Bicycle Mechanics - Seatpost Clamp

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jignall

08-31-08, 08:40 PM

Hi. I have a 2007 trek 520 which uses a 27.2mm seatpost. I need to replace the seatpost clamp but it doesn't appear the measurements are based on the seatpost diameter but instead the seattube diameter. Is this correct? If so, anyone have any idea what size seatpost clamp I should be looking for?

operator

08-31-08, 10:25 PM

Seatpost collar is independent of the seatpost size. Obviously the collar can't be smaller in diameter than the post.

JiveTurkey

09-01-08, 01:52 AM

Probably 31.8mm (1-1/4"). Measure the diameter of the seat tube (frame) where the seatpost enters.

HillRider

09-01-08, 06:46 AM

Seat post collars commonly come in three diameters 1-1/8" (28.6 mm), 1-1/4" (31.8 mm) and 1-3/8" (34.9 mm). Your bike most likely takes one of these.