A friend of mine is a Factory Team Green rider for the Hare & Hound Series and the Best in the Desert Series. His mechanic brings three to six fresh factory owned bikes to every race. Normally three of each, KX-250s and KX-500s. When they are sure which bike will be best for the course before the race, they only bring three. They arrive three days before the race. He works with the mechanic and suspension tuner (Acme) the first day getting the set-up (suspension valving, jetting, gear ratios, etc) just right. They may change tires and chain/sproket combinations several times during set-up. They never use a sproket, chain or tire twice. They do all three bike this way. He rides for practice the second day in an area with conditions similar to the race course. When finished practicing, the factory mechanic rebuilds the top ends, clutches and brakes along with installing fresh tires. They set up all three bike exactly the same, test them all, then line them up in the back of a van. On race day the truck moves from checkpoint to checkpoint along the race course ahead of the rider. If he arrives at a checkpoint with a bad clutch or a flat tire they rob one from the spare bike, install it in record time and he continues the race. It takes a pro mechanic about 2 minutes to change a clutch and 30 seconds to change a rear wheel. All-in-all they go through about 5- to 10 rear tires, three top ends, and a couple of clutches for each series race. Multiply that times the number of races in both series and you get lots of parts. He also rides in other non-series races to impove his skill and stay in shape. Last year he rode over 60 races as a professional. In these non-series races he rides one of his five practice bikes (factory provided). It isn't unusual to walk into his home-shop and see 100 tires, twenty-five pipes, dozens of handlebars and cabinets full of new clothing. Rough life, isn't it?