Not quite, not saying his brakes can't be improved, especially after reading what he is riding on but simply saying that at 250lbs and on a bike that has pretty darn good brakes when I'm going really fast down a hill my bike does not stop very quickly. as compared to being on flat ground. there is a big difference between going 20mph and 35-40 and as clydes, we often hit much higher speeds going downhill than our skinny counterparts and if our skinny friends are going just as fast as us, they have much less mass to stop so they can stop easier (i.e. the tour de france example someone else gave.)

I have the koolstop pads that are half salmon half regular, they work pretty well but ultimately i'm conscious of my speed when going downhill, especially if it's a hill that I've never been down.