Sizing question - what do the numbers mean?
10-09-06, 08:39 AM
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Sizing question - what do the numbers mean?
Newbie here. I calculated my size on wrenchscience, and it recommends a "center-to-center" 50cm height, or center-to-to 51cm. How does this correspond to size? I am looking at the Trek Pilot 2.1, which has the relaxed geometry, which I guess complicates the measurements a bit. On the trek website, I see an "EFF Top Tube" measurement, and a "Top tube" measurement, that differ by about 1.5 cm. (EFF on the small-52 is 53.1, top tube is 50.8). Does this sound like the right size? I know it is more about what size feels right, but I've never ridden a road bike, so it's hard to tell what feels right. Also, how come the XS size (50) has measurements that are only about 1cm smaller? Is the "frame size" a meaningless number? As a frame of reference, I am about 5'8" with a 30inch inseam - I have relatively short legs and a large head, so I am bit "small" for my height. Thanks a lot.
10-09-06, 09:05 AM
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To be honest your post is a bit rambling and covers a lot of ground. But here goes.
"Size" traditionally refers to the height of the seat tube. bikes are usually said to be 52cm, or 54 cm, etc because the seat tube is 52cm,or 54 cm. "center to Center" or "Center to Top" refers to how they measure that i.e. from the center of the tube, or to the top of the tubes.
Compact frames (frames with sloping top tubes) start throwing these measurements off, at least as compared to traditional frames. Thus the concept of effective measurements (i.e what a measurement on a compact bike would equate to on a bike with a traditional frame)
The top tube measurement is from the seat post to the head tube. Teh effective top tube is what that measurement would be on a tradtional frame (i.e coming back straight from the head tube to the seat post on a line parrallel to the ground.)
the fact that you have compartively long legs may indicte you want a bike with a longer top tube, in relation to the seat tube.
Otherwise, you've just got to try them on.
"Size" traditionally refers to the height of the seat tube. bikes are usually said to be 52cm, or 54 cm, etc because the seat tube is 52cm,or 54 cm. "center to Center" or "Center to Top" refers to how they measure that i.e. from the center of the tube, or to the top of the tubes.
Compact frames (frames with sloping top tubes) start throwing these measurements off, at least as compared to traditional frames. Thus the concept of effective measurements (i.e what a measurement on a compact bike would equate to on a bike with a traditional frame)
The top tube measurement is from the seat post to the head tube. Teh effective top tube is what that measurement would be on a tradtional frame (i.e coming back straight from the head tube to the seat post on a line parrallel to the ground.)
the fact that you have compartively long legs may indicte you want a bike with a longer top tube, in relation to the seat tube.
Otherwise, you've just got to try them on.
10-09-06, 09:10 AM
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Look for a bike with the right "effective" top tube size for you. Of course, there is more to a bike's geometry than one measurement. Take some test rides to make sure the bike really fits you. This is especially important when buying bikes with non-standard geometry, such as the Trek Pilot or Specialized Roubaix.
Don't try mail order unless you are an experienced cyclist who knows exactly what they want (i.e., the same size and geometry as your current bike).
Don't try mail order unless you are an experienced cyclist who knows exactly what they want (i.e., the same size and geometry as your current bike).
10-09-06, 09:22 AM
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i agree unless you know how to dial in a frame size then its best not to bother with Mail order. have a fit done at the a GOOD LBS. some one who caters to the roadie. they will set you with the proper size and get you a good stem lenght, bars, crankarms exec. i tend to believe that Top Tube is the most important issue in a bikes fit but some believe that its seat tube and standover.. but unless you know your position on a bike and what fits Online is a very bad idea for the buyer.
10-09-06, 09:26 AM
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Originally Posted by scuzzo
i agree unless you know how to dial in a frame size then its best not to bother with Mail order. have a fit done at the a GOOD LBS. some one who caters to the roadie. they will set you with the proper size and get you a good stem lenght, bars, crankarms exec. i tend to believe that Top Tube is the most important issue in a bikes fit but some believe that its seat tube and standover.. but unless you know your position on a bike and what fits Online is a very bad idea for the buyer.
