Ride around with your brake on for a while few minuites), then pour cold water over the rotor and continue riding round for the next few minuites the again pour water on the rotor, continue this for a couple more times untill the brake has a really nice sharp bite happy to help. tom reason for doing this is that the rotor gets really hot and instantly pouring cold water on it seems to do something to it, dont ask me i just know it works as i have seen it done .. EDIT: brake not fully on, rubbing