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Thread: Fork reduction

  1. #1
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    Fork reduction

    I am considering a rigid fork on on a 29er frame that was designed around a 100mm suspension fork and has listed angles of 70 HT, 72 ST and a 12" BB height. If I were to install a 468mm rigid fork, would the geometry end up somewhere in the area of a 71.5 HT and 73.5 ST with a BB height of around 11.7"?

  2. #2
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    Have some one measure the AC dimension of your susp fork with you on the bike (meaning the fork sagged), and use that to compare for replacing with a rigid fork.

  3. #3
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    Clarification: I currently ride a large '02 Gary Fisher Supercaliber 29er and it has the following #'s HT 71.5, ST 73.5, and an 11.5" BB. It is time to replace the old wiggly noodle with something more modern in stiffness, yet keep the same geometry that I have come to love over the last 10 years. I am considering a Yeti Big Top and running a Niner RDO fork to stiffen things up yet retain the same, in the bike geometry that I like.

  4. #4
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    The best way to futz with measurements like these is to go online to BikeCAD and enter in the stuff yourself and see what happens. I think it has the fork dimensions available (?) for you to input. It's so dependent on the suspension fork's dimensions and what you're replacing it with (atc and offset).
    You'll have to enter in your bike's current HTA , STA, BB height and current fork specs and then 'lock' the bike in that position before changing the fork's ATC and offset to see what happens with the bike's geometry.

  5. #5
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    FUK DA GEOMETRY AND MEASURMENTS...just do it.....i put a 200mm fork on my trek 3900.....turned out great....sold dat bike 4 $600..

  6. #6
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    Thanks for the BikeCad tip Whit... ptr1, strange that you chose this thread for your second post! Can't say it is going to help your rep much.

  7. #7
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    Quote Originally Posted by kustomz View Post
    ... ptr1, strange that you chose this thread for your second post! Can't say it is going to help your rep much.
    I can verify that it did not.
    Don't you hate it when a sentence doesn't end the way you think it octopus?

  8. #8
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    General rule of thumb is that a 20mm change in fork AC length will change the HTA by 1.

  9. #9
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    try this too:
    geometryCalc
    I can't remember where I saw that first

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