So far I've been on my new K2 Radical 100s for probably 10-12 miles. I went out Friday after work for a lap around Creve Couer lake. By the time I was done I was completely exhausted. The Radicals definitely have far less ankle support than I am used to, and after my first day on the skates that made a huge difference. Today I went out again with Eric and we skated our usual two laps. These skates are fast, exceptionally fast. The fit is great though I'm going to Heat Mold them later this week, probably before I skate again. If you're in the market for a pair of long distance fitness skates definitely look into the Radical 100s. The biggest change for me so far, besides the ankle support, is the turning radius. I am far less nimble on these than my older skates with much smaller wheels. But these skates weren't made for agility, so if I want to do some hockey stops I'll throw on my other pair of K2s or my hockey...