Smartravel DK400 Review 2026: $699.99, 873.6 Wh

Moped style · fat tires · one rear hub motor Smartravel rates at 750 W sustained and 1,000 W peak · a removable 48 V 18.2 Ah pack, 873.6 Wh · 28 mph published · dual suspension · Shimano 7-speed · turn signals included · 68.3 lb · a fixed 32.3-inch bench · $699.99 · verified September 26, 2026

Quick Answer — The Smartravel Explorer DK400 is a $699.99 moped-style e-bike on 20 × 4.0 fat tires, with a rear hub motor rated 750 W sustained and 1,000 W peak and a removable 48 V 18.2 Ah pack, 873.6 Wh. Held to 15 mph on the throttle over flat pavement, a full charge carries a 180 lb rider a computed 51 miles.

Hold 20 mph and the same pack gives about 35 miles; add easy pedaling at 15 mph and it stretches to 83. Smartravel's product page prints 45+ miles on pedal assist, and the range section works out your own ride by speed, climbing, load, air temperature and tires.

The seat is a bench fixed at 32.3 inches, so the fit section starts at the stop: seated, 66 of 100 riders at 5'8" put both feet flat, and 94 of 100 at 5'10". Smartravel publishes 28 mph beside a motor that holds 750 W, and the class section sets both against the statutes.

What this review covers

What $699.99 buys · What it is · Will it fit you · The motor · The battery · How far it goes · Brakes, lights and display · Suspension and tires · Weight and load · The Mercer fit test · UL · Recalls · The class question · Where to ride it · Green and red flags · The verdict · Checklist · Buying it from us · FAQ · Limitations · The bottom line · References

How we verified this Smartravel Explorer DK400 review

Every figure here was read on September 26, 2026 from Smartravel's DK400 product page on its US store, that page's product record, the DK400 owner's manual its manuals page links, ZOONLAI's listing of the same bike, our listing or the statutes quoted in the class section. The range and fit figures are computed, and each formula names its inputs.

This review is specification-verified: every number is Smartravel's, a statute's, or arithmetic shown on this page. We sell the DK400, so give the red flags the weight you give the green ones.

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

What $699.99 buys

Every row was read on September 26, 2026 from Smartravel's product page, the dimension photograph in its gallery and the owner's manual. Where the page prints two figures for one row, both are shown, and Limitations lists the rest. At 48 V and 18.2 Ah, the pack holds 873.6 Wh, the figure every range row below starts from.

A moped-style fat-tire bike for $699.99

Smartravel describes the DK400 as a bike that "combines power and style", built "for both urban commuting and outdoor rides", in the words of its product page. The shape does the talking: a long bench, a round headlight, a tall fork and 4-inch tires, with a rack behind the seat.

On a residential street in Smartravel's own photograph, with a full-face helmet and gloves.

Suspension at both ends, a removable 873.6 Wh pack, seven Shimano gears, a color display, a rack and fenders come on one frame, with turn signals included, so the headline figure is 873.6 Wh for $699.99.

Owners write about it in their own words on Smartravel's page, where 60 of the 73 reviews give five stars, 9 give four and 4 give three, as the review panel read on September 26, 2026. One owner who rides it to work wrote: "Had this bike over a year and she's still purring like a kitten."

The bench, the rack and the lettering on the frame, cropped from Smartravel's street photograph.

One name, two motors, depending on the market. ZOONLAI's listing of the bike, which sells it as the Explorer DK401 at the same $699.99, puts a 1,200 W peak motor on the version sold in another market and says "the U.S. version comes with a 1000W motor." That is why some listings print 1,200 W; the bike on Smartravel's US page, and on our store, is the 1,000 W version.

Smartravel's listing for the DK400 was created on March 15, 2023, and has carried more than one battery figure since, so every number on this page comes from the US page as it read on September 26, 2026.

Will the DK400 fit you?

The DK400's seat is a bench fixed at 32.3 inches, so fit comes down to how your feet meet the ground at a stop and how bent your knee stays when you pedal. Seated, 66 of 100 riders at 5'8" in the US Army's survey put both feet flat on the ground; pedaling, the bench sits below the height the 109%-of-inseam formula asks for at every height from 5'3" up.

The model sets the 6,068 bodies the US Army measured for its 2012 survey against Smartravel's published figures and its dimension photograph.

To place yourself on this frame:

1. Measure your inseam. In socks, stand with your back to a wall, draw a hardcover book up firmly between your legs, and measure from the floor to the book's top edge.
2. Find your row in the stop table to see how your feet meet the ground astride a 32.3-inch bench.
3. Read the pedaling table if you plan to pedal far; it shows how far below the formula's height the bench sits for your size.

Smartravel prints three rider windows for the DK400, and all three sit beside the model's rows here.

Smartravel's dimension photograph, as its gallery shows it, with the seat height lettered F.

Will I pedal with a bent knee?

Yes, from 5'3" up: the bench sits below the pedaling height the formula sets for every rider at those heights. The formula puts the top of the saddle at 109% of your inseam above the pedal axle (Peveler et al., 2005), with a published range down to 106% (Ferrer-Roca et al., 2012).

The bench does not move, so this table measures the knee bend you will pedal with. Turning the formula into a height off the ground runs through the 12.2-inch crank axle and the 6.0-inch cranks measured on Smartravel's photograph.

The floor-to-saddle height the 109% formula asks for, how far the 32.3-inch bench sits from it for the middle rider of each height, and how many riders of 100 at that height have the bench inside their 106 to 110.4% band; Army survey bodies, men and women together.

The bench runs 1.7 inches below the formula's height at 5'0" and 9.5 inches below it at 6'3". A seat below that height bends the knee further at the bottom of each stroke; on the DK400 the throttle and pedal assist carry the pace, and the effort table prices what your legs save the pack.

Can I put a foot down at a stop?

From about 5'8" up, yes for most riders: seated on the bench, 66 of 100 riders at 5'8" put both feet flat, 94 of 100 at 5'10" and 100 of 100 at 5'11". Lower down the count falls quickly, to 27 of 100 at 5'6" and 10 of 100 at 5'5", so shorter riders stop on their toes.

On a moped-style frame you sit astride the bench at a light, and your legs meet the seat's height. Standing in front of the bench, the frame's lowest point measures 31.5 inches at the bench's nose on Smartravel's photograph, and at 5'8" it sits no more than 0.4 inch above the inseam of 95 of 100 riders.

Barefoot inseam minus each figure: 31.5 inches at the bench's nose on Smartravel's photograph, 32.3 lettered F on the same photograph, and 33 in the product page's FAQ. The inseam column is the median rider's; each clearance is the one 95 of 100 riders at that height have or exceed, with a minus sign where the frame sits higher than that inseam.

Until the bike is in front of you, plan on the higher of Smartravel's seat figures. A rider on tiptoe can still stop well by sliding forward off the bench toward its nose, the lowest point the frame offers.

Will I feel cramped, or stretched?

