Originally Posted by
wobblyoldgeezer
........You mention that the biopace was a recent change. I would suspect that the front changing mechanism that worked well on your previous double chainring has the reach for 2 chainwheels, as you state, but not for the additional one ...........
(In short, I think its a 'double to triple' issue, not a 'biopace' issue
I think you may be on to something here!
Is the FDER at the max range of it's outer travel?
If "centered" properly over the large ring, the chain should hit the inner cage before "falling" to the middle ring.