I don't know which of these 2 things my chain does, but it's not good! If I apply much pressure at all to the pedals when riding, a "skip" occurs as if the chain is slipping off the gears briefly, or something else is happening. It's a sudden jerk that causes my feet to slip off the pedals. So when I ride this bike, I have to pedal very, very gently and build up speed very gradually.

I've tried to figure out what is happening by watching the gears while riding and applying more pressure when pedaling to make it skip. It doesn't [I]appear[I] that the chain jumps off the gears. Also, I've put hard pressure on a pedal while stationary while applying the brakes at the same time so I could watch everything up close. It "skipped" and my foot slipped off the pedal and I scraped my ankle on it.

I've sprayed lube on the chain and also into the hub. It didn't help. I also cleaned the chain, which didn't help either.

This is a bike I've ridden alot in the rain and Winter, which I understand can cause problems.

Does anyone know what might be causing this problem?