You'd be surprised at how often your rear tire is actually spinning, even at moderately high speeds . When you run thru the gears hard your prolly spinning the rear wheel and not even knowing it. One way to see this..do a good holeshot. Get your tire good and hot, Then hammer a few gears like you would getting on the freeway, or if your make a high speed pass down the road. You'll have the front wheel off the ground a good bit of the way. You don't realize your spinning the back wheel.....untill it is hooked up tight and NOT spinning