a steady 24.3 mph on the throttle, and its 50 miles with assist matches 20 mph with easy pedaling. None of the four comes with a rider weight, a speed or a temperature on Ridstar's pages.

For each figure Ridstar prints, the Wh per mile that empties 960 Wh in that distance, and the steady flat speed at which a 180 lb rider uses it on the throttle alone, with easy pedaling (75 W) and with steady pedaling (150 W); "—" means no speed in the model's range uses that much. The 65 miles prints on the battery image as "Max Range 35-65 Miles" and again on the motor image, over the label "Max speed".

Read in that light, the 30 miles is a ride above the 20 mph factory speed, which needs the unlocked setting, and the 65 is a slow 13.2 mph on the throttle. At the factory 20 mph, the model's throttle-only figure is 40 miles.

How the range figures are computed

The model adds the power to roll the tires, lift the rider and push the air, following Martin et al. (1998): power at the wheel equals speed times the sum of rolling resistance, the grade's pull and air drag. It then divides by the motor's efficiency at that torque and speed and by the battery's efficiency at that current, and the pack's 960 Wh, adjusted for temperature, sets the miles.

Worked at 15 mph, 180 lb rider: the bike and rider weigh 244 lb (110.7 kg); rolling takes 76.7 W and air 114.2 W, so the wheel needs 190.9 W.

At 272.5 wheel rpm that is 6.69 N·m from the motor, which draws 244.4 W from the pack at 78.1% efficiency; with the pack's own 96.8% efficiency the cells give 252.4 W, or 16.8 Wh a mile, and 960 Wh lasts 57.0 miles.

The physics was checked against Martin et al. (1998): their Appendix I ride, 45.7 W of rolling and gravity and 158.8 W of air, comes out at 45.7 W and 158.8 W in this model. At its rated point the comparable motor returns the 80% efficiency Bafang's workbook prints, and no published Q16 ride log exists to check it against, which Limitations records.

Brakes, lights and the display

Ridstar's specification block says "Mechanical Disc Brakes", and so does the sentence under its own heading "Full Suspension & Hydraulic Dual Brakes": "The mechanical dual brakes enhance safety by cutting braking distance by 50%". The CA-only copy of the listing changes that one sentence to "The hydraulic dual brakes system", so ask which caliper ships before you order and expect mechanical, the type the specification block names.

Ridstar's "cutting braking distance by 50%" names nothing it was compared with, so read it as the maker's claim when you judge your own stopping distance.

The lighting is a caged round headlight between the fork legs and a taillight under the back of the bench, which the text calls "waterproof headlights and brake lights" and "bright LED headlights", with "IP5 waterproof protection" for the bike.

The caged headlight, the fourth Q16 photograph on ridstar.net.

The taillight sits under the bench's rear edge; fifth on ridstar.net.

The display is a small LCD with power, plus and minus buttons, and the switch block beside it carries a light button and a horn. Ridstar's text lists what it shows you: "speed, mileage, battery level, PAS, and other essential information".

The display as Ridstar's image shows it, 47.9 km/h in mode 5, which converts to 29.8 mph, near the 30 mph "Unlocking speed"; second on ridstar.net.

Frame, suspension, tires and the seat

The Q16 has a fork up front and a shock at the rear, which Ridstar describes as "The front suspension fork is strengthened by 100%" and "The rear hydraulic shock absorber", and its Technical Details tab files the frame as "Aluminum" with "Suspension Type Dual". Ridstar prints no travel for either, no spring rate and no adjustment.

Its tires are 16 × 4.0, the "puncture-resistant fat tires" of Ridstar's text, which its size drawing puts at 18.5 inches across, and the text lists "grass, dirt, sand, snow, and gravel" as the ground they are for.

The drive is a twist-grip throttle, which Ridstar's text says "releases your thumb", and a Shimano 7-speed thumb shifter, spelled "Shamano" in the text and "Shimano" in the specification block.

Shimano's 7-speed thumb shifter, third on ridstar.net.

The bench is one long seat, 22.4 inches by Ridstar's drawing, and Ridstar sells a "7.2'' phone holder" and "a spacious storage box" with the bike. Its sixth photograph shows them together as a frame bag on the top tube with a clear window over a phone.

The phone window and storage bag on the top tube, sixth on ridstar.net; Ridstar gives the phone holder as 18.5 × 8.5 cm and the box as 22 × 14 × 11 cm.

Ridstar ships it "90% pre-assembled", and its page notes "Front tires must be securely installed, Self-modification may posesafety risks" (sic), so check that the front axle nuts are tight before your first ride.

The Mercer fit test

We set the same seven people, the Mercer family, beside every bike we review, and here each is checked against the Q16 four ways: Ridstar's two windows, the 109% saddle height for their build, how many riders of their height reach the floor flat from the 31.4-inch bench, and what the class section says about the law.

The figures come from the model's ANSUR II bodies at each member's height, so read the family as archetypes and start with the row nearest your own height.

Ages and heights: the Mercers' page. Saddle and flat-foot figures come from our fit model, which sets every ANSUR II body of each height against the 31.4-inch seat on Ridstar's size drawing.

Ridstar's FAQ window takes in four of the five adults, and the bench sorts them more sharply than the window does. Ruth, inside it at 5'5", is one of the 62 in 100 riders her height who cannot sit flat-footed on it, while Jack, an inch above it at 6'1", has 4.2 inches to spare; the drawing's "To 5'2"" takes in none of the five.

So the same bike that is an easy stop for the tallest adult asks Ruth to slide forward off the bench at every light, which the stop section walks through. If a seated stop matters more to you than the Q16's look, Qiolor's page gives the Tiger JR we sell a "Recommended Height" of "5'1" - 5'9"".

For Cole, 16, and Ivy, 12, the answer is no. ridstar.net's shipping policy reads "E-Bikes Are Not for Sale to Persons Under the Age of 18" and "Underage riders MUST be accompanied by parents or adults when riding", and at its printed 1500W the Q16 is outside 46 of the 49 US e-bike definitions even at 20 mph, so whatever age rule your state attaches to the class it gives this bike would govern.

One of the three owner reviews on Ridstar's page, quoted in the record section, describes a "teenager boy" riding the Q16 "to school every day"; if you are buying for a rider under 18, our kids and teens guide groups our bikes by the rider's age and sets out each state's age rules.

Is the Ridstar Q16 UL certified?

The phrase "UL-certified" appears a single time on the Q16 listing, attached to the battery, with no standard number, certificate holder or file number beside it. The sentence is "The UL-certified battery incorporates BMS security protection and power-saving capabilities.", and it appears in the text of both ridstar.net listings.

A battery line and a bike certification are not the same claim. UL 2849 is, in UL Solutions' words, "the Standard for Electrical Systems for eBikes", and it looks at the drive train, the battery and the charger together, as the combination fitted to a given e-bike.

YVY's K16 page, whose description repeats most of the Q16's word for word (the K16 section counts them), leaves the UL sentence out. Whoever sells you a bike marketed as UL-certified should be able to name, in writing, the certificate holder and the file number; Smartravel's DK400 page prints "Safety Certified in Accordance with UL 2849", and the same two details are worth having there.

What the "Our Qualifications" links hold. The footer of the Q16 page, read October 24, 2026, links three files: "US trademark" and "European trademark" open registrations owned by "Huizhoushi Xingqishi Sports Goods Co., Ltd." for goods that include bicycles, US Reg. No. 6,936,242 of December 27, 2022 and EU 018609888 of March 16, 2022.

The link labeled "CE trademark" opens a test report, EN 15194:2017 report ATS240329142LR of April 2, 2024, for a "Cargo electric bicycle", model "FM-002, CDDA20", with a measured maximum power of "250W". None of the three names the Q16, and none comes from UL, whose page notes that "EN 15194 does not cover the safety of electrical systems utilizing battery packs in the same manner that UL 2849 covers this subject."

Has the Ridstar Q16 been recalled?

No recall or warning names the Q16 or the K16. The Commission's two Ridstar warnings pair the Q20 first with the Q20 Pro and then with the Q20 Lite, and its recall list, read October 25, 2026, carried nothing from Ridstar.

The list's 10,058 entries ran to October 22, 2026, and not one named Ridstar, its manufacturer, YVY, a Q16 or a K16. Nor did the 40 recalls in the CPSC's feed from September 24 to October 22, and across the 379 rows of its warning list Ridstar appears in the two warnings above and a Q16 or K16 in none.

Neither release comes with a remedy for owners. To Q20 and Q20 Lite owners, the June release's instruction is to "stop using the e-bikes immediately and dispose of them". Search the recall list for the model name again on the day you order any Ridstar or YVY.

The maker's record

Ridstar's record holds two lawsuits, two CPSC warnings and one UK safety report, and none of them names the Q16; what ties the Q16 to the warned Q20 is a set of parts listings and one buyer's account of a bike ordered as a "Q20 16’" that arrived marked Q16. Every line in this section is quoted from its author, whether a regulator, a court or an owner.

Both releases as served on October 24, 2026.

In both, the CPSC gives the warned bikes' maker as a Chinese company, Huizhou Xingqishi Sporting Goods Co., Ltd. In March the Commission wrote that the company "has refused to agree to an acceptable recall", printing its reply, "The company objects to this press release"; in June, that it "has been unresponsive" to the agency's requests.

What to check on a 16-inch Ridstar you already own

Read the purchase receipt first. The Commission identifies the warned bikes by name, not by wheel size: the March release says "The model number Q20 or Q20 Pro may be located on the purchase receipt", and the June release "The model number Q20 or Q20 Lite is printed on the purchase receipt". If your receipt names one of those models, the Commission's instruction is addressed to you.

Your receipt matters for this bike because of one buyer's account. In September 2025 an r/ebikes poster wrote, under the title "Ridstar Q20 from amazon came but says Q16?", that "i ordered the Ridstar Q20 16’ from amazon and it came and says Q16 on the side", and later added "i saw a listing on amazon called the Q20 16 inch and separate listing on the ridstar website called the Q16". That is one person's report.

