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Thread: Seat Post Trauma :(

  1. #11
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    Okay, I think I will tighten seat post to the point of secure fit and working properly (as in dropper). Lube the bike and all that and go and ride If the post drops again, then I reckon it's back to the shop for a replacement. I did also think the LBS were a bit sure of the creak location, I know my BB will be up soon...

  2. #12
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    How good a fit is the Reverb in your frame with the clamp backed right off? Any wobble fore and aft, side to side?

    It sounds like it's not a perfect fit to me, even with the clamp done up tight the section of post below the clamp can rock very slightly in the frame and the post will creep down. It could also explain the creak and why the Reverb is binding when you do the clamp up tight - it's not clamping evenly, more likely just pinching it either side (depends on the design of the seat clamp collar).

    If this is the cause it may be possible to shim the frame...

  3. #13
    Senior Member Rob_A's Avatar
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    My reverb doesnt work properly either if the seatpost clamp is too tight, and it is surprising how little force is actually needed to hold it securely while maintaining the dropper function.

    Maybe a different seat clamp may help? One that spreads the load a bit more?

  4. #14
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    Perhaps my torque wrench is duff!! But it's new Anyone recommend a good Torque wrench, 1-24NM, easy to set and read?!? 1/4 " please

  5. #15
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    Can't help with a torque wrench - but if your post is binding before you stop it slipping then there is something else wrong somewhere. I checked and I can do mine up pretty tight before it starts to bind, but then my Reverb is 9 months old now and has been up and down more times than, well you know the rest of that one...

    Did you check the fit of the post in the frame with the clamp undone? Might not be the answer but it's one more thing to tick off.

  6. #16
    Senior Member Tazzedx's Avatar
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    You can usually get the Torque Wrench re-calibrated someone on here will doubtless be along with a name of company to help you.

    Alternatively:http://www.chainreactioncycles.com/S...=Torque+Wrench

    But don't go mad just yet, someone on here will know how to help you or suggest a possible fix.
    MTB'ing As addictive as Cocaine And Twice as Expensive! Mace Just Makes Me Horny!
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  7. #17
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    Well the plot thickens! When I first fitted my reverb, the LBS fitted it and applied grease!! They used my existing Q/R clamp. The post slipped on a ride, I then tightened the Q/R clamp, as anyone would, but not over doing it and hey presto the seat dropper did not function (the binding happened). So I fitted my Q/R Hope clamp but that didn't seem to be working well. So I bought a new Hope clamp, non Q/R and this was okay until it slipped again and then well you know the rest.

    Anyway, I have just fitted my old Q/R again and the creaking has gone and I have no binding, so maybe I have sussed it?!

    Seat post in tube without any clamp, there is very slight movement, as in it's not the tightest fit, same pretty much as my Thomson post, 30.9 seat posts and 34.9 clamps.

    How should a seat post sit in a frame without any clamp; surely just goes in and out?

  8. #18
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    6Nm is not a great deal. Nm is short for Newton-metre, ie a Newton of force applied at the end of a one metre lever. Very approximately a Newton is about a quarter of a pound in weight and a meter is 3.3 feet. So 6Nm is about 5 pound-feet or a five pound weight at the end of a 12" lever, or ten pounds at the end of a six" lever.

    Here is a handy torque converter to download.
    http://www.boltscience.com/pages/convert.htm

    To calibrate your torque wrench, watch this:
    http://www.youtube.com/watch?v=RUD81N_TlS8
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  9. #19
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    Thinner clamps with slender bands of even thickness tend to give the most even clamping around the tube - some of the thicker bling ones can work like a vice, just clamping the sides of the tube - maybe this is what was happening here?

    With no clamp, your post should be a snug fit in the frame, ideally needing very light pressure to get it to slide. If there's any obvious wobbling then either the post is the wrong size or the frame is worn or stretched.

    I had an old aluminium Cannondale that was so badly worn by many years of gritty grease that I had to have it resized.

  10. #20
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    Oh my word! The post that was in there in a Thompson jobby. The new seat post is of course the reverb. The Thompson did seem to rock a bit unclamped. Anyway, the reverb post without a clamp moves more right and left than it does front to back. Blimey, has my frame worn out?! Only had her since 2008.... The Hope clamp seems to be doing the right thing again now, but would this 'unfitting type play' without clamp make that bigger a difference to how torque settings work? Calling all the engineers out there?

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