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  1. #1
    Senior Member IcySmooth52's Avatar
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    S-Bend Down Tubes

    Why do manufacturers shape them this way? What is the technical benefit? (It certainly isn't an aesthetic one!)

    '12 Fuji Altamira 2.0 "Raven" - '13 Marin Palisades Trail SE 29er "2B dermined" - '11 Trek T1 "Voskhod"

  2. #2
    Senior Member IthaDan's Avatar
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    Increased wheel clearance for long travel forks.

  3. #3
    Pedals, Paddles and Poles Daspydyr's Avatar
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    I've heard of problems with toes hitting the front tire on 29ers. Don't have any personal experience with it. I personally like the traditional frames.
    I think its disgusting and terrible how people treat Lance Armstrong, especially after winning 7 Tour de France Titles while on drugs!

    I can't even find my bike when I'm on drugs. -Willie N.

  4. #4
    Senior Member IcySmooth52's Avatar
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    Quote Originally Posted by IthaDan View Post
    Increased wheel clearance for long travel forks.
    Almost every 29er has the head tube side with that curve, but look at the bottom bracket side. Curves so the seat tube is almost at a right angle to the chainstay and downtube. That's what makes is an "S".

    Why that?
    '12 Fuji Altamira 2.0 "Raven" - '13 Marin Palisades Trail SE 29er "2B dermined" - '11 Trek T1 "Voskhod"

  5. #5
    one less horse cryptid01's Avatar
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    More weld at downtube/bb junction = stronger

  6. #6
    Senior Member IthaDan's Avatar
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    Quote Originally Posted by IcySmooth52 View Post
    Almost every 29er has the head tube side with that curve, but look at the bottom bracket side. Curves so the seat tube is almost at a right angle to the chainstay and downtube. That's what makes is an "S".

    Why that?
    Probably a multi faceted solution based around tire clearance, bottle cage access, and overall strength.

    Draw a straight line from the bb shell to the bottom of the headtube and see how much closer it is to the tire, then think about fitting a bottle and cage in there. Then notice the inherent gusseting on the headtube junction, material you'd have to add otherwise.

    This is an interesting topic. Perhaps a second iteration in the frame builder forum?

  7. #7
    ÖöÖöÖöÖöÖö Dannihilator's Avatar
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    Quote Originally Posted by cryptid01 View Post
    More weld at downtube/bb junction = stronger
    This.
    Quote Originally Posted by scrodzilla
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  8. #8
    Senior Member commo_soulja's Avatar
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    Hydro-formed tubes are the new hotness.

    beauty is in the eye of the beholder.
    Mythical Creatures Touched Me in my Bathing Suit Area.

  9. #9
    Senior Member Dilberto's Avatar
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    And, the S-bend eliminates the need for added welds and gusseting.
    2001 Cannondale Bad Boy Ultra - Shimano XTR/SRAM X0; Magura, Velocity Blunt SL
    2012 Trek Superfly 100 Pro - SRAM XX; Bontrager RXL; Easton Haven; Rock Shox Reba XX

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