[OwenM]

Come on.....If $20 is the difference between buying and not the prospective purchaser really cant afford to run a motorcycle IMHO, let alone a BMW. Most would spend that much on lunch, add in fuel, running costs etc and a days ride would cost me $100.

Perceived difficulty in fitting the sprockets, or the cost - inconvenience of having someone else fit them would seem like a much bigger issue to me than a measly $20.