Hydraulic Drive Explained

 The Idea is good i had also thought about something like this. But the problem is the Efficiency, a normail chain gear has a efficiency of 95% even the best hydraulic system woud just reach an effiency of 80-90%.
For a German Science Competion i worked on a special CVT-Gear for bikes perhaps you will hear some news about the first prototypes in summer on pinkbike.

 great! but you still didn't explain your "gear box".