10 Electric Bike Conversion Kits Compared for 2026

An electric bike conversion kit adds a motor and battery to a bike you already own, for a fraction of the price of a complete e-bike. The catch is that “which kit?” is really several smaller questions about how your bike is built and where you will ride. This guide compares ten kits across four practical groups — road-legal commuting, lightweight and removable systems, mid-drive hill-climbing builds, and high-power private-land builds — and assesses every product against the same criteria, including our own. Start by browsing the conversion kit and battery options, but read the fit and legal notes before you buy anything.

10 Conversion Kits at a Glance

Each kit is included for a defined rider or use case rather than presented as a universal winner. Choose the system that matches your bike, riding conditions and legal use.

How We Compared the Same Criteria for All Ten

To keep the comparison fair, each kit was checked against an identical list rather than a personal favourite:

• Bicycle compatibility — wheel sizes, open dropout or thru-axle, front/rear spacing, rim or disc brakes, freewheel or cassette, and bottom-bracket fit for mid-drives
• Complete-kit value — whether the price includes motor, battery, controller, display, sensors, charger and torque arms, or leaves some as separate buys
• Installation difficulty — easy (wheel swap and wiring), medium (rear gearing and brake alignment) or advanced (bottom-bracket work or high-current systems)
• Support and parts — manuals, technical support, spare controllers and displays, replacement batteries, warranty and UK servicing
• Legal use — stated neutrally: a private-land kit is not penalised for exceeding EAPC limits, but its use is never presented as road-legal commuting

Evidence status: the two KirbEbike entries are manufacturer-verified against our own product data; all other kits are desk-researched from each brand’s live product pages. None of the non-KirbEbike kits was hands-on tested for this article.

The 10 Kits, Reviewed

1. Bafang BBS02B Mid-Drive — Best for Configurable Hill-Climbing

Bafang’s crank-mounted mid-drive is the best-known name in DIY conversions, and for one clear reason: it drives the chain through your existing gears. Drop into a low gear and the motor spins in its efficient band while the bike climbs slowly — which is why a mid-drive out-climbs a hub motor of the same rated power. The feel is natural, the weight sits low and central, and the ecosystem is enormous: wheel size doesn’t matter, displays and batteries are chosen to suit, and community firmware knowledge runs deep.

The honest costs are threefold. First, the install is the most demanding in this guide — both crank arms, the chainring and the bottom bracket come off, and cable routing, speed-sensor alignment and chain line all need to be right. Second, all that torque runs through your chain and cassette, so the drivetrain wears faster, especially if you shift under full power. Third, the battery is usually a separate purchase, so the real project cost is well above the motor price once a quality pack, tools and possibly a professional fit are added.

Fit & legal: needs a 68–73mm threaded bottom bracket. The BBS02B’s continuous rated output is above the 250W EAPC ceiling, so it does not qualify as a road-legal EAPC in Great Britain — limiting it to 250W/15.5 mph in the controller does not change the motor’s rated output, and GOV.UK’s detailed guidance treats products with a switchable off-road mode as motor vehicles. Treat it as a private-land build with the landowner’s permission, or choose a genuinely 250W-rated kit for road use.

2. KirbEbike EZ Rider 250W — Best for a Bundled First Conversion

The EZ Rider exists for the rider who wants one box, one price and no drivetrain surgery. The front wheel arrives pre-built with the 250W motor laced in, and the kit bundles everything a first conversion actually needs: a 36V dual battery, charger, colour display, sensors and mounting bracket. Because it’s a front-wheel fit, the cassette, chain and gears are never touched — a typical install is around twenty minutes with basic tools. There’s even a dedicated Brompton version for folder commuters.

Where it stands out against other 250W kits is the battery: the 22Ah dual pack stores 792Wh, which is why its 40–60 mile estimate is longer than many single-battery rivals. The trade-offs are those of any front hub — a little extra steering weight, and grip that runs out sooner than a rear hub on steep, wet starts. For flat-to-rolling UK commutes, that limit rarely shows up.

