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  1. #1
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    going from 45mm to 38mm rake

    how much will this change the geometry?

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    The frame geometry doesn't change because of rack. The frame geometry changes because of axle to crown length.

  3. #3
    Wil
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    Brake chatter on CX forks Wil's Avatar
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    It will increase the trail, in the steering geometry, of your bike. Your bike will be more stable, and less twitchy/responsive.

    http://sheldonbrown.com/gloss_tp-z.html#trail
    http://www.phred.org/~josh/bike/trail.html

  4. #4
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    dramatic change.

  5. #5
    partly metal, partly real sp00ki's Avatar
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    Quote Originally Posted by darksiderising View Post
    The frame geometry doesn't change because of rack. The frame geometry changes because of axle to crown length.
    why would you mention frame geometry in a question about a fork?
    Quote Originally Posted by bonechilling View Post
    Road [racing] is one of the only sports where adult men can compete in a non-scholastic setting, so inevitably 8/10 racers are fiercely-competitive nobodies. It's fun as hell, but it's also the foremost refuge of defeated and aging jocks, turned middle-management types.

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    Quote Originally Posted by sp00ki View Post
    why would you mention frame geometry in a question about a fork?
    Because that was the only other non-answered question. The OP asked how much a 45mm-38mm = 7mm change in the rake would affect the geometry. You should be asking the OP why they would ask a question to which they already knew the answer if the question was, in fact, about the fork geometry.

  7. #7
    Ths Hipstr Kills Masheenz cc700's Avatar
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    use your words...

    if you mean handling, it will make it turn easier and twitch more, as well as fall over easier at speed. that is if the wheel clears.

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    Quote Originally Posted by cc700 View Post


    use your words...

    if you mean handling, it will make it turn easier and twitch more, as well as fall over easier at speed. that is if the wheel clears.
    Surprisingly it's actually the opposite. Because the contact point of the tire is behind a straight line going down from the headtube, decreasing the rake moves the contact point further back behind that line thereby increasing the trail. This makes the bike more stable (generally) rather than more twitchy.

    Rich

  9. #9
    Ths Hipstr Kills Masheenz cc700's Avatar
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    whoops. i was thinking trail.

  10. #10
    partly metal, partly real sp00ki's Avatar
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    Quote Originally Posted by darksiderising View Post
    Because that was the only other non-answered question. The OP asked how much a 45mm-38mm = 7mm change in the rake would affect the geometry. You should be asking the OP why they would ask a question to which they already knew the answer if the question was, in fact, about the fork geometry.
    again, 0 to do with frames.

    hell, bringing up stems would've made more sense...
    Quote Originally Posted by bonechilling View Post
    Road [racing] is one of the only sports where adult men can compete in a non-scholastic setting, so inevitably 8/10 racers are fiercely-competitive nobodies. It's fun as hell, but it's also the foremost refuge of defeated and aging jocks, turned middle-management types.

  11. #11
    Ths Hipstr Kills Masheenz cc700's Avatar
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    he meant handling. not geometry. use your words, then get over it.

  12. #12
    . blickblocks's Avatar
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    Depending on the fork design, it can slightly change the head tube and seat tube angles, as well as the bottom bracket height. Depends on the axle to crown length and the offset.

    The differences are probably negligable though.

  13. #13
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    Quote Originally Posted by sp00ki View Post
    again, 0 to do with frames.

    hell, bringing up stems would've made more sense...
    you really take offense to my simple interpretation of a question. geez internet wise-guy.

  14. #14
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    Quote Originally Posted by blickblocks View Post
    Depending on the fork design, it can slightly change the head tube and seat tube angles, as well as the bottom bracket height. Depends on the axle to crown length and the offset.

    The differences are probably negligable though.
    careful, sp00ki has declared this area off-limits. watch yourself.

  15. #15
    Senior Member divineAndbright's Avatar
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    I put a fork on before with about 38mm rake and my only complaint was the mega toe over lap, not that it will affect your normal riding, but if you're pulling up at a stop light and wanna attempt to do any kind of track standing you may find yourself trying to turn your bars and finding your front wheel hitting your foot, im not great at track standing and always find myself turning the bars back and fourth to maintain balance so it always pissed me off. Other than that I loved the handling with the 38 fork!

  16. #16
    aka mattio queerpunk's Avatar
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    http://www.anvilbikes.com/images/1064634020.xls
    That link will let you calculate your bike's trail.

    http://www.urbanvelo.org/issue3/urbanvelo3_p44-45.html
    That link will teach you a little bit about trail and different handling characteristics.

    I find that a lower-rake fork on a bike that's not meant for it offers really undesirable handling. So, while this doesn't answer your question, I hope it provides some helpful information.
    the hipster myth.

    i practice vagabondery.

  17. #17
    helmet brake jakerock's Avatar
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    Quote Originally Posted by sp00ki View Post
    again, 0 to do with frames. hell, bringing up stems would've made more sense...
    Why be a jerk?

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