[mikeraj]

I need to replace the Shimano FD4503 Tiagra Triple front derailleur on my Trek 1.5 2010. However, I'm unsure of what the correct clamp size is: 31.8mm or 34.9mm? Thanks in advance.

 

[Cyclo-phile]

Have you tried measuring it???

31.8mm = 1-1/4"
34.9mm = 1-3/8"

 

[pmt]

Yeah, just measure it with a caliper. They have calipers at Sears for as little as $7.

 

[echo7]

I need to replace the Shimano FD4503 Tiagra Triple front derailleur on my Trek 1.5 2010. However, I'm unsure of what the correct clamp size is: 31.8mm or 34.9mm? Thanks in advance.

34.9..

i used to own a trek 1.2 (2010)

 

[PlatyPius]

I need to replace the Shimano FD4503 Tiagra Triple front derailleur on my Trek 1.5 2010. However, I'm unsure of what the correct clamp size is: 31.8mm or 34.9mm? Thanks in advance.

Did you think about taking it off and looking at the inside of the clamp where the size is stamped/cast?