Manufacturer-verified · road legal

EZ Rider Ebike Conversion Kit

£587.99 · complete kit + 22Ah dual battery

• 250W front hub, 50 Nm geared — 15.5 mph cut-off set from the factory
• 36V 22Ah (792Wh) LG dual battery — 40–60 mile estimate
• Wheel sizes 20″–29″ and 700C, plus a Brompton version
• Colour display, keyed connectors, charger and bracket in the box
• UK support with a 1-year warranty and spare parts stocked

View the EZ Rider Kit →

Fit & legal: needs a 100mm front dropout; check fork material and condition, and fit the included torque arm. Road-legal at the 15.5 mph cut-off when the completed bike meets EAPC rules.

3. Swytch Go — Best for Simple Frame-Mounted Commuting

Swytch made its name making conversion feel unthreatening, and the Go is the frame-mounted version of that promise: a 250W front motor wheel, a pedal sensor, and a power pack that straps to the frame where a bottle cage would sit. Installation is genuinely beginner-friendly — about an hour for most people — and the different battery tiers let you trade range against weight at order time.

Its limits are worth knowing. The front hub fits standard 100×9/10mm axles only, so thru-axle forks are out; the pedal sensor gives cadence-based rather than torque-based assist, which feels more on/off than a mid-drive; and delivery has historically run on campaign cycles, so order timing matters. As a matched, low-power system it’s deliberately not a platform you upgrade later.

Fit & legal: 100×9/10mm front axle, rim or disc versions; confirm wheel size when ordering. Road-legal in its UK configuration.

4. Boost — Best for a Bespoke Rear-Wheel Fit

Boost takes the opposite approach to the one-size wheel swap: it builds a rear motor wheel to your bike’s exact specification — rim size, spoke count, freewheel or cassette — and pairs it with a bottle-style battery with a lockable on/off. Because the motor drives the rear wheel, where most of your weight sits, the traction feels natural and secure, particularly on damp tarmac and gentle climbs where front hubs can scrabble.

The rear-wheel format brings the usual homework: your drivetrain type and over-locknut width must be confirmed before ordering, punctures take longer to fix than on a front hub, and a display is an optional extra rather than standard. The bespoke build and UK shop-fitting network offset that for riders who want the wheel done properly rather than cheaply.

Fit & legal: rear fitting needs drivetrain and dropout compatibility confirmed. Road-legal in its 250W configuration.

5. Rubbee X — Best for Tool-Free Removable Assist

The Rubbee X is the only kit here that touches neither wheel nor drivetrain. The whole system — motor, battery and electronics — lives in one unit that clamps to the seatpost and presses a roller against the rear tyre. Clip it on for the commute, lift it off for the weekend club ride; it moves between bikes in seconds and adds app control and regenerative braking for good measure.

Friction drive has natural physics limits: the roller can slip in heavy rain or on worn tyres, tyre wear increases slightly, and the base battery module is short-range unless you add modules. It rewards smooth tarmac riding on a bike whose tyres you keep in good condition — and it is easily the least-commitment way to try electric assist at all.

Fit & legal: fits most 22–35mm seatposts and 16–29″ wheels. Road-legal at 250W with the 25 km/h cut-off.

6. Swytch Air — Best for a Portable, Removable Battery

The Air uses the same front motor wheel as the Go but moves the battery to a handlebar pack that clips off in a second. That single change defines who it’s for: flat-dwellers who carry the bike upstairs, commuters who park in public racks and take the battery with them, and anyone who values the smallest possible pack over range. Handlebar weight changes the steering feel slightly, and the smallest pack is honest short-commute territory.

One caution matters for travellers: removable is not the same as flight-approved. Swytch quotes the AIR pack at roughly 98Wh and the larger MAX at around 180Wh. Under IATA rules, batteries of 100–160Wh generally need airline approval and anything over 160Wh is normally not permitted in passenger baggage — so the ~180Wh MAX is typically not allowed, and even the smaller pack should be cleared in writing with your carrier before travel.