Neither for most: the median rider leans 17° from upright at 5'0" and 5° at 6'3", because the grips sit 17.8 to 18.7 inches ahead of the crank axle and 29.6 to 30.5 inches above it. Shorter riders reach a little further forward; taller ones sit nearly upright.

Twenty recreational cyclists, asked to rank three trunk positions, found the most upright of them the most comfortable (Priego Quesada et al., 2017). Each angle below is the least lean at which a straight arm meets the grip from the bench, worked out from that body's measured torso and arm.

Trunk lean from vertical for the middle rider of each height; the spread covers where the sit bones rest along the flat of the bench and the length of the grip on Smartravel's photograph.

How much weight goes through my wrists?

At most 15% of your body weight at 5'0" and 8% at 6'3", for the median rider with the back fully relaxed. In a lab study, 10 road racers pedaling with their hands on the hoods put 15% of their weight through the bars (Carahalios, 2015); on the DK400 the median rider's ceiling meets that figure only at 5'0" and falls below it above.

Leaning forward shifts the load onto the heel of the hand, over the ulnar nerve, and in 36 riders that pressure peaked in the most stretched-out hand position (Slane et al., 2011). Padded gloves cut palm pressure by 10 to 28% in the same work.

The most the hands carry with a relaxed back, from each body's segment weights (Clauser et al., 1969) at the survey's median weight for that height; the range spans the bench and grip positions.

How do I set it up when it arrives?

The bench stays where it is, so setup means the handlebar, the pedals and the controls. Smartravel's FAQ calls the bike "90% assembled", and the manual walks the handlebar, kickstand, front wheel, front fender, pedal and headlight steps with pictures.

The manual also recommends that "you use a trusted professional bike technician to assemble your E-Bike." For the pedaling itself, cycling research sets the knee to bend 25 to 35 degrees with the pedal at the bottom (Peveler et al., 2007); on a fixed bench most riders' knees bend more, as the pedaling table shows.

The heel check shows where you stand: sit on the bench, put a heel on the pedal at its lowest point, and see how far the leg is from straight. With the saddle raised until that leg just straightened, the method put 70% of 19 cyclists in the knee range, more than either inseam formula did (Peveler et al., 2005); on the DK400 the bench cannot rise, so the check tells you how much bend you will ride with.

How we computed fit

Pedaling height is 1.09 × inseam above the pedal axle; the stop is inseam minus the seat's height; the lean is the smallest trunk angle at which a straight arm reaches the grip; and the hand load is the upper body's weight times its lean, divided by the reach to the grip.

Take a 5'8" rider with the survey's median 32.6-inch inseam: the formula asks for 35.6 inches from the pedal, which is 29.6 inches from the crank axle (88.3% of inseam gives 28.8), a floor-to-saddle height of 38.0 inches, 5.7 inches above the bench.

Before any length was taken from the photograph, its scale, set by the published 32.3-inch seat height, was held against four other figures Smartravel prints.

Every length is scaled from the published 32.3-inch seat height at Smartravel's own lettered station; all four checks agree to within three percent. Smartravel publishes no crank length, grip position or crank-axle height, so those come from the photograph.

The formulas agree with each other on this crank. For the median 5'8" rider, LeMond's 88.3% from the crank axle plus the 6.0-inch crank comes to 106.8% of inseam from the pedal, inside the 106 to 110.4% band the studies accept, beside Hamley's 109%; Peveler's riders measured 109.2 ± 0.9.

One 1,000 W peak rear hub motor, 750 W sustained

Smartravel's page describes "The 1000W upgraded brushless geared hub motor", with "a high-temperature resistant inner ring for improved heat dissipation", and a controller whose "FOC (Field-Oriented Control) system optimizes motor performance in real-time".

Two ratings sit side by side in its specification table: "750W (sustained), 1000W (peak)". The peak is the short burst for a start or a steep pitch; the sustained figure is what the motor holds, and it is the figure the range model uses and the class section comes back to.

The hub motor sits in the rear wheel behind the seven-speed cassette.

Throttle or pedals, your choice. The owner's manual says "The motor on our bikes is both throttle and pedal assist controlled", and the FAQ on the product page lists "0 to 5 levels of pedal assist", with level 0 as "Pure pedal mode" in the manual.

The manual's brake note matters on a heavy bike: "All of our bikes are equipped with brake levers that have a built-in safety switch that automatically cuts off the motor power under normal braking conditions."

For hills, the manual's FAQ says that with "a reasonable amount od effort" a rider "should be able to tackle anything from a 10% gradient up to a 14% gradient." The hills table puts a speed and a cost on each grade.

A hub motor turns with the rear wheel, so a gear change moves your cadence and leaves the motor's speed alone. For how hub and mid-drive motors differ on any bike, our e-bike motor guide lays out both, and our hub-drive picks set rear-hub bikes side by side.

One removable 48 V 18.2 Ah pack, 873.6 Wh

48 V × 18.2 Ah comes to 873.6 watt-hours, in one pack that runs everything on the bike. Smartravel's battery panel credits it with "80% capacity even after 800 charges", managed by a BMS.

The pack rides in the frame's front triangle, below the SMARTRAVEL lettering and the frame bag.

Two keys come with the bike, one for the battery lock. The manual notes that "Your SMARTRAVEL electric bike comes with two keys", and shows the pack lifting out of the frame so it can charge indoors while the bike stays outside. It adds a step that is easy to miss: "You need to turn on the red button of the battery before riding."

Charging: plan on an evening, or on a night from empty. Smartravel's FAQ quotes 5 to 6 hours, and the manual "around 3-6 hours if completely discharged". The charger in the box is rated 54.6 V 2 A, and 18.2 Ah at 2 A is 9.1 hours of full charging current, so a pack run to empty takes most of a night on that charger.

For storage, the manual gives one rule for long breaks and one for every ride: "If the battery will not be used for an extended period of time, charge it fully and recharge it every 2 months", and "Recharge battery after every use."

How far the Smartravel DK400 goes on one charge

On level pavement with 180 lb aboard, a full pack runs about 51 miles at 15 mph on the throttle, 35 at 20 mph, and 83 at 15 mph if you pedal easily. Up an 8% grade at 10 mph on the throttle, that charge covers 8 miles.

Three steps turn these tables into your figure:

1. Pick your pace and your pedaling in the first two tables.
2. Hold back 178 to 264 Wh for every 1,000 feet of climbing at 10 mph on the throttle on 4 to 10% grades, or 147 to 220 if you pedal easily (the hills table).
3. Correct for your load and the air temperature, then plan with 25% kept in the pack as a reserve.

Each table computes one steady ride at a time from Smartravel's specifications, Bafang's published figures for a comparable 48 V geared hub motor, drum readings for ten fat tires, the tires as Smartravel photographs them, and a cycling-power model validated on an open road. The last subsection shows the formula and one ride worked through.

Does riding faster cut range? Miles at each speed

Settle your speed first: on the throttle, a full charge runs 72 miles at 10 mph and 35 at 20. The air takes power in proportion to the cube of your speed, so going from 15 mph to 20 needs about 2.4 times the air's share, which is (20 ÷ 15)³, and the pack's 51 miles at 15 mph become 35.

