Figuring out bike size...online help?
Hi. I've been checking out ebay for bikes...I want a P3. Last year I went to a Cervelo dealer an hour from me, and he fit me on a 60cm P3(I'm 6'4"), but he said he never let his customers try the bike on the road. He had the bike sitting on a trainer, so I just sat on it there...and, well, I couldn't be sure it was the right size. He really wanted to sell the bike, and he happend to have that 60cm frame at his shop at the close of the season, so I was not too sure my "perfect" fit wasn't, in part, a push for the sale. At my height, it's so rare to find a shop that has a frame my size within its walls (without having to order it), so I'm a bit mystified as to how to comfortably know the frame size I'll need. In talking to our local shop--which sells only low-end Cannondales--I get the impression that they can sort of fit me onto any frame. I've been riding a 56cm Panasonic road bike for 20 years--my back hurts when I ride it...always has. Aside from the dealer an hour away, the next closest Cervelo dealer is 5 hours away--one way. I've heard some folks speak of online size calculators...is there such a thing? It seems like there are so many articles that render position down to angles and tube lengths that I should be able to punch in my own key measurements and be able to determine what size P3 I need to look for...from there, I might be able to order it online without travelling?
I'm frustrated, and I hate to make a mistake on such an expensive bike...what do you guys think?