Originally Posted by
Chi_Z
Using SRAM red 2012 chainrings with 10sp 1070 chain. It only happens under force like you said. Never had this problem with my old bike, then I switched the components over to a new bike. Could it be a FD adjustment problem?
Seems like the chain could not shift down in time and gets stuck between the gap of large chainring and FD outer cage
Any insight and help is greatly appreciated
It shouldn't be possible even with a poorly adjusted FD. However, it might help to adjust the inside trim inboard a bit so the FD pulls the chain in more. The flip side is that this can also increase the odds of chain drop to the inside. Also consider that as chains wear they also get more flexible and that can contribute to the problem. A newer chain is stiffer (sideways) and so it carries in a bit more as it's angling off the outer ring.
As so often happens here, we can only offer possibilities and things to look for. But we don't have the bike, so you need to review and observe and see if you can form a theory.
Since the crank used to shift OK, I'd focus on the FD. Try adjusting the trim, or possibly twisting it heel in or out (trial and error) a degree or two and see if that's enough to nudge the chain in a bit more without dumping it.
meanwhile, if it only happens when shifting under load, stop doing that.