Ridstar's own parts catalog puts the two names side by side. ridstar.net's catalog held 85 products on October 24, 2026, and 17 of them sell a part with a "US / Q16" option, and every one of the 17 also sells Q20-family options, the front-wheel parts among them: the front hub at $179, both front axles at $35 and the front wheel nut kit at $25, the same US prices as their "US / Q20" options.

Each of those options is its own stock item, and no Ridstar page says whether a Q16 part and a Q20 part on one listing are the same part, so ask the seller in writing which front hub, axle and nuts your Q16 carries. Then follow the note on Ridstar's own product page, "Front tires must be securely installed", and check the axle nuts before every ride.

The UK report and the Q20 Mini

Nine months before the first CPSC warning, Britain's Office for Product Safety and Standards published report 2506-0011, dated June 19, 2025, on a serious fire risk from Ridstar's Q20-Plus, Q20-Mini and E26 Pro bikes and their chargers. The fault is in the chargers: "poor quality soldering", and a transformer that "does not meet the minimum requirements for creepage and clearance distances"; the action taken was "The import has been rejected at the border."

No Ridstar or YVY catalog we read on October 24, 2026 lists a bike called the Q20 Mini, yet ten of the 17 Ridstar parts listings that offer a "US / Q16" option also offer a "Q20MINI" one. Neither Ridstar nor the UK report says which bike the Q20 Mini is.

Two suits against the sellers

Two federal suits turn on a Ridstar front wheel that came off. A "Ridstar Q20" is the bike in the Oregon case, Cunanan v. Amazon.com Services LLC (3:26-cv-00692), whose docket has had no new entry since July 8, 2026.

The bike in Florida's L.E. v. Walmart Inc. (9:26-cv-81045) has no model name in the complaint, only the Walmart title it sold under, "Ridstar Electric Bike, Peak 1500W30MPH,48V 15.6Ah Electric Bicycle, Full Suspension Mountain Bike UL2849", and the complaint points to both Q20 warnings. That title's 48V 15.6Ah pack is not the Q16's 20Ah, and the complaint gives the bike no other name.

The Florida court entered an "Order on Motion to Dismiss" on October 23, 2026, and the free copy of the docket lists the order without its text, so its outcome was not readable on October 25. Each suit is against the store that sold the bike, neither names Ridstar as a party, and nothing in either has been proved.

What Q16 owners wrote on ridstar.net

The structured data on Ridstar's Q16 listing carries an average of "5" from "6" ratings and three written reviews, each five stars. "Brian" calls it "the best bike I've ever had" and "the batmobiel of lectric bikes" (sic), and "Kubota Saki" writes "My teenager boy love it he rided it to school every day."

The third, from "Satoru Osawa", is the one with numbers: "This is great bike for the money: 31 mph top speed and range of 27 miles with 40Ah battery in fastest PAS 5 mode with no pedaling", after the advice to "Spend the extra for Q20-2000W which has hydraulic brakes". Ridstar sells no 40Ah pack for the Q16, and the review gives no rider weight, so read each line as one owner's account of one bike.

Who would you be buying from?

The business behind ridstar.net is "HK RIDSTAR TRADE LIMITED", by its company page, at a room in Hung Hom, Hong Kong; the Q16's warranty bullet nonetheless begins "Established in New Jersey and proudly serving the US since 2008", and no New Jersey address appears on that page.

The US and EU trademarks belong to "Huizhoushi Xingqishi Sports Goods Co., Ltd.", the CPSC names "Huizhou Xingqishi Sporting Goods Co., Ltd." as the maker of the warned bikes, and the Q16's Technical Details tab lists "Brand Bopzin" and "Manufacturer Bopzin", a fourth name no other part of the page explains.

Which Ridstar store would you be buying from?

On service, ridstar.net's official statement leaves no doubt. It names its own site "The only official website of ridstar", files the rest under "Except ridstar.net, other similar websites are our dealers.", and draws the line at buyers elsewhere: "Except for customers who purchase from ridstar.net, we will not provide any after-sales service to customers who purchase ridstar products from other places."

On October 24, 2026 a storefront at ridssttaar.it.com, whose home page calls itself "The Only Ridstar Official EBike Shop", listed a "Ridstar Q16 1500W Fat Tire Electric Bicycle" in stock at $329.70, $519.30 under ridstar.net's US price, with nine photographs bearing the file names of Ridstar's own nine. Neither ridstar.eu nor ridstar-ebike.com had a Q16 in its catalog that day.

Before you pay a shop that uses Ridstar's name, other than ridstar.net, set its claim beside Ridstar's statement and get in writing whose warranty covers your order. Ridstar's warranty page offers "One year warranty on all products", and Buying it from us sets out what we do.

YVY's K16: the Q16's figures under another badge

YVY sells a bike it calls the K16 that prints the Q16's figures, and YVY's company page names the same business as Ridstar's, "HK RIDSTAR TRADE LIMITED". YVY's K16 listing, created May 11, 2026, sits at a web address that still reads yvy-q16, and its specification block prints "Model Number : K16".

The rest of that block reads like the Q16's: "Battery : 48V/20 Ah", "Max Load : 330lbs", "Brake : Mechanical Disc Brakes", a Shimano 7-speed, 30 and 50 miles by mode, and an FAQ answer of "Recommended height range is 5.2 to 6.0 feet". Compared word by word on October 24, 2026, 646 of the 675 words in the K16's description appear in the same order in the Q16's.

Both listings read October 24, 2026 under the US market. Both specification blocks print "Riding Range: 30miles (pure e-bike mode) to 50miles (assist mode)"; a second YVY listing that opens with the same K16 photograph prints "28 MPH Speed Limit" and "85 NM Max Torque" on its motor image.

A third name turns up on ridstar.com, Ridstar's other storefront: on October 24, 2026 it listed a "【UK Stock】YVY C16 1500W 48V 20AH 16*4.0 Fat Tire Electric Bike", created August 20, 2026, with one variant marked "UK" and no description, so this page reads nothing from it beyond the title.

The photographs are another matter. YVY's six K16 images are its own, with a YVY wordmark on the battery, and none of them is one of Ridstar's nine by a pixel-by-pixel comparison; they show the same outline, the caged round headlight, the perforated side plate and the long bench. Neither company says the K16 and the Q16 are one machine, and this page does not say it for them.

YVY's own photograph of the K16, the first image on its listing; the blue rings on the tires are YVY's artwork.

The K16 is the one you can buy from us today, at $861.35 on October 25, 2026, with free shipping in the lower 48. YVY's warranty page says its limited warranty "is issued by YVY Bikes" and "will be verified by YVY"; buy the K16 here and a fault on arrival is one we take up with YVY, since our refund policy reads "covered under manufacturer warranty — we coordinate repair or replacement remotely".

Everything in the record section applies to YVY's company as well. No CPSC warning or recall names a K16, and the Oregon complaint against Amazon alleges of its Ridstar Q20 that "The intermediary for the sale involving the bike purchased by the Plaintiff is “YVY Bikes.”" (the Cunanan complaint, ¶ 30).

At its printed 1500W, the class section reads the K16 as it reads the Q16, outside 46 of the 49 US e-bike definitions even at 20 mph, so it suits private land and the roads your state opens to a bike of its class.

Where the Q16 sits among Ridstar's bikes

On Ridstar's own figures the Q20 is the Q16's nearest relative: the same 48V 20Ah pack and a rear hub it also calls 1500W, on 20 × 4.0 tires, and both of the Commission's 2026 warnings name it. Every other Ridstar you can read about here is listed below, each worked from figures on Ridstar's own pages:

• Ridstar Q20 review: that pack and motor rating on bigger wheels, and the receipt check the June warning gives Q20 owners.
• Ridstar Q20 Pro review: the March fire warning's other model, still without a recall.
• Ridstar Q20 Lite review: named beside the Q20 when the Commission warned about detaching front wheels, on a pack holding less than the Q16's.
• Ridstar Q30 review: a printed top speed beyond every e-bike class, where the Q16 lands once unlocked.
• Ridstar Q30 Pro review: a motor in each wheel and two packs, against the Q16's one rear hub and one pack.
• Ridstar Q30 Lite review: one bike under three names, much as the Q16's page names it Q16, Q16 Lite and, by brand, Bopzin.
• Ridstar Q30 Luxe Lite review: a bench bike Ridstar also rates at 1500W, its seat 35.8 inches up to the Q16's 31.4.
• Ridstar Q30 Luxe review: the Luxe Lite's bench design with a 2000W motor and a choice of a 20Ah or 25Ah pack.
• Ridstar Q50 review: one 1,200 Wh pack, a quarter more energy than the Q16's 960.
• Ridstar MN26 review: the Q16's 960 Wh on a step-through rolling on 26 × 4.0 tires.
• Ridstar FM001 review: two riders on one step-through, inside the 330 lb load Ridstar also prints for the Q16.
• Ridstar H20 review: a folding bike with five printed top speeds, two more than the Q16's three.
• Ridstar H26 Pro review: two ratings, 1,500 W and 2,000 W, printed for the single motor of a folding bike, where the Q16's motor gets three.
• Ridstar DC26 review: a folder on bigger fat tires than the Q16's, whose spare pack Ridstar lists beside the Q20's.
• Ridstar E26 Pro review: a motor in each wheel on full-size fat tires, and a charger named in a UK safety report.
• Ridstar MN20 review: a folding step-through whose dealer prints its folded length and two seat heights on a drawing.
• Ridstar Q20 Luxe review: a bench-seat moto bike whose size drawing labels its seat and standover heights.
• Ridstar Q20 Luxe Lite review: a bench-seat bike for which Ridstar prints only a rider-height window, so its fit is worked out from your inseam.

If you are comparing makers, our e-bike reviews hold every bike we have worked through this way, and our Ridstar profile covers the company and the storefronts that sell under its name.

At 20 mph, 3 to 29 definitions fit; at 30, none

At its 20 mph factory speed and its printed 1500W, the Q16 fits the e-bike definitions of the District of Columbia, Montana and Oregon; at the specification block's 1,200 W, Rhode Island's too; at the Technical Details tab's 750 watts, 29 of the 49 definitions in US law. Unlocked to 30 mph, or at the FAQ's "28+++ mph", it fits none of them at any of the three ratings.

