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  1. #1
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    Bontrager XXX Mast Seat Post Adjustment

    Hey Trek riders. I noticed that the left and right hand side on my Bontrager XXX lite mast is not tilted the same... I went to the Bontrager website.. They rave about the "Infinitly adjustable Tilt" seat post... Hey that's great, but they don't state how to adjust it. I found a couple of other posts that had the same problem, but the thread never extended with an answer.

    It's the post that comes on Trek Top Fuel SSLs.


    Anyone know how to adust the tilt on one of these??? It is NOT like any other post I have used. It's the full carbon model (the only metal parts are the single screw and seat rail clamps)... There is an inner nylon part that 'looks' like it should rotate.. but I don't want to force it and snap the seat post. Loosening the seat post screw (I completely removed it along with the rail clamps and seat)... does not result in 'loosening' the tilt adjustment.

    Thanks
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    Last edited by Bruce M; 02-11-2011 at 01:29 PM.

  2. #2
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    If it is like my RXL ACC, just loosen the screw (do not remove the seat) and tilt the seat to the correct angle without moving the saddle fore or aft. Tighten to the proper torque.

  3. #3
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    I should have clearly stated that loosening the seat clamp does not work

    I've been riding and racing mnt bikes since the early 90s. I built most of my bikes. This is not a case of the user doesn't know how to adjust a standard seat... The last response from Bontrager is "Sometimes the circular rail carrier gets stuck"... I loosened the seat clamp and then tried to use the seat rails to tilt the seat (front or back)... no joy. It's REALLY stuck.

    It is supposed to be "infinitely" adjustable... which is funny as mine is locked - Luckily it is only tilting a tiny bit too high.

    Note that this is the Trek Custom 34mm 'Mast' Seat Post... it is no the same as the Standard XXX Lite Posts

    I'll take it to the LBS tomorrow.

  4. #4
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    I've seen them get stuck like that before. It just needs to be taken apart and greased (slightly).
    Worked at Trek/Fisher dealer 2008-2013. Only a little biased.

  5. #5
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    dun dun dun du du dun dun! hammer time!

  6. #6
    I hate that name.
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    Quote Originally Posted by William42
    dun dun dun du du dun dun! hammer time!
    I think you meant to say duuuuu dududu, duudu, duudu
    Worked at Trek/Fisher dealer 2008-2013. Only a little biased.

  7. #7
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    How to set up Bontrager race xxx lite seatpost

    1. Clamp seatpost in seat tube. 2. Remove saddle fixing bolt and upper saddle rail clamps. 3. Carefully pry out the two lower saddle rail clamps. (I used a hex key.) 4. Apply a thin layer of carbon assembly paste to the lower clamps and insert them back into the seat post head. 5. Hold the lower clamps in place and place a level across each lower clamp to ensure the are positioned to give the desired saddle tilt. Once this is achieved apply some tape to the bottom edge of the clamp just to ensure they do not move during the next steps. (you can remove the tape afterwards) 6. Reinstall upper saddle clamps and fixing bolt. 7. Apply thin layer of carbon assembly paste to saddle rails and carefully install it between the clamps in the desired fore/aft position. 8. Slowly tighten the fixing bolt making sure the saddle clamps are correctly positioned around the rails. Tighten to max 16 Nm unless you have carbon rails that have lower specs.

  8. #8
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    Aha!!!!.. I whittled a 5" wood dowel so it would just fit into the head of the seat post..with the seatpost clamped in the seat tube and the top of the seatpost against a 4"x4" that I leaned against a tree.. I Slammed the holy shite out of the wood dowel it took about 6 swings with everything I had and the seat rail popped out..The other side was easier to get to (now that the one side was open).. The florida heat/salt/sand must have caused corrosion that sealed the little bugger... once free, both sides do spin freely. I put in some paste and now the seat adjusts like new.. Thanks for the distructions...
    Last edited by Bruce M; 05-05-2011 at 04:41 PM.

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