Advertisement
If you have a new account but are having problems posting or verifying your account, please email us on hello@boards.ie for help. Thanks :)
Hello all! Please ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere. If you need help to verify your account contact hello@boards.ie

Seat post and Seat tube size

Options
  • 06-02-2011 6:29pm
    #1
    justo
    Registered Users Posts: 242 ✭✭


    O.k. dopey question:

    Does a seat tube size 27.0 mm take a 27.0 seat post, or does the seat post have to be slightly smaller in diameter to fit in? Say 26.8 for example?

    Cheers.


Comments

  • Options
    #2
    bcmf
    Closed Accounts Posts: 6,679 ✭✭✭bcmf


    yeah seatpost a couple of mms smaller then seattube.


  • Options
    #3
    justo
    Registered Users Posts: 242 ✭✭justo


    So...

    I just tried to order a 26.6mm seat post for my 27.0 seat tube, but the dealer told me 'for a 27.0 seat tube, you need a 27.0 seat post'.

    Confused.

    Any insights?


  • Options
    #4
    karlmyson
    Registered Users Posts: 144 ✭✭karlmyson


    bcmf wrote: »
    yeah seatpost a couple of mms smaller then seattube.

    No.

    Seatpost diameter should match exactly the seat tube aperture diameter, so 27.0mm seatpost for a 27.0mm seat tube opening. It's no more complicated than that.


  • Options
    #5
    kumate_champ07
    Closed Accounts Posts: 7,150 ✭✭✭kumate_champ07


    its a 27mm seatpost you need. no seatube has a 27mm diameter, its usually 28.6mm for steel frames and larger for alluminium and carbon.


  • Options
    #6
    justo
    Registered Users Posts: 242 ✭✭justo


    kumate_champ07 wrote: »
    its a 27mm seatpost you need. no seatube has a 27mm diameter, its usually 28.6mm for steel frames and larger for alluminium and carbon.

    Thanks. This is helpful.

    The documentation that came with the bike says '27mm Seattube' it also came with a seat post 27.0mm diameter but I can only just get it in the top of the seat tube. I just can't see how it could possibly be pushed down the necessary amount. Also, I don't really want a seat post that is not easily moved when I want to.

    I think I need to get a calliper to the seat tube to get the exact measurement.

    grrrr.


  • Advertisement
  • Options
    #7
    penexpers
    Closed Accounts Posts: 4,038 ✭✭✭penexpers


    kumate_champ07 wrote: »
    its a 27mm seatpost you need. no seatube has a 27mm diameter, its usually 28.6mm for steel frames and larger for alluminium and carbon.

    28.6 mm is the external diameter of the seattube (for band-on FD). The internal diameter will usually be smaller. On my (steel) bike it takes a 27.2mm seat post.


Advertisement