Federal law comes first. 15 U.S.C. § 2085(b) sets out a low-speed electric bicycle in three tests: "fully operable pedals", "an electric motor of less than 750 watts (1 h.p.)" and a top speed "less than 20 mph" on the motor alone, "while ridden by an operator who weighs 170 pounds"; Ridstar's 1500W and 1200W ratings both miss the motor line, and its 750 watts misses it too, since 750 is not less than 750.

Sources, each read October 24, 2026: govinfo's copy of the federal text, the California Legislature's code pages and both Ridstar Q16 listings, photographs included.

In California, § 312.5(a) takes a motor that "does not exceed 750 watts of power", so the Q16 fits class 2 only on the tab's 750 watts and only at the factory 20 mph. At 1,200 or 1,500 W it leaves the three classes before speed is asked about.

California's moped line is § 406(a), the motorized bicycle: a motor producing "less than 4 gross brake horsepower", a test the Q16's 1,500 W, roughly 2.0 horsepower, passes, and a speed "not more than 30 miles per hour on level ground", which the 30 mph unlocking speed meets at the line.

Section 406(a) sets two more conditions: pedals, which it words as "fully operative pedals for propulsion by human power", and "an automatic transmission". Whether a 7-speed derailleur counts as one is a question you would put to the California DMV in writing; the rest of the code is on our California page.

The 49 definitions in US law

The motor limit in 44 of the 49 US e-bike definitions is 750 watts, phrased "less than" in 17 of them, "not more than" in 7, and in smaller groups of wordings elsewhere. Of the other five, Rhode Island's counts horsepower and four print no power figure; Alaska and Kentucky, outside the 49, write no e-bike definition.

The four without a power figure are where a 1,500 W bike can still qualify at 20 mph, and three of them take it: the District, Montana and Oregon. The fourth, New Jersey's, reaches only a motor that "provides assistance only when the rider is pedaling", which leaves the Q16's twist throttle out.

Rhode Island's "not more than two (2) (S.A.E.) horsepower" works out near 1,492 W, so the 1,200 W rating passes it and the 1500W does not.

Two of those three definitions test what the motor can do, and that is where the unlocking speed bites. The District's motor must be "incapable" of driving the bike past 20 miles per hour "on level ground", and Montana's must manage "no faster than 20 miles an hour" with "a rider who weighs 170 pounds" aboard "on a paved, level surface".

Ridstar prints a "30 MPH Unlocking speed" for the same motor on its motor image. One reading takes the bike as set at the factory, at 20 mph, and fits it; another takes the motor's capability, which Ridstar puts at 30 mph, and does not. Neither statute says which applies to a speed the owner can change, so ask the agency in your state before you count on the 20 mph reading.

Paths, parks and forest roads

Paths that admit e-bikes by class leave the Q16 out wherever its rating falls outside the class, so read the posted rule at each place you ride and stay off any path that does not admit a 1500W bike.

California gives the motorized bicycle its own path rule, § 21207.5(a): it "shall not be operated on a bicycle path or trail, bikeway, bicycle lane", nor on equestrian, hiking or recreational trails, except where the path runs "within or adjacent to a roadway" or a local authority "permits, by ordinance, that operation". Should the state class the Q16 that way, those paths are closed to you on it unless one of the two exceptions applies.

Where the managing agency posts its own rule, follow it over this table, setting any wattage or speed it names against Ridstar's 1500W, its 20 mph factory speed and its 30 mph unlocking speed.

National Forest rules begin with a wide net. 36 CFR 261.2 defines a motor vehicle as "any vehicle which is self-propelled", leaving out only vehicles on rails and devices made for mobility-impaired people, and the Q16 falls inside it.

Where you may take a motor vehicle is then set by the motor vehicle use map of each Ranger District, and under 36 CFR 261.13 riding off those designations is a violation, which 36 CFR 261.1b can punish with "imprisonment of not more than six months", a fine under 18 U.S.C. 3571, or both.

Ridstar's text lists "grass, dirt, sand, snow, and gravel" for its tires, and on each of those surfaces the rule you ride under is the land manager's; our public-land guide takes federal land agency by agency for any ride that crosses it.

Green flags / Red flags

Eight things the Q16 has going for it and ten to settle before you pay, with a next step for each one, either on this page or on a bike in our store.

Green flags

• Suspension front and rear. Ridstar's text says "The front suspension fork is strengthened by 100%" and names "The rear hydraulic shock absorber", and its Technical Details tab reads "Suspension Type Dual".
• Feet flat for 61 in 100 riders at 5'6". On the 31.4-inch bench that share rises to every rider by 5'10", by the bench table.
• Torque left over on climbs. The text claims "a torque of up to 85Nm", and the steepest row of the climbing table, 15% at 10 mph, asks the motor for 42.3 N·m, about half of that.
• A 960 Wh pack on 16-inch wheels. On flat pavement at 15 mph with no pedaling, a 180 lb rider gets 57 computed miles, or 43 with a quarter of the pack held back, by the speed rows.
• About 17 cents a charge. At 18.16 cents per kWh, the EIA's residential average for August 2026, a full refill costs about 17 cents, and a thousand throttle miles at 15 mph about $3.06.
• A phone holder and a storage box. Ridstar's text lists "a 7.2'' phone holder" and "a spacious storage box"; ask whoever sells you one to confirm both are in the carton.
• Five stars from every rating on Ridstar's page. Six ratings there average "5", and "Brian" calls it "the best bike I've ever had".
• Freight and transit damage are ours to sort out. When it is back, we ship it free within the contiguous United States, and photos of damage sent within 48 hours of delivery become a carrier claim we file, with the replacement or repair arranged by us.

Red flags

• Sold out here. The YVY K16, which prints the Q16's 16 × 4.0 tires, pack and load, is ready to order at $861.35; to hear when the Q16 returns, email us.
• A 20 mph factory speed and a 30 mph unlocking speed. At 30 mph it fits none of the 49 US e-bike definitions and at 20 mph its 1500W fits three, so work through the class section for your state, or turn to the Qiolor Tiger JR, sold by its maker as "Class 2".
• Brakes printed both ways. The bold heading says "Hydraulic Dual Brakes" while the text and the specification block say mechanical, so ask any seller which ships; for hydraulic discs today, the Samebike VOYAGER carries "Hydraulic disc brakes" on its maker's page.
• Three motor ratings on one page. At 20 mph, "750 watts" fits 29 US definitions, "1200W Motor(PEAK 1500W)" four and "1500W" three, so the class section runs all three; ask the seller for a photograph of the hub's label before you pay.
• "UL-certified" with no standard, holder or file number. The UL section names the two details to ask for, and Smartravel's page for the Explorer DK400 prints "Safety Certified in Accordance with UL 2849".
• Parts listings shared with the warned Q20s. Every one of the 17 ridstar.net parts listings with a Q16 option also sells Q20-family options, so get the front hub, axles and nuts named in writing, for the reasons in the record section.
• A receipt that may not say Q16. One buyer ordered a "Q20 16’" and received a bike marked Q16, so match the model on your receipt and frame with the owner's checks.
• Two rider windows. The size drawing says "To 5'2"" and the FAQ "5.2 to 6.0 feet"; set your inseam against the bench table instead of either window.
• No spare pack sold under the Q16's name. ridstar.net lists no battery with a Q16 option, and YVY sells a "US / K16" option on a 48V 20AH pack at $429; the battery section has both, and get a seller's written word on fit before you buy any spare.
• After-sales service for ridstar.net buyers only, in Ridstar's own words. Buying it from us shows who handles a fault when you buy here.

Buy it if / Buy something else if

Buy it if the Q16 comes back and you want a moto-style 16-inch fat bike with a fork, a rear shock, a 960 Wh pack and a 330 lb load for $976.35; you can stop on a 31.4-inch bench, which 61 in 100 riders of 5'6" reach flat-footed and every rider from 5'10" does; and you will follow your state's rules for a 1500W bike at 20 mph.

At 1,000 throttle miles a year, all at 15 mph, its electricity would come to about $3.06 a year at the national residential rate for August 2026.

Buy something else if you want this bike's size and pack now. The YVY K16 is $861.35 here, and YVY's listing prints "Model Number : K16", "Battery : 48V/20 Ah", "Max Load : 330lbs", "Brake : Mechanical Disc Brakes" and, on its motor image, "20 MPH Speed Limit"; on October 25, 2026 it showed "$729" beside "$1,249" and "Many in stock".

Buy something else if you want a bike its maker sells inside an e-bike class, or you stand between 5'1" and 5'9". Qiolor sells the Tiger JR as "Class 2" with a "Recommended Height" of "5'1" - 5'9"" on its page, beside "Rated 48V 500W(Peak 750W)", "Max Load 400 lbs", "Net Weight 87 lbs" and a "5-Year Warranty".

We charge $899, Qiolor's own figure on October 25, 2026, where $1,399.00 sits next to it and Black and Blue were both in stock.

Buy something else if hydraulic discs settle it. The Samebike VOYAGER is $899 here in four colors, the price Samebike's own cart charged with its Black Friday code BF100 on October 30, 2026.

Samebike's page prints "Hydraulic disc brakes", the Q16's "48V 20Ah" and "960Wh", and "20''*4.0'' fat tire | 1500W peak", at $999.00 before the code, against a "Regular price $1,499.00" on October 25, 2026.

Samebike's size chart runs its seat from "Min Seat Height 810 mm" to "Max Seat Height 960 mm", 31.9 to 37.8 inches, and our listing adds the rear rack and fenders, which "Both ship with your VOYAGER at no charge".

Buy something else if price and a UL 2849 line come first. The Smartravel Explorer DK400 costs $665 here, matching the sale price Smartravel's page showed on October 25, 2026 beside a "Regular price $1,599.99".

That page prints "Safety Certified in Accordance with UL 2849", "28 Mph", "The seat height is 33 inches." and "Recommended rider height is 5'4" ~ 7'", and our DK400 review works out 51 miles from a charge at 15 mph with a 180 lb rider.

Before you buy: the checklist

Seven things to close, first with the seller and then on your driveway, before a Q16 goes out on a public road.

