Chain comes off under high load When I ride up a particularly steep hill my chain nearly always comes off. It didn't used to do this but now happens practically every time. I presume something has either worn or come out of alignment. It's fine in normal riding, but can't seem to handle this more extreme situation.

What is it most likely to be?


Chain wear?
Chainring wear?
Front Derailleur issue?
I would look for a bent or damaged chainring tooth or even a bent portion of the front chainring. Depending on the damage it can behave “normally” under a low load, but eject the chain under a higher torque load.