Bicycle Mechanics - 30.9 seat post in 31.6 seat tube

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qr409tz8
05-09-08, 07:22 PM
Title says it all I think. I have a 30.9 seat post and a frame that takes a 31.6. Does that 0.7mm matter? I dont see as anyone making a shim that small... does it hurt anything to just crank down the collar a little more? Should I cut a strip of aluminum flashing and stick it in there? couple wraps of tin foil? Im thinking as I type so I may be spurting stupid ideas. But any and all opinions are welcome.

relyt
05-09-08, 07:47 PM
It does matter, a lot. Don't do it. Don't shim it either. Buy a new post.
Ex Pres
05-09-08, 08:16 PM
0.7mm is huge. Heck, 0.2mm kept my seatpost slipping down and made me crazy. I have used a shim before on a really odd sized Mongoose (30.2mm IIRC-something I could only find in a Colnago post). It worked, but I won't say it was an ideal fix. If you can find a 31.6, buy or swap for the correct post.

qr409tz8
05-09-08, 08:41 PM
I was afraid you guys were going to say that. I might have to give up my nice Thompson post for a cheaper one... Cant afford to replace that thing at the moment.
Ex Pres
05-10-08, 06:25 AM
I was afraid you guys were going to say that. I might have to give up my nice Thompson post for a cheaper one... Cant afford to replace that thing at the moment.

Put it on the for trade threads in the other subforums. you never know. you might get to swap for only the cost of shipping