Chain breaks are rare on S-Pedelecs, as are belt breaks. However, both do occur. In the case of the belt, there is also the damage pattern of missing teeth.
The reasons for belt breakage can be complex. They range from a lack of care and a certain 'carelessness' on the part of the user, to structural damage due to incorrect loading, to low/too high tension, twisting, force, skewing...
The belt shown in the picture above right broke at ~5,000 km and just under two years in operation. The reasons could not be determined. The belt on the bottom right had a mileage of ~20,000 km.
If a belt has tooth failure, this is usually caused by the belt skipping. This is caused by the belt tension being too low or objects (e.g. branches) getting caught between the belt and the pulley. Small stones in the 'center track groove' can also cause this type of damage.
In general: carbon parts are smart, extremely resilient and durable as long as the structure is not damaged. Extremely little damage occurs to carbon belts, which shows that the technology has considerable 'redundancy'.
> See SHIFT - CHAIN vs BELTS - 'Comparison'
> See FAQ - 'Maintenance - chain and belt - what does Stromer say?
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