A few years ago I bought a 56 Cervelo P2 (the current shaped frame) and then got a fit at a LBS (it was a BG Fit). They had a proper fit bike which they didn't have when I got a fit for my road bike previously, and had I known this I may have got the fit first and then looked for a bike that suited my dimensions best, although I don't think this store offers the option of providing a list of bikes that would fit, so I don't know how I would do this exactly? Anyway, I managed to get fitted on to the 56, but the saddle was about as part back on the rails as it would go, so it was close. I think I remembered the fitter saying I had long femurs which may be the reason? In every other way I seemed to get my 'optimum' fit without having to do anything drastic with stems etc.

I have had a couple of years off tri's and sold that P2. I am now considering buying another tri bike, and I have started to have a bit of a look around to see what is available, and I think I may go 2nd hand this time. Since I am having another go at it, ideally I would get a frame that didn't require me to have the saddle all the way back. Looking at the geo chart for the P2, would the measurement that would effect this be the 'rear centre'? If so, this appears to be the same in all sizes as I guess they use the same rear triangle. If that is the case, I would assume that moving to an XL frame wouldn't have any impact on the fore/aft position of the seat? at 5'11 (181cm) an XL just seems like it would be too big too? I see the front end is roughly 2cm higher but I think I could still get it to work by removing all the spacers and maybe getting a stem with more negative rise, but the stem would need to be about 70cm if I got the XL.

From what I understand, in general terms some bikes are long and low or short and tall etc. Is there any particular brand/model that I should be looking at that would suit someone with longer femurs/has the saddle all the way back on a bike like the P2?