Frame sizing ?

Discussion in 'Bike buying advice' started by Harri_in_NS, Jul 14, 2010.

  1. Harri_in_NS

    Harri_in_NS New Member

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    Hi all,

    I am thinking of buying a bike online and am wondering if the bike I am looking at will work for me. I am 6'1" with a 33" inseam. The bike is a 2009 Kestrel Evoke. It has a 56.5cm toptube with a 79.3cm standover height. Any thoughts or advice would really help.

    Thanks,

    Harri:)
     
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  2. cyberlegend1994

    cyberlegend1994 Moderator

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    You're roughly looking at a 56 cm seat tube, measured from center of bottom bracket (crank axle). The seat tube length is used as the frame size.
     
  3. Harri_in_NS

    Harri_in_NS New Member

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    Hi, thanks for the reply. Do you think that this bike would be big enough for me?

    thanks again:)
     
  4. cyberlegend1994

    cyberlegend1994 Moderator

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    That depends on the seat tube length, the dimension you posted earlier was for the top tube. A 56 cm frame means the seat tube is 56 cm. The top tube & down tube are proportional to the seat tube, but it's the seat tube measurement that's used as the frame size.

    If the frame is only 1 or 2 cm too small, you can compensate with longer seat posts and handlebar stems.
     
  5. Harri_in_NS

    Harri_in_NS New Member

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    The seat tube lenghth is 56cm so hopefully that should work. You have been alot of help.

    cheers:)
     
  6. alfeng

    alfeng Well-Known Member

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    The frame is large enough ... you will probably just need a 120mm or 130mm stem to get a proper fit (presuming that you don't have any physical abnormalties). The reach can also be adjusted by (i.e., is affected by) choosing one handlebar, or another.

    Presuming that you are currently riding/using a bike which you find to be comfortable, measure the length of the real-or-virtual top tube + stem -- presuming the combined length of the two measurements on your bike isn't more than 70cm, then that Kestrel frame size will work for you.

    If you feel cramped on the bike which you are currently riding, then (presuming it is almost the right size) measure it and add a centimeter-or-two to the length.
     
  7. swampy1970

    swampy1970 Well-Known Member

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    No, I don't.

    I have an almost 34" inseam and ride a 58. Given that you're two inches taller than me and are slightly taller then I have to assume that your body is also longer. With a 56 you'll have a shorter top tube and a few manufacturers use the 56 to 58cm sizes to alter the seattube angles, with 56 and below being slightly steeper and 58cm being about 0.5 of a degree slightly slacker.

    Of course I'm assuming you don't have T-Rex arms or something proportionally that short. If you have a pair of knuckle draggers then you might even look at a slightly larger bike to get the top tube length that you need.

    In general, using a slightly longer top tube and a slightly shorter stem will put less weight on the front wheel. You don't want to have it where you're having to use a 8cm stem or shorter but you don't want a frame that's too small and then jamming a 14cm on there because it's all you can do to get the required position. If you end up doing that there's much more weight on the front end which isn't always a good thing going down hill. A well fitted bike puts the ride in a position that they can ride comfortably in the manner they need to AND balances the weight properly across the bike.

    As it is on my 58cm Cannondale I'm going to need a 130mm to replace the stock sized stem that measures 115mm but the 61cm frame would be like riding a horse! Given the weight (or lack thereof) and stiffness of most modern frames, I wouldn't be too worried about big increases in weight or lack of stiffness when progressing t the next size up.

    Correct fitting trumps everything when it comes to going fast.
     
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