A 180 lb rider on level pavement in 77 °F air, throttle only. The model holds the motor to the 750 W Smartravel says it sustains, which carries this bike at 26.2 mph on the flat; the published 28 mph draws on the 1,000 W peak, so that row prints no steady figure. The last column keeps 25% of the pack in reserve.

Easy pedaling pays off at every speed: 75 W from your legs at 15 mph takes a full charge from 51 miles to 83. Here easy pedaling is 75 W and steady pedaling 150 W; with the motor off, 75 W alone would carry this bike at about 9.1 mph on the flat and 150 W at about 13.2, so pick the column you could hold unaided.

Miles per full pack for a 180 lb rider on the flat. Easy pedaling at 15 mph takes 10.6 Wh a mile from the pack, where the throttle alone takes 17.2. In the 152- and 191-mile cells your legs push harder than the motor, so those two lean most on the model's motor losses at light load (Limitations item 6); "legs alone" marks a speed that 150 W holds with no help from the motor.

Pedal assist in a speed-sensor bike adds help by how fast you turn the cranks, so read the row for the speed you hold and the effort you give. The manual's own advice when the pack runs low points the same way: "switch off your motor and keep it just for the difficult bits."

Which gear saves battery? On a hub motor, your effort does

Pick the gear for your knees and pedal for the pack. The motor spins with the rear wheel in every gear, so a shift changes your cadence and leaves the motor's load untouched. At a fixed speed and grade, the pack's draw falls as your effort rises:

Watt-hours drawn from the pack per mile, 180 lb rider, 77 °F air; easy pedaling adds 75 W from the rider and steady pedaling 150 W.

Up an 8% grade at 10 mph the throttle alone takes 108.9 Wh a mile; easy pedaling brings that to 83.6 and steady pedaling to 62.3. Every watt from your legs is one the motor does not have to supply, along with the heat the motor and the pack would have shed making it.

Use the seven gears to keep a cadence your knees like, the low ones for starts and climbs. On the fixed bench your knee bends further than the formula's height would set it (the pedaling table), which is one more reason to let a low gear spin easily.

Does going uphill drain the battery faster?

Much faster. At 10 mph on the throttle up 4 to 10% grades, each 1,000 feet of rise costs 178 to 264 Wh on top of the level distance, or 147 to 220 when you pedal easily. A 180 lb rider on the 68.3 lb DK400 weighs 248.3 lb together, and lifting that through 1,000 feet takes 94 Wh at the wheel; the motor and the pack lose the rest.

At 10 mph on the throttle an 8% grade takes 230 Wh from the pack per 1,000 feet, so the full 873.6 Wh would lift you about 3,798 feet and leave nothing for the flat. The model takes no credit for coasting downhill, so a budget built from these rows keeps a margin.

A 180 lb rider on the throttle. "Fastest steady" is the speed the modeled motor holds at its sustained 750 W; the other two columns are at 10 mph, and at 15% that speed is past 750 W. With easy pedaling the full-charge figures at 10 mph run 55, 26, 16, 10, 7, 5 and 3 miles from 2% to 15%.

The manual's 10 to 14% climb fits the table: the modeled motor holds 12.5 mph up 10% and 11.0 up 12% on its sustained rating, and it keeps 15 mph up grades to 7.5%. The peak rating gives more for a short pitch; the table prices steady climbing.

A hilly ride costs its level miles plus its climbing. Ten level miles at 15 mph on the throttle use about 172 Wh, and 1,000 feet of 8% climbing adds about 230, near 402 Wh of the 873.6. Wind and stop-and-go traffic come on top of that, as the model holds every mile to an even pace.

Does rider weight affect range?

A little on the flat, a lot on a hill. Weight adds to the tires' work and to the grade's, and nothing to the air's share, so the gap widens as the road tilts up.

The rider plus everything they carry; the bike's own 68.3 lb is added to every row, since the motor moves it too. Throttle only. The 330 lb row is the load capacity on Smartravel's dimension photograph, the lower of the two load figures it prints.

Moving from a 180 lb to a 300 lb load trims the level 15 mph ride by 9 miles, 51 to 42, and halves the 8% climb from 8 miles to 4. At the 330 lb limit the level 15 mph ride still covers about 40 miles, while the 8% climb falls to 3, because on a grade most of the wheel's power goes into lifting the load.

Does cold weather drain the battery?

Yes, and more with each colder row. Pedaling easily at 15 mph, a charge that lasts 83 miles at 77 °F lasts about 61 at 32 °F and 55 at 14 °F.

Level ground, 180 lb aboard. The middle figure in each row comes from McMaster University's LG HG2 cell data, recomputed at a 0.5C discharge, with the cells assumed to sit at air temperature; the lab measured 77, 50, 32 and 14 °F and the rows between are interpolated. The brackets show how far published cell data sets disagree.

Each low end is the smallest capacity Samsung's data sheets give at that temperature for a cell discharged at one to four times its capacity per hour (25R and 30Q at 32 °F, 35E at 14 °F); each high end is the most energy Casado and colleagues measured in 2025 at a slower rate.

Three losses stack up near freezing. The cells give back less energy, the air thickens by about 9% under the U.S. Standard Atmosphere's gas law, and the tires roll harder as their rubber stiffens.

The model raises rolling resistance 0.5% for each °F below 77 °F, between Rothhämel's fit for a 42 mm tire and Bicycle Rolling Resistance's road-tire average, and holds the 41 °F value below 41 °F. Smartravel names LG cells in its FAQ without a model, so the HG2 is an LG cell used as a stand-in, not a confirmed match.

Whatever the weather on the ride, the manual wants the battery stored "in a cool, dry place", so a winter rider carries the pack indoors between rides.

Do fat tires cut range? Tires and riding position

Across the flat, tire choice outweighs how you sit. Ten 26 × 4.00 fat tires on Bicycle Rolling Resistance's drum took 23.2 to 42.1 W at 12 psi, 18 mph and a 94 lb load.

The drum has no reading for a 20 × 4.0 tire or for the CHAO YANG fat tire printed on the DK400's sidewalls, so the model takes the middle of the ten, a coefficient of 0.0105, as a stand-in.

The front wheel: the disc brake, the fork leg and the fat tire, with CHAO YANG on its sidewall.

A full pack's miles, 180 lb rider, level ground. Of the ten, Schwalbe's Jumbo Jim LiteSkin rolled with the least drag and Kenda's Juggernaut Pro with the most, at 0.01262 on the site's list.

The drum has no reading for sand, dirt or grass; email us the route and we will put that ride through the model.

Posture counts as speed rises. Tengattini and Bigazzi recorded 0.640 m² of drag area for 37 upright cruiser riders, the value used here for a bench where the median rider leans 5 to 17 degrees, and 0.603 m² for 90 everyday mountain-bike riders, which would lift the 20 mph throttle ride from 35 miles to 37.

