Right frame size for me.

Discussion in 'Cycling Equipment' started by A.J.T.73, Oct 24, 2007.

  1. A.J.T.73

    A.J.T.73 New Member

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    I just got a Giant scr 3.0 and i got it off the internet but went into a bike shop to find what size i needed. The guy recommended a 55cm frame, measured from bottom bracket to seat post clamp. I am 5 feet 8 inchs, with 32 inch inside leg. The frame is a large. and i have the seat post 10cm out, from bottom of saddle to clamp. Is this the right size for me and how do i know?
    I know its a little late now but i dont want to hurt myself if its wrong. I have rode it quite a bit.
    My friend is taller than me and has a smaller frame, so this has brought up the question.
    Sorry its so long and thanks for any comments.
     
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  2. Eden

    Eden New Member

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    This is a bit counter intuitive, but your taller friend may need a smaller frame than you if he has long legs and a short torso/arms, and you have short legs, long arms.... (and of course different manufacturers measure differently, so your friend's bike may not be smaller than your own- what's more compact frames generally measure smaller than similarly sized traditional ones)

    Purely measuring stand over is not a great way to size a bike, you need to take into account a person's proportions. I can stand comfortably over a bike that is a size too large for me - I'm in the short torso, longer leg camp.

    Most important is how does the fit of your new bike feel to you? Do you feel stretched out - can you ride comfortably with your elbows bent or are your arms straight out to reach your handlebars? Are you hunched over and cramped feeling? Does anything hurt - do your knees hurt or your shoulders hurt? Minor things can be taken care of by a good bike fit and possibly some small swaps - like a different stem, wider/more narrow handlebars, but its of course always best to start with the best fitting frame.
     
  3. capwater

    capwater New Member

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    Height is a very rough factor to use in frame sizing. Also, some frames have longer top tubes than others and then the whole compact vs. traditional geometry debate. I'm 5'10" (average torso/legs) and I ride a 54cm or M in a compact. You can do some tweaks such as stem length, but they are very minor and shouldn't be used to drastically alter things.
     
  4. A.J.T.73

    A.J.T.73 New Member

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    I will see how bent my arms are today. What angle are you meant to be sat at on a racing road bike? i.e. the ratio or saddle height to handle bar height.
    thanks for the help
     
  5. capwater

    capwater New Member

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    Still comes down to personal preference and also riding style/intent. My bikes are set up rather agressively with minimal stack height because I race so the saddle is a fair bit higher than the bars. Might not work for everyone.
     
  6. velovie34

    velovie34 New Member

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    well I think the right way is for the tip of the saddle is that you put your elbow on the tip and stretch your arm to the front of the bicycle.it should be 2 inches short of the handlebars,If youre starting off cycling 3 inches.You should also be 2 inches behind the centre of the bottom bracket or more.To find your correct height you should have your leg extended parrallel to the seat tube with your socks on and when your leg is fully extended you should just touch the pedals with your heel.hope this helps in getting right position saying that im 5 7 and I have a 54 and it fits ok
     
  7. kk4df

    kk4df New Member

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    I am 5' 8.25", 32.25 inch inseam, and ride a 55cm frame. Virtual top tube length is 55.5 cm with a 90mm stem.
     
  8. dgregory57

    dgregory57 New Member

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    If you have ridden the bike quite a bit, and you are comfortable on it, then it probably won't do a lot of damage.

    Do your feet reach the pedals? Do your hands reach the bars? Does your butt reach the saddle?

    People rode bikes for decades without people on the internet to tell them the evils of riding a bike that was a centimeter too big or small for them! To deride them for riding a bike with a top tube that was obviously 0.5 cm too short.

    There were decades when people rode bikes hundreds of miles without even knowing that cranks came in different lengths... They just adjusted their bikes until things felt right, and made sure their tender parts didn't get crunched. But we still all rode bikes and survived.

    If you start to get any pains, or weaknesses, or inabilities to improve, then there may be some issues that you may want to address. Otherwise, enjoy your bike.

    If you get to the point where you want to compete, and get a coach, your coach will guide you through all the details, until then ride... unless there is regular discomfort or pain, you are probably not hurting anything.

    EDIT: To add to the confusion, read the various forums... There are people that argue vehemently that everyone they see rides bikes that are too big, and there are others that argue just as strongly that there is a conspiracy to get everyone on too small a bike.

    Then there are various schools of thought on bike fit... There are bik fit calculators online, that have you measure everything including shoe size, then you have to pick between three different styles of fit, then they'll tell you frame size (seat post and top tube plus more), seat post set back, crank size, and stem length... and then tell you that it is all just a starting point. :)
     
  9. A.J.T.73

    A.J.T.73 New Member

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    Thanks for all the info, I did the elbow on the saddle idea and found i am way off 2 inch mark and also, my arms are a little to straight when riding, so i have ordered an 80mm stem, and then will take out one of the spacers.
     
  10. garage sale GT

    garage sale GT New Member

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    I read someone else's online comment that your knee should have 30 degrees of bend when the crank is at the bottom and you are clipped in. That sounded a bit extreme but I have cycled many miles with my seat lower than the heel-just-touches standard. I greatly prefer it and my knees have not yet exploded.
     
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