Design of continuously variable bicycle transmission

As the people’s needs develop, so does the technology. Bicycles exist already for a long time, and ever since the appearance of electrically driven ones, the necessity to change their drivetrain and transmission started getting more important. What makes the development of bicycles even more impressive is the fact that their efficiency ranks first among travelling animals and machines, if we consider the energy consumed by moving a certain distance as a function of body weight. Different bicycle drivetrains are researched and explained in this report, especially CVT hubs. A continuously variable transmission based on a patent of Hiroyuki Urabe has been designed with the CAD method, and their main parts were analysed using the FEA method. The final construction has a theoretical total ratio of 400% and a mass of about 2.7kg (without lubricant). This transmission is using the principles of frictional traction to transfer torque. In general, this work shows how the designing process proceeded and gives an idea, how this type of gearbox could be constructed.