1. The class your state gives it. Check it at both printed speeds, 20 mph and 30 mph, in our state law atlas, and meet that class's rules before the first ride.
2. Your inseam against the bench. Find your height in the bench table; at 5'4" or under, plan each stop standing over the frame ahead of the seat.
3. The brakes, in writing. Ask whether your bike carries mechanical or hydraulic discs, since Ridstar's page prints both.
4. The name on the paperwork. Make sure the receipt, the frame and the carton all say Q16, for the reason the record section gives.
5. The front-wheel parts. Get the front hub, axle and nut kit named in writing, then check that the axle nuts are tight before every ride, the step Ridstar's own line "Front tires must be securely installed" points to.
6. The weight aboard. Add up rider, gear and the storage box's contents and stay at or below Ridstar's 330 lb; the load rows put a mileage on each total.
7. Delivery day. Open the carton the day it lands, because damage reaches us with photos inside 48 hours under our shipping policy; Ridstar says its bikes "come 90% pre-assembled", so recheck every bolt you fit, and set the bench with the heel method if it moves.

Buying it from us

Our Q16 listing read sold out at $976.35 on October 25, 2026 and takes no orders until stock returns. The terms below come with whichever bike you buy here in its place, the K16, the Tiger JR, the VOYAGER or the DK400, and with the Q16 once it is back. Each row quotes or follows the policy that holds us to it.

Read off our own terms of service, shipping policy, refund policy and contact page on October 25, 2026, and the payment row off our checkout on October 24.

Changing your mind runs under our refund policy: ask within 72 hours (3 days) of delivery, with the carton unopened and factory-sealed. If you return a bike, a 15% restocking fee applies and the return shipping is yours to pay; the policy also puts a 3% transaction fee on any canceled order.

Ridstar's own store had no Q16 for US delivery either. On October 25, 2026 its first listing read unavailable at $849 for the US and $599 for "CA", and the one Q16 it would take an order for was the second listing's "CA" variant, at $1,499.

Right-hand column: ridstar.net's own return policy, warranty page and first Q16 listing, as served for US delivery on October 25, 2026. That return policy also sets a "5 % transaction fee" for canceling before shipment and "a 15% processing fee" after it. The middle column is ours.

Frequently asked questions

How much does the Ridstar Q16 cost?

Ours is $976.35, and our listing read sold out on October 25, 2026. That day ridstar.net's first Q16 listing showed its US variant unavailable at $849, while its second listing offered a "CA" variant at $1,499. A .it.com shop calling itself "The Only Ridstar Official EBike Shop" listed it for $329.70 on October 24, set beside Ridstar's statement in the record section. The YVY K16 is $861.35 here.

Where can you buy a Ridstar Q16?

Ridstar's official statement calls ridstar.net "The only official website of ridstar" and says its other sites are dealers. On October 25, 2026 the only Q16 ridstar.net would sell was its second listing's "CA" variant, ridstar.com listed no Q16 at all, and ours read sold out. To hear when ours is back, email us; for the same 16 × 4.0 tires and pack today, the YVY K16 is $861.35 here.

How fast does the Ridstar Q16 go?

Ridstar's motor image prints a "20 MPH Factory speed" and a "30 MPH Unlocking speed", and its FAQ "28+++ mph in pure electric mode (ensure a full charge)". With 30 mph as the unloaded motor's speed, our model has a 180 lb rider top out at 26.8 mph on the flat. Unlocked, it fits no US e-bike definition; at 20 mph its 1500W fits three, named in the class section.

Can the Ridstar Q16 be unlocked to 30 mph?

Ridstar's motor image prints "30 MPH Unlocking speed" beside the "20 MPH Factory speed", and no Q16 page or tab says how the unlocking is done or who does it. The listing's own caution reads "Self-modification may posesafety risks." (sic). Above 20 mph the bike leaves the three US e-bike definitions its 1500W meets at that speed, so check the class section against your state before changing anything.

How far can the Ridstar Q16 go on one charge?

On the throttle over flat pavement, the model's 180 lb rider gets 79 miles from the 960 Wh at 10 mph, 57 at 15 and 40 at 20. With 25% left in the pack at the end, the 15 mph figure becomes 43 miles. Ridstar prints 30 miles in "pure electric mode" and 50 with assist; the range section finds the 30 on a throttle ride near 24 mph.

What battery does the Ridstar Q16 use?

One removable 48V 20Ah pack, "48V/20 Ah" in the specification block and 960 Wh by our arithmetic, which Ridstar's text charges in "4-6 hours at 3A". On October 24, 2026 ridstar.net's parts catalog sold no battery with a Q16 option, while YVY's catalog offered "US / K16" on a 48V 20AH pack at $429. Have the seller confirm a spare fits your frame, in writing, before you pay for one.

How heavy is the Ridstar Q16?

64 lb, the "64 LBS Bike Weight" on Ridstar's size drawing; its text and tabs give no weight. You, your gear and your cargo together stay within the 330 lb load Ridstar prints, and the load rows give a rider at the full 330 lb 46 miles at 15 mph on the throttle.

What are the Ridstar Q16's specs?

By Ridstar's own figures: one rear hub motor printed as "1500W", "1200W Motor(PEAK 1500W)" and "750 watts", with "a torque of up to 85Nm"; a 48V 20Ah pack; 16 × 4.0 tires; disc brakes listed as mechanical under a hydraulic heading; a fork and a rear shock; a twist throttle and seven speeds; 64 lb; a 330 lb load; a 31.4-inch seat; and a "20 MPH Factory speed" beside a "30 MPH Unlocking speed".

What size rider fits the Ridstar Q16?

Ridstar prints "To 5'2"" on its drawing and "5.2 to 6.0 feet" in its FAQ, over a 31.4-inch bench. From it, 3 in 100 ANSUR II riders of 5'2" reach the floor flat-footed, 61 in 100 of 5'6" and all from 5'10". A 5'8" rider with the median 32.6-inch inseam wants the saddle 35.6 inches over the pedal axle; the fit section has every height.

How is the Ridstar Q16 different from the Q20?

By Ridstar's pages the Q16 rolls on 16 × 4.0 tires and the Q20 on 20 × 4.0, each with a 48V 20Ah pack and a rear hub Ridstar calls 1500W. The 2026 CPSC warnings name the Q20 and leave the Q16 out, yet all 17 ridstar.net parts listings with a Q16 option also sell Q20-family options. Our Q20 review computes 56 miles to the Q16's 57 at 15 mph on the throttle, 180 lb aboard.

Is there a Ridstar Q16 Lite, Pro or Mini?

Not as a listing. On October 24, 2026 neither ridstar.net's 85 products nor ridstar.com's 56 included a Q16 Lite, Q16 Pro or Q16 Mini, though the Q16's specification block prints "Model Number : Q16 Lite". The Q20 Mini is another name: 10 of the 17 Q16 parts listings also carry "Q20MINI" options, and the UK's 2025 product safety report names a "Q20-Mini".

Does the CPSC warning cover the Ridstar Q16?

Neither 2026 warning names it: 26-337 covers the Q20 and Q20 Pro, 26-584 the Q20 and Q20 Lite, and the CPSC's recall list carried no Ridstar bike on October 25, 2026. The June warning says "The model number Q20 or Q20 Lite is printed on the purchase receipt", so if your 16-inch bike was sold as a Q20, read the record section.

What tires does the Ridstar Q16 have?

Ridstar's text gives "16-inch x 4.0 wide tires" and calls them "puncture-resistant fat tires", naming no maker, tread or pressure, and the size drawing marks the wheel 18.5 inches across. Run the pressure printed on the sidewall. ridstar.net sells a Q16 "Outer tire" at $159 and an "Inner Tire" at $59.

Does the Ridstar Q16 have a throttle?

Yes. Ridstar lists a "Twist Grip Throttle" with a Shimano 7-speed and names "three riding modes: pure electric, electric assist, and pedal". Every range figure on this page is for the throttle alone unless its row says otherwise, and the pedaling rows show what your legs add at each speed.

Where can you buy Ridstar Q16 parts?

From ridstar.net, whose catalog on October 24, 2026 sold a "US / Q16" option on 17 parts listings, among them the controller at $89, the LCD display at $69, the front fork at $159, the motor at $209 and a rear hub with its motor at $379. Each of the 17 also sells Q20-family options, so give the seller your bike's model and the motor code the listings ask for, and get the part confirmed in writing.

Is there a manual for the Ridstar Q16?

One is promised. The Technical Details tab of Ridstar's Q16 listing puts a "manual" in its "Included Components" with the charger, an assembly tool and the pedals, and the page links no copy to read before you buy. Ask the seller to send it ahead of delivery, and keep the listing's line "Front tires must be securely installed" beside it while you assemble.

Is a 16-inch e-bike made for adults?

This one is: Ridstar's FAQ gives "5.2 to 6.0 feet", its specification block a 330 lb load, and its shipping policy sells only to buyers 18 and over. The wheel stands 18.5 inches tall on the drawing and the bench 31.4 inches up, so set that bench against your inseam in the fit section. Five of the 481 bikes and trikes on our store on October 24, 2026 roll on 16 × 4.0 tires.

Can a teenager ride the Ridstar Q16?

Ridstar sells it to adults only: its shipping policy reads "E-Bikes Are Not for Sale to Persons Under the Age of 18" and "Underage riders MUST be accompanied by parents or adults when riding". At its printed 1500W the Q16 is outside 46 of the 49 US e-bike definitions even at 20 mph, so your state's rules for its class decide who under 18 may ride it. Our kids and teens guide covers younger riders by age.

Is the Ridstar Q16 street legal?

That turns on the rating your state reads and the speed. At the factory 20 mph, "1500W" fits 3 of the 49 US e-bike definitions, those of DC, Montana and Oregon, "1200W" adds Rhode Island, and the tab's "750 watts" fits 29; at 28 or 30 mph none fits. Where it fits none, the vehicle class is your state's call, and that class's rules apply, and the class section shows each case.

What should you check on a used Ridstar Q16?

Start with the name: the June 2026 warning says "The model number Q20 or Q20 Lite is printed on the purchase receipt", and one buyer's "Q20 16’" arrived marked Q16. Then ask which brakes it has, look over the front axle nuts and the fork, and check that the pack reads 48V 20Ah. The record section lists what to look at once you own a 16-inch Ridstar.

