In legal terms, a motorcycle is considered an 'attractive nuisance', if someone sits on your unattended bike, knocks it over and damages it, believe it or not, you don't have much in the way of legal recourse to get the person to pay for damages .
I've got a co-worker that's a Ducati fanatic, his wife is an attorney, one of his bikes got knocked over by someone sitting on it, caused around $4500 damage to the carbon fiber bodywork, after all of the legal hassle his wife went through, the only reimbursement they got, was the $500 insurance deductible .
If you were thinking, gee I wonder if his insurance went up due to the claim, it did .