I didn't know I needed choo-choo train noises in my bicycles but I do! You can use this for anything, a choo-choo garage door opener, a choo-choo elevator, a choo-choo plane!
Oscar Wildcat Gotta hand it to Phineas T. Freakears. I thought the energy density would be terrible but it's roughly comparable to lead acid/DC motor!!! Which is still way heavy for a ten speed but hey if you don't mind that whopping steam engine tank on the back you're golden.
Monkey Napoleon Maybe he can get the same running time as an equivalent weight electric drive, which I seriously doubt, but the inefficiency of his fuel source (an air compressor) totally rapes the overall efficiency of the system.
If you had ass-dreads long enough to try and convert a regular bicycle into a powered one, you'd be way better off getting a custom li-ion cell made.