Smartravel's 26 to 80 miles, matched to real rides

Smartravel prints five range figures for the DK400 across its page, its FAQ and its manual, and each maps onto a steady ride. Its battery panel gives "26+ miles in electric mode and 45+ miles in PAS mode"; its FAQ gives "40-60 Miles" in one answer and "50-80 Miles on a single charge" in another; the manual says pedal assist on a straight road "should last about 50-70km".

Each band is read at its top: 60 and 80 miles, and 70 km, which is 43.5 miles. The per-mile figure is the 873.6 Wh pack divided by the miles; the speeds are where the model's level ride with a 180 lb rider draws exactly that.

So the 26+ miles in electric mode fits riding the throttle near 24 mph, the 45+ on pedal assist fits easy pedaling near 20 mph, and the top of the FAQ's 50 to 80 miles fits easy pedaling near 15 mph. The model's own 15 mph throttle ride, 51 miles, sits above the page's 45+ and inside the FAQ's 40 to 60 miles.

The manual says what shapes every published range: "road surface, wind resistance, weight of the rider and tire pressure will affect your range." Plan on 75% of whichever row fits your ride, keeping 25% of the pack in reserve so a headwind or a detour does not end the ride on pedals alone. That makes 38 of the full 51 miles at 15 mph on the throttle.

On the move in Smartravel's photograph, on a residential street.

How every figure here is worked out

Holding a steady speed takes a steady flow of power at the rear wheel, and Martin and colleagues' 1998 model, validated on an open road, gives that power, P, in one line for a constant speed in still air:

P = v × [ m g (Crr cos θ + sin θ) + ½ ρ CdA v² ]

Here v is speed, m the mass of rider, cargo and bike together, g gravity, θ the slope's angle, Crr the tires' rolling resistance (0.0105 is a drag of 1.05% of the weight on the tires), ρ the air's density and CdA the drag area, a measure of how much air the rider pushes aside.

The first bracketed term covers the tires and the grade and the second the air, which grows with the cube of speed once multiplied by v.

Four steps lie between the wheel and the pack:

1. Your legs drive the rear wheel through the chain at 97.7% efficiency, Martin and colleagues' figure, and the motor makes up the rest.
2. The rear hub motor turns with the wheel and does all of the motor's pushing.
3. The motor follows the published figures of a comparable motor. In Bafang's 2021 OEM workbook the RM G0H0, a 48 V geared hub, has an n0 of 510 rpm, an nT of 426 rpm and an efficiency of "≥ 80" percent; its rating is taken at the 750 W Smartravel says the DK400 sustains. On the DK400's 22.7-inch tires those speeds read as 34.4 and 28.8 mph, and the modeled motor holds 26.2 mph on the flat.
4. The pack gives up a little energy internally, at the battery efficiency Arango, Lopez and Ceren measured on a 48 V pack.

That gives watt-hours per mile = battery watts ÷ mph, and miles = 873.6 Wh × the part of the pack's energy still available at that temperature ÷ watt-hours per mile.

A worked example: 180 lb aboard at 15 mph on level pavement, throttle only. The tires take 78.1 W and the air 114.2 W, 192.3 W in all at the rear wheel.

At 15 mph the 22.7-inch wheel makes 222 rpm. With 0.899 N·m of torque per amp, a 0.405 Ω winding and a 0.83 A no-load current, each worked out from Bafang's published figures, the modeled motor makes 8.3 N·m on 10.0 A at 77% efficiency, below its 80% because the load is light, and draws 250.2 W.

With the pack's own losses added, the battery supplies 258.7 W: 17.24 Wh a mile at 15 mph, and 873.6 ÷ 17.24 comes to about 50.7 miles, or 38.0 with 25% kept.

Two published benchmarks, recomputed. Both halves of the model return the figure their source prints:

Both rows come from the model's own self-test: Martin and colleagues' worked example in Appendix I (8.36 m/s ground speed, a 90 kg system, a 0.3% grade) and the RM G0H0's rated point in Bafang's workbook.

Brakes, lights and display

Smartravel specifies a "Dual Mechanical Disc Brake system", "two independent mechanical disc brakes" on a bike that stops 68.3 lb plus its rider. The manual sets them up the way cable brakes are set, "by increasing the tension on the cable" or with "the threaded barrel adjuster on the brake lever".

Use both levers, rear first. The manual is direct about it: "The rear brake should always be applied before and while the front brake is applied." It also warns that "Wet weather will require a longer distance to stop", so brake earlier in the rain.

The cockpit: the round headlight on the fork, the bar with its controls, and the display.

Lights and signals come fitted. Smartravel lists "headlights, rear taillights, and turn signals", with "Integrated turn signals" so that riders and drivers around you can read your next move. The manual's control diagram puts the headlight switch and the horn on the handlebar.

The color LCD, in Smartravel's description, shows "speed, battery level, distance traveled, and motor performance". The manual has you "Press & hold M button to switch on/off e bike" and step the assist up or down with the plus and minus buttons.

Dual suspension and 20 × 4.0 tires

Smartravel describes "a dual suspension system with independent front and rear shock absorption", and its photographs show a coil shock under the bench and a fork up front. Paired with 20 × 4.0 tires, that is the DK400's answer to broken pavement, gravel and dirt.

The tires, in Smartravel's specification, are "Unibody, puncture protection". If one does go flat, the manual keeps the fix simple: "Simply replace the tube with a tube of the right size and inflate it."

Around them sit a Shimano 7-speed derailleur, fenders front and rear, a rear rack and an alloy kickstand, all included in Smartravel's specification. The frame appears as "Upgraded 6061 Aluminum" in the feature copy and as carbon steel in the specification table; Limitations records both, and none of the range or fit figures depends on the material.

68.3 pounds and a 330 to 350-pound limit

Smartravel lists 68.3 lb (31.0 kg), with a "Maximum total weight limit (combined weight of rider and cargo) of 350 pounds". Its dimension photograph prints a load capacity of 330 lb and a bike weight of 68 lb.

Plan on the lower figure, 330 lb, for you and everything you carry; the 68.3 lb bike sits outside it. A 200 lb rider with 30 lb of groceries on the rack comes to 230 lb, which leaves 100 lb in hand under 330.

Size a hitch rack, a lift or a stair plan for the 68.3 lb plus whatever rides on the bike, and for the 68.9 inches of length and 42.3 of height the dimension photograph prints.

The Mercer fit test

The DK400 meets the same seven archetype riders as every bike we review, the Mercers, so its fit answers read straight across to our other reviews (meet the Mercers).

Each verdict below rests on a figure Smartravel publishes (its three height windows, the seat height, the weight, the load, the age range in its product record) or on the model's row at that height in the fit tables. The bench sits below the 109% pedaling height for every member of the family, so each adult row reads the stop: how many riders of that height sit flat-footed on the 32.3-inch bench.

Ruth and Jack show where the DK400 divides a family. At 6'1" Jack sits flat-footed on 100 of 100 bodies his height, while at 5'5" Ruth's inseam falls short of the bench on 90 of 100. Both are inside Smartravel's windows; the bench decides how their stops feel.

Is it UL certified?

