Quick answer: Most hardtail mountain bikes will fit our kits. Run through the 4 quick checks below, which only take about 2 minutes and a tape measure.
4 quick checks
| Check | Fits | Won't fit |
|---|---|---|
| 1. How the back wheel comes off | Quick-release lever, and the slots are open at the bottom | A thick bolt through a closed hole (called thru-axle) |
| 2. Gap for the back wheel | 135mm for 250W to 3000W, 150mm for 5000W | Other sizes: email us, as we may have an option |
| 3. Frame | Aluminium or steel | Carbon (it can crack) |
| 4. Battery space | Room inside the main triangle | No room? A slim downtube battery may work |
How to do each check
1. The back wheel. Have a look where the wheel meets the frame. If there's a lever you flip open, that's a quick release and you're good to go, but if a thick bolt passes through a closed hole, that's a thru-axle and our kits won't fit.
2. The gap. Take the back wheel out and measure the space between the inside of the two slots. Most mountain bikes come in at 135mm.
3. The frame. The material is usually written on the frame itself or listed online. Aluminium (alloy) and steel are both strong enough for a hub motor.
4. Battery space. Measure the main triangle, which is the space between the top tube, down tube and seat tube, then compare it with the sizes in our battery guide.
One small extra: our motor uses screw-on gears (called a freewheel). If your bike has the slide-on kind (a cassette), don't worry, because a new freewheel is cheap and easy to swap in.
Bikes we know fit
In the table below, M+ means size Medium or bigger and L+ means Large or bigger. Bigger kits need a bigger frame so there's room for the larger battery.
| Bike | 1000W to 2000W | 3000W | 5000W |
|---|---|---|---|
| Giant Talon 4 | pre-2023, M+ | 2017-2024, L+ | pre-2023, L+ |
| Giant Talon 3 | 2017-2024, M+ | 2017-2024, L+ | - |
| Giant Talon 1 and 2 | 2017-2024, M+ | 2017-2024, L+ | L+ |
| Giant Fathom | 2017-2018, M+ | 2017-2018, L+ | 2017-2018, L+ |
| Giant ATX 3 | All years, M+ | All years, L+ | All years, L+ |
| Norco Storm | Storm 4, pre-2023, M+ | Storm 4, pre-2023, L+ | pre-2023, L+ |
| GT Aggressor | pre-2023, M+ | pre-2023, L+ | pre-2023, L+ |
| Merida Big Nine | pre-2023, M+ | pre-2023, L+ | pre-2023, L+ |
| Merida Big Seven | pre-2023, M+ | pre-2023, L+ | - |
| Trek Marlin 5 and 7 | Gen 1-2, M+ | Gen 1-2, L+ | Gen 1-2, L+ |
| Specialized Rockhopper | M+ | L+ | pre-2021, L+ |
| Fluid Summit and Nitro | M+ | L+ | - |
| Norco Fluid | - | - | L+ |
| GT Avalanche Elite | - | - | L+ |
| Polygon Xtrada 7 or 8 | - | - | L+ |
Plenty of other bikes work too, so if yours passes the 4 checks, that's a really good sign.
Watch out for newer models, because some bikes changed design over the years. For example, the Trek Marlin 7 Gen 2 has open slots and fits nicely, but the Gen 3 has closed ones and won't.
Buying a bike to convert?
- Facebook Marketplace is a great place to find a good second-hand bike.
- Look for a quick release, an aluminium frame and disc brakes.
- Go for a size M or L so there's plenty of room for the battery.
Common questions
Does wheel size matter?
Only in that you should pick the kit in the same size as your wheels now (26, 27.5 or 29 inch), which you'll find printed on your tyre.
My bike isn't on the list, can I still use it?
Most likely, yes. If it passes the 4 checks above, it should fit just fine.
Still not sure? Email a photo of your bike's back wheel to sunny@ampx.com.au and we'll happily check it for you.