1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Seat clamp

Discussion in 'Bicycle Mechanics and Repairs' started by Mister Paul, 9 Mar 2008.

  1. Mister Paul

    Mister Paul Honky

    Location:
    North Somerset
    I need a replacement for the wife's Carrera Subway.

    Is there an easy way to find out what size I need? How does the size relate to the diameter of the seat post?
     
  2. Smokin Joe

    Smokin Joe Legendary Member

    You just need to know the OD of the seat-tube.
     
  3. kyuss

    kyuss Über Member

    Location:
    Edinburgh
    Assuming it's a 27.2 diameter seatpost (which most modern bikes are) it's almost certainly a 31.8mm clamp. Best thing to do though to be on the safe side is take it to the lbs and they'll measure it for you.
     
  4. bonj2

    bonj2 Guest

    Easiest and best method is to measure it.


    Why haz the seatpost clamp broken anyway? It shouldn't be the sort of thing that wears out.
     
  5. OP
    OP
    Mister Paul

    Mister Paul Honky

    Location:
    North Somerset
    It hasn't broken. We've got a Hamax child seat which slots into a bracket on the seat tube. Because the bike has a 14" frame you can't get the child seat on without removing the bike saddle. I'm fed up of having to get the allen key out every time I do this. So I want a quick release clamp.
     
  6. trio25

    trio25 Über Member

    They do break though Bonj, mine did on my road bike.
     
  7. e-rider

    e-rider crappy member

    Location:
    South West
    I'm slightly worried that you've put the 4 bolt clamping box mechanism thing for your Hamax child seat onto the seatpost and not onto the seat tube of the frame where it should be. If this is the case, it's very dangerus and NOT safe. If you are attaching this child seat to a small framed bike you often need an adaptor to make it fit - DO NOT attach it to the seat post!
     
  8. 02GF74

    02GF74 Über Member


    good point. If the post breaks, you'll end up on your back side staring up at the sky, and f*** know where the kiddie attachment witll end up.
     
  9. bonj2

    bonj2 Guest

    *sigghhhhh...*** - well you know i don't agree with child seats that only clamp onto the seat post, but given that you're happy with this, then fair enough yes just measure the outer diameter of the seat tube.
    Get a hope one for bling value.
     
  10. bonj2

    bonj2 Guest

    what possible force exerted during normal riding could cause the seatpost clamp to break, unless it's not been put on right? (and even so?)
     
  11. bonj2

    bonj2 Guest

    and what, a 14" frame? that sounds small, it's not a jump bike style one is it? (didn't have you down as the type...)
     
  12. llllllll

    llllllll New Member

    I broke one by overtightening the bolt and stripped the threads ;), I suppose that comes under the 'not been put on right' though.
     
  13. OP
    OP
    Mister Paul

    Mister Paul Honky

    Location:
    North Somerset
    Don't worry, I haven't. And I've got the special bracket for smaller frames. The bracket works well, but you can't clip it in when the saddle is in place, as it gets in the way. So you have to remove the saddle, clip the seat on, then put the saddle back.

    Sorry for not making sense.
     
  14. OP
    OP
    Mister Paul

    Mister Paul Honky

    Location:
    North Somerset
    Nope. It's for the petite person.

    You know what a Subway is bonj. Stop being silly.
     
  15. e-rider

    e-rider crappy member

    Location:
    South West
    A quick-release clamp would be the best option but beware as they tend to offer less tightening force then a normal bolt style clamp - if you are heavy (14 st+) you might find that your saddle goes down over time as you ride. They are also popular with theives!!! Why they take saddles I'll never know. I had a friend who kept having his handlebar stem stolen - what's that all about!!??!!

    Back to sizing, there are only about 3 or 4 common sizes - 31.8, 34.9, 36.4 etc.(or smaller for 'old' style narrow steel tubes) Most likely to be 31.8 if your seatpost is 27.2 (which is a very common size) You'll have to either measure it or read it, as the size is often printed/stamped on the post below the min insertion line.