Originally Posted by erk
Ok to be clear. When I am doing 30-40 mph I am going down hill. I like to climb a big hill just so I can go down hill really fast. In fact I will get a ride to the top of a mountain pass 9500 ft. Down to 5500 ft in less than 5 miles. On the flat I do about 20mph with a 48/15 ratio. Cadence is about 110-120. Going down hill I coast on my single speed set up not fixed. My issue is going that fast at my weight can be sketchy at hairpins or just in general and thought that disk breaks could be the answer. I live in New Mexico and there are some really fast areas that can get dangerous with guys that weight over 200lb. I know it's hard for you small guys to imagine a 250bl powering up a 12% grade at 10 mph. And then Down the other side( coasting) at 35 mph and then suddenly have to come to a stop due to unforeseen circumstances. put some more years under your belt and maybe this will happen to you.
Erk, plug in your numbers here http://www.bikecalc.com/speed_at_cadence
If you're doing 20 on the flats in 48/15 your cadence is 80. I'm also surprised your speed downhill isn't greater than 35-40, if it's a 12% grade, especially at your weight. I weigh 185. I'm not the greatest descender (well, not as bad as Ullrich), and on that kind of a grade, if long enough, will start to feather the brakes at 50. In my youth, when i was more confident, I descended Whiteface mountain in Lake Placid at speeds up to 56mph, over 4 miles at around 8% I think.
You might want to try feathering the brakes as you descend. If you stay on them, they'll heat up and be of no use. As for the hairpins, you know you need to brake in advance and try to set up for it. It sounds like you know the course well. What brakes are you using? Good quality calipers are all you need, but if you want to go disc, that's certainly your decision. Their use on the road is pretty new and I have no knowledge of the issue.