Seat post sizes

craigzeroone Posts: 9
edited October 2008 in Workshop
Hi all,

Would you recommend using a 31mm seat post in a 30.9mm frame? Looking at some websites they suggest a possible 0.2mm allowance either way.

Thanks for your help.

Cheers, Craig


  • Monty Dog
    Monty Dog Posts: 20,614
    Depends on the tolerances of both the frame and seatube - a seatpost is made to the actual diameter whereas the seatube is nominally 0.1-0.2mm bigger to give a sliding fit. In theory they should fit, but it depends on the actual sizes of the components. A decent LBS should have a pair of calipers or a tapered sizing gauge for the job, Trouble is, not all seatposts and frame tubes are round.
    Make mine an Italian, with Campagnolo on the side..
  • redddraggon
    redddraggon Posts: 10,862
    I like bikes...

  • Bugly
    Bugly Posts: 520
    .1 mill generally wont be a major issue but you may need to get your seat tube reamed - force fitting wont cut the mustard.

    Unless you have a reaming tool you may find the LBS route as expensive as buying a new seat post
  • That's great, cheers for all the advice.