I figure you know this and you want to lock up just so you can do a sweet skid stop in front of some hot babes to impress them, but locking up a tire reduces the tires frictional force, reducing it's stopping ability. for performance reasons, I'd adjust the brakes, especially the back one, so that you're about to lock up at full braking force. the point where a tire is about to lock up, but doesn't, is where it brakes the best. "Optimal Braking."
But again, I'm not trying to impress with info you don't know, I just believe in covering all the bases. Skid Mark=Hot Chick On the Back Of The 'Ped!