Some motorcycles and many electric bikes and scooters drive the rear wheel with a toothed rubber belt instead of a chain. A belt is quiet, clean and needs no oil, but a stone caught between belt and pulley can crack it, and a loose belt can skip teeth. This page is for the final drive belt. A scooter CVT belt is different: see Replace a CVT belt.
Safety
- Engine or motor off, key out. On an electric bike, switch off and make the drive safe before touching the belt: Make an electric bike safe to work on.
- Turn the wheel by hand only. Never put fingers near the belt while the wheel can be driven.
- A belt that is cracked through or missing teeth can break and lock or free the rear wheel. Do not ride on it.
Steps
- Put the bike on its stand with the rear wheel free.
- Turn the wheel slowly and look at the whole belt, inside and outside, with a torch. Look for cracks across the teeth, missing or torn teeth, frayed edges and stones stuck in it.
- Look at the pulleys (belt sprockets). Check for hooked or worn teeth, sharp edges and stones or grit packed between the teeth.
- Check the belt runs in the middle of the pulleys and does not rub on its guard or the pulley flange.
- Check tension at the point and with the method in the manual. Many makers give a deflection with a set force, measured with a gauge. Do not set a belt by feel like a chain.
- If tension is out, adjust with the rear axle adjusters as for a chain, keeping the wheel straight: Check and adjust chain slack. Tighten the axle to torque.
- Clean the belt with water and mild soap only. Do not use oil, chain lube or solvent.
When to replace
- Cracks that go into the cords, missing teeth, or a stone hole: replace the belt.
- Worn or damaged pulley teeth: replace the pulley too, or the new belt will wear fast.
- Do not twist or fold a new belt hard. Folding can break its cords before you fit it.
Check your work
- No cracks or missing teeth, pulleys clean, belt centred, tension within the manual value.
- Quiet running with no ticking or skipping when you pull away.
If it did not fix the problem
- Clunk or shock when you pull away: Rear wheel clunks when pulling away.
- Electric motor or hub noise: Electric motor is noisy.