Sydney - I don't know why it is that way but it is. When I bought the bike used a year ago, I tried lowering the der to the proper height but couldn't get there. I even took it to the local Trek dealer and they scratched their heads for a half hour before I discovered that the big ring was a 50. I changed it to a 53 and the der got to where it needs to be. I don't mind going to a clamp-on if it makes sense and doesn't look weird - is the 1 3/8 the right size? I believe the tube measures in at 34 mm.

Thanks.

55/Rad