Fit & legal: same 100mm front-axle and brake checks as the Go. Road-legal in its UK configuration.

7. Cytronex C1 — Best for a Lightweight Premium Conversion

Cytronex is the conversion for riders who don’t want their bike to feel — or look — converted. The 250W front-hub system with its bottle-style Bluetooth battery adds so little weight that the bike still rides like a bicycle with the power off, and the app diagnostics, boost button and factory-fitting option give it a polished, almost OEM character. A rear thru-axle version now covers modern 142×12mm hubs, which no other lightweight kit here manages.

You pay for the engineering: it’s a premium price for modest range, and the detailed ordering process (exact fork, brake and wheel specs) is thorough rather than quick. For a good road or hybrid bike that deserves a sympathetic conversion, it’s the benchmark.

Fit & legal: front kit fits 100mm quick-release forks (disc or V-brake); the rear option covers 10/11/12-speed 142mm hubs. UK/EU version road-legal at 25 km/h.

8. Pendix eDrive — Best for a Dealer-Fitted Premium Mid-Drive

Pendix answers the mid-drive question differently from Bafang: instead of a DIY project, it’s a German-engineered, torque-sensing system sold and installed through a dealer network. The torque sensor is the point — assistance rises with how hard you pedal, so the delivery is smooth and quiet rather than switch-like, and the weight sits low at the cranks. It fits most threaded bottom brackets, including Brompton and Tern folders, which makes it a favourite for premium folder conversions.

Dealer fitting removes the DIY risk and gives you a human to go back to, but it adds cost, and the system itself is relatively heavy for a 250W unit. Think of it as buying a finished e-bike drivetrain for the bike you already love, rather than a box of parts.

Fit & legal: requires a compatible threaded bottom bracket and professional fitting. Road-legal 250W in its EU/UK configuration.

9. Skarper DiskDrive — Best for the Easiest On/Off Conversion

Skarper’s idea is the cleverest here: replace your rear brake rotor with its patented DiskDrive rotor once, and after that a single self-contained 250W unit clicks on and off in seconds. No wiring lives on the bike; take the unit off and your bicycle is exactly a bicycle again. Fast charging and a Dynamic Climb sensor round out a genuinely premium product for riders who want an e-bike on Monday and a light bike on Sunday.

The requirements are specific: you need a disc-brake bike (160mm rotor, with adaptation for 140mm or rim-brake setups), the unit price is firmly premium, and a kickstand won’t coexist with it. Built for tarmac, gravel and light trails rather than hard off-road.

Fit & legal: disc-brake bikes; check rotor size compatibility. Road-legal at the 15.5 mph cut-off.

10. KirbEbike High-Power Rear-Hub Range — Best for Bundled Private-Land Performance

At the opposite end of the legal spectrum from everything above sits KirbEbike’s high-power range: rear direct-drive kits from the 48V 1000W through the 52V 2000W MTX to the 72V 4000W, all built around reinforced MTX rims, waterproof harnesses and fully potted FOC controllers with app tuning. The rare thing at this power level is the bundling — a matched Taishan or HS-II battery with a 60A BMS can ship in the same box, so the motor, controller and pack are engineered together instead of assembled from guesswork.

These kits demand respect and a proper donor bike: a strong frame, torque arms, upgraded brakes and correctly rated wiring are requirements, not suggestions. They are also unambiguously not road bikes — above 250W/15.5 mph they are private-land machines in the UK, ridden with the landowner’s permission.