Limitations of this review

Twenty-three places where the published record runs out, numbered, with what each leaves for you to check.

1. Ridstar prints rival figures, and this review carries each one. Motor "1500W", "1200W Motor(PEAK 1500W)" and "750 watts"; top speed 20, 30 and "28+++" mph; range 30, 50, 35 to 65 and 65 miles; rider height "To 5'2"" and "5.2 to 6.0 feet"; climbing 35° and 30°.
2. Which brakes ship is not stated. The heading says hydraulic, the text and specification block mechanical, and the text of the "CA"-only listing hydraulic.
3. Three names, one bike. Q16, "Q16 Lite" and the brand "Bopzin" all appear on one page, and neither Ridstar store lists another model under them, so this review treats them as one machine.
4. The model's top speed is the 30 mph unlocking figure, used as the speed the motor reaches unloaded; at the 20 mph factory setting, the rows above 20 mph describe a bike Ridstar does not ship that way.
5. The continuous rating is unsettled. The model takes the specification block's 1200 W as rated and checks 750 W and 1500 W: at 15 mph the three give 57.6, 57.0 and 55.9 miles.
6. No controller limit is printed. At 10 mph up a 15% grade the model pulls 1,498 W, 51.6 A, from the pack, and a controller limited below that would slow the climb.
7. Torque comes from one sentence, "a torque of up to 85Nm", and the steepest row asks for 42.3 N·m.
8. The motor curve is a comparable's, Bafang's RM G0H0 rescaled to 48 V, with its no-load speed set at the printed 30 mph.
9. The wheel is Ridstar's 18.5 inches across, read off a drawing whose arrows do not all agree; it sets only the torque a climb needs.
10. The tire is unnamed, so its rolling resistance is taken from ten 26 × 4.00 fat tires on one drum at 12 psi, the median of them, bracketed by the best and worst of them; no 16-inch tire was among them.
11. The cold figures rest on a single cell type, LG's HG2, because Ridstar names no cell.
12. The 64 lb is the size drawing's alone; the text and tabs print no weight.
13. No published Q16 ride, with a rider weight, speed and distance, checks the model. The one owner review with numbers rode a 40Ah pack and gave no weight.
14. One seat figure and no adjustment. Beside the 31.4 inches, Ridstar prints no crank length, bottom-bracket height, standover, grip position, reach or bench travel, so lean, hand load and the saddle verdict stay uncomputed.
15. The size drawing is not to scale. Its wheel base and length disagree by 7.9 inches, so nothing is measured off it.
16. ANSUR II measured soldiers: 6,068 bodies, 4,082 men and 1,986 women, a different population from the general public; a height with fewer than 30 bodies gets no row, which drops 4'10".
17. Saddle formulas are averages. At 5'8" the band from 106% to 110.4% spans 1.4 inches of saddle height; the heel check on your own leg, and the knee range at the bottom of the stroke, find your place inside it.
18. No document on Ridstar's pages ties the Q16 to a UL certification. The battery line says "UL-certified" and names no standard, and the files in Ridstar's footer are two trademark registrations and an EN 15194 report on another machine.
19. Shared listings are not shared parts. Whether a Q16 option and a Q20 option on one parts listing are the same part, Ridstar does not say, and the Q16 and K16 appear in no warning, report or suit.
20. The K16 comparison is of two listings. The photographs differ, and neither company says the two are one machine.
21. The owner record is three written reviews and six ratings on Ridstar's own page, quoted in the owners' words and never turned into a score.
22. The dealer record is partial. ridstar.eu and ridstar-ebike.com listed no Q16 on October 24, 2026, ridstar.uk could not be read, the .it.com shop's listing was read on October 24 alone, and Walmart's Q16 pages returned a bot check in place of the listing each time they were opened, so this review says nothing about them.
23. Every state result comes from one rule table of 51 rows, each with its statute linked and that statute's own boundary word, "less than" or "not more than", applied as written; the federal and California wording on this page was checked again on October 24, 2026.

The bottom line

Buy the Q16 once it is back if a 16-inch moto-style fat bike with a fork, a rear shock, 960 Wh and a 330 lb load is what you want for $976.35, a 31.4-inch bench suits your legs, and you will follow your state's rules for a 1500W machine at its 20 mph factory speed.

On level pavement at 15 mph, one charge lasts the model's 180 lb rider 57 miles with the throttle doing the work. Before you pay anyone, get the brakes and the front-wheel parts confirmed in writing, and check the name on the receipt against the maker's record.

Ours read sold out on October 25, 2026. The nearest bike you can order here today is the YVY K16 at $861.35; for a "Class 2" label from the maker, the Qiolor Tiger JR at $899; for hydraulic discs and the same 960 Wh, the Samebike VOYAGER at $899, matched to Samebike's Black Friday code BF100; and for a UL 2849 line at the lowest price of the four, the Smartravel Explorer DK400 at $665.

Photographs: past the cover, nine images are Ridstar's own Q16 files from ridstar.net and one is YVY's own photograph of the K16, each shown whole, scaled evenly and not retouched.

Cover: the bike is the lead photograph from Ridstar's own Q16 listing, cut from its rock-ledge background and only scaled, with the blue light streaks Ridstar drew on that photograph kept; the empty studio behind it is a Nano Banana Pro render from Playcut (playcut.ai), made for an earlier cover and reused, with shadows added under the tires and the kickstand and the type set in the open space.

Source register

Every source behind this page, with its tier, the claim it supports and the date it was read.

Expiry conditions

This review is due a fresh pass when the Q16 is back in stock here; when ridstar.net changes the Q16's stock, prices or figures, or YVY the K16's; when the CPSC recalls a Ridstar or YVY bike, or issues or amends a warning; and when the October 23 order in L.E. v. Walmart can be read or either suit reaches a judgment.

It is due again when our own prices, stock, listing text or store policies change; when 15 U.S.C. § 2085, California Vehicle Code §§ 312.5, 406 or 21207.5, or any state's e-bike definition changes; and when Qiolor, Samebike or Smartravel publish new figures for the Tiger JR, the VOYAGER or the DK400.

References

The documents this review rests on, each with its publisher, the exact place cited, the day it was read and a link.

