I’ve always assumed that it is a safety measure. If one falls off, the other continues to drive the wheel and you don’t fall. I could be wrong, though.
I always assumed that too, but, recently was talking to a (double chain) giraffe rider, and he reckons that if a chain goes on a double, you’re coming off anyway.
One suggested benefit to the double chain is symetry i.e. less likely to scew the hub- don’t know how true that is.
I think it’s all about bending forces through the frame.
two chains won’t twist the frame like one chain will.
I think it’s less about a “chain falling off” and more about a chain breaking. Chain failure on a giraffe would be seriously dangerous.
Between that, less frame flex (always pulling to one side) and the likelihood of less chain lash when changing directions, two chains would be better.
Just had a thought- if it is true that a chain breaking on a double chain giraffe is as dangerous as the chain breaking on a single chainer- then, arguably, wouldn’t a double chainer actually be less safe than a single?
Because, having 2 chains, there’s double the chance of a breakage.
… but half the stress per chain, dramatically reducing chance of failure.
- They look cooler
- Less torque on the frame (the frame will still get torqued front-to-back, but not to the side)
- 50% reduction of stress on each chain virtually eliminates worries of chain breakage