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  1. #1
    Junior Member
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    I'm sure this has been asked before, so sorry for the repeat... Where is the measurement taken to get the bike size 49, 51, 53, ect. Is it taken from the centerline of the crank to the top of the tube ?

    I bought this bike in the early 80's,( I think ).. The bike is a Schwinn "Super Le Tour" and the number on the front badge is 2083..

    Thanks for the help folks,
    Frankie

  2. #2
    Keep on climbing
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    Unfortunately, it depends on the manufacturer. Some measure it c-c (center to center; i.e., center of the bottom bracket axle to the center of the junction between the seat tube and top tube). Others measure it c-t (center to top, or the center of the bottom bracket axle to the top of the seat tube). Easiest way is to find the manufacturer's web-site and look at their bike geometry diagrams; that should make it clear how they measure things.

  3. #3
    Senior Member Retro Grouch's Avatar
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    Most bicycle manufacturers measure from the centerline of the crank along the seat tube to the top of the top tube. Some measure to the centerline of the top tube. A few even measure to the top of the extended seat tube. Unless you're buying the bike sight unseen it doesn't matter much because you should really try it on just as you do when buying shoes.

  4. #4
    Junior Member
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    Mr Grouch / Kevin,

    Thank for the reply.. I understand that I should sit on one to get the fit. I was trying to figure out what size my bike was because it's too big. Using the handy dandy formula, [ Inseam 29 X 2.54 X .67 = 49.35 ] says somewhere in the 49cm / 50cm range should be what I'm on.. Problem being my Schwinn is a 56cm (top of tube).. So you two did a great job on telling me what I needed to know..

    Now if you could just tell me how to either shrink my bike or make my legs longer..

    Thanks again guys,
    Frankie

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