geometry
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Thread: geometry

  1. #1
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    geometry

    Come winter, when i get a break from school, im hoping to build a cyclo-cross frame, but i have yet to ride cross and thus don't know what i would want to keep in mind when drawing up geometry, if anyone can help me out in anyway, just give me some design tips or w/e, id greatly appreciate it.
    thanks,
    Sam

  2. #2
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    Quote Originally Posted by Worthless Son Frames
    Come winter, when i get a break from school, im hoping to build a cyclo-cross frame, but i have yet to ride cross and thus don't know what i would want to keep in mind when drawing up geometry, if anyone can help me out in anyway, just give me some design tips or w/e, id greatly appreciate it.
    thanks,
    Sam
    check-out the tech section of cyclocrossworld.com. there is an article about cross bike fit.

  3. #3
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    they have a higher bottom bracket, the chain stays appear to be a bit longet and the clearance between the tires and all the tubes / fork crown must be large enough to allow a large tire covered with mud to not hit.

    Cable routing is often done poorly. The latest thing is running the cable for the rear derailer down the seatstay. This works OK, but the cable gets full of water and crap in a hurry. I'd almust rather see a long cable that has a boss around the seat tube, then runs fully enclosed right down to the derailer. It would weight a little more, but who cares.

    Also, a lot of frames don't seem to have much of a plan for how brakes will be mounted--some sort of hanger that won't be in the way but will allow for a decent cable route would be key.

    The use of a pully / bottom pull front derailer seems to be pretty popular and works OK enough.

    In terms of balance and geometry, I want a bike that keeps enough weight over the back end even with the shorter cockpit. I have had a couple that seem to plow the front tire out when you crank on the steering wheel, I don't know if that's a fork thing or not.

  4. #4
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    There was a thread a few weeks ago concerning this subject, but here it goes anyway. Use a normal bb height or maybe 1-2 mm higher. The lower center of gravity and lower saddle height will benefit you more than any increase in clearance. I'll steal someone elses saying here, "it's cyclocross, not junglecross".

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    find equal TT length

    and a ST 1-2 cm shorter is always a good starting point

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    Piling On

    Quote Originally Posted by euro-trash
    There was a thread a few weeks ago concerning this subject, but here it goes anyway. Use a normal bb height or maybe 1-2 mm higher. The lower center of gravity and lower saddle height will benefit you more than any increase in clearance. I'll steal someone elses saying here, "it's cyclocross, not junglecross".
    Just to second EuroTrash's note, the high bottom bracket design is largely a vestige of the days of cyclocross in toe clips -- you needed plenty of clearance for those first few pedal strokes after a barrier when you were riding with the pedals upside down and the clips hanging beneath. No such issue, of course, with clipless pedals.

    I suppose there could be a modest benefit to having a little higher pedal clearance to pedal through long off-camber sections, but that's never been an issue with my (not excessively high) BB, even with 175 cranks and even on the infamous "wall traverse" at the Baltimore Nats course a few years back.

    Cheers!

  7. #7
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    thanks

    thanks for the information, i talked to a local shop here ( santa cruz) and they told me to visit rocklobster for more information. I'm really getting excited for this bike, the sport looks like a lot of fun. If anyone has more tips about HT and ST angles itd be a great help. Im planning on running a single ring up front to save money (being a college student) and just to make the bike that much simpler. Thanks again, if im lucky you may be seeing me on the trails in about 3 months.
    sam

  8. #8
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    Agree with statement about about bb height. Here's geometry info on some very popular cross frames.

    http://www.ifbikes.com/frames2/steel...ss_specs.shtml

    http://www.steelmancycles.com/eurocr...#anchor1548925

  9. #9
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    rock lobsters

    are fine rides. go see them, they'll build it around ya.Frankenbike the rest, it's the most fun. Once you start cxing all those Santa Cruz trails you've grown tired of will become as fresh as a daisy

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