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help with frame size(5 posts)

help with frame sizedobby
Feb 11, 2003 4:27 AM
I'm looking at buying a road bike. I'm over 6'3" and looking at the Treks. I would love to get the 5200 but that's a bit out of my price range so would like to get the 2300. However, the sizes are 60 or 63 and my recommended size is either 61 or 62. Does anyone have any experience with the Trek bikes to know whether their frames are smaller than normal or whatever. Do you think the 63 would be too big??

Thanks
help...C-40
Feb 11, 2003 5:31 AM
Check out www.cyfacusa.com for fit information. Apparently you somehow figured that you need a 61-62 frame, but you don't mention your inseam or whether the frame size is center to top (c-t) or center to center (c-c). Trek frames sizes reflect the length of the seat tube, which is extended above the top tube, so their sizes are not c-t or c-c. Trek frames do run (vertically) small for the "advertised" size. Their geometry charts are available for comparison on the Trek website.

A 63cm Trek will measure very close to a 61cm c-t frame. The standover height is 33.7 inches or 85.6cm. This frame will fit a rider with an 88-91cm or 34-5/8"-35-3/4" cycling inseam.

Cycling inseam should be measured very carefully, to saddle-like crotch contact in bare feet. A bike with a horizontal top tube makes a great measuring tool. Block up the wheels (equally) until you get very firm crotch pressure when standing over the bike in bare feet. Then measure the distance from the floor to the top of the top tube. For large riders, the center to top frame size is 28-30cm less than inseam.

Top tube length is another sticky issue, but in general, most stock frames don't vary enough to warrant a lot of concern. It's rare to find a brand that varies more than 1cm in TT length. A change is stem length will handle this variation, unless you prove to have a very long or short torso that would require a very short or very long stem. In that case, selection of a particular brand might be helpful.

Stem length can't be determined until the saddle position is set. The cyfac website has the info on setting the saddle to its initial position. This position is often adjusted later to suit the rider's pedaling style.
Man, you´re a saint and a guru!castrello
Feb 11, 2003 5:40 AM
How do you know all this? Do you work as a professional fitter?

I know most of these things too (thanks to your insightful replies) but how do you find time/strength/whatever to keep coming up with these often long and precise replies?

Man, (I guess you´re a man) you rock! You´re a number 1 guru on this forum! :)
help...dobby
Feb 11, 2003 6:07 AM
Wow. Well, I measured my inseam last night and got a measurement of 89.3 so if what you say is correct then the 63cm frame should fit me ok...I hope. The 60cm would definitely be too small.

Thanks
What he says is correct. nmmainframe
Feb 11, 2003 8:20 AM