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frame size??(5 posts)

frame size??spazzion
Jul 16, 2001 12:37 PM
I'm buying my first road bike and Im trying to buy a used bike instead of a new one from a shop. I will be using it to commute to work and to get into triathlons. Can somehow give some pointers on how to tell if the frame fits you correctly, and what the proper position feels like on a bike. I am about 5'6, 125 lbs and think that a 50 cm frame is about right. I found a bike that is a 47 cm frame, though I havent tried it out yet. Do you think this frame might work, or is it obviously too small? Also, what kind of things should I look for to make sure it is a good bike for me? Thanks.
Improperly Fit Bikes Can Cause Injury . . .sidley
Jul 16, 2001 1:21 PM
so before you buy a bike, make absolutely sure it fits properly. Good starting points can be found at or Sizing variables include true inseam (not your pant length), torso length, desired position, manufacturer and rider flexibility.

Once you have a general idea of what frame size you need, go to a bike shop and test ride different sizes and models.

If you want a junker commuter, I would say buy whatever you want but if you really want to put in the training required to compete in triathalons, I think you should invest the time and money needed to obtain a bike that you can ride comfortably for a long time.

I must sound like a old hen but I made the mistake of jumping at a bargain before being properly sized and not only did my knee sweel like a mellon but I had to sell the bike for way below what I paid for it.
undoubtedly too small...C-40
Jul 16, 2001 2:08 PM
Read up on fit at An accurate inseam measurement is critcal. At your height a 52-54cm frame would be common, with 2 to 4cm of standover clearance in bare feet. I'm only an inch taller and ride a 55cm to fit my 83cm (32-5/8) inch inseam. The most common frame size formula is .67 times inseam.
I am just an inch taller and five pounds heavier than you.Jim Burton
Jul 16, 2001 4:06 PM
And I just recently was fit and purchased a 52cm Serotta. After the fit, the Serotta guy gave me the correct sizes for all of the bikes I was considering. 51cm for Bianchi, 51cm for Lemond, 53cm for Waterford; I went with the Serotta. All companies measure thier bikes differently. Now, just because I am close to your size may not mean that these bike fit you. You really need to be measured comprehensively to get a proper fit. Standover height and inseam are just not accurate enough these days, in my opinion. There are so many variables, top tube length for instance, that are more important to fit.

47 is probably WAY too small for you. You would feel cramped. Don't let the bike shop talk you into this bike and get a second opinion from another shop.
re: frame size??quinroo
Jul 16, 2001 4:51 PM
i am about the same height and weight as you (5'7", 140lbs, and female). i just bought a bike last week, and during my search for one, my size changed from 54 to 52 to 50 cm. my boyfriend thought i would fit best on a 54 (he's an experienced cyclist, but likes his bikes big), one shop thought i would do well on a 52, and the other a 50 (in the same brand). i probably *could* ride all three, but the 50 is much more optimal for me. definetly go to a shop and ride some different sizes around a given size.

also, you say you want to get into triathlons? i know they generally use 650c wheels as opposed to road standard 700c wheels. they also have a slightly different geometry. you may want to consider that. has some good classifieds. also, quintana roo makes great tri-specific bikes, which are a bit pricey, from what i see, but they list all the measurements for the bikes which i guess could tell you something about the geometry. plus i just think they're so cool because i was named quintana roo too. ;)