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Seat post

twizatwiza Posts: 38
edited August 2013 in Workshop
I'm trying to replace the seat post on a fixie I've just been given as it wouldn't go high enough. I took the old one into my local shop who measured it at 26.8mm and supplied me with a new one.

However when I try to insert it, it will only go in about 3 inches before it gets stuck, only about half of the minimum insertion length. I've got the clamp fully undone, applied plenty of grease, and given it as much persuasion as I dare. I also tried removing and inspecting for a blockage, running a file around the inside in case of some fakes of paint but still no joy.

Does anyone have any suggestions for loosening/inserting, or if it is a case of getting a skinnier post, how much less should I go for?



  • brearleybrearley Posts: 165
    do you have a vernier to measure the OD of the seatpost new and old?
    does it get hot when you try and get it any further in?
    if it is definitely the wrong size go for a 26.6mm post
  • twizatwiza Posts: 38
    They measured the old seat post in the shop, haven't done internal but assume the top at least is the same. Will test the warmth later
  • crankycrankcrankycrank Posts: 1,830
    Did your old seatpost go down further than 3 inches? If so then the new one is the wrong size. It's not likely but the new post could have been damaged so that it's not perfectly round or not machined properly. Best to check with some calipers to rule it out. Also, I've seen some seatubes not reamed properly so that there is a slight step at where the reamer insertion stopped but may be hard to detect by eyeballing. Run your finger down the tube to see if you can detect any ridges.
  • twizatwiza Posts: 38
    The old post wasn't so much of a post as a fitting, it didn't allow for any variation of height. The new post appears to be sound, no ridges or variations in diameter. It is quite a long new post as I'm 6'7" but would expect a 60cm Dawes frame to be capable of taking a larger post
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