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Frame size: What Lemond corresponds to my Gunnar?(8 posts)

Frame size: What Lemond corresponds to my Gunnar?ortman
Nov 30, 2003 9:19 PM
I have 54 cm Gunnar Crosshairs which fits me well and am looking into buying a Lemond Buenos Aires road bike. Because of the different goemetries and methods of frame measuring I'm having difficulty deciding on an appropriate size for the Lemond. Here's the specs:
Gunnar: seat tube 54 cm (center to top)
theoretical top tube (sloping) 56.5 cm.
(According to Richard Schwinn actual top tube is
about 1 cm shorter).

Lemond measures their seat tubes center to center, and their top tube does not slope. Therefore, would a 53 cm Lemond with a 54.5 cm top tube or a 55 cm Lemond with a 56.5 cm top tube be closest to the Gunnar? Thanks for any advice. My head is spinning.
Dec 1, 2003 5:49 AM
I assume that you are looking at a 2003 or older Lemond. The new Buenos Aires has a sloping top tube.

If your Gunnar has a horizontal top tube length of 56.5 and the 55cm Lemond has the same TT length, isn't it obvious that it's would be a better choice than a frame with a 54.5cm TT?

You should also be sure that the standover height of the Lemond is not too tall for you. The standover height of a 2003 model is listed at 80.3cm or 31.6 inches. You shouldn't buy a frame based solely on TT length. If you can't standover the frame with at least 2cm of clearance to hard crotch contact, then it's too big.
C-40, I think you should...PsyDoc
Dec 1, 2003 6:02 AM
...consider explaining in your posts what you mean by "hard crotch contact." Though, I believe I know what you mean by this term, others may think that if the top tube touches their crotch, then it's hard contact. If the top tube hits your soft tissue in the crotch, then you have about 2 - 2.5cm of clearance to your pelvis, which is what you want. One question though, should the standover height be made with cycling shoes on or not?
a novel in every answer...C-40
Dec 1, 2003 6:13 AM
Hard to include a complete lesson in frame sizing with every answer, but for clarity, cycling inseam is measured from the floor to saddle-like (weight bearing) crotch contact in bare feet. The generally accepted maximum standover height would be 2cm less than this dimension, so that means 2cm of clearance in bare feet to weight-bearing contact, not a brush of the crotch on your cycling shorts.

Some folks may fudge on this rule and ride a frame that's a bit larger, but I wouldn't. There are even folks who ride bikes with NO standover clearance.
Yup. If I need to worry about standover, I'm doing it wrong.nmSpunout
Dec 1, 2003 6:49 AM
what about theoretical vs. actual?ortman
Dec 1, 2003 9:52 AM
You're right, the bike I'm looking at is a 2001, which I think has a straight top tube.

The part that confused me is that the Gunnar's 56.5 top tube measurement is "theoretical", and I was told that the actual is about 1 cm shorter. I assume that means the actual length is 55.5. From what I understand the Lemond top tube measurement is actual.

I guess I'm also asking if I'd be better off getting a road bike that's a little smaller or bigger thant the Gunnar. I use the Gunnar for commuting, not racing.

I don't think standover will be a problem. The Gunnar SO ht. is 31.2", the lemond 30.6". Thanks for your help.
theoretical is a misnomer...C-40
Dec 1, 2003 10:08 AM
When the top tube length of a sloping TT bike is listed as "theoretical" or "effective" the proper term is horizontal, the same as a conventional frame with a horizontal TT. The actual TT length is meaningless.

You better recheck the standover of you Gunnar, the value that you posted is lot larger than the Gunnar geometry chart lists.

Whether you'd be better off with a different size depends on the rest of your setup. Do you have an unusually long or short stem or need a lot of steering tube spacers or stem angle to produce a comfortable handlebar height? If the the answer to any of these questions is yes, then you may indeed benefit from a different size.
are you sure about the Gunnar SO ht?ortman
Dec 1, 2003 8:54 PM
The 2002 specs I have lists the 54 cm Crosshairs as having a 31.2" SO ht. The Lemond is 31.6".

The Gunnar has a 105 cm stem with a 105 angle. I'm using about an inch of spacers.

I do think a 53 cm Lemond with a 54.5 cm top tube might be too small, as you said a few posts back. Thanks.