Smartravel says so: its DK400 page carries a "UL Certified" badge that reads "Safety Certified in Accordance with UL 2849", and a "TUV Certified" badge further down reads "In accordance with UL 2849". ZOONLAI's listing of the same bike carries the same "UL Certified" badge.

Should a landlord, a building manager or an insurer ask for the certificate itself, email us and we will request it from Smartravel in writing, with the model and the date it names.

Has it been recalled?

No. Our September 26, 2026 search of the Consumer Product Safety Commission's recall database found no recall naming Smartravel, Smart Travel, Smartravelor, ZOONLAI or ZonMen in the recall title, the product name or the manufacturer field, and none of 623 bicycle, e-bike, battery and scooter records names the brand or the DK400 or DK401 model codes.

Before its empty answer counted, the same search had to find recalls known to exist, and it did: Ancheer 1, Specialized 54, Trek 24.

The class question: 28 mph published, 750 W sustained

Settle this before you order, because the DK400's published figures sit near the lines the statutes draw. Smartravel's page gives "750W (sustained), 1000W (peak)" and "a top speed of 28 mph", and the manual confirms a throttle beside the pedal assist.

15 U.S.C. § 2085(b) defines a low-speed electric bicycle as "a two- or three-wheeled vehicle with fully operable pedals and an electric motor of less than 750 watts (1 h.p.), whose maximum speed on a paved level surface, when powered solely by such a motor while ridden by an operator who weighs 170 pounds, is less than 20 mph."

Sources: § 2085(b) and Smartravel's product page, read September 26, 2026.

On the watt line, 750 W sustained sits on the federal line, not under it. Your state then decides what the DK400 is on its roads and paths.

California's code shows one state's version of that line. Vehicle Code § 312.5(a), read on September 26, 2026, covers a bicycle "equipped with fully operable pedals and an electric motor that does not exceed 750 watts of power", and a sustained 750 W does not exceed that, though the statute does not say whether it means a sustained figure or a peak one.

The classes come next in the same section: a class 2 bicycle's motor "is not capable of providing assistance when the bicycle reaches the speed of 20 miles per hour", and a class 3 bicycle helps "only when the rider is pedaling" and "ceases to provide assistance when the bicycle reaches the speed of 28 miles per hour".

From § 312.5(a)(2) and (a)(3) and Smartravel's product page, each read on September 26, 2026.

Ask for the throttle's top speed, in writing, before you order. Where your state draws a class line at 20 mph on the throttle, we will get that figure from Smartravel for you. Our 50-state e-bike law atlas prints each state's definition, and our California e-bike law page sets out that state's rules in full.

A related search turns up in the DK400's autocomplete: removing the speed limiter. The manual's warranty excludes "Damage or loss caused by modification, alteration, or repair by any unauthorized party", and a bike altered past a class line leaves that class.

Where you can ride it

Off the pavement, the agency that manages the land decides whether the DK400 may go there, and the federal agencies write their e-bike rules around the three classes and a 750-watt motor, as the BLM's definitions do.

For National Forest land, the Forest Service's notice at 87 FR 41278 says its final e-bike directives of March 31, 2022 "provide for managing all classes of e-bikes as motor vehicles" and "require local-level decision-making and environmental analysis to allow use of e-bikes on non-motorized trails".

Where a Ranger District has published a motor vehicle use map, 36 CFR 261.13 prohibits operating a motor vehicle "other than in accordance with those designations".

On Bureau of Land Management land, 43 CFR 8340.0-5 defines the classes around "an electric motor of not more than 750 watts (1 h.p.)" and counts an e-bike as a non-motorized bicycle only where "the authorized officer has expressly determined" it.

The land manager's rule governs; the bike's specification settles none of these on its own.

On a National Forest, 36 CFR 261.1b sets the penalty for breaking the part's prohibitions at "imprisonment of not more than six months or a fine in accordance with the applicable provisions of 18 U.S.C. 3571 or both". Our public-land e-bike guide takes the agencies one at a time. Riders heading for motor-vehicle trails can read our Smartravel M23 review, the group's electric dirt bike.

Down a residential street in Smartravel's photograph.

Green flags / Red flags

Green flags

• One removable 873.6 Wh pack: for a 180 lb rider, a computed 51 miles at 15 mph on the throttle and 83 pedaling easily.
• Suspension at both ends: a front fork and a rear coil shock, on 20 × 4.0 tires.
• Lights and signals fitted: a headlight, a taillight and turn signals, with the switches on the bar.
• A rack, fenders and seven Shimano gears, all in the $699.99.
• Brake levers that cut the motor under normal braking, in the manual's words.
• Flat feet at a stop from about 5'8": 66 of 100 riders at 5'8" and 94 of 100 at 5'10" sit flat-footed on the bench.
• No federal recall names Smartravel or the DK400 in the CPSC database.
• Owners rate it well: 60 of 73 reviews on Smartravel's page give five stars.

Red flags

These are about fit: who the DK400 is wrong for, and where to go instead.

• Wrong if you want to pedal long distances with a near-straight leg. The bench is fixed below the formula's height for every rider from 5'3" up; send us your inseam and we will match you to a bike with an adjustable seat post from our range. Our ZOONLAI UrbanX review covers a 24-inch commuter whose seat post rises, and works out the saddle height your inseam calls for.
• Wrong if you are under about 5'6" and want both feet flat at every stop. At 5'5" 10 of 100 riders sit flat-footed; our Freesky Rocky Pro A-320 review covers a step-through whose frame sits far lower.
• Wrong for a daily carry up the stairs. At 68.3 lb, tell us about the stairs and we will suggest a lighter bike from our range.
• Wrong if your ground needs two driven wheels. Only the rear wheel is driven here; our Eahora Luna II review covers a fat-tire bike with a motor at each end.
• Wrong if you want the biggest pack a moped-style bike can carry. 873.6 Wh computes to 51 miles at 15 mph on the throttle; our Riding'times GT73 Pro review covers a machine carrying two packs, 2,160 Wh. Smartravel's own two-pack machine carries 2,600 Wh, with a 1,200 W motor in each wheel and a 35 mph top that sit above the e-bike class lines; our Raptor ST202 Pro review has its range table. For one bigger pack on a single motor, also rated above those lines, read our Raptor ST202 review.
• Wrong if you want hydraulic brakes. The manual sets the DK400's discs by cable; email us and we will point you to a bike with hydraulic brakes in our range. Smartravel's own Rocket ST201F stops on hydraulic discs front and rear from $749.99; our Rocket ST201F review prices its two packs ride by ride.
• Wrong for Class 1-only trails. The throttle keeps it off those trails; our public-land guide quotes each agency's rule, and we will look up your trail with you.
• Not for riders under 18. Smartravel's product record lists the age range as "Adult"; our 50-state law atlas lists each state's age rules for younger riders.

Buy it if / Buy something else if

Buy it if you want a moped-style fat-tire bike with suspension at both ends, turn signals included and a removable 873.6 Wh pack, for neighborhood rides, errands, beach paths, bike lanes where your state's class allows it, gravel and your own land. It suits adults who ride mostly on the throttle and pedal assist, and from about 5'8" up the stops come flat-footed.

