HKM-3915219 Folding E-Bike Carries a 250W Hub and a 36V 10Ah 360Wh Pack on 14 x 2.125 Tires in Black or Red With Disc Brakes

250W · 36V 10Ah 360Wh · 14 x 2.125 · 15.5 mph · 37 miles · single speed · 53 lb · disc brakes

A Rigid Fork and a Curved Beam That Hides the Battery PackSimple Light and Ready for the Road

A 250W rear hub, a 36V 10Ah 360Wh pack inside the curved main beam, 14 x 2.125 CST tires, a rigid fork and mechanical disc brakes front and rear, on a folding steel frame that comes in black or red. It is listed at up to 37 miles, 15.5 mph and 265 lb, and at 53 lb it is light enough to carry up a flight of stairs in one hand rather than parking it on the street. A folded bike that weighs 53 lb is a bike you take inside rather than lock up outside.

The shape is the argument. A single curved beam runs from the head tube to the rear axle, the battery sits inside it under a cover carrying the brand mark, and there is no top tube to swing a leg over. Folded, the bars drop alongside the front wheel and the whole thing is narrow enough to stand in a hallway or slide under a desk, which is what separates a folder that gets used every day from one that lives in a cupboard.

One gear, a rigid fork and a 250W motor is a deliberately small specification, and it is the right one at this weight. There is no derailleur to knock on a kerb, no suspension to service, and no motor big enough to make the bike feel heavier than it is. The trade is that a long climb is your legs' problem.

At a Glance

• 250W Rear Hub — Rated 250W, no peak figure published
• 360Wh Pack — 36V 10Ah inside the curved beam
• Up to 37 Miles — Listed maximum on pedal assist
• 14 x 2.125 CST — Small wheels, red rim lines
• 15.5 mph — 25 km/h, the European assist limit
• Single Speed — One gear, nothing to index
• Mechanical Discs — Front and rear rotors
• 53 lb Complete — Carry it up a flight of stairs
• Folds in Two Steps — Beam and stem, no tools
• Black or Red — Two paint options in one listing
• 265 lb Rating — 120 kg for rider and a bag
• Five Hour Charge — Small pack, short charge

Curved Beam Frame and Small Wheels

The frame is steel in a single curved beam, with the battery enclosed under a cover that runs the length of it. There is no top tube and no down tube in the usual sense, so the standover is effectively zero and getting on with a bag in one hand takes no thought at all.

Folding happens at two points: the stem drops the bars alongside the front wheel, and the frame hinge brings the two halves together. There is no tool in the sequence and the folded package is short enough to stand upright against a wall in a hallway.

The wheels are 14 inch on CST tires with a red line on the rim, a rigid fork up front and a rigid rear. That is what keeps the weight at 53 lb: no suspension and no big wheel means less material, and on smooth pavement the 2.125 casing is doing the comfort work instead.

• Frame: steel, single curved beam
• Battery: 360Wh inside the beam, key-locked
• Fork and rear: rigid, no suspension
• Brakes: mechanical disc, front and rear
• Tires: 14 x 2.125 CST
• Drivetrain: single speed

Fitted as shipped: a rear fender, a front light with a red bezel, a kickstand and the battery keys. There are mechanical disc rotors at both ends, which is more braking than most 14-inch folders carry and the reason it can live with the 15.5 mph limit on a wet street.

250W Hub and a 360Wh Pack

The motor is a 250W brushless rear hub, and it is the rated figure: the brand does not publish a peak number for this model, so 250W is what the bike is specified at rather than a short-duration claim. On 14-inch wheels that is enough to hold 15.5 mph and to help on a bridge ramp, and it is not meant to be more. The assist is set from a small panel on the bar rather than a screen, through several levels, and it is the only thing that changes how hard the bike pulls.

The pack is 36V 10Ah, 360Wh, inside the beam and charged through a port on the frame. A full charge takes about five hours on the supplied charger, which is the useful part of a small battery: it is an afternoon rather than a whole night, so a second charge in the same day is realistic. The pack comes out with a key, so a flat with no garage is not a problem.

Range is listed at up to 37 miles, and the words up to are doing the work. That figure assumes pedal assist on level ground with a light rider; at 15.5 mph with the assist high and a headwind it is closer to half. For the trips this bike is built for, five to ten miles at a time, it is two charges a week.

Who It Fits and How It Rides

The seat post and the bars both adjust, so one frame covers riders from about 5 ft to 6 ft 2 in, and the 265 lb rating includes a bag on the bars. The riding position is upright with the bars close to you, and the short wheelbase makes it easy to thread between parked cars.

On pavement it is quick to steer and firm over cracks, because there is no suspension to soften them. On gravel the 2.125 casing copes at a walking pace and no faster. The small wheels are the limit, not the brakes.

• A flat or a walk-up where the bike comes inside
• The last mile between a station and a door
• Short errands at 10 to 15 mph
• Not for kerbs, stairs under load, gravel at speed or touring

What's in the Box

Before the first ride: unfold the frame and check that the hinge is fully seated, fit the pedals, set the seat post and bar height, check both brake levers and the throttle return, then charge the pack. Fold and unfold it once at home before you rely on it in a station forecourt.

Color and Finish

Two finishes are offered: gloss black with red lines on the rims and red detailing around the front light, or gloss red over the whole beam with the same black cockpit. Both hide road film well, and the red version is the more visible of the two at dusk.

Touch-up paint is available on request in both colours. The wear points are the hinge, the stem release and the chainstay under the chain.

Battery Care and Maintenance

Charge the pack between 20 and 90 percent for daily use and take it to full about once a month so the management system can balance the cells. A 360Wh pack charges in about five hours, so there is no reason to leave it full and warm for weeks. Never leave one empty for a season.

Check tire pressure weekly at 40 to 50 psi on 14-inch wheels, and check the hinge and stem release for play every month, since those two joints carry the whole load on a folder. Check the brake pads monthly and the cable tension at the lever, and wipe the rims after a wet ride because disc rotors and small wheels collect grit.

Specifications

Frequently Asked Questions

Service and Policies

Coverage that lasts beyond the box. Orders ship free with a tracking number in 2 to 5 business days. From delivery, the product is protected for 180 days against manufacturing defects and transit damage, returnable within 30 days for a full refund, and covered by a 24-month parts-and-labor warranty on manufacturing defects. Four policies, one idea: ship it free, protect it for 180 days, take it back for 30, and stand behind it for two years.

HKM-3915219 · 14 in folding electric bike · 250W brushless rear hub, rated, no peak figure published · 36V 10Ah 360Wh pack inside the curved beam, key-locked · up to 37 miles listed range · 15.5 mph, 25 km/h · single speed drivetrain · mechanical disc brakes front and rear · rigid fork and rigid rear · 14 x 2.125 CST tires with red rim lines · folding beam hinge and folding stem, no tools · steel frame in gloss black or gloss red · 53 lb complete · 265 lb load rating · about five hour charge · rigid frame by design, no suspension to service · CST tread on 14 in wheels · folding pedals · single frame size for riders 5 ft to 6 ft 2 in · built for stairs, stations and short errands rather than kerbs, gravel at speed or touring