Manufacturer-verified · off-road

52V 2000W MTX Rim Kit

From £357.85 · kit-only, or bundled with a 48V–52V battery

• Rear direct-drive on a reinforced MTX rim — 26″–29″/700C variants
• Freewheel and cassette fittings; 135mm open dropout
• Waterproof harness, potted FOC controller, Ride Power App tuning
• Optional Taishan / HS-II packs with 60A BMS and 5A charger
• Private land / off-road only in the UK

View the 52V 2000W Kit →

Manufacturer-verified · off-road flagship

72V 4000W Extreme Performance Kit

From £670 · MTB and fat-tyre builds

• 72V direct drive for extreme trail and fat-tyre projects
• Pairs with 72V 20Ah (1,440Wh) Taishan / HS-II packs
• Torque arms and upgraded brakes are mandatory equipment
• 1-year UK warranty with stocked spares

View the 72V 4000W Kit →

Fit & legal: confirm dropout width, rotor clearance and drivetrain per variant — the Off-Road Kits collection lists every option. Above 250W/15.5 mph, so private-land or off-road use only in the UK.

Which Kit Suits Your Type of Riding?

Hub motor vs mid-drive, in one paragraph

Hub motors drive the wheel independently of your gears — simpler to fit (especially at the front) and gentler on the chain. Mid-drives drive through the chain and cassette, so they climb efficiently in low gears but wear the drivetrain faster. Front hubs are the easiest fit; rear hubs feel the most natural; mid-drives climb best. If your rides are flat, that ranking is also your buying order.

250W vs 1000W vs 2000W

250W is the UK road category — when the whole system also meets the speed and pedal-assist rules. 1000W and 2000W are performance categories for private land, not automatically better for commuting: more power needs a higher-current battery, stronger torque restraint and better brakes. And wattage never sets your range — stored energy in watt-hours does.

Five Checks Before Buying Any Kit

Five minutes with the bike saves an expensive return. Wheel size: read the tyre sidewall (26″, 27.5″, 29″, 700C or a folder size) and match it exactly. Dropout standard: record the internal spacing, open dropout vs thru-axle, and axle diameter — 100mm front and 135mm rear are clues, not guarantees. Freewheel vs cassette: confirm which your rear wheel uses before any rear-hub order. Brakes: rim or disc, rotor size and pad condition. Battery space: measure the frame triangle or rack, and compare packs in watt-hours (volts × amp-hours), never amp-hours alone. Work through your exact figures on the wheel and dropout size guide, and have any bike with cracked dropouts, corrosion or damaged carbon professionally inspected first.

UK Conversion Law in 2026, Briefly

A converted bicycle rides as an EAPC in Great Britain when it has usable pedals, a motor with a continuous rated output no higher than 250W, and assistance that stops at 15.5 mph, ridden by someone 14 or over (GOV.UK). The bike should carry the required markings: manufacturer, continuous rated power, and battery voltage or maximum assisted speed.

A system exceeding those limits is treated as a motor vehicle in public — registration, insurance, tax, licensing and a motorcycle helmet can all apply (Cycling UK). Higher-power kits are private-land products used with the landowner’s permission — “off-road” does not make public trails, bridleways or cycle paths lawful for an unregistered high-power vehicle. Road riders should shop the Road Legal Kits collection and nothing else.

Conversion Kit vs Complete E-Bike

Conversion is the weaker choice when the donor bike is worn, the brakes would need costly upgrades, the frame uses incompatible thru-axles, the battery can’t be mounted safely, or professional labour cancels out the saving.

Conclusion: Choose by Fit, Use and Support — Not Wattage

This comparison covers different riders rather than crowning one universal winner. Bafang and Pendix suit mid-drive hill-climbers; Swytch, Cytronex and the EZ Rider suit road-legal commuters; Rubbee and Skarper suit riders who want assist that clips on and off; Boost builds a rear wheel around your bike; and KirbEbike’s high-power kits are bundled private-land performers.

So decide where the bike will be ridden, measure the donor bicycle, choose front hub, rear hub or mid-drive, match the battery to the motor and the range you need, and confirm installation support before ordering. The correct kit is the one that matches your wheel, axle, brakes, drivetrain, battery space and legal use.

Frequently Asked Questions