Originally Posted by
Al1943
I had the same problem with my wife's TA chainrings. The chain would "skate" on the tips of the middle chainring teeth instead of dropping over. I cured the problem by filing the inside edge of the teeth with a flat file. The aluminum these rings are made of is soft and files down quickly. It won't take a lot of work to thin them, and the strength of the teeth where the chain runs will not be compromised.
I also moved the chainline outward 1.5 mm with a bottom bracket spacer, but I think filing the teeth was the primary cure.
Barring any real tech info regarding the engineering behind stepping the height of ring teeth, I gave it a shot using as examples the FSA Super Road 53T and 52T, and a middle 39T from a triple. All these had pins and varing tooth heights. So with a fine file in hand I set out to profile (file down the height of) some teeth in the vicinity of where the pins are located.
Result... seems to be working. Shifting up from the granny is a touch less quick, but otherwise the chain is no longer "skating" on the teeth. Will need more time & riding to see how this goes. If this is indeed the solution, then it baffles me why TA does not review the tooth profiling of some other manufacturers.