Originally Posted by staehpj1

In the Rockies, we went somewhere in the 40's maybe 48 mph or so. The extra weight is offset to some degree by the drag of panniers and stuff.

Just like in a car on extreme grades, you to need to use the brakes in a way that doesn't overheat them. I typically use one brake fairly hard for a few seconds, coast a bit, use the other, coast a bit, etc. If there aren't intersections or turns I tend to let it roll pretty good. I never just keep the brakes steadily applied. If I am worried about overheating the rims and pads I stop for a bit. The worst was a descent in the Appalachians where the grade was in the mid to upper teens and the curves were tight and constant.

You can keep speed down some by sitting upright for more wind resistance.