There's a fairly straight section on the "front" (West) side of Monitor Pass that has a low double-digit grade (10-15%), for about 0.5 miles.

I weigh 135 lbs soaking wet, and I've reached 55 mph on that section before (chin over bars, no jacket). Bigger folks and tandems have gone considerably faster.

I don't think of descending quickly as an athletic thrill ride, but a way to minimize braking and its wear and tear on my rims. From descending with bigger riders who have an advantage over me, I have picked up some techniques that help me keep up (pick good lines on curves, sprint out of the turns, etc.).