1. U.S. Consumer Product Safety Commission, CPSC Warns Consumers to Immediately Stop Using Ridstar E-Bikes Due to Fire Hazard; Risk of Serious Injury or Death. CPSC warning 26-337, March 19, 2026: 'Ridstar Q20 and Q20 Pro e-bikes'; 'The e-bikes' batteries and wires can ignite, posing a fire hazard to consumers'; the manufacturer named as Huizhou Xingqishi Sporting Goods Co., Ltd., of China; sold on 'Amazon.com, Ridstar.net, and Walmart.com'; neither the Q16 nor the K16 is named. Retrieved Oct 25, 2026. https://www.cpsc.gov/Warnings/2026/CPSC-Warns-Consumers-to-Immediately-Stop-Using-Ridstar-E-Bikes-Due-to-Fire-Hazard-Risk-of-Serious-Injury-or-Death
2. U.S. Consumer Product Safety Commission, CPSC Warns Consumers to Stop Using Ridstar E-Bikes Immediately Due to Crash Hazard; Risk of Serious Injury or Death. CPSC warning 26-584, June 25, 2026: 'Ridstar Q20 and Q20 Lite e-bikes'; 'The front wheel can detach without warning, posing a crash hazard to consumers'; 'The model number Q20 or Q20 Lite is printed on the purchase receipt.'; neither the Q16 nor the K16 is named. Retrieved Oct 25, 2026. https://www.cpsc.gov/Warnings/2026/CPSC-Warns-Consumers-to-Stop-Using-Ridstar-E-Bikes-Immediately-Due-to-Crash-Hazard-Risk-of-Serious-Injury-or-Death
3. U.S. Consumer Product Safety Commission, Recalls & Product Safety Warnings. The CPSC recall list on October 25, 2026: 10,058 records, the newest dated October 22, 2026, none naming Ridstar, YVY, a Q16 or a K16; the recall feed's 40 items (September 24 to October 22) match none of them, and the warning list's 379 rows hold the two Ridstar warnings and no Q16 or K16. Retrieved Oct 25, 2026. https://www.cpsc.gov/Recalls
4. Office for Product Safety and Standards (UK), Product Safety Report: Ridstar E-Bikes and Chargers (2506-0011). UK Office for Product Safety and Standards report 2506-0011, June 19, 2025: 'Ridstar E-Bikes Q20-Plus, Q20-Mini, E26 Pro and Chargers presenting a serious fire risk'; 'poor quality soldering'; a transformer that 'does not meet the minimum requirements for creepage and clearance distances'; 'The import has been rejected at the border.'; no Q16 or K16 named. Retrieved Oct 25, 2026. https://www.gov.uk/product-safety-alerts-reports-recalls/product-safety-report-ridstar-e-bikes-and-chargers-2506-0011
5. U.S. District Court for the District of Oregon (docket via CourtListener RECAP), Cunanan v. Amazon.com Services LLC, No. 3:26-cv-00692. Cunanan v. Amazon.com Services LLC, D. Or. case 3:26-cv-00692: a suit against the retailer over a 'Ridstar Q20' whose front wheel is alleged to have come off; Ridstar is not a named party; the newest docket entry on October 25, 2026 is dated July 8, 2026; allegations only. Retrieved Oct 25, 2026. https://www.courtlistener.com/docket/73159439/cunanan-v-amazoncom-services-llc/
6. U.S. District Court for the Southern District of Florida (docket via CourtListener RECAP), L.E., a minor, v. Walmart Inc., No. 9:26-cv-81045. L.E. v. Walmart Inc., S.D. Fla. case 9:26-cv-81045: a suit against the retailer over a bike the complaint names only by the Walmart title 'Ridstar Electric Bike, Peak 1500W30MPH,48V 15.6Ah Electric Bicycle, Full Suspension Mountain Bike UL2849', citing both Q20 warnings; entry 16, 'Order on Motion to Dismiss' (October 23, 2026), listed without its text; no judgment; allegations only. Retrieved Oct 25, 2026. https://www.courtlistener.com/docket/74691512/le-v-walmart-inc/
7. US Government Publishing Office, 15 U.S.C. § 2085 — Low-speed electric bicycles. 15 U.S.C. § 2085(b): a low-speed electric bicycle has 'fully operable pedals and an electric motor of less than 750 watts (1 h.p.)', and its top speed 'when powered solely by such a motor while ridden by an operator who weighs 170 pounds, is less than 20 mph'. Retrieved Oct 24, 2026. https://www.govinfo.gov/content/pkg/USCODE-2024-title15/html/USCODE-2024-title15-chap47-sec2085.htm
8. California Legislative Information, California Vehicle Code § 312.5. Cal. Veh. Code § 312.5(a): an electric bicycle has 'fully operable pedals and an electric motor that does not exceed 750 watts of power'; class 2 has 'a motor that may be used exclusively to propel the bicycle' and 'is not capable of providing assistance when the bicycle reaches the speed of 20 miles per hour'. Retrieved Oct 24, 2026. https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH&sectionNum=312.5.
9. California Legislative Information, California Vehicle Code § 406. Cal. Veh. Code § 406(a): a motorized bicycle has 'fully operative pedals for propulsion by human power', 'an automatic transmission and a motor that produces less than 4 gross brake horsepower', and a top speed 'of not more than 30 miles per hour on level ground'; 1,500 W is about 2.0 horsepower. Retrieved Oct 24, 2026. https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH&sectionNum=406.
10. California Legislative Information, California Vehicle Code § 21207.5. Cal. Veh. Code § 21207.5(a): a motorized bicycle 'shall not be operated on a bicycle path or trail, bikeway, bicycle lane', or an equestrian, hiking or recreational trail, unless it is 'within or adjacent to a roadway' or the local authority 'permits, by ordinance, that operation'. Retrieved Oct 24, 2026. https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH&sectionNum=21207.5.
11. Forest Service, USDA (eCFR), 36 CFR § 261.13 — Motor vehicle use. 36 CFR 261.13: where a Ranger District has designated its roads, trails and areas on a motor vehicle use map, operating a motor vehicle on its National Forest System lands other than as designated is prohibited. Retrieved Oct 23, 2026. https://www.ecfr.gov/current/title-36/chapter-II/subchapter-B/part-261/subpart-A/section-261.13
12. U.S. Department of Agriculture, Forest Service (Office of the Federal Register, eCFR), 36 CFR 261.2 Definitions. 36 CFR 261.2: 'Motor vehicle means any vehicle which is self-propelled', apart from a vehicle on rails and a wheelchair or mobility device designed solely for use by a mobility-impaired person. Retrieved Oct 23, 2026. https://www.ecfr.gov/current/title-36/chapter-II/part-261/subpart-A/section-261.2
13. U.S. Department of Agriculture, Forest Service (Office of the Federal Register, eCFR), 36 CFR 261.1b Penalty. 36 CFR 261.1b: breaking a Part 261 prohibition is punishable by 'imprisonment of not more than six months' or a fine under 18 U.S.C. 3571, or both. Retrieved Oct 23, 2026. https://www.ecfr.gov/current/title-36/chapter-II/part-261/subpart-A/section-261.1b
14. U.S. Army Natick Soldier Research, Development and Engineering Center, 2012 Anthropometric Survey of U.S. Army Personnel (ANSUR II), public data release 2017. US Army ANSUR II survey, 6,068 bodies (4,082 men, 1,986 women): the inseam medians and bands behind the Q16's fit tables, its Mercer rows and the 5'8" worked case on the 31.4-inch bench. Retrieved Sep 25, 2026. https://www.army.mil/article/188601/for_good_measure_natick_releases_raw_data_from_army_wide_anthropometric_survey
15. Journal of Exercise Physiology Online (American Society of Exercise Physiologists), Peveler et al., Comparing methods for setting saddle height in trained cyclists, JEPonline 8(1):51-55. Peveler et al. (2005): the 109%-of-inseam saddle height compared with the heel method, and LeMond's setting at 109.2 ± 0.9% of inseam from the pedal. Retrieved Sep 25, 2026. https://www.asep.org/asep/asep/JEPonlineFEBRUARY2005_PevelerSaddle.doc
16. Journal of Strength and Conditioning Research (NSCA), Ferrer-Roca V, Roig A, Galilea P, Garcia-Lopez J. Influence of saddle height on lower limb kinematics in well-trained cyclists: static vs. dynamic evaluation in bike fitting. J Strength Cond Res 26(11):3025-9; doi 10.1519/JSC.0b013e318245c09d. Ferrer-Roca et al. (2012): the 106% low end of the literature range they cite and the 110.4% top of the range their own equation gives, the two ends of this page's saddle band; their study aimed for 30 to 40 degrees of knee bend. Retrieved Sep 25, 2026. https://pubmed.ncbi.nlm.nih.gov/22190163/
17. Journal of Strength and Conditioning Research (NSCA), Peveler, Pounders & Bishop, Effects of saddle height on anaerobic power production in cycling, JSCR 21(4):1023-7. Peveler, Pounders and Bishop (2007): 25 to 35 degrees of knee bend at the bottom of the stroke, a range they take from the cycling literature. Retrieved Sep 25, 2026. https://pubmed.ncbi.nlm.nih.gov/18076230/
18. University of Colorado Boulder (MS thesis), Carahalios A. An Analysis of the Bicycle-Rider Interface Forces in Stationary Road Cycling (MS thesis, Department of Integrative Physiology, University of Colorado). Carahalios (2015): about 15% of body weight on the stem across ten road racers on the hoods, a reference point from a stretched racing posture. Retrieved Sep 25, 2026. https://scholar.colorado.edu/downloads/70795789x
19. BAFANG, BAFANG Workbook OEM 2021. Bafang OEM workbook 2021, RM G0H0: the comparable hub-motor curve the Q16 range model rescales to 48 V and a 1,200 W rating, with Ridstar's 30 mph as its no-load speed, and its 'Efficiency (%) ≥ 80' at the rated point. Retrieved Sep 23, 2026. https://www.bafang-e.com/Uploaded/Labels/BAFANG%20Workbook%20OEM%202021.pdf
20. Bicycle Rolling Resistance (Jarno Bierman), Fat Bike Tires Test Results. Bicycle Rolling Resistance fat-bike tests: ten 26 × 4.00 fat tires on one drum at 12 psi, median rolling resistance 0.0105, lowest 0.0070, highest 0.0126; no 16-inch tire among them. Retrieved Sep 25, 2026. https://www.bicyclerollingresistance.com/fat-bike-reviews
21. Journal of Applied Biomechanics (Human Kinetics), Martin JC, Milliken DL, Cobb JE, McFadden KL, Coggan AR. Validation of a Mathematical Model for Road Cycling Power. Martin et al. (1998): the cycling-power equation the range model uses, with its Appendix I ride (45.7 W and 158.8 W) reproduced by the model, and the climbing cost per 1,000 feet of rise. Retrieved Sep 23, 2026. https://collections.lib.utah.edu/dl_files/b4/8e/b48ef26086091662c561e673d7bd990d77868437.pdf
