Then you have several options, you could choose to go for the safe, conservative and very common alternative – bikes that has bike chains.
But if you want to be more innovative, maybe want to prove that you are an early adopter in the urban market (ha-ha), you could go for the Trek District Bike. It uses a belt instead of a chain, in fact it might be a good alternative for my single speed. I have already had to replace two chains this year, and I give the one mounted on it right now just another month before that one must be replaced as well.
But you can be even more innovative, take a look at the Stringbike. That is for sure innovation! But it looks a bit complicated I must admit.
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