It is the most common question bikers have. The fear of a broken chain is based on the conviction that the chain „ can normally” break at some time. It doesn't break normally - there is a specific reason for that. The chain in a bike drive breaks always when it gets loaded working out of alignment, which is normal in a traditional drive because this is exactly how it works to achieve different ratios. Especially it happens in situations while changing gears and applying pedaling force at the same time. Forces of various directions generated then, simply disconnect particular pieces of the chain - pay attention to the way how the chain gets usually damaged and you will see that it is always about disconnecting the pieces, not about breaking pieces into half itself, and even if one side of the chain breaks - it happens because of the other side gets disconnected first. So it is all about the wrong and risky way of how the chain is being used - which comes from an out of date drive design.
The Inner Drive System has a solution for this. It uses a gearbox to change gears while the function of the chain is limited to transfering the power from the gearbox to the wheel. The chain cooperates with only one chainring in the gearbox section and one in the hub section. It's kept in alignment all of the time. In this configuration it is simply impossible to break the chain with the force coming from the riders legs only. This force can be precisely counted and the right chain can be used to carry it - and this is a proper engineering.
The perfect example of succesfull usage of the chain is a timing-gear in a car engine. The Inner Drive System is about to work exactly the same way.