@Agek g-forms are for impact not much for speed, I fell on some triple 8s and killers going 45 and they didn't slip. It also counts on how you land on them. If you don't fall on the shell it might grip with the road and slip down.
@ApolloSkating you can't really control how you fall on your knees, g forms have no cushion, so that's not really for impact. I've worn triple 8s too. Regardless once you land they can slip, yours didn't? Great. But the guy who did this would have been helped much by padd