What are the two components of rear-tire grip on corner exits?
- Lean Angle
We learn to not “grab a handful of throttle” on corner exits. Some riders learn it on a dirt bike, some riders learn it while lying in the dirt with their street bike.
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BikeMinds readers and graduates of YCRS have it explained in such a way that we can add a third way of learning this lesson:
3. The rear tire has 100 points (100 percent) of grip and can take a tremendous load… but not an abrupt load.
Okay, so we’re always linear with the throttle and that means we’ll never crash from a loss of rear-tire grip on corner exits, right?
No, wrong. It’s not just too much throttle on corner exits that causes the problem. Let’s examine the second component of rear grip on exits: Lean Angle.
On a recent day at the track, a very good and high-mileage rider crashed from a loss of rear-tire grip on a third-gear corner exit. The day before, we noticed his habit of quickly adding lean angle with bar pressure if he was a bit wide of his apex and had to tighten his exit line. We talked about slowing his bike better. We talked about using more body off the bike to tighten the radius at the same lean angle, and we talked about giving away a bit of throttle if he needed to add lean angle after the apex.
He understood. Made sense. He earnestly worked on these three things and made huge strides. But they were new concepts, and the next day he was caught out by his habit of whipping a bit more lean angle after the apex. The rear end came around and he spun harmlessly into the grass, with almost no damage to bike and rider, fortunate to not be high-sided.
The two reasons it caught him out that time and not the first day must be understood: First, he was lapping faster, using more lean angle and throttle, consistently closer to the tire’s 100-point maximum. Second, his rear tire was another day older. The tire’s 100-point scale was lower due to wear and heat cycles. Everything YCRS teaches matters when the pace is up or the grip is down.
Whipping the bike on corner exits is done with handlebar pressure—a quick jab on the inside bar to redirect the exit line slightly.
Did you spot “quick jab” in the preceding sentence? Tires don’t like abruptness.
There are several solutions to the problem of your bike running wide off the apex:
- Allow the bike to turn longer off-throttle because Radius Equals Miles-per-Hour
- Use the brakes slightly longer, see above equation
- Pick up initial throttle more gently so the bike doesn’t increase speed so early, same equation
- Reduce throttle slightly if you must add lean angle on the exit; if you’re adding lean angle points, reduce throttle points
- Move your shoulders and head off the inside of the bike more, allowing you to tighten your radius at the same lean angle
For those coming into the two-wheeled world from cars: I’ve been around car instructors who use the term “Go to Power” as if it’s a switch that the driver throws. In fact, it’s the driver’s foot mashing down on the throttle as if it’s a switch. Please remove that term from your motorcycling vocabulary, because the rider that “switