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TCR Advanced seatpost torque ratings - 2 dead seatposts

Hermes3000Hermes3000 Posts: 23
edited April 2010 in Workshop
I've destroyed 2 seatposts in 6 months - by tightening to 3.5Nm.

The new, and considerably more competent bike shop just replaced it again. I tested the bolts with the torque wrench, and they were less than 2Nm - finger tight with the short end of a hex-key. This is considerably less than 4Nm, which the old bike shop told me.

I just spend 20 minutes riding up and down the street, while I bounced up and down on the saddle - it hasn't slipped so far.

Given this expensive experience, and my failure to find any useful information on the web, I thought others might find this helpful.

Posts

  • rakerake Posts: 3,281
    so effectively then your torque wrench wrecked your bike twice.plaesed i didnt buy one.
  • HonestAlHonestAl Posts: 406
    I've got a TCR advanced too. I mailed Giant asking specifically about torque settings. They sent me a PDF generic manual for Giant bikes but which has detailed specs for carbon frame torque settings, which states 7.8 - 11.7 Nm for binder bolts. Admittedly it doesn't specify whether that's for a carbon seatpost but I've done mine to 7Nm without any ill results (yet!) and I'm no lightweight Having said that I've stripped the threads on the seatpost collar and had to replace it. If you want a copy of the manual feel free to pm me with an email address
    "The only absolute statement is that everything is relative" - anon
  • I spoke with a giant mechanic today.

    He told me that 3Nm should be Ok for an aero seatpost.

    4Nm for the stem/steerer

    It would be difficult to damage the frame by over-torquing the front derailleur (braze-on) clamp - he said the shimano specs of ~5 - 6.8 Nm is Ok

    Brake bolts should be just tight enough to ensure the caliper does not rotate - the shimano spec of 8-10Nm is for aluminium frames - too high for carbon

    Hopefully useful for others.
  • maddog 2maddog 2 Posts: 8,114
    get yourself some carbon paste. That effectively reduces the torque required to hold something steady. I use it everywhere now :wink:
    Facts are meaningless, you can use facts to prove anything that's remotely true! - Homer
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