I can't imagine doing a forward aikido roll going 20mph, but I'm just a newbie at aikido too.
qestion for anyone...any tecnique to doing a slide besides making sure you have little vertical speed? My first student jump I screwed up the flare/ldg and seemed like i had a too much forward speed to plf so I tried to slide (at least I think I sort of tried) and 6 months later I can still feel my tailbone everytime I get up from sitting. must have still had some vertical speed going also. is there any difference in how slide and plf tecnique might differ when jumping on a student type canopies versus other types i.e more floaty. Guess I should have forward plfed..been practicing them since!