I am between sizes and having a hard time deciding. I am 6' and the calculator says I need a 56 but I know someone that is my height with a 58 and says it fits him better. What size is everyone else riding?

I am 5'11" and I ride a 58. I could and should according to calculations ride a 56, but I prefer a bigger size.

@ 5'10". Had a 56 R2.5 and felt streched on it.

I am 6' and ride a 58. But don't take these figures as a given. It depends a lot on your leg size and various other factors.
Take a look at http://www.competitivecyclist.com/za/CCY?PAGE=FIT_CALCULATOR_INTRO. This is by far the most comprehensive site I've seen thus far on the web.
And if you decide to buy an R3, it is one sweet comfy ride. This coming from someone who used to ride a Softride.

At 6', you are probably on the border of 56 and 58 like myself. I used that calculator and it determined that I would be best on a 56...but you are the third guy that I have heard that is riding a 58 at 6' tall. I am starting to wonder. There was one guy that is 6'2 and rides a 56 because he has longer legs and a shorter torso which is more in check with my body type so its safe to say...I am still undecided.

The crazy thing is the LBS only has a 56 in stock...no 58 to try. Hmmmmmm...:idea:

You're quite right. When the LBS guy took my measurements I remember he came out with a figure like 57.1, but since there was no frame of that size we went with the 58.
We could've gone the other way too, meaning 56, with minor adjustments in stem size, handle bar height etc.
Keep in mind that these are centimeters we're talking about. 1 centimeter isn't even 1/2 inch. (1 inch = 2.54 centimeters). As long as he doesn't try to put you on 48 frame you should be OK. Everything else should be adjustable with different components.
Have fun choosing your new ride.

I'm 5'11" and am on a 56, with a lot of seatpost (I had to ditch the standard one and get a 330) but the stretch feels about right, though I'm not entirely convinced. I'd like to try a 58 as I think it might be a bit better.

fww:
I've been reaserching this and everyone i have spoken with at shops across town recommend a 58 for me over a 56 or 61, and I am 6-6'1 with longish legs, the drop on a 56 would be excessive.

I did a small road test and tried a 58 and 56...but just felt more comfortable on the 56. I come from a mountain bike backround and have always liked my frames smaller. Not saying I should ride a 56 but I just feel more comfortable on it. I agree...an LBS in the area that had Cervelo Soloists in stock said I should be riding a 58...however he was 2 inches shorter than myself and said he road a 54 because he has a bad back/neck. I think it just goes to show...you can make anything really work for ya...its just what your comfortable with.