I had good luck with : http://www.competitivecyclist.com/za...LCULATOR_INTRO
shoot for exactness with the measurements. On your rides, stem lengths and seat setbacks can make a huge difference in how a bike fits and feels. I got a road bike this year after 10 years on an ill-fitting mountain bike. I started out smaller than I should have (54) because flexibility needed to come. After a thousand or so miles, I lengthened the stem to where the fit calculator recommended after getting the seat in the appropriate position. Enjoying the ride so much more now.