Clipless in Coeur d'Alene
Joined: Mar 2012
Posts: 1,996
Likes: 22
From: Coeur d'Alene, Idaho
Bikes: Tandems: Calfee Dragonfly S&S, Ventana ECDM mtb; Singles: Specialized Tarmac SL4 S-Works, Specialized Stumpjumper Pro, etal.
Chainring tooth profiling question - Specialites TA Alize
I'm using a Specialites TA Alize 48T chainring in conjunction with a 10spd Ultegra Di2 6770 front derailleur and Ultegra 10spd chain. The Alize is the "big ring" outer.
A problem I'm having is with the upshifts from the inner to outer, where the chain frequently rides up on the Alize teeth and does not quickly settle into the valleys between the teeth. This "walking the teeth" has caused the chain to derail to the outside.
Looking at the Alize chainring I observed there is no variation in the teeth profiles, other than one single mid-height tooth around the entire circumference. On other outer position chainrings I have on hand (ie: FSA for example) those teeth of tall, medium and low height profile.
Question 1:
I am wondering if filing down the heights of some teeth on the Alize would help the chain to drop into the proper position better and aleviate it from walking along the tops of the teeth?
Question 2:
Also, I looked at my 53T and 52T FSA Super Road chainrings for examples of where to place tooth height variations in relationship to the chainring pins, but it seems a bit random to me. Perhaps one pattern is to reduce the height of the teeth immediately above and after (in the direction of power rotation) a pin location. Is there any guide or wisedom to creating a pattern for teeth profiles?