Azikara

I've looked at www.bikefitting.com and Colorado cyclist to figure out my frame size. I also went into a store and had a Trek dealer fit me. I think I have a 83cm inseam and stand 5'9.5" I came out as a 56 on the Trek. I'm trying to buy a Look. The Look choices are either L (55) or M (53).

When using the above calculators with my 83cm inseam I should have a C-C size frame of 54 cm and C-T of 55.6 cm.
When I look at the Look geometry they have a real C-C and a virtual C-C.
For example, for the L frame: real C-C = 50.5cm and virtual = 55.7cm
Q1: Is the L frame too big for me?
Q2: This is puzzling, the C-T (Actual) measurement is 55cm but the C-C (virtual) is 55.7!! Can the C-T actual really be smaller than the C-C virtual?

Note: the Look website is for the 2008 555 frame not the 2007 which is the one I'm thinking of. Are there any differences?

Thanks in advance for your help:

Azzy

merlinextraligh

1. Yes most likely, 56cm frame at 5'9' is likely too big for you, particularly since the calculaters suggest 54cm.


2. The C-T actual can definitely be smaller, than C-C virtual. The actual is measuring from the BB to the top of the top tube. The C-C Virtual is measuring from the BB to where the center of the top tube would be IF the top tube were parallel to the ground not sloping.

3. On a compact geometry bike, I'd be more concerned about the virtual C-C measurement. The actual C-T would be relevent for standover clearence, but that's not likely to be an issue with compact geometry, if the bike fits you otherwise.

4. Focus more on the top tube length anyway.

Azikara

Thanks but when I go to the calculators none of them talk about how top tube length is calculated w.r.t. your body dimensions. The C-C virtual top tube length of the L frame. The M frame is 54.5cm.

Funny that you say that I'd be a 54 at 5'9.5". That's what every bike shop said and when they actually measured me (this was for a Trek Madone) I turned out to be a 56. I want to buy a Look that's on sale over the internet so I was thinking that the 55 (L) Look frame would work. Now I'm not so sure. Hence why I'm asking.

Appreciate your help.

Surferbruce

Nothing is better than real world testing, but fwiw, I'm 5'10" and ride a 56cm (L) LOOK with a 120mm stem and it fits really well. I used to ride smaller frames and going a little bigger feels really good.
you sound close to right in the middle, you could probably go either and compensate the reach with the stem. now modern thinking is go smaller, but for me if i do that i end up with lots of saddle to bar drop and a very aggressive fit. fine if that's what you want, but if you're north of 30 like me a little headtube goes a long way.
you could probably go with the medium and a stem somewhere in the 12 cm range, or a L with a 10cm stem and be close in reach and fit. the difference will be how low you wanna go with the bar position (and how flexible you are.)
one things for sure, LOOK frames ride freakin sweet.