22. Journal of Sports Sciences (Taylor & Francis), Tengattini S, Bigazzi AY. Physical characteristics and resistance parameters of typical urban cyclists. Tengattini and Bigazzi (2018): a drag area of 0.640 m² for upright riders, the Q16 model's air-drag input. Retrieved Sep 23, 2026. https://civil-reactlab.sites.olt.ubc.ca/files/2022/11/Tengattini_2018_Physical-characteristics-and-resistance-parameters-of-typical-urban-cyclists.pdf
23. World Electric Vehicle Journal (MDPI), Arango I, Lopez C, Ceren A. Improving the Autonomy of a Mid-Drive Motor Electric Bicycle Based on System Efficiency Maps and Its Performance. Arango, Lopez and Ceren (2021): the battery-efficiency curve, 96.8% at the 15 mph ride's current. Retrieved Sep 23, 2026. https://mdpi-res.com/d_attachment/wevj/wevj-12-00059/article_deploy/wevj-12-00059.pdf
24. IEEE / EPE'19 ECCE Europe (Karlsruhe Institute of Technology authors), Schmitt M, Decker S, Doppelbauer M. Measuring and Characterization of a Pedal Electric Cycle (Pedelec) on a Full System Test-Bench. Schmitt, Decker and Doppelbauer (2019): a pedelec system on the bench delivered 75% of its nominal capacity, the source of the 25% planning reserve. Retrieved Sep 23, 2026. https://publikationen.bibliothek.kit.edu/1000100371/50695920
25. McMaster University (Kollmeyer et al.), Mendeley Data, LG 18650HG2 Li-ion Battery Data and Example Deep Neural Network xEV SOC Estimator Script. LG HG2 cell discharge data by temperature: the pack-energy column of the Q16 cold table and its brackets at 32 °F and 14 °F, used because Ridstar names no cell. Retrieved Sep 23, 2026. https://doi.org/10.17632/b5mj79w5w9.2
26. Bicycle Rolling Resistance (Jarno Bierman), CRR at Different Temperatures: Examining Temperature Dependence of Rolling Resistance. Bicycle Rolling Resistance temperature test: rolling resistance 17.6% lower on average with a 40 °C tire surface than a 20 °C one, the tire-warmth input of the cold rows. Retrieved Sep 23, 2026. https://www.bicyclerollingresistance.com/specials/crr-temperature-test
27. NOAA, NASA, US Air Force, U.S. Standard Atmosphere, 1976 (NOAA-S/T 76-1562; NASA TM-X-74335). U.S. Standard Atmosphere, 1976: air density by temperature, 1.184 kg/m³ at 77 °F. Retrieved Sep 23, 2026. https://ntrs.nasa.gov/api/citations/19770009539/downloads/19770009539.pdf
28. U.S. Energy Information Administration, Electric Power Monthly, Table 5.6.A. Average Price of Electricity to Ultimate Customers by End-Use Sector. US EIA Electric Power Monthly Table 5.6.A: residential electricity averaged 18.16 cents per kWh in August 2026, about 17 cents to refill the Q16's 960 Wh and $3.06 for 1,000 miles at 15 mph on the throttle (16.8 Wh a mile). Retrieved Oct 24, 2026. https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_06_a
29. UL Solutions, E-Bikes Certification: Evaluating and Testing to UL 2849. UL Solutions on UL 2849, the standard for e-bike electrical systems: 'EN 15194 does not cover the safety of electrical systems utilizing battery packs in the same manner that UL 2849 covers this subject'. Retrieved Oct 25, 2026. https://www.ul.com/services/e-bikes-certificationevaluating-and-testing-ul-2849
30. United States Patent and Trademark Office (copy hosted by Ridstar), US trademark registration certificate No. 6,936,242 (Ridstar), as hosted on ridstar.net. US trademark registration 6,936,242, owner 'Huizhoushi Xingqishi Sports Goods Co., Ltd.', Class 12 bicycles; linked as 'US trademark' under 'Our Qualifications' in the footer of the Q16 listing. Retrieved Oct 25, 2026. https://cdn.shopify.com/s/files/1/0696/9960/0602/files/Ridstar_12_6936242.pdf?v=1720059854
31. European Union Intellectual Property Office (copy hosted by Ridstar), EUIPO certificate of registration, EU trade mark No. 018609888 (Ridstar), as hosted on ridstar.net. EU trademark registration 018609888, proprietor 'Huizhoushi Xingqishi Sports Goods Co., Ltd.'; linked as 'European trademark' in the footer of the Q16 listing. Retrieved Oct 25, 2026. https://cdn.shopify.com/s/files/1/0696/9960/0602/files/Ridstar-12_018609888.pdf?v=1720059857
32. Shenzhen ATS Testing Technology Co., Ltd. (copy hosted by Ridstar), TEST REPORT EN 15194:2017 Cycles - Electrically power assisted cycles - EPAC Bicycles, No. ATS240329142LR, as hosted on ridstar.net. EN 15194:2017 test report ATS240329142LR, linked as 'CE trademark' in the Q16 listing's footer: a 'Cargo electric bicycle', model 'FM-002, CDDA20', maximum power '250W', issued April 2, 2024; it names no Q16 and is not a UL document. Retrieved Oct 25, 2026. https://cdn.shopify.com/s/files/1/0696/9960/0602/files/FM-002_ATS240329142LR_EN15194.pdf?v=1730083922
33. Ridstar (ridstar.net), Ridstar Official Statement. Ridstar.net's official statement: 'The only official website of ridstar'; 'Except ridstar.net, other similar websites are our dealers'; 'Except for customers who purchase from ridstar.net, we will not provide any after-sales service to customers who purchase ridstar products from other places'. Retrieved Oct 25, 2026. https://ridstar.net/pages/ridstar-official-statement
34. Ridstar (ridstar.net), Company Address — ridstar.net. Ridstar.net's company page: 'Name of Business: HK RIDSTAR TRADE LIMITED', an address in Hung Hom, Hong Kong. Retrieved Oct 25, 2026. https://ridstar.net/pages/company-address
35. YVY / HK Ridstar Trade Limited (yvyebike.com), Company Address. YVY's company page names the same business as ridstar.net's, 'HK RIDSTAR TRADE LIMITED'. Retrieved Oct 25, 2026. https://yvyebike.com/pages/company-address
36. Ridstar (ridstar.net), Ebike Warranty — ridstar.net page. Ridstar.net's warranty page: 'One year warranty on all products'; 'Ridstar dealers or Ridstar authorized partners will repair or replace, at no charge,' products or parts that prove defective in regular use. Retrieved Oct 25, 2026. https://ridstar.net/pages/ebike-warranty
37. Ridstar (ridstar.net), Return & Refund Policy — ridstar.net page. Ridstar.net's return policy: returns 'within 15 days of receiving the bike', none for bikes 'over 10 miles in total mileage', return shipping of '$200 per ebike', 'up to a 15% restocking fee', a '5 % transaction fee' to cancel before shipment and 'a 15% processing fee' after it. Retrieved Oct 25, 2026. https://ridstar.net/pages/return-refund-policy
38. Ridstar (ridstar.net), Shipping policy — ridstar.net. Ridstar.net's shipping policy: 'E-Bikes Are Not for Sale to Persons Under the Age of 18'; 'Underage riders MUST be accompanied by parents or adults when riding'. Retrieved Oct 25, 2026. https://ridstar.net/policies/shipping-policy
39. Ridstar (ridstar.net), ridstar.net catalog feed (products.json) — ridstar.net. Ridstar.net's catalog feed on October 24, 2026: 85 products, the Q16 in two listings and no Q16 Lite, Pro or Mini; 17 parts listings sell a 'US / Q16' option and every one also sells Q20-family options, 10 of them 'Q20MINI'; the Q16 options include the rear hub with its motor at $379, the motor at $209, the controller at $89, the LCD display at $69, the front fork at $159, the front hub at $179, two front axles at $35, the front wheel nut kit at $25, the outer tire at $159 and the inner tire at $59, the front-wheel parts at the same US prices as their Q20 options; no battery listing offers a Q16 option. Retrieved Oct 24, 2026. https://ridstar.net/products.json
40. Redtail eBikes, Shipping policy. Our shipping policy: free shipping 'on every electric bike within the contiguous United States'; dispatched 'within 1–3 business days of confirmation'; 'most e-bikes arrive within 5–10 business days after dispatch'; a tracking number by email 'as soon as your order ships'; damage photos within 48 hours; Alaska, Hawaii, U.S. territories, P.O. boxes and remote areas 'may incur additional charges or be excluded'. Retrieved Oct 25, 2026. https://redtailebikes.com/policies/shipping-policy
41. Redtail eBikes, Refund policy. Our refund policy: change-of-mind returns unopened, in factory-sealed packaging and requested 'within 72 hours (3 days) of delivery', with 'a 15% restocking fee plus return shipping, which is the customer’s responsibility'; damage in transit reported within 48 hours with photos, 'we file the carrier claim and arrange a replacement or repair'; defective on arrival 'covered under manufacturer warranty — we coordinate repair or replacement remotely'; cancellations 'subject to a 3% transaction fee'. Retrieved Oct 25, 2026. https://redtailebikes.com/policies/refund-policy
42. Redtail eBikes, Terms of Service. Our terms of service: the agreement is with a Florida corporation doing business as Redtail Ebikes, a retailer and not the manufacturer. Retrieved Oct 25, 2026. https://redtailebikes.com/policies/terms-of-service
43. Redtail eBikes, Contact. Our contact page: 'We typically respond to email within one business day' (support@redtailebikes.com). Retrieved Oct 25, 2026. https://redtailebikes.com/pages/contact
44. Rhode Island General Assembly, R.I. Gen. Laws § 31-1-3. R.I. Gen. Laws § 31-1-3(g): Rhode Island's electric bicycle motor is 'rated not more than two (2) (S.A.E.) horsepower', about 1,492 W: above the Q16's 1,200 W rating and below its 1500W. Retrieved Oct 24, 2026. https://webserver.rilegislature.gov/Statutes/TITLE31/31-1/31-1-3.htm
45. District of Columbia (DC Council), DC Code § 50-2201.02. D.C. Code § 50-2201.02: the District's definition prints no watt figure and asks for 'A motor incapable of propelling the device at a speed of more than 20 miles per hour on level ground'. Retrieved Oct 24, 2026. https://code.dccouncil.gov/us/dc/council/code/sections/50-2201.02
46. Oregon Legislature, ORS chapter 801 (ORS 801.258). ORS 801.258: Oregon's electric assisted bicycle definition sets speed limbs and no motor-watt limb, so a 1,500 W bike held to 20 mph fits it. Retrieved Oct 24, 2026. https://www.oregonlegislature.gov/bills_laws/ors/ors801.html
47. New Jersey Legislature, P.L.2025, c.285. New Jersey P.L.2025, c.285: a 'Low-speed electric bicycle' has 'an electric motor that provides assistance only when the rider is pedaling', so a throttle bike falls outside it at any wattage. Retrieved Oct 24, 2026. https://pub.njleg.gov/Bills/2024/PL25/285_.HTM