For $699.99 you get a 1,000 W peak rear hub motor that sustains 750 W, seven Shimano gears, a color display, a rack and fenders. On our listing Shop Pay offers 4 interest-free payments of $174.99, or $63.18 a month for 12 months at 15% APR, $758.16 in all, subject to an eligibility check.

Owners on Smartravel's page gave it five stars in 60 of 73 reviews as of September 26, 2026, reviews written across the builds its listing has carried since 2023.

Buy something else if you want two driven wheels (our Eahora Luna II review), a bigger moped-style machine with two packs (our Riding'times GT73 Pro review), or a low step-through for shorter riders (our Freesky Rocky Pro A-320 review). Every review we have written sits on our e-bike reviews hub.

Before you buy: the checklist

Ten checks before you spend $699.99; the first three settle whether the DK400 is yours to ride.

1. Check the rule where you ride: your state's e-bike definition for roads and paths, and the land manager's for trails.
2. Confirm the rider is an adult, as Smartravel's listing describes the bike.
3. Ask us for the throttle's top speed in writing wherever a 20 mph line applies.
4. Measure your inseam and find your row in the stop table; under about 5'8", expect to stop on your toes.
5. Check your height against Smartravel's windows: 5'3" to 5'9" on the dimension photograph, 5'3" to 6'3" on ZOONLAI's copy, 5'4" to 7'0" in the product record.
6. Keep rider plus cargo at or under 330 lb; the DK400's own 68.3 lb sits outside that figure.
7. Plan the storage and the lift for a 68.3 lb, 68.9-inch bike.
8. Read your ride off the range tables, plan on three quarters of it, then add the climbing.
9. Pick a charging spot indoors and dry, with a night's time for a pack run to empty on the 2 A charger.
10. Read the class section before any ride past 20 mph.

Buying it from us

Why buy the DK400 from Redtail

Our listing priced the DK400 at $699.99 on September 26, 2026, with $1,599.99 shown as the regular price, the same pair of figures on Smartravel's own US store that day. Our side of it begins the day you order.

Changing your mind works differently: a bike still sealed in its factory packaging, requested within 72 hours of delivery, carries a 15% restocking fee plus return shipping, and canceling an order carries a 3% transaction fee. We would rather answer your fit, range and class questions before the order goes in.

Frequently asked questions

How far can the Smartravel DK400 go on one charge?

Smartravel prints 26+ miles in electric mode and 45+ miles on pedal assist; its FAQ gives 40 to 60 and 50 to 80. Computed for a 180 lb rider on flat pavement, a full charge covers about 51 miles at 15 mph on the throttle, 35 at 20 and 83 at 15 with easy pedaling; each 1,000 feet of climbing at 10 mph adds 178 to 264 Wh on the throttle (the range tables).

What is the top speed of the Smartravel DK400?

Smartravel publishes 28 mph. The range model holds the motor to its sustained 750 W, which carries the bike at 26.2 mph on the flat; the published 28 mph draws on the 1,000 W peak. Smartravel's documents read here do not say at what speed the throttle stops helping, so ask us and we will get it in writing (the class section).

Is the DK400 street legal?

It depends on your state. Its 750 W sustained motor sits on the federal 750-watt line, not under it, and California's class 3, the 28 mph class, helps "only when the rider is pedaling", so a bike with a throttle fits California's classes only as a class 2 whose help stops at 20 mph. We will get the throttle's cut-off from Smartravel in writing (the class section).

Do I need to assemble the Smartravel DK400 when it arrives?

A little. Smartravel's FAQ calls the bike "90% assembled", and the manual pictures the handlebar, kickstand, front wheel, front fender, pedals and headlight steps. The manual also recommends a professional bike technician for the assembly.

What is the seat height on the DK400?

The bench is fixed at 32.3 inches on Smartravel's dimension photograph, and its FAQ says 33 inches. Seated on it, 66 of 100 riders at 5'8" put both feet flat; a 5'8" rider with the survey's median 32.6-inch inseam sits flat-footed, while the pedaling formula would set that rider's saddle at 38.0 inches (the fit section).

How long does it take to charge the DK400 battery?

Smartravel's FAQ says 5 to 6 hours and the manual 3 to 6 hours from empty. The included charger is rated 2 A, and 18.2 Ah at 2 A is 9.1 hours of full charging current, so plan on a night for a pack run to empty and an evening for a top-up (the battery section).

What is the DK400's battery capacity?

48 V 18.2 Ah, 873.6 Wh, on Smartravel's US page and in its specification table. Older figures on its other pages give 15, 17.5 and 20 Ah; every range figure here uses 873.6 Wh, and Limitations scales them for the smaller packs.

Does the DK400 have hydraulic or mechanical brakes?

Mechanical. Smartravel's feature copy describes "Dual Mechanical Disc Brake", and the manual adjusts the brakes by cable tension at the lever's barrel adjuster. One line of the specification table reads "hydraulic disc"; Limitations records it.

How much does the Smartravel DK400 weigh?

68.3 lb (31.0 kg) in Smartravel's specification, and 68 lb on its dimension photograph. Plan racks and lifts for that plus whatever rides on the bike; the 330 lb load on the photograph counts the rider and cargo only (the weight section).

Does the DK400 have turn signals?

Yes. Smartravel lists "headlights, rear taillights, and turn signals" as standard, with the switches on the handlebar, so the turn signals come fitted on the bike (brakes, lights and display).

Is the Smartravel DK400 1000W or 1200W?

In the US, 1,000 W peak and 750 W sustained. ZOONLAI's listing of the same bike puts a 1,200 W peak motor on the version sold in another market and says "the U.S. version comes with a 1000W motor", which explains the 1,200 W in some listings (the motor section).

Will the DK400 still work if the battery is dead?

Yes, as a pedal bike. Smartravel's FAQ says that "When the battery runs out, the DK400 seamlessly transitions into a traditional bike", and the seven gears help; at 68.3 lb on fat tires it is a heavy bike to pedal unaided, so keep 25% in reserve (the range section).

Can you replace the DK400's battery?

Yes: the pack locks into the frame with a key and lifts out to charge. Ask us for a spare and we will confirm with Smartravel that it fits your DK400 before you order (the battery section).

Where do I find the DK400 manual?

Smartravel publishes it on its owner's manual and assembly video page: the DK400 PDF quoted throughout this review, covering assembly, the controls, charging, brakes and the warranty.

Can I remove the speed limiter on the DK400?

We do not recommend it. The manual's warranty excludes "Damage or loss caused by modification, alteration, or repair by any unauthorized party", and a bike altered past a class line leaves that class under your state's law (the class section).

Is the Smartravel DK400 worth it?

At $699.99 on our store on September 26, 2026, with free shipping to the contiguous United States, it puts suspension at both ends, turn signals, seven gears and a removable 873.6 Wh pack on one moped-style frame. It suits adults who ride mostly on the throttle and pedal assist, flat-footed at stops from about 5'8" (the verdict).

