Sand is great - but not on that sort of bike. Too heavy, power band all wrong, wheelbase too short etc etc. Would wear yourself out wrestling the things, or spend most of the time on your backside. Tried Gold Stars on sand and they were useless too. Turned to Hagon/J.A.P. and they were the most fun you could have with your trousers on.
mod edit: typing J.A.P. without the dots ends up reading Japanese.