Big ring over-shifting problem: flummoxed!
Completely bamboozled by this one, so calling on the collective wisdom of the road.cc community.
I recently replaced the chain on my road bike, and now when I shift from small ring to big ring, it jumps off the outside edge of the chainring. Every time.
Things I've tried without success:
1. Adjusting the big ring limit screw so the mech doesn't move so far.
2. Moving the whole mech closer to the chainring so there isn't enough room for chain to pass between mech and chainring. Just falls off the chainring in front of the mech instead.
3. Changing to the big ring slowly.
4. Putting the old chain back on (not too worn, about 0.75mm stretched) Still happens!!!
The only thing I can think of is that the big ring has worn out and needs replacing, but I'd be very surprised if this would cause such a sudden change in behaviour; I'd expect the overshifting to happen a little at first, then increasingly often, but it happens everytime now!