From Unofficial Zero Manual
Drive belts fail by snapping or by stripping the teeth.
- On Landing
- The most common situation for a belt snap is when going over a major bump or jump where the rear wheel leaves the ground.
- If, while airborne, the throttle is not immediately relaxed, the rear wheel will rapidly spin up.
- A wheel that is moving extremely quickly in the air will get jerked back to its regular speed on landing. This is transmitted to the belt through the rear sprocket and can easily strip teeth.
- From Debris
- Gravel or sand that gets thrown between sprocket teeth and the belt will force the belt to expand quickly under load, and can cause it to snap.
- Reportedly, sand is a much more reliable path to belt failure than gravel.
- The sprocket tooth design is meant to deflect gravel to the inside of the swingarm towards the wheel.
- The bike has an upper debris guard made of soft ABS plastic, but does not have a lower guard.
- From Mis-Alignment
- An unaligned belt can wear really badly and break sooner.