Chris,

If you include roller blade wheeled roller skis ... I think you will
find that they can go much faster than 30 mph. In Alaska there is the
legend of John Svenson, a former UAA xc skier and now roller blade
product manager for K2, hitting 57 mph on roller blades coming down a
freshly paved long hill near Anchorage called Turnagain Pass. The
story goes that he was tucking right next to a car the assistant UAA
alpine ski coach was driving who was calling out the speeds. Things
got exciting when a wheel started to seize, John climbed through the
window when the car was going over 50 and dripped molten plastic over
the back seat (which ****ed off the coach). This speed run was 20
years ago - so I imagine rollerblade composite and bearing technology
has improved so that you can go even faster these days. Like I said,
this is a "legend" and I can't verify the actual speed. But Svenson
was/is a wild man and I don't doubt the claim.

TK