I've been thinking a lot lately about how bicycle transmissions could be simplified. My bike has crappy components and the chain slips often during shifting and the like. I was thinking about using a belt driven mechanism. It seems like a belt drive would be much more reliable. Continuous speed transmissions are used in belt driven electronic power tools such as lathes. "A belt drive continuously-variable speed automatic transmission comprises two variable-pitch pulleys and a belt which is V-shaped or trapezoidal in cross-section, extended between the two variable pitch pulleys." I don't know how practical this could be on a bike because I don't know how widely variable the belt positions would be in the limited space the rear cassettes are generally located. I just thought this would be cool but I don't have the resources to design and build this myself.