We used to do this on gravel at bout 30-40k's (20miles/hour) and it did hurt when you fell!! but i was wearing sneakers. I wouldnt want to have a go on the motorway tho!!
yes !! I gotta admit that takes some guts ... on the freeway !! the craziest we ever did was bumper sledding in the winter ... and that was nuts. hanging on to the bumper of a car and on your haunches.you know their sandals have to be melting !!