VTUVIA SX20 Antelope Folding Step-Through Electric Bike

A torque sensor at $1,599, and it fits riders from five feet up.

• 750 WMotor
• 672 WhBattery
• Class 2Class
• 70 miRange
• 330 lbMax load

What you get with the SX20

Torque sensor

The torque sensor is the reason to pick this one

A cadence sensor knows only that the cranks are turning, so assist arrives in steps. A torque sensor measures how hard you are pushing and answers in proportion. On the SX20 that makes pulling away from a intersection smooth rather than sudden, and it is the single mechanical difference a rider feels first.

Fits from 5′0″

It starts at five feet

VTUVIA sizes the SX20 from 5'0" to 6'2" — the widest fit in the range and four inches lower at the bottom than the SF20H. The step-through frame and the folding hinge are the same 6061 aluminum construction.

Lighting

Brighter lighting than its sibling

A 48 V 10 W headlight rated at 150 lux, against the 5 W, 130 lux unit on the SF20H, with a brake light at the back. Dual LOGAN hydraulic discs on 180 mm rotors do the stopping.

Four colors

Four colors, and a real anchor on each

Teal Blue, Red, Cream White and Silvery, all at $1,599 against VTUVIA's own $1,899 list; a fifth finish, White, lists at $1,799 and is sold out. Same 85 N·m and 1,200 W peak as the SF20H, on an EXSHO suspension fork.

VTUVIA packs fenders, a rear rack, a front basket and a basket bag with the SX20 — a set it values at $326 on its own listing, read September 19, 2026 — and the same box ships from us.

Why buy the SX20 from Redtail

$1,599, against VTUVIA's own $1,899

VTUVIA lists the SX20 at $1,899. It is $1,599 here, a $300 difference, and the price was read from VTUVIA on September 19, 2026.

Who the SX20 folding step-through ebike is for

Get the SX20 if you want the motor to answer how hard you pedal rather than whether you are pedalling — and if you or the person you are buying for is closer to five feet than six.

Two things to check before you order

1. Your height. 5'0" to 6'2" in VTUVIA's sizing. Taller than that and the Zeal XT8 runs to 6'2" on bigger 27.5-inch wheels.
2. Lifting it. 70 lb with the rack and fenders — ten pounds more than the SF20H, because the step-through frame carries more material low down.

How the SX20 compares with what else we sell

Inside VTUVIA's own folders the choice is simple: the SX20 has the torque sensor and the lower 5'0" fit, the SF20H is $200 less and carries a passenger. Outside them, the Velotric Fold 1 is $300 less and lighter.

Range and load are each maker's own published rating, read September 19, 2026. Makers measure range differently, so the column compares claims rather than a single test.

SX20 specifications

Every row is VTUVIA's own published figure, read from its specification for this model on September 19, 2026.

Riding the SX20 legally

Federal law defines a low-speed electric bicycle at 15 U.S.C. § 2085(b): a "low-speed electric bicycle" is a two- or three-wheeled vehicle with fully operable pedals, a motor of less than 750 watts, and a maximum motor-powered speed on a paved level surface of less than 20 miles per hour when ridden by an operator weighing 170 pounds.

The SX20's published figures are 750 W and a Class 2, 20 mph cap.

On its own page VTUVIA writes: “The SX20 can reach speeds of up to 20MPH with both throttle and pedal assist.”

As shipped it is a 20 mph bike. Ridden faster than 20 mph on motor power alone it is outside the federal low-speed definition and outside Class 2 in the states that use the class system, so check your state's line before you change that setting.

States then set their own rules on top of that, and most use a three-class system that decides where you can ride, whether a helmet is required and whether there is a minimum age. Our state-by-state guide sets out what each one says.

Frequently asked questions

What is the top speed of the SX20?

VTUVIA answers this on its own page: “The SX20 can reach speeds of up to 20MPH with both throttle and pedal assist.” That is the Class 2 shape, and 20 mph is the speed limb of the federal definition, so you can ride it where a Class 2 is allowed.

What is the difference between a cadence sensor and a torque sensor?

A cadence sensor detects that you are pedalling and applies a preset level. A torque sensor measures how hard you push and scales assist to match. The SX20 has the torque sensor; VTUVIA's SF20H uses a cadence sensor.

How far can the SX20 go on one charge?

Up to 70 miles on pedal assist and 40 on the throttle, in VTUVIA's rating, from a 48 V 14 Ah LG pack — 672 Wh.

Can the SX20 handle steep hills?

85 N·m from a 750 W hub rated to a 1,200 W peak. For a mid-drive that gears its torque through the cassette instead, VTUVIA's CMB 8-Speed makes 175 N·m.

Does the SX20 come fully assembled?

No. It arrives part-assembled in the box, as every freight-shipped e-bike does. Handlebars, pedals, front wheel and saddle are the usual steps.

Does the SX20 fold?

Yes — the same 6061 folding frame as the SF20H, with a step-through top tube.

Is the SX20 good value for the money?

At $1,599 against VTUVIA's $1,899 list, the SX20 is the cheapest torque-sensor folding fat bike on our shelf. The Velotric Fold 1 is $300 less with a torque sensor and narrower tires if the fat tires are not the point.

What is the weight limit of the SX20?

330 lb total, rider and cargo together, in VTUVIA's rating.

Do I need a license to ride the SX20?

Class 2 at 20 mph, on 750 W — inside the federal speed limb.

What’s next after you order

Orders are prepared and dispatched within 1–3 business days of confirmation, and most e-bikes arrive within 5–10 business days after dispatch, depending on location. It arrives part-assembled in a freight box: the front wheel, handlebars, pedals and saddle are the usual steps, and the tools come with it.

Inspect your shipment at delivery. Damage, defects or an incorrect item must be reported with photos within 48 hours. Damaged in transit, reported within 48 hours with photos: Redtail files the carrier claim and arranges a replacement or repair. If we shipped the wrong product or made an error, we correct it in full and cover all shipping.

Further reading

our folding e-bike guide · our step-through e-bike guide · our fat-tire e-bike guide · our under-$2,000 guide