HELP!! Sloping frame size

peanut1978
peanut1978 Posts: 1,031
edited January 2011 in Road beginners
187cm height

89cm inside leg


56cm frame?

Comments

  • P_Tucker
    P_Tucker Posts: 1,878
    I thought most sloping frame sizes represent what size it would be if it had a flat top tube? Certainly Specialized label them this way.
  • Monty Dog
    Monty Dog Posts: 20,614
    Reach is more important - measure your top tube length - the actual or theoretical measurement along the horizontal between the centrelines of the headtube and seattube. Most geometry charts give this dimension.
    Make mine an Italian, with Campagnolo on the side..
  • neeb
    neeb Posts: 4,473
    56cm frame?
    Very much depends on the manufacturer...

    There's a really useful article by Lennard Zinn in the new 2011 VeloNews Buyer's Guide in which he tells you how to measure frame reach (horizontal distance from a vertical line going through the bottom bracket and vertical a line going through the top (centre) of the headtube) and frame stack (vertical distance from a horizontal line through BB and a horizontal line through top of head tube). Frame reach in this sense is different from the reach you get from the effective horizontal top tube length.

    The problem with effective horizontal TT length is that it's shorter if the seat tube angle is steeper, without the frame reach (forward from BB) being affected. Similarly the height of the bottom bracket changes the effective level of the top of the steerer tube even if the steerer tube is the same length.

    You can roughly measure frame reach by putting the rear wheel of a bike against a wall, measuring horizontally from the wall to the top of the steerer tube, then subtracting the horizontal distance from the wall to the center of the BB. Frame stack can be measured from the floor to the top of the steerer tube, then subtracting the distance from the floor to the center of the BB. Doesn't matter what tyres you have on, as you are subtracting that distance anyway.

    When I saw this article I realised that these two measurements pretty much completely solve the problem of knowing whether a frame will fit. Unfortunately not many manufacturers quote these figures, but apparently some have started to do so.

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