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How big is too big?(4 posts)

How big is too big?Iwannapodiumgirl
Apr 8, 2003 8:55 PM
I have had myself "measured" up using a professional fitting service... 55.6cm c-c seat tube, 57.2 c-c cm tob tube.

I have just seen an "as new" steel frame for a reasonable price ($200), yet it is 57cm c-c square.

This may seem like a silly question, but will this be too big for me? Will the 1.4cm really make a difference? Can I not just adjust the high of the saddle and stem length to accommodate?
Fitting service should give a range of Top Tube / Stem lengthsteamsloppy
Apr 8, 2003 10:03 PM
I think you are right.

A fit kit should give you a range of Top Tube Lengths with Stem lengths. This is the "cockpit" feel of a bike.

The seat tube length is a subset of the the Saddle Pedal Start. The variation in seat tube length is easily compensated using Seat Post Length (and Crank arm length and pedal height stack and other stuff with some consideration for Seat Tube Angle). The Seat Tube Length is listed at the top many fit reports, but IMO that does not mean it is the most important. I think that top tube length is more important the seat tube length. You can use some pretty big seat post lengths. The steerer spacers usually required (1.5 cm usually) are within the 1.4 cm you mention and probably can be eliminated or a flatter stem angle used.

Your fitting service should have given you somethig like this (here's mine as an example):

Seat Tube length 57.5 cm center to center
Seat Tube Angle 75 deg or less
Crank Length 170 / 172.5
Saddle Pedal Start 93.1 - 95.3 cm
Handle bar width 40 - 42
Handle bar drop L
Top Tube Stem Combinations
Top Tube 56 cm Stem 140 cm
Top Tube 56.6 cm Stem 130 - 130.5 cm
Top Tube 57 cm Stem 125 - 130 cm
Top Tube 57.5 cm Stem 120-125 cm
Top Tube 58 cm Stem 115 - 120 cm
probably not a big dealtarwheel
Apr 9, 2003 4:04 AM
With regard to fit, top tube length is the most critical dimension and the 57x57 frame comes close enough. The only issue would be if you didn't have enough standover height to safely clear the top tube, but the importance of that is often overemphasized. You may even find that the 57x57 frame fits you better if you don't like a lot of drop from your saddle to handlebars.

I've got two frames, one a 56x55 c-c and the other 57x56.8. The both fit fine, but I've got a stem that's 1 cm longer on the 56 frame. The seat tube angle is also a lot steeper on the 56, so they end up fitting almost identical across the top. I've had to use a lot of spacers to get my handlebars high enough on the 56, less so on the 57.
when dismounting is painfull???C-40
Apr 9, 2003 7:40 AM
If you have access to any bike with a horizontal top tube, take an accurate inseam maeasurement by blocking up the wheels until you get firm (saddle like)crotch contact when standing over the frame in bare feet, wearing cycling shorts. This is your cycling inseam.

The standover height of your frame should be at least 2cm less than this amount, IMO. I prefer more like 3-4cm less to yield a saddle height that is about 17cm above the TT. I would not purchase any larger frame.