Originally Posted by acape
Well that's the thing, I don't have it beside me, it's at home. I was planning to just get a new FD, but after some reading discovered that it might not be necessary. It sounds to me like the 31.8 and 34.9 Tiagra FDs are the same, a braze on, just with a different clamp. I was hoping to get confirmation so I could run by the LBS without having to go home first.
And the seatpost is the same size, no problem there.
Bad news. I have a couple of bikes with Tiagra front derailleurs in my basement so I just walked down to check. One's a 28.6 clamp, the other's a 31.8. Neither bolts onto a separate clamp.