What speed should I not exceed in low gear?

Bike was driven around a little today. When they went to park the bike, they put it in reverse and when they put it back in Low, the front wheels would not turn. This is basically a brand new bike. Any suggestions?

Just picked up a brand new 400. Problem, the bike was driven around with the parking brake set. They stopped riding when they realized there was an issue, the bike would not go over 12 mph. What can I expect to have to be replaced on the bike?