48. Montana Legislature, MCA § 61-8-102. Mont. Code Ann. § 61-8-102: an electrically assisted bicycle has a motor 'capable of propelling the vehicle and a rider who weighs 170 pounds no faster than 20 miles an hour on a paved, level surface', with no watt figure. Retrieved Oct 24, 2026. https://mca.legmt.gov/bills/mca/title_0610/chapter_0080/part_0010/section_0020/0610-0080-0010-0020.html
49. Ridstar (ridstar.eu, a dealer under ridstar.net's statement), ridstar.eu catalog — dealer storefront, searched for Q30 and Q50. Ridstar.eu, a Ridstar dealer by ridstar.net's statement: no Q16 in its store search or product sitemap on October 24, 2026 (its Q20 control found). Retrieved Oct 24, 2026. https://ridstar.eu/
50. Ridstar (ridstar-ebike.com, a dealer under ridstar.net's statement), ridstar-ebike.com catalog — dealer storefront, searched for Q30 and Q50. Ridstar-ebike.com, a Ridstar dealer by ridstar.net's statement: no Q16 in its store search or sitemaps on October 24, 2026 (its Q20 control found). Retrieved Oct 24, 2026. https://ridstar-ebike.com/
51. Smartravel, Smartravel Explorer DK400 — product page (buy box). Smartravel's Explorer DK400 page on October 25, 2026: 'Sale price $665.00', 'Regular price $1,599.99', in stock; 'Safety Certified in Accordance with UL 2849'; '28 Mph'; 'The seat height is 33 inches.'; 'Recommended rider height is 5'4" ~ 7''. Retrieved Oct 25, 2026. https://www.smartravelor.com/products/smartravel-electric-bike-for-adults-fat-tire-ebike-with-1200w-motor-48v-17-5ah-removable-battery-up-to-28-mph-shimano7-speed-dual-shock-absorber-mountain-ebike
52. Qiolor, TIGER JR product page. Qiolor's TIGER JR page on October 25, 2026: $899.00 beside $1,399.00 ('SAVE $500'), Black and Blue in stock; 'Class 2'; 'Rated 48V 500W(Peak 750W)'; 'Recommended Height 5'1" - 5'9"'; 'Max Load 400 lbs'; 'Net Weight 87 lbs'; '5-Year Warranty'. Retrieved Oct 25, 2026. https://qiolor.com/products/tiger-jr
53. SAMEBIKE US, VOYAGER Large Battery Fat Tire Powerful Peak 1500W City Electric Bike — product page. Samebike's VOYAGER page on October 25, 2026: $999.00 against 'Regular price $1,499.00', Black, White, Navy and DarkGreen in stock; 'Hydraulic disc brakes'; '48V 20Ah'; '960Wh'; '20''*4.0'' fat tire | 1500W peak'; 'Min Seat Height 810 mm' and 'Max Seat Height 960 mm'. Retrieved Oct 25, 2026. https://us.samebike.com/products/voyager-large-battery-fat-tire-powerful-peak-1500w-city-electric-bike
54. YVY (yvyebike.com), E-Bike Warranty - YVY US. YVY's warranty page: its limited warranty 'is issued by YVY Bikes' and claims 'will be verified by YVY'. Retrieved Oct 25, 2026. https://yvyebike.com/pages/ebike-warranty
55. YVY (yvyebike.com), YVY US catalog, products.json. YVY's catalog feed on October 24, 2026: 48 products; the 'YVY K20/DC26/H20 48V 20AH Removable Electric E-Bike Battery' listing offers 'US / K16' at $429.00, and no listing offers a Q20 option beside a K16 one. Retrieved Oct 24, 2026. https://yvyebike.com/products.json
56. YVY (yvyebike.com), YVY Q16 1500W fat tire electric bicycle product page (our K16). YVY's 'YVY K16 1500W 48V20Ah 16" x 4.0" Fat Tire Electric Bicycle' listing (created May 11, 2026, at a yvy-q16 address): 'Model Number : K16'; 'Battery : 48V/20 Ah'; 'Max Load : 330lbs'; 'Brake : Mechanical Disc Brakes'; '1500W Motor'; 'Riding Range: 30miles (pure e-bike mode) to 50miles (assist mode)'; 'Recommended height range is 5.2 to 6.0 feet'; motor image '20 MPH Speed Limit'; size image '64LBS' and '4'5" To 5'2"'; six photographs, none of them one of Ridstar's nine; on October 25, 2026 '$729' beside '$1,249' and 'Availability: Many in stock'; 646 of its description's 675 words appear in the same order in the Q16's. Retrieved Oct 25, 2026. https://yvyebike.com/products/yvy-q16-1500w-fat-tire-electric-bicycle
57. U.S. District Court, District of Oregon (CourtListener RECAP document), Cunanan v. Amazon.com Services LLC, No. 3:26-cv-00692, complaint (document 1). The Cunanan complaint (D. Or. 3:26-cv-00692, document 1, filed April 7, 2026), ¶ 30, pages 5 to 6, of a Ridstar Q20 bought on Amazon: 'The intermediary for the sale involving the bike purchased by the Plaintiff is “YVY Bikes.”'; an allegation the court has not decided. Retrieved Oct 14, 2026. https://storage.courtlistener.com/recap/gov.uscourts.ord.193206/gov.uscourts.ord.193206.1.0.pdf
58. Playcut, Playcut. Playcut (Nano Banana Pro): the empty studio, generated for an earlier cover and reused unchanged around Ridstar's photograph; nothing of the bike generated. Retrieved Oct 15, 2026. https://playcut.ai
59. Ridstar (ridstar.net), Ridstar® Q16 1500W Fat Tire Electric Bicycle — ridstar.net. Ridstar.net's 'Ridstar® Q16 1500W Fat Tire Electric Bicycle' listing (created March 29, 2024): US variant $849.00 and 'CA' variant $599.00, each with a compare-at price of $1,099.00, both unavailable on October 24 and 25, 2026; title and text '1500W'; specification block '1200W Motor(PEAK 1500W)', '48V/20 Ah', 'Brake : Mechanical Disc Brakes', 'Max Load : 330lbs', 'Model Number : Q16 Lite', 'Riding Range: 30miles (pure e-bike mode) to 50miles (assist mode)', 'About 4-6 Hours'; Technical Details 'Wattage 750 watts', 'Brand Bopzin', 'Manufacturer Bopzin', 'Model Name Q16', 'Suspension Type Dual', 'Included Components Ebike; charger;manual ;assembly tool; pedals', 'One-year warranty for the e-bike components and lifetime tech support'; text 'a torque of up to 85Nm', 'a gradient of up to 35°', 'removable 48V 20AH lithium-ion battery', 'The UL-certified battery incorporates BMS security protection and power-saving capabilities', '4-6 hours at 3A', '16-inch x 4.0 wide tires', 'puncture-resistant fat tires', heading 'Full Suspension & Hydraulic Dual Brakes', 'The mechanical dual brakes enhance safety by cutting braking distance by 50%', 'The front suspension fork is strengthened by 100%', 'The rear hydraulic shock absorber', 'Twist Grip Throttle & Shamano 7-Speed' (sic), 'three riding modes: pure electric, electric assist, and pedal', 'IP5 waterproof protection', 'a 7.2'' phone holder' and 'a spacious storage box', 'a strengthened pole & hollowed-out bracket', 'a unique & imaginative design', 'come 90% pre-assembled', '1-year warranty on the motor, battery, and charger'; FAQ 'Recommended height range is 5.2 to 6.0 feet' and '28+++ mph in pure electric mode (ensure a full charge)'; note 'Front tires must be securely installed, Self-modification may posesafety risks.'; structured data rating '5' from '6' with three written reviews, by 'Brian', 'Satoru Osawa' and 'Kubota Saki'; nine photographs; the footer's 'Our Qualifications' links. Its warranty bullet opens 'Established in New Jersey and proudly serving the US since 2008'. Retrieved Oct 25, 2026. https://ridstar.net/products/ridstar-q16-1500w-fat-tire-electric-bicycle
60. Ridstar (ridstar.net), Ridstar® Q16 1500W Fat Tire Electric Bicycle (second listing) — ridstar.net. Ridstar.net's second Q16 listing, a '-copy' (created August 29, 2025): the same title, the same nine photographs and the same text apart from one sentence, 'The hydraulic dual brakes system reduces the average braking distance by 50% compared to mechanical brakes'; one variant marked 'CA', $1,499.00 and available on October 24 and 25, 2026. Retrieved Oct 25, 2026. https://ridstar.net/products/ridstar%C2%AE-q16-1500w-fat-tire-electric-bicycle-copy
61. Ridstar (ridstar.net), Size drawing, ridstar.net Q16 photograph 9 (file 1464-10). Ridstar's Q16 size drawing (photograph 9 of 9): arrows marking total length 59.8", total height 41.7", wheel base 49.2", seat height 31.4", 'Wheel diameter 18.5"', 'Head tube lenght' (sic) 10.2" and seat pack length 22.4", beside 'To 5'2"' over 'Rider Height', '330 LBS Max Load' and '64 LBS Bike Weight'; at the 31.4-inch seat arrow's 12.04 pixels to the inch the other arrows measure 22.35, 18.94, 57.82, 41.78 and 45.02 inches. Retrieved Oct 25, 2026. https://cdn.shopify.com/s/files/1/0696/9960/0602/files/1464-10.jpg?v=1749607101
62. Ridstar (ridstar.net), Motor image, ridstar.net Q16 photograph 7 (file 2_c91dd277). Ridstar's Q16 motor image (photograph 7 of 9): '1500W POWERFUL BRUSHLESS MOTOR', 'POWERFUL & FAST', and the lines '65 Miles' over 'Max speed', '20 MPH' 'Factory speed', '30 MPH' 'Unlocking speed' and '30° Slope'. Retrieved Oct 25, 2026. https://cdn.shopify.com/s/files/1/0696/9960/0602/files/2_c91dd277-c8e9-421b-9b08-2a555a9f760a.jpg?v=1749607101
63. Ridstar (ridstar.com), ridstar.com catalog feed (products.json) — ridstar.com. Ridstar.com's catalog feed on October 24, 2026: 56 products, none of them a Q16; one titled '【UK Stock】YVY C16 1500W 48V 20AH 16*4.0 Fat Tire Electric Bike' (created August 20, 2026), one variant marked 'UK', no description. Retrieved Oct 24, 2026. https://ridstar.com/products.json
64. Internet Archive (Wayback Machine), capturing ridstar.net, Wayback Machine capture of ridstar.net's Q16 listing, March 28, 2025. The Wayback Machine's capture of ridstar.net's Q16 listing on March 28, 2025 carries the same nine photograph file names the listing serves on October 24, 2026. Retrieved Oct 24, 2026. https://web.archive.org/web/20250328024846/https://ridstar.net/products/ridstar-q16-1500w-fat-tire-electric-bicycle
65. u/T1lt3dTav3n on r/ebikes (Reddit), Ridstar Q20 from amazon came but says Q16? — r/ebikes. A buyer's post of September 20, 2025, 'Ridstar Q20 from amazon came but says Q16?': 'i ordered the Ridstar Q20 16’ from amazon and it came and says Q16 on the side', and later 'i saw a listing on amazon called the Q20 16 inch and separate listing on the ridstar website called the Q16'; one person's report. Retrieved Oct 24, 2026. https://www.reddit.com/r/ebikes/comments/1nm5o1b/ridstar_q20_from_amazon_came_but_says_q16_answer/
66. ridssttaar.it.com (a storefront using Ridstar's name), WooCommerce Store API product search for 'q16' — ridssttaar.it.com. A storefront at ridssttaar.it.com, home page titled 'Best Electric Bikes for Adults – The Only Ridstar Official EBike Shop – Ridstarebike': its Store API returned 'Ridstar Q16 1500W Fat Tire Electric Bicycle' (product 26110) at 32970 minor units, $329.70, in stock on October 24, 2026, with nine images carrying the file names of Ridstar's own nine. Retrieved Oct 24, 2026. https://ridssttaar.it.com/wp-json/wc/store/v1/products?search=q16&per_page=100