I've decided on a couple of bikes. I'm at that height where I could be on a 52cm or 54cm. With a Pro fit, would it really matter on which frame size to go with? I dont want to get talked into one size over the other because its "in stock". I'm not asking what size to go with, just asking if 2cm is going to make a difference after getting a Pro fit.

Thanks

1. See if you can ride one of each size. This will only help if they are the same geometry, and the bike you finally purchase is also that geometry. Don't know if there are a lot of LBS in your area, but try to go to several and try bikes.

2. Conventional wisdom seems to be if you are between sizes, pick the smaller.

Good luck.

how aggressive do you want your set up? pros are known to go a size down & compensate with a 130-140mm stem to dial in the right reach. main advantage is that you can get a ridiculous saddle-to-bar drop, which allows you to be more aero

Sure it makes a difference. With the large frame you might not be able to get the bars low enough. The larger frame might also require a stubby 90-100mm stem. Some brands only increase the reach by about 10mm between sizes, but some go as far as 15-20mm. You have to compare both the TT length and the seat tube angle to determine the change in reach. If the geometry chart lists the reach, a correction must still be made to account for the difference in stack height. A 20mm taller head tube will make the reach difference 6mm larger than listed.

To add to DaveSSS. The bigger bike will have a longer head tube and so the bars will be higher off the ground and will be higher relative to the saddle height (which remains the same height off the ground because the BB is the same height from the ground regardless of what size the bike is). Sorry, long clumsy sentence!

Head tube length the ONE 'dimension' you can't 'effectively' change, so that's where I'd start... if you want a more relaxed geometry go for the bigger bike and shorten the stem to suit.

I was looking at two Specialized Roubaix frames, one 56cm and one 58cm since I seemed to be on the line between both. I initially felt the top tube of the 58 seemed more comfortable (this is my first road bike in quite a while). The LBS talked me into the 56 saying I looked to be in a better position on it. Boy, am I glad I did--after a month and about 700 miles, I am not only comfortable, but contemplating moving the stem angle down a bit more to get into a more aggressive position--I wouldn't have had that choice on a bigger frame. I say go with the smaller.

Thanks everyone, I'm going to check out (and buy hopefully) a Scott CR1 today. I'll report back later.

Well I ordered a Scott CR1 Team today in a 52cm frame. I'm stoked and cant wait for it to show, hopefully in 1-2 weeks. Maybe I can ride my wifes XS Defy until it arrives!

It's easier to make a bike fit that is too small than one that is too big...

That's usually correct, unless you're like me.