What do owners say about the Smartravel DK400?

On Smartravel's page, 60 of the 73 reviews give five stars, 9 give four and 4 give three, as of September 26, 2026. One owner who commutes on it wrote, "Had this bike over a year and she's still purring like a kitten."

Is the DK400 UL certified?

Smartravel states on its page that the DK400 is "Safety Certified in Accordance with UL 2849", and a "TUV Certified" badge reads "In accordance with UL 2849". Email us if you need the certificate and we will request it from Smartravel in writing (the UL section).

Can I finance the DK400?

Yes. On September 26, 2026 Shop Pay offered 4 interest-free payments of $174.99, or $63.18 a month for 12 months at 15% APR, $758.16 in all, subject to an eligibility check by Affirm's lending partners.

What warranty does the DK400 have?

Smartravel's manual warrants its e-bikes against manufacturer defects for twelve months from delivery, for the first owner, with accessories excluded. Bought from us, a fault comes to us: send photos or video with your order number, and our listing says "Redtail coordinates repair or replacement remotely at no cost to the customer".

Limitations of this review

Twenty-one things this review cannot settle, listed so you can weigh them.

1. We sell this bike. Read the red flags as closely as the green.
2. This is a specification-verified review. Its figures come from Smartravel's published documents, statutes, our own store record, the published research the range and fit sections cite, or arithmetic on this page.
3. Each range figure is for a steady ride: one speed on one grade with no wind and no stops. Stops, starts and headwinds cost more, and a tailwind less.
4. Bafang's figures stand in for Smartravel's motor. Smartravel gives 750 W sustained, 1,000 W peak and a geared hub; the model uses Bafang's published figures for a 48 V geared hub, with its rating taken at 750 W. At 82% efficiency in place of Bafang's 80% floor, the 15 mph throttle figure moves from 51 miles to 53.
5. The model holds the motor to its sustained rating. It therefore prints no steady figure at 28 mph or up a 15% grade at 10 mph, where the 1,000 W peak would work for a stretch.
6. No ride of this model to an empty pack checks the model. The owner reviews on Smartravel's page describe riding without a measured distance, speed and rider weight together. The physics reproduces Martin and colleagues' worked example and the motor reproduces Bafang's 80% at the rated point; no measured hub-motor map was available to check the model at light loads.
7. Every range figure assumes the 873.6 Wh on Smartravel's US page. Its FAQ names "LG 48V 15Ah" in one answer, the product record "Samsung 48V/17.5AH" and "48V/20AH", and the page's web address "17.5ah". On a 15 Ah pack each full-charge figure would be about 18% lower; on 17.5 Ah about 4% lower; on 20 Ah about 10% higher.
8. The documents read here do not say how much of the pack the battery management releases. On one measured pedelec, researchers at KIT found 75% used in a standard range test, and the planning column keeps that 25% back.
9. The tire coefficient is the median of ten 26 × 4.00 fat tires at 12 psi, a stand-in for the CHAO YANG 20 × 4.0 on the bike, and the tire table brackets it with the lowest and highest of the ten.
10. The wheel is measured from Smartravel's dimension photograph. The model uses the tires as photographed, 22.7 inches across at the seat-height scale; Smartravel's "Wheel diameter 20"" is the rim size.
11. The cold figures rest on one cell's laboratory data. Smartravel names LG cells without a model, so the central line uses McMaster University's LG HG2, bracketed by other published cell data, with the cells assumed to be at air temperature.
12. The charge time is arithmetic on the charger's rating. Smartravel quotes 5 to 6 hours and 3 to 6 hours; 18.2 Ah at the 2 A rating is 9.1 hours of full current, and the last part of any charge runs slower.
13. Where Smartravel's documents differ, this review follows the US product page read on September 26, 2026. Its specification table lists "carbon steel" and "front & rear mount hydraulic disc" while its feature copy describes a 6061 aluminum frame and mechanical disc brakes; the product record lists an aluminum frame, "dual hydraulic disc brakes" and a "1200W Brushless Motor". The manual's cable-tension brake setup supports the mechanical reading. On request we will get any of these confirmed by Smartravel in writing.
14. Two load figures and three rider windows. The page gives 350 lb and its dimension photograph 330 lb, which this review uses; the windows run 5'3" to 5'9", 5'3" to 6'3" and 5'4" to 7'0", and all three are printed beside the model.
15. The fit figures use the US Army's ANSUR II bodies: 6,068 soldiers aged 17 to 58, measured in 2010 to 2012, who are not the US public, so your own inseam decides your row.
16. The cockpit is the one in Smartravel's dimension photograph. The crank axle, the cranks and the grips are measured on it, and where your sit bones rest on the bench is bracketed along its flat.
17. The hand figure is a ceiling with a relaxed back. On a real ride your back and arms carry part of it, and the 109% formula is a starting point that the knee range and the heel check refine.
18. The UL statements are Smartravel's own. The pages read here do not link the certificate itself.
19. The owner reviews span builds. The 73 reviews on Smartravel's page carry no build name, and the listing has existed since 2023.
20. Trail access is set locally. Your land manager's rule decides, it can change, and neighboring systems differ.
21. The price, the colorway and the stock state were read on September 26, 2026, and each can change; the recall search covers the CPSC's US database under the names listed.

The bottom line

For $699.99, the DK400 puts a 1,000 W peak rear hub motor that sustains 750 W and a removable 873.6 Wh pack on a moped-style frame, with suspension at both ends, 20 × 4.0 tires, seven Shimano gears, a rack and fenders, and turn signals included.

A full charge carries a 180 lb rider about 51 miles at 15 mph on the throttle over level pavement, or 83 pedaling easily; each 1,000 feet of climbing at 10 mph on the throttle adds 178 to 264 Wh. For the Rocket's and the ST202 Pro's miles, and the three other Smartravels we carry, turn to our Smartravel brand profile.

It suits adults who ride on the throttle and pedal assist and can store a 68.3 lb bike; from about 5'8" up the stops come flat-footed on the 32.3-inch bench. Through Shop Pay on our listing it comes to 4 interest-free payments of $174.99, or $63.18 a month for 12 months at 15% APR, subject to an eligibility check.

Settle the class before you pay: the motor sustains 750 W and Smartravel publishes 28 mph. Tell us where you ride before ordering, and where a 20 mph throttle line applies we will get the throttle's cut-off from Smartravel in writing.

Source register

Each document this review relies on, and what it supports.

T1 is the record itself, read from the party that issued it: a statute, a federal regulation or notice, the maker's own product page, record and manual, our own store record.

T2 is a party's own publication about its product or its measurements: the motor maker's workbook, the research groups' and laboratories' published measurements.

Expiry conditions

Re-read this page if Smartravel changes the DK400's price, specification, range figures, seat height, rider windows or dimension photograph on its US product page; if Smartravel publishes or confirms in writing the throttle's cut-off or the certificate; or if the price, the colorway or the Shop Pay terms change on our store.

