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How can I tell if a bike fits?(3 posts)

How can I tell if a bike fits?Strom
May 16, 2001 10:50 AM
I have a lead on a good deal for a barely used road bike locally, but I'm not sure if it will fit. I'm 5-11 with an 83cm (32.7") inseam in my socks. My torso is 67cm (26.4"), if I remember correctly. The bike I'm considering is a 57cm Bianchi Veloce. The stand-over height is 32" (81.3cm) and the top tube length is 55.5cm.

I'll obviously ride it before buying, but I'm not an experienced rider (yet!), so I'd appreciate any advice on fitting.
re: How can I tell if a bike fits?PsyDoc
May 16, 2001 11:23 AM
Assuming your inseam and torso height were measured correctly, I would say initially that the 57cm may be too big. But, your inseam is a bit on the short side for someone who is 5'-11". The BSN site (listed below) associates someone who is 5'-11" with an 84.8cm inseam.

You need to take your inseam measurement from your pubic bone to the floor in bare feet about 8 inches apart. Place a book with a 1 1/2" or so binding between your legs and pull up until you cannot pull up any further (a short section of a 2x4 works well, too). In other words, you want to measure to the pubic bone so pull up hard. Make sure the book is level. Have a friend measure from the floor to the top of the book binding.

To take your torso height measure, you would basically follow the same procedure, but you would measure from the top of the book binding or 2x4 to your sternal notch. A photo of the location of the sternal notch appears below as I cannot figure how to post it right where I want it to go.

I am 5'-9" and I have a 33 3/8" inseam (or 84.77cm). My torso height measurement is 23 3/16" 58.90cm. But, even body measurements are only a good starting point for the "correct" size frame. Someone who has similar body measurements as I do may be more comfortable on a 57cm, others a 56 or 55. The real question is: How does the bike feel to you? If it feels too big, then it probably is.

I found that the more I knew about frame sizing, the more confused I became. Here are a few links on sizing information that will benefit and/or confuse you.

http://www.bsn.com/Cycling/

Note: click on "Ergobike: Competition Bicycle Size/ Proportions Analysis" and at the bottom of the new page that opens, you can choose your inseam measurement. The program then calculates all the other measurements that are "average" for someone with your inseam. You will get a plethora of information back.

http://www.coloradocyclist.com/BikeFit/index.cfm

http://www.wrenchscience.com/WS1/guest1.asp

http://www.electriciti.com/~bikelane/sizing.html

http://www.rivendellbicycles.com/frameinfo/Frame_Sizing.htm

http://www.sheldonbrown.com/frame_sizing.html

http://www.PeterWhiteCycles.com/fitting.htm

Just remeber, this information should be used as a good starting point for frame sizing. Frames differ not only in their size, but also in the angles that are used which may influence your choice of frame size. Good luck!
ride it.Hap
May 17, 2001 8:38 PM
Very nicely done, PsyDoc, I hope you have that saved to repost each week as needed. : )

I say ride it to see how it feels. I'm 5'10" and I am very comfortable on a 56cm Trek. I also have a 58cm Trek set-up to fit me. Based on you height, a 57cm could work, but manufactures are different and we're different and we all like different things. Used bikes can be great deals but expect to need some refitting. Stem, bars, and seat will probably need to be change to suit your style. Maybe pedals too.

Ride it and if you like it tweak it to fit.

Hap