Is the Conversion Kit Compatible with My Bike? Verification Guide

If you haven't picked a kit power yet, our guide to choosing the right conversion kit power is worth reading first — every power option from 250W to 3000W shares the same fitment criteria below, so choosing power and confirming compatibility are two separate decisions. Once you've confirmed compatibility here, our complete installation guide walks through the full fitting process step by step.

Criterion 1: Wheel size

The most important criterion. The conversion kit is a complete wheel with the motor integrated into the hub — the original rear wheel is replaced with this motorised wheel. The size must be identical to your original rear wheel so that your tyre and inner tube fit and the bike geometry remains correct.

How to check: look on the sidewall (side of the tyre). You’ll find the size printed there, for example “26 x 2.0”, “27.5 x 2.1” or “700 x 35c”. The first number is the wheel diameter.

Criterion 2: Rear axle type

The axle is the metal rod on which the wheel is secured in the frame’s dropout. MTX All4eBikes kits are designed for quick-release (QR) axle with 135mm spacing — the most common standard on MTB, trekking and city bikes produced until approximately 2015.

How to check: open the rear dropout of your bike. If the wheel comes out by simply flipping a small lever (QR), you’re in the right. If you need to unscrew an axle with a key, it’s a thru-axle — contact us before ordering.

Criterion 3: Brake type

Good news: MTX kits are compatible with all common brake types. The motor hub has ISO 6-bolt holes for a disc brake rotor and is also compatible with v-brake (rim brake) systems.

Disc rotor size doesn't affect compatibility either — 160mm, 180mm and 203mm rotors all bolt onto the same ISO 6-bolt pattern on the motor hub flange. If your current rotor is a different diameter to what came with the kit, it will still fit; only the corresponding brake caliper mount position on the frame or fork needs to match, which the conversion doesn't change since the front end of the bike is untouched.

Criterion 4: Sprocket count (cassette)

The kit comes with a motorised wheel without a cassette. Your original cassette or freewheel transfers onto the motor hub — so the number of speeds is an installation step, not a compatibility issue.

Any cassette (7, 8, 9, 10, 11 or 12 speed) can be fitted to the motor hub. The hub has a standard cassette thread or freewheel body. If your existing freewheel is worn or the wrong fitment, a replacement sprocket from our parts range can be fitted in its place.

How to measure your dropout width and axle

If you can't find the specifications in your bike's manual, measuring directly takes about five minutes with a tape measure or a set of calipers.

1. Remove the rear wheel from the frame so you have a clear line of sight across the dropouts.
2. Measure the distance between the inside faces of the two rear dropouts, where the axle sits — not the outside of the frame. This is your rear spacing, typically 135mm for QR bikes.
3. Measure the axle diameter itself with calipers if available — 10mm indicates QR or solid axle, 12mm indicates a thru-axle.
4. Check for a lever — if the axle has a cam lever you flip to release it, it's QR. If it requires a hex key or has a threaded end cap, it's a thru-axle or bolt-on axle.
5. Photograph the open dropout with a coin or ruler next to it for scale if you want a second opinion — send it to us via the contact form below and we'll confirm compatibility.

What does NOT affect compatibility

• Frame material (aluminium, steel, carbon) — doesn’t matter for fitting the kit on the rear wheel
• Bike brand — kits are universal, not brand-specific
• Age of the bike — a 20-year-old bike with QR 135mm is just as compatible
• Suspension type (hardtail or rigid) — kit works on both; full-suspension requires checking battery clearance
• Front derailleur speed count — not affected by the conversion

Frame clearance for battery and controller mounting

Wheel, axle, brakes and sprocket cover whether the motor fits — but you also need somewhere to mount the battery and controller. This is rarely a blocker, but it's worth checking before you order rather than after.

• Downtube batteries mount inside the front triangle along the downtube — check there's a clear run without bottle-cage bolts or cable routing in the way.
• Triangle batteries sit inside the main frame triangle and need enough standover clearance between the top tube and the battery casing — tighter on smaller frame sizes.
• The controller is usually strapped under the saddle or to the seat tube — on smaller frames, confirm there's room without it fouling the rear tyre at full suspension travel or full pedal-stroke clearance.

Full-suspension bikes: what to check

The kit itself — motorised wheel, controller, display, sensors — works identically on hardtail and full-suspension frames; nothing about the rear shock or linkage affects electrical or mechanical fitment. The one thing worth checking is battery placement: full-suspension frames often have a smaller or oddly-shaped front triangle to accommodate the shock and linkage pivots, which can limit which battery shape fits without rubbing against the shock body during travel. If your front triangle is unusually compact, a downtube battery mounted along the seat tube, or a rear-rack battery, is often a more reliable fit than a triangle battery on a full-suspension frame.

Fat bike compatibility

Fat bikes (typically 4"–5" tyres on wide rims) follow the same four criteria above, but wheel size and dropout spacing both tend to differ from standard bikes — fat bike rear spacing is very commonly 170mm or 190mm rather than the 135mm standard covered here, and rim/tyre combinations vary more between models. If you're converting a fat bike specifically, our fat bike conversion kit guide covers the additional dimensions to check before ordering.

Step-by-step: confirming compatibility before you order

If you're ordering online without a bike shop nearby to check for you, this short process avoids the most common fitment mistakes:

1. Read the tyre sidewall for the wheel size code (e.g. “27.5 x 2.1” or “700 x 35c”) and note it down.
2. Open the rear dropout and note whether release is by lever (QR) or requires a tool (thru-axle), then measure the spacing as described above.
3. Identify your brake type — disc rotor bolted to the hub, or rim brake pads gripping the wheel rim. Drum and coaster brakes are the only exclusions.
4. Count your cassette or freewheel speeds — this confirms drivetrain compatibility but doesn't change which kit you order, since any speed count transfers to the new hub.
5. Cross-check all four against the tables above before adding a kit to your cart. If everything lines up, you're clear to order; if anything is uncertain, send us a photo before you buy rather than after.

Frequently asked questions