Trying to find out a good bike fit. Just came back from LBS tried out Giant TCR C2, I tried size M and S, they both fit OK. I am 5' 8" with 30" inseam 150 lbs; Giant recommends M. This is my first try for a compact frame. Thanks.
My last road bike is a 54cm Battaglin CrMo back in 1987, I still own it. The saddle to BB length is 70cm, and the top tube length is 55cm. I used to run it pretty quick but my lack of fitness has its toll on me. I need a more relaxed geomtry. I have two MTB in 19" frame, also with top tube length more or less around 54 cm, but somehow I have saddle height set at 67 cm (or 83 cm from the top of saddle to the down stroke of the pedal) to get best fit. So the size M TCR did not stretch me out.
The size S also works with smaller frame, stiffer and quick. I believe S will set up more agressive since I have to raise the seat tube higher to get the same efficient stroke. On the other hand, M will set me up in a more upright comfortable position.
You are almost exactly like me, right on the edge of S or M. I got an M and am using
a 90 stem with the seat way back. The main thing is, are you OK with hip flexibility
i.e., rotating hips forward and not humping your upper back. The M is ok for me a
lot of people go for the S and longer stem. Do a search in the giant forum.
There's about 15mm difference in the reach and 15mm difference in the head tube length. Unless you must have the handelbars real high, I'd go with the small. I've got 3cm more saddle height and I'd still pick the small. The head tube is 10mm taller than my LOOK 585. The only other reason to pick a medium would be if a 130mm stem on the small is too short. Then you'd probably use a 110mm on the medium. I would not choose the medium if it required a 90-100 stem length.
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