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100mm or 120mm fork???

Discussion in 'Beginners Forum' started by Air23, Jan 21, 2008.

  1. Air23

    Air23 Chimp

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    Hi
    I want to change my old RST 100mm fork with a new one Marzocchi/Rock Shox but i don't know what is better to install 100mm or 120mm???I ask this because i like to do small jumps/little downhill.Will i have problem with my hardtail bike geometry???
     

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  2. Jimmi707

    Jimmi707 Chimp

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    20mm wont effect geometry too drastically. Me and my brother have same frame where initially mine had 130mm to his 100. Now I have 100 reba and he 120 MX pro eta, it hasn’t been an issue. There are more features and performance characteristics that you want to consider beyond just travel, including cost.

    But all things being equal no really complains about having an inch more than what they need.
     
  3. r464

    r464 Turbo Monkey

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    For each inch increase in fork height/travel, you will generally slacken the angle of the head tube (steering angle) by one degree. This will result in slower, but more stable, steering.

    It will also raise your bottom bracket by a small amount.

    The longer the fork, the more stress there is placed upon the frame as well. For a 20mm increase, this is not significant, but it is something that would be of concern if you were to install a drastically longer fork onto a frame.
     
    #3 -   Feb 1, 2008
  4. fuct

    fuct Chimp

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    i look at it for as much as you do more. if you hit jumps that 1 percent more go with the 100mm but if you like goin down more go with the 120mm or you could go with a rock shox u-turn were if your on a mission traveln down leave that u-turn alone but if your ripen the trails crank that u-turn down tilll you fell like is a little stifffer and lower. but deffinitly get a 20mm.
     
  5. BMXman

    BMXman I wish I was Canadian

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    hmm well since it's such and old fork...is the frame old as well? That would be the determining factor IMO...many older frames geometry can't handle a 120mm fork without some pretty significant differences in geometry...D