Originally Posted by
Carbonfiberboy
Since the 39T is a 10-speed ring, I get better shifting from this setup by replacing the 52 with a 53T type B ring, which is meant to be used with the 39T. The 52 is designed for a 42 middle ring.
I'm running a 52 from a Tiagra double 52/39, shifts great. The 53 I bought for the 105 crankset is off a 53/42 crankset, again shifts great. In theory my front derailleur should explode if internet experts are to be believed....