Ok when I was in east LA I found a glitch

Ok first get on the BMX and do your special,and you will be driving your skateboard as a bike,but you can only do that if you go in the cave on the train tracks,also if you do your special and don't go in the cave you will be driving your skate but standing on it with your arms up's stright out,it may not work on your first try but it does work.