Bike keeps suddenly changes gears w/o me shifting I've noticed that there are times that my bike suddenly changes gears, without me touching the shifters. It usually happens when I'm on a hard gear and I suddenly power out of a full stop, it pops into an easier gear and my foot drops from the pedal. What's happening, and how do I prevent it from happening again?
If your chain is dropping on the front ring, it can be:
1. your BB is lose and shaking.
2. your derailleur not properly adjusted.
3. your crank is lose and shaking.
4. your derailleur or crank is bent.