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  1. #1
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    Stumpjumper 29 HT 100mm fork conversion

    I could use the 100mm fork on my bike because some tracks here are very rough, I am wondering how this will affect the bike's geometry though. As I understand the head tube will be higher - that is not really a problem, I can just remove the spacers from under my stem, but I am more concerned about the head tube angle becoming less steeper (is that right?), I am concerned on how this will affect my climbing, as for example comparing stumpjumper ht with epic (epic has less steep head tube) I can feel the epic's front wheel lurking a bit during climbing Any ideas on how to calculate the head angle with 100m fork? thoughts?

  2. #2
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    When I bought my 2012 Expert 29er I had the shop remove the spacers from the Rockshox SID fork so max travel was 100mm. Climbing was OK (thats largely technique dependent), but the steering was not as sharp as I wanted. Have since replaced the SID/Brain with a Manitou Tower Pro 100mm fork which has 48mm offset. The ride and and especially the handling are much improved: sharper steering, stiffer front end with the 15mm axle. I can also adjust the platform lock-out and low-speed compression damping on the fly with the top knob.


  3. #3
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    Quote Originally Posted by madhead View Post
    I could use the 100mm fork on my bike because some tracks here are very rough, I am wondering how this will affect the bike's geometry though. As I understand the head tube will be higher - that is not really a problem, I can just remove the spacers from under my stem, but I am more concerned about the head tube angle becoming less steeper (is that right?), I am concerned on how this will affect my climbing, as for example comparing stumpjumper ht with epic (epic has less steep head tube) I can feel the epic's front wheel lurking a bit during climbing Any ideas on how to calculate the head angle with 100m fork? thoughts?
    I believe that for every 10mm of axle to crown height change, there is a .5 (1/2) degree change in the head angle. The Stumpy's head angle is at 71.5, so that should bring you to 71. It will also raise your BB height by a small amount and change your seat angle as well. That amount of change on that bike is within reason and might feel good to you, then again, might not. Give it a shot.

    Levity's change seems to have worked out for him. The different offset is probably the key there.

  4. #4
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    Just a thought - maybe you can simulate the change by mounting a larger tire to the front wheel? This would have a similar effect of creating a slacker head tube angle.

  5. #5
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    depends also on the fork height. for example Fox is lower than carbon crowned Sids (5-10 mms). I put it a fox in 100mm and thought it worked great.

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