Good topic here. My experience so far. I have been riding fixed/ss since about last april or may. I came from ss mountain biking of about 2 years. I think the benifit of fix and ss is the climbing power you have. I blow by so many people on road bikes i lost count long ago. Now, comparing the exact routes running a freewheel vs. fixed. I was always a few minutes faster on the freewheel. I would say it is because you can fly down steep hills faster,that's all. So, after all is said i prefer fixed. Just to dial in my bike handling skills as poster above stated. I think the disadvatages of each are. fixed=slow downhills.freewheel = seems sloppy wheel and a noisy racket going on down there. However, if i ride in the "mountains" around 3,000ft of elevation change. A freewheel is a must, i don't have a geared bike.