Originally Posted by
kbarch
There's a simple way to find out whether a custom frame is necessary for a better fit than standard production: get yourself measured and compare the numbers the bike fitter gives you with the specs of the available sizes of the frames you like.
Yes, and be sure to have a good idea of how much deviation from ideal is reasonable. It is first important to understand how much error there is likely to be in the fit measurements. Measuring the human body precisely is very difficult. The error in the fit specifications could easily be several times the difference between them and what you find on a bike. So understanding how close you have to be and how much adjustment is possible with saddle placement and stem without compromising the handling of the bike to get a good fit is very important.