Seat Post Clamp Snapped...AGAIN!!

Grenouille
Grenouille Posts: 50
edited November 2013 in Workshop
I have a Spesh Roubaix Elite and last month the seat post clamp snapped on a ride (what fun!)





I got a replacement on warranty so that was fine but last night I was putting it on the bike and tightening it with a torque wrench when it happened again!



I will go back to the shop for another replacement on warranty but I don't plan on fitting it as I have no confidence now it its ability to stay in one piece.

What replacement would anyone recommend? These look somewhat tougher:

http://www.wiggle.co.uk/hope-single-bol ... ost-clamp/
http://www.wiggle.co.uk/thomson-seat-collar/
http://www.wiggle.co.uk/chromag-non-qr-seat-post-clamp/

Also, the Spesh seat post collar is 32.6mm - will 31.8mm be ok as they are the closest for the Thomson and Hope collars?

Comments

  • sungod
    sungod Posts: 16,521
    looks like it failed at the same place, is there burr/edge/whatever at that point on the tube?

    if you're replacing, stick to the correct size clamp
    my bike - faster than god's and twice as shiny
  • Wooliferkins
    Wooliferkins Posts: 2,060
    32.6 is odd by any measure. I doubt the 31.8 will slide over the top of the seat tube. Forgive me for an egg sucking question but you're not getting your Nm and lb/f mixed up on the torque wrench are you?
    Neil
    Help I'm Being Oppressed
  • Grenouille
    Grenouille Posts: 50
    I forgive you! But no, the torque wrench is set to 6n-m.
  • desweller
    desweller Posts: 5,175
    I'd be inclined to find the right size clamp. You might be able to force a smaller one on but it is quite a big size difference. Have you tried calling one of the Specialized high street stores?
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  • Wooliferkins
    Wooliferkins Posts: 2,060
    Grenouille wrote:
    I forgive you! But no, the torque wrench is set to 6n-m.
    Thanks. Years of working in an environment where, "It just snapped boss" sent a despairing shiver down my spine
    Neil
    Help I'm Being Oppressed
  • andyrr
    andyrr Posts: 1,819
    Max torque is 6.2 ? Does it actually need to be torqued right up to close to that ? Sorry for asking what might seem an impertinent question but if your wrench is a little out and reading low then your 6 could be 6.5 and that, for what is not a particularly sturdy bit of metal, could just tip it over the edge. If it is a carbon post then mabe use some assembly compound which could allow a lower torque on the post clamp.
  • Wooliferkins
    Wooliferkins Posts: 2,060
    When designing something the loads required to cause failure are usually at least 50% over the user loading
    Neil
    Help I'm Being Oppressed
  • slowbike
    slowbike Posts: 8,498
    Wooliferkins wrote:
    When designing something the loads required to cause failure are usually at least 50% over the user loading

    Which makes you wonder if the OPs torque wrench is not calibrated. 50% over 6Nm is only 9Nm - easy to apply by hand ...
  • Monty Dog
    Monty Dog Posts: 20,614
    Yup, consistent failure would suggest over-tightening, easy with a badly adjusted torque-wrench. I wouldn't attempt to fit a 31.8 in place of a 32.6 either.
    Make mine an Italian, with Campagnolo on the side..

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