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Fit question?(5 posts)

Fit question?SLR
May 22, 2003 3:16 AM
I just got fit tested and my optimum reach is 66.8cm center to center. The bike I'm looking at comes with top tubes of 53.9 and 55.3. I'm 5'9" and used to have a 56cm Cannondale and it felt too big, which combo would you recommend:

53.9cm TT + 115mm stem + 1.4cm setback post = 66.8cm
55.3cm TT + 100mm stem + 1.5cm setback post = 66.8cm

I'm leaning towards the 53.9TT because I think a 110/120 stem is what most people are running. Wouldn't the 100mm stem be funky on the 55.3??
Thanks in advance,
May 22, 2003 4:46 AM
Even the best professional fitting can't determine your optimum reach, since it is dependent on saddle position and your personal level of fitness. Optimum saddle position can only be determined by many miles of on the road experimentation. A fitting will only get you to a decent starting point.

I don't understand the 1.4cm amd 1.5cm "setback post" dimensions. You must consider the seat tube angle(STA)to determine the true TT length of the two frames. Post the brand of frames that you are considering and I can provide a more exact analysis.

You should also not ignore the vertical size of the frame. The smaller frame may use a longer stem, but it will also require a higher rise stem or more steering tube spacers, whch can look worse than a short stem.
May 22, 2003 1:19 PM
They are Litespeed Sirius, Med and Med/Lrg. Both frames have the same size head tubes 13.4cm. The frame comes with a setback post...I would just move the saddle forward on the ML. BTW my inseam with feet spread 6" apart is around 32".
get the size MC-40
May 23, 2003 4:49 AM
You never move the saddle to compensate for differences in TT length. Saddle adjustment is inteneded to allow changes in the relation of the knee to the bottom bracket, for optimum pedaling efficiency. Stem length is change to adjust the reach to the bars.

This bike has unusual geometry. No changes to the seat tube angle, and the same head tube length on both sizes. In this case, the only difference in the setup of the two frames would be the stem length. At your height, you should go with the size M. A 110-120 stem will probably be required.

You may find that the relatively short head tube length requires a "flipped" stem to get the bar height that you need. Flipping an 80 degree stem will raise the bars over 3cm, flipping and 84 degree stem will raise the bars by just under 2cm. When using a stem in the flipped position, you may also need the next longer length.
Thanks C-40!!SLR
May 23, 2003 11:20 PM
I got the Med and everything you said was on point! I kind of figured it out myself but wanted some expert advice since I consider myself a newbie. I'm a MTB'r but am starting to love the road!