Re-read it as well if a recall is published naming Smartravel, ZOONLAI or the DK400. Verified September 26, 2026.

References

The full bibliographic record for each document cited above, with the date it was retrieved.

1. Smartravel, Smartravel Explorer DK400 1000W Moped Style Offroad Electric Bike Fat Tire — product page (headline figures, feature copy, Spec&Size table, dimension photograph, FAQs, customer reviews, trust badges, as rendered under the US market). Retrieved September 26, 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
2. Smartravel, Explorer DK400 — product record, body_html listing text, variant price and compare-at price, SKU DK401 and creation date. Retrieved September 26, 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.json
3. Smartravel, Model: DK400 owner's manual: controls, assembly steps, battery installation and charging, battery care, pedal assist, keys, brakes, cleaning, FAQ, warranty. Retrieved September 26, 2026. https://cdn.shopify.com/s/files/1/0704/0172/0642/files/DK400-compressed.pdf
4. Smartravel, Download my owner's manual or view assembly video (manuals page). Retrieved September 26, 2026. https://www.smartravelor.com/pages/download-my-owners-manual-or-view-assembly-video
5. ZOONLAI, Explorer DK401 — product page (specification figures, dimension photograph, the note on the US version's motor). Retrieved September 26, 2026. https://www.zoonlai.com/products/zoonlai-explorer-dk401
6. US Government Publishing Office, 15 U.S.C. § 2085 — Low-speed electric bicycles, subsection (b). Retrieved September 26, 2026. https://www.govinfo.gov/content/pkg/USCODE-2024-title15/html/USCODE-2024-title15-chap47-sec2085.htm
7. California Legislative Information, California Vehicle Code § 312.5, subdivisions (a), (a)(2) and (a)(3). Retrieved September 26, 2026. https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH&sectionNum=312.5.
8. Bureau of Land Management, 43 CFR § 8340.0-5, paragraphs (a)(5) and (j) (85 FR 69223, Nov. 2, 2020). Retrieved September 26, 2026. https://www.ecfr.gov/current/title-43/subtitle-B/chapter-II/subchapter-H/part-8340
9. Forest Service, US Department of Agriculture, 36 CFR § 261.13 — Motor vehicle use. Retrieved September 26, 2026. https://www.ecfr.gov/current/title-36/chapter-II/subchapter-B/part-261/subpart-A/section-261.13
10. Forest Service, US Department of Agriculture, 36 CFR § 261.1b — Penalty (89 FR 92815, Nov. 25, 2024). Retrieved September 26, 2026. https://www.ecfr.gov/current/title-36/chapter-II/subchapter-B/part-261/subpart-A/section-261.1b
11. US Forest Service, Directive Publication Notice, 87 FR 41278 (July 12, 2022), recording the final e-bike directives issued March 31, 2022. Retrieved September 26, 2026. https://www.federalregister.gov/documents/2022/07/12/2022-14777/directive-publication-notice
12. US Consumer Product Safety Commission, Recall database, recall title, product name and manufacturer queries for Smartravel, Smart Travel, Smartravelor, ZOONLAI and ZonMen, a model-code read of a 623-record corpus, and controls Ancheer / Specialized / Trek. Retrieved September 26, 2026. https://www.saferproducts.gov/
13. Redtail eBikes, Shipping policy. Retrieved September 26, 2026. https://redtailebikes.com/policies/shipping-policy
14. Redtail eBikes, Refund policy (48-hour damage window, change-of-mind and cancellation terms). Retrieved September 26, 2026. https://redtailebikes.com/policies/refund-policy
15. Redtail eBikes, Smartravel Explorer DK400 storefront record and Shop Pay terms (price, compare-at price, availability, warranty and repair terms, installment plans). Retrieved September 26, 2026. https://redtailebikes.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
16. Affirm, Affirm's lending partners (the lenders behind Shop Pay Installments). Retrieved September 26, 2026. https://www.affirm.com/lenders
17. BAFANG, Workbook OEM 2021, MOTORS table, RM G0H0 column: n0, nT, efficiency and maximum torque at 48 V. Retrieved September 23, 2026. https://www.bafang-e.com/Uploaded/Labels/BAFANG%20Workbook%20OEM%202021.pdf
18. Martin, J. C., Milliken, D. L., Cobb, J. E., McFadden, K. L. and Coggan, A. R., Validation of a Mathematical Model for Road Cycling Power, Journal of Applied Biomechanics 14(3):276–291 (1998), Eq. 14 and Appendix I; doi 10.1123/jab.14.3.276. Retrieved September 23, 2026. https://collections.lib.utah.edu/dl_files/b4/8e/b48ef26086091662c561e673d7bd990d77868437.pdf
19. Bierman, J., Fat Bike Tires Test Results, BicycleRollingResistance.com, rolling resistance at 12 psi, 28.8 km/h, 42.5 kg. Retrieved September 25, 2026. https://www.bicyclerollingresistance.com/fat-bike-reviews
20. Bierman, J., Kenda Juggernaut Pro 2016, BicycleRollingResistance.com, rolling-resistance results. Retrieved September 25, 2026. https://www.bicyclerollingresistance.com/fat-bike-reviews/kenda-juggernaut-pro-2016
21. Bierman, J., CRR at Different Temperatures: Examining Temperature Dependence of Rolling Resistance, BicycleRollingResistance.com. Retrieved September 23, 2026. https://www.bicyclerollingresistance.com/specials/crr-temperature-test
22. Rothhämel, M., On rolling resistance of bicycle tyres with ambient temperature in focus, International Journal of Vehicle Systems Modelling and Testing 17:67–80 (2023); doi 10.1504/IJVSMT.2023.132317. Retrieved September 23, 2026. https://www.inderscience.com/filter.php?aid=132317
23. Tengattini, S. and Bigazzi, A. Y., Physical characteristics and resistance parameters of typical urban cyclists, Journal of Sports Sciences 36(20):2383–2391 (2018), Table 4; doi 10.1080/02640414.2018.1458587. Retrieved September 23, 2026. https://civil-reactlab.sites.olt.ubc.ca/files/2022/11/Tengattini_2018_Physical-characteristics-and-resistance-parameters-of-typical-urban-cyclists.pdf
24. Arango, I., Lopez, C. and Ceren, A., Improving the Autonomy of a Mid-Drive Motor Electric Bicycle Based on System Efficiency Maps and Its Performance, World Electric Vehicle Journal 12(2):59 (2021), Eq. (40); doi 10.3390/wevj12020059. Retrieved September 23, 2026. https://mdpi-res.com/d_attachment/wevj/wevj-12-00059/article_deploy/wevj-12-00059.pdf
25. Schmitt, M., Decker, S. and Doppelbauer, M., Measuring and Characterization of a Pedal Electric Cycle (Pedelec) on a Full System Test-Bench with Full Range Emulation of a Cyclist, EPE'19 ECCE Europe (IEEE, 2019); doi 10.23919/EPE.2019.8915567. Retrieved September 23, 2026. https://publikationen.bibliothek.kit.edu/1000100371/50695920
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