• This topic has 12 replies, 7 voices, and was last updated 9 years ago by br.
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  • Seat clamp sizing. Help needed.
  • gsm7
    Free Member

    Hi all,

    Thanks for taking the time to look at this post and hopefully provide some answers…

    I have a GT Peace 9r that has a tatty seat clamp. I want to replace it with a QR one.
    Does anybody know the size of these or where I might find out?

    (The seatpost diameter is 26.8mm – not sure if that helps…)

    Thanks in advance

    scaredypants
    Full Member

    my guess is it’ll be about 31mm (the old clamp may even have it written on it somewhere)

    or you could measure and work it out (not my site or sums)

    lobby_dosser
    Free Member

    measure the diameter of the seat tube.

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    gsm7
    Free Member

    Thanks for the replies.

    I guess I’ll take it to my lbs and get them to measure it. I don’t have accurate means of doing that.

    takisawa2
    Full Member

    29.8 officially.
    Does the post ever slip?
    Should have been 27.0 apparently.

    Either way, a Salsa 30.0 clamp would be my first choice.
    Hope 30.0 kept slipping in my Niner (which should be 29.6 dia post).

    gsm7
    Free Member

    Interesting,

    I have never ridden it, just bought it second hand and building it at the moment. So I don’t know if the post will slip…

    SO the seatpost (26.8mm) is too narrow for the frame potentially?

    AND either a 29.8 or 30.0 clamp should work? (if I find a 27.0 seatpost…)

    Thanks for the advice.

    takisawa2
    Full Member

    GT apparently designed it for a 27.0 post, but sold them with 26.8 as that was a more common size… 😐
    (Or something like that, allegedly)though.d luck finding a 29.8 clamp. I think Thomson do a non-QR version, & Niner sell a 29.6 made from Brie.
    Salsa’s 30.0 clamp will have no issues though.

    gsm7
    Free Member

    I have managed to locate a 29.8mm QR clamp.

    If I buy that and a 27.0 post, it should all be dandy….???

    Thanks again

    br
    Free Member

    You can buy calipers for a couple of quid from Halfords and the like, and then you’ll ALWAYS be able to measure stuff.

    gsm7
    Free Member

    noted! thanks

    ratherbeintobago
    Full Member

    Thomson do a 27.0 seatpost.

    timba
    Free Member

    Occasional use; adjustable spanner, adjust to fit the tube, ruler. There can be some play/inaccuracy in an adjustable though…

    br
    Free Member

    gsm7

    I was been only half sarcastic as I’ve learnt not to trust any manufacturers stated measurements, especially where seatposts/clamps are concerned.

Viewing 13 posts - 1 through 13 (of 13 total)

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