My cycle fit (in London - at CycleFit) was more about me than the bike - it measured my flexibility through my legs and upper body, told me my leg lengths are effectively different (caused by one tight IT band in the left leg) even though their actual lengths are the same - however, many people do have different leg lengths and so many problems around saddle comfort, knee pain and cleat alignment can all stem from this. They gave me custom food beds and a wedge under the left cleat which has completely stopped my left knee 'waggle' and the pain. The knee now tracks straight. Also they reminded me about cycling with neutral spine (ie. straight back, not 'humped'!). They measured my power output (for each leg) so I could see they were fairly equal - which is good. You fill out a form before you go for your fit to tell them of any existing problems you want them to address. Obviously if I'd had back or other trouble they would have concentrated on that but for me it was pain in my knee that was the issue I wanted sorting. They set you up to get the best pedalling efficiency and comfort (though it's usually a compromise between the two, and the extent to which you compromise depends on the type of riding you'll be doing and for how long - which they also take into account). The actual bike measurements were of secondary importance to me, as I am not about to buy a new bike at the moment, though I'll obviously take them into account when I do. The measurements actually do not match any of my current bikes exactly, though they are fairly close.
