Should You Convert Your Own Bike to Electric?

Manufacturer, retailer and public-agency sources · 2026-09-24 · no ratings, no road tests

Summary

It makes sense when the bike you already own fits you, is in good mechanical shape, and matches the kit's published requirements for wheel size, tire width, brakes or bottom bracket. It makes less sense when the bike needs new wheels, brakes and drivetrain parts first, or when the only kit that fits has a motor above the 750-watt e-bike limit. A converted bike also depends on a battery and charger from the kit maker for as long as you ride it.

Front-wheel kits and mid-drive kits ask different things of the bike

A front-wheel kit swaps your front wheel for one with a motor in the hub. Swytch's kit is one example: it includes "the wheel, power pack, pedal sensor (PAS – Pedal Assist System), charger and all necessary cables," uses a motor rated at 250 W with 40 Nm of torque, and is set to a maximum of 20 mph for the U.S. Swytch says the kit works with rim and disc brakes and all wheel sizes, but only with "tire widths ranging from 1.1 to 2.5 inches (28 to 64 mm)," which rules out fat tires and very narrow road tires.

A mid-drive motor mounts at the cranks and drives the chain, so the fit question moves to the bottom bracket, the frame shell the cranks pass through. Bafang's catalog shows how much that varies by motor. Its M215 is rated at 250 W and fits "frames with 68 mm bottom bracket width." Its M615 is rated at 750 or 1,000 W and fits bottom brackets from 68 to 120 mm. The installation manual for Bafang's M625 and M325 adds more conditions: room on the upper down tube 390 mm long and 170 mm high for the battery, a bottom bracket length that "matches the length of motor shaft," and a chainring line compatible with the original bike.

The motor you pick can change what the bike is

Some conversion motors are rated well past the e-bike definitions. The BLM's definition stops at a motor of not more than 750 watts, so a 1,000-watt option like the M615 or M625 is outside it. Bafang's own manual says the M625 and M325 "can only be used on vehicles intended for off-road use and designed to travel on unpaved surfaces," and warns that "unauthorized changes to the pedelec system can lead to criminal offences, such as a change of the speed limit."

A 250-watt front-wheel kit limited to 20 mph stays well inside those limits. On Bureau of Land Management land, a conversion with more than 750 watts is managed as an off-highway vehicle, not an e-bike.

Battery size and where it mounts

Swytch sells two kinds of power pack. The MAX packs mount on the handlebar and are the compact option. The GO packs strap to the frame "via a set of velcro straps," run from 187Wh to 378Wh, and in the largest GO++ version weigh about 2.6 kg with a claimed 45 to 60 miles of range. Swytch puts the whole kit at "approximately 3.5 – 4 kg." A mid-drive frame battery, by contrast, needs the down tube space Bafang specifies.

The charger has to come from the kit maker

CPSC warns against so-called universal chargers for micromobility products, which it says "may fit into your device but still be incompatible with it," and advises using only the charger provided with or recommended by the device manufacturer. It also says never to use a battery pack "modified or reworked by unqualified personnel or with repurposed or used cells." For a kit, the device manufacturer is the kit maker, and a replacement battery or charger has to come from them.

Bafang's manual draws a similar line for service: "Only trained personnel can maintain or repair the product," and "Do not disassemble the motor."

Sources

Data checked, sources, and what we did not test

Data checked: 2026-09-24. Figures and quotations were read on that date from the pages listed under Sources and can change without notice.

Sources: manufacturer, retailer and public-agency pages, listed above. No review sites, forums or retailer ratings were used.

What we did not test: ride quality, brake feel, real-world range, durability and customer service. We have not ridden these bikes and publish no ratings or rankings.