I have a 2004 Trek Fuel 98, it came with full XTR (XT brakes) and Rolf dolomite tubeless wheels- nice free upgrades. I ride XC, nothing crazy, still trying to learn. I was off my bike due to injuries during ski seasons for about 3 years! I don't want to buy a new bike, this one seems more than adequate for my needs. So finally, i started to ride again last summer. I was not feeling like I was dialed in and decided to take it to a fitter to see if I could improve the fit. I was feeling cramped in bike and I would get sore knees. This was a simple fitting, $30 from a local shop.
What did they do for $30? after evaluating pedal stroke angle, I was at 50 degrees, they moved the seat up about 2-3" to get me to 35 degrees, Then after some riding on the trainer, they did some other measurements with a plumb-bob and ended up moving the seat back about 2cm's. then the adjusted the brakes by lowering them to better allign my wrist/hand/arms.
One thing I did last year with the help of some here was to buy a 115 stem, turns out it was the right lenght!
So, after all that I rode on the trainer a few minutes and could really tell a difference in efficeincy and could feel there was much less pressure on the quads. I am riding tomorrow AM on a tame trail but I hope to notice a difference.
Bottom-line: All I can say is if you haven't been fitted, you need to go to a pro. Thanks to Greg Merz for the suggestion! BTW- the boy has a sweet new ride!