Frame Geometry

Discussion in 'Cycling Equipment' started by ibis315, Mar 28, 2003.

  1. ibis315

    ibis315 New Member

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    I'm looking to buy a new frame, but I have some interesting geometry numbers I got from the manufacturer :

    Size : 52.5 cm
    Top Tube : 53.5 cm
    Head Ang : 72 Degrees
    Seat Ang : 74 Degrees
    Chain Stay : 38 cm (really short)
    Fork Rake : 4.3 cm
    BB drop : 9 cm (wow!)
    BB Height : 25 cm (wow!)
    Wheelbase : 95.8 cm (short)

    My question is, with such a low bottom bracket height combined with short wheelbase and shallow head tube angle, how would the bike handle? My current frame is :

    Top Tube : 53 cm
    Head Ang : 73 Degrees
    Seat Ang : 73 Degrees
    Chain Stay : 41 cm
    Fork Rake : ?
    BB drop : 6 cm
    Wheelbase : about 98 cm

    My main concern is the low bottom bracket and shallow head angle making the bike handle too slow. However, does the short chain stay/wheelbase compensate for BB and HA? Thanks for the information.
     
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  2. Neo

    Neo New Member

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    are you sure these figures are correct? these numbers seem very, well, outside the norm. BB drop is usually around 70mm giving a BB height of around 263 depending on tyres used, and the head angle of 72 would normally be matched with a 45mm offset.

    Nevertheless, I'll draw it on a CAD program to see if the numbers you give will work.

    Neil
    www.billato.com
     
  3. dexmax

    dexmax New Member

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    the chainstay is too short, i guess??? shortest i've seen is 39.5cm.
    good for 650c maybe....
    wheelbase too short. i think.

    bb height? is this some kind of sports car? hehe...

    is this a triathlon bike?

    I'll check the angles....
     
  4. steve

    steve Administrator
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    Thats what I was thinking: 74 Degree seat angle, 38cm chain stay lenght, 25cm BB height sounds like a tri bike to me.

    What sort of racing/riding are you doing idis?

    cheers!
     
  5. Neo

    Neo New Member

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    KACHUNK!!!!:)

    of course, it's the numbers for a 650c wheel frame. Haven't had to build one for a while, that's why it wasn't immediately obvious
    (to me anyway!)

    On the other hand, if it's not......

    Neil
    www.billato.com
     
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