the chain is not too short...I can go big big without any problems and when this happened I was in 2nd gear so there was def no shortage of chain! Isnt if the chain is too short it would pull hte derailler forward not backwards...direction of chain.
I thought it might have got caught in the spokes since it was bumpy and spun back around but nothing like that has ever happened before...is that common?
I cant think of anything else but the derailler has to flex a shat load to get into the spokes. I was thinking my brute force may have tweaked the wheel off center as I pedaled and made it go closer to the derailler and then the derailler went into the spokes and spun around...
I know the front wheel flexes side to side about an inch (much better then the original wheels and these wheels are true as the day I bought them when put on a stand) when im out of the seat hammering but I never thought about the back and I wastn out of the seat hammering...I was sitting hammering.