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  1. #1
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    Reputation: timallard's Avatar
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    cyclo-cross frame design

    This is a first try at a frame geometry specifically for cyclo-cross, the humpback to allow the shoulder to be closer to the headtube than standard. While it may look flexy it's at least as stiff in all ways as standard geometry, didn't expect that but that's the way it rides.

    http://tinyurl.com/yfecmw3

    Next one will have the whole humpback area moved down, for racing the seat-tube is turned the other way. Right now all the frames I'm building are from abandoned or donated bikes so this was a Univega comfort bike, good trainer weight, next one will be from lighter tubing.
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  2. #2
    duh...
    Reputation: FatTireFred's Avatar
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    is the shoulder closer to the headtube an advantage? triangle looks tight for the chaos of racing... but nifty looking for cruising fireroads and such
    .


    Quote Originally Posted by mikagsd
    Fat tire Fred....you are the bike god of the universe and unless someone agrees with your reasoning they are just plain stupid

  3. #3
    Hucken The Fard Up !
    Reputation: Salsa_Lover's Avatar
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    u g l y

    Do not want
    Quote Originally Posted by zank
    They're just bikes. Ride 'em in the rain, salt, snow and crap to fully appreciate them.
    Quote Originally Posted by Sean Kelly
    The thing about the cold is that you can never tell how cold it is from looking out a kitchen window. You have to dress up, get out training and when you come back, you then know how cold it is.

  4. #4
    Dirty. Nerdy. Unemployed.
    Reputation: Sojourneyman's Avatar
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    Quote Originally Posted by Salsa_Lover
    u g l y

    Do not want
    it's unique, I like it.

    Needs a better fender though...

  5. #5
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    Quote Originally Posted by Salsa_Lover
    u g l y

    Do not want
    This post was more for the geometry to get the shoulder forward, works well for that ... some of the bends were just to get the right headtube angle, fwiw ...

  6. #6
    Fat aging guy on a bike..
    Reputation: cyklopath's Avatar
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    Hmmmmmmmmm. uhhhhhhhhhhhh......

    With a standard seattube location, your design might make more sense. As it is, it looks more like novelty for the sake of novelty rather than a functional design.

    The chainstays merely look like they'd increase chainslap on the upper side of the driveside chainstay rather than do anything valuble. Also really cannot see any value in the shaped chainstays.........

    I'm not a framebuilder, so take the above with a grain (or bucket) of salt, but if you're gonna deviate from classic designs, make sure you're doing it for a valid reason rather than just looking for an excuse to exercise your tubing bender......
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  7. #7
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    Quote Originally Posted by cyklopath
    Hmmmmmmmmm. uhhhhhhhhhhhh......

    With a standard seattube location, your design might make more sense. As it is, it looks more like novelty for the sake of novelty rather than a functional design.

    The chainstays merely look like they'd increase chainslap on the upper side of the driveside chainstay rather than do anything valuble. Also really cannot see any value in the shaped chainstays.........

    I'm not a framebuilder, so take the above with a grain (or bucket) of salt, but if you're gonna deviate from classic designs, make sure you're doing it for a valid reason rather than just looking for an excuse to exercise your tubing bender......
    Good eye, the chainstays do slap more, it was more bend that I wanted 'cause I had to use that to adjust the headtube angle. I'm learning how to rebuild from existing bikes so it's a bit different, learned where & how you put the seat-tube is rather arbitrary, rides well and I like the extra clearance, only 1-1/4" drop to the bb.

  8. #8
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    I'm a big person

    anything making the front triangle smaller is a no-go for me
    it does look kewl though
    one nation, under surveillance with liberty and justice for few

    still not figgering on biggering

  9. #9
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    Quote Originally Posted by atpjunkie
    anything making the front triangle smaller is a no-go for me
    it does look kewl though
    Right on, did a drawing this morning and moved the seat-tube to wrap the rear wheel to open that whole area, looks pretty nice, still has the headtube to rear-axle curve, it'll be the next try, have done two frame since so have the sequence of cuts & bends down better, am curving the chainstays up instead of down ...

  10. #10
    Growing Older, Not Up
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    I think this is a better execution of a humpback crosser.

    http://www.lugoftheirish.com/Shamroc...ocross.html#12

  11. #11
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    Quote Originally Posted by crumjack
    I think this is a better execution of a humpback crosser.

    http://www.lugoftheirish.com/Shamroc...ocross.html#12
    Nice ... yeah, my stuff is experimental, using a recycled bike you can't bend well near the old bosses or braze-ons as you get a rip in the tubing so my bends look kinky, getting better at it tho'.

    Also, a standard diamond sucks in the wind tunnel so you see plenty of "cheater" frames now with cut down seat-stays, seat-tubes that wrap the rear wheel, totally illegal a decade ago but even seat-tube fairings are on some of the bikes in the peloton now.

    All this is for lower drag, the cut-away front end of this design does better in the wind tunnel ... so there's a bit of advantage to the weird design that way over the geometry in the pic due to the turbulence created down near the bb by the downtube.

    The curved top-tube to a curved set of seat-stays is pretty old, Boardman's Corima hour machine was a really nice job of that, early 1990's or something, the frame in the pic has stays reinforced for the canti's as well as looking sculpted for wind.

  12. #12
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    design drawing

    here's the sketch of #2 ...

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