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Fit Question ... Frame question ...please help ...(3 posts)

Fit Question ... Frame question ...please help ...El Guapo
Aug 19, 2003 7:56 AM
Inseam = 29 inches
Trunk = 26.5 inches
Forearm = 14 inches
Arm = 26.5 inches
Thigh = 23 inches
Lower leg = 21.75 inches
Sternal notch = 56.75 inches

Competitive Cyclist and Serotta recommend the following:

Seat tube range (c-c) = 47.8 - 48.2 (c-t) = 49.2-49.7
Top tube range (c-c) = 57.1 - 57.5
bb - saddle position = 67.9 - 69.9
saddle - handlebar (tip to back) = 53.9 - 54.5

Question: Should I ignore the seat tube recommendation? It seems to be impossible to find a 48 cm seat tube with a 57+ top tube. I currently ride a 54.61 tt (c-c) with a 52.07 st (c-c). saddle - handlebar position on current rig is 53.975. If I go with the shorter tt related to the 48 cm suggested st and offset this shortcoming with a setback seatpost, won't I change the effective angles and handling characteristics of the frame? Should I ignore the st length since it really only determines the seatpost exposure? I get the feeling that there are really only 4 measurements to adhere to: tt length, saddle setback (relative to bb), saddle height (relative to floor), and saddle to bar distance. Please help, I am in quite a quandary. New frame considerations: Viner V6 ProTeam (airplane), Cannondale CAAD5 (both from GVHbikes) and FetishCycles Pena (airplane). Any advice on these considerations will be greatly appreciated.
re: Fit Question ... Frame question ...please help ...MShaw
Aug 19, 2003 9:41 AM
In my experience, the only things that really matter are ST angle, and TT length. The ST itself is only there to get the saddle high enough for the TT. Standover isn't really an issue on a road bike. When was the last time you had to dismount quickly that didn't involve crashing?

The saddle setback is taken care of by the seatpost and ST angle: too steep for your legs and you're too far forward, too slack and you go the other way.

The saddle height needs to be measured to the center of the BB. Since BB drops vary, it is a better number than to the floor

I have a friend that rides a 52cm ST x 61cm TT bike that he had custom built by the guy that was building the GT Superbikes. You may want to try him (the name escapes me at the moment).

Sounds like you're the perfect person for a compact frame... My little brother just bought a Tommasso on ebay that was 52 ST x 56 TT... I ride something really similar 48x54.5. Compact frames are a Godsend!

Mike
I guess I'd say "fudge it" more than "ignore it."djg
Aug 19, 2003 10:37 AM
Recommended standover seems to me the most plastic of the sizing recommendations. On the one hand, it's relatively objective as it keys on your physical dimensions and only your physical dimensions, whereas, say, horizontal reach and drop to bars is substantially a function of your flexibility, riding style, etc., as well as size. On the other: who needs it? It is not at all easy to fall off your seat and onto your top tube, and most of the circumstances in which you are liable to suffer such a fall (see Lance and the pedal incident) are not ones where you are likely able to save yourself by putting your feet out on either side, with legs nice and straight. Seat tube length is mostly useful as a proxy for top tube length, not for any inherent value in a certain length of seat tube. Now it is possible for a bike to be too tall--at some point you'll run into trouble mounting and dismounting a bike. At some other point you'll run into trouble getting your saddle in the right place. But most folks can fudge the "recommended" standover (and seat tube) by a couple of cm without it being an issue at all, and I'd be surprised if you couldn't easily manage 3. Now if you're willing to look at compact frames, it shouldn't be any sort of a problem to find a 50 or even 48 cm seat tube with a 56 cm top tube, and that's without going custom. Add a cm to the stem and you're home free on the recommended sizing.

I'd try to borrow a compact with roughly these dimensions to see how it feels. If the sizing seem ok you're home free, albeit not on the Canny (which would require either that you go WAY long on the seat tube or way short on the top tube). Seems like compact or custom is likely the way to go.

In the end, whatever is comfortable and works for you should be the guide.