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  1. #1
    mtbr member
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    How to know if I can replace ridgid front fork with suspension fork?

    I have a '98 or 99 GT Avalanche bike that is currently rigid forked. I would like to add a front suspension to it, but realize this may "throw off the geometry". What measurements should/could I take to see how bad it is. This brings me to a bunch of questions.

    1. Did they really make 2 types of every frame that year? one for rigid fork and one for suspension.

    2. I only want to put a 80 or 100mm fork on it, will this give me a "chopper" when I am done? Is there a good way to tell before I start the rebuild?

    3. Its a 18.5" frame (medium I think, measured 18.5 from center of crank to center of top tube at the seatpost). Does that matter?

    4. Can I alleviate any of the "chopperness" or "twitchyness" of the handling by going to a longer stem and wider bars?

    5. By the time I dump the money on forks, brakes, etc. am I better off building up a different frame (I really like the new 29ers)

    Thanks!

  2. #2
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    You will probably be ok with an 80mm fork (I wouldn't go 100). I doubt they made separate frames for the rigids (though I don't know that for a fact). To be honest, I'm surprised they were still selling rigid avalanches in 98 or 99. Are you sure your bike is not older than that?

    Also, you can measure the axle-to-crown of your current fork to see if it is a suspension-corrected fork (which would have been likely around that time for that type of frame if they offered a rigid version).

    Edit: as to your last question, I think most people that ask this question about a 10+ year old bike will probably be happier if they just buy a new bike, but a lot depends on how much you like your current bike, what condition it's in, and the quality of the components.
    Warning: may contain sarcasm and/or crap made up in an attempt to feel important.

  3. #3
    spec4life???..smh...
    Reputation: spec4life's Avatar
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    1. probably not...
    2.trailville pretty much covered it...measure the a2c length of your fork and compare it to some susp. forks that your looking at but most likely you wont be able to go over 80mm of travel...the new fork will be a little longer most likely a2c wise but it will be ok just dont go to much...
    3.nope
    4."chopperness"(new word, but i like it) not really.....twitchyness yeah a wider bar/ longer stem will slow down the steering...
    5. as long as you dont invest to much go ahead...just use some common sense and dont poor more into the bike than its worth....

  4. #4
    There's no app for this.
    Reputation: JimC.'s Avatar
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    As early as 1992 forward, GT made frames

    that were either rigid or suspension fork compatible - not 2 frames, but one.

    1. Did they really make 2 types of every frame that year? one for rigid fork and one for suspension. No.

    2. I only want to put a 80 or 100mm fork on it, will this give me a "chopper" when I am done? Is there a good way to tell before I start the rebuild?an 80mm fork with a similar axle to crown measurement will work just fine

    3. Its a 18.5" frame (medium I think, measured 18.5 from centre of crank to centre of top tube at the seat post). Does that matter? No

    4. Can I alleviate any of the "chopperness" or "twitchyness" of the handling by going to a longer stem and wider bars? it won't be different from what you have now

    5. By the time I dump the money on forks, brakes, etc. am I better off building up a different frame (I really like the new 29ers)perhaps, and don't forget that the older GT likely doesn't have disc tabs for a rear disc.

    The 99 Avalanche came with a 3.3" marzocchi bomber, if that helps

    http://www.bikepedia.com/QuickBike/B...2081&Type=bike

    Thanks!

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