I bought my first motorized bicycle last summer, a cheapo 49cc, and it seemed to work quite well. One of the biggest downers, however, was the single-speed transmission; while fine for speeds of about 15-25 kph, lower speeds would cause stalling and higher speeds produced excessive vibration. The worst part was having to push the bike up steep hills. I'm wondering if there's any way to modify this rig to allow multiple speeds, like a manual-shift transmission (or if there's another kit with this feature available). It would be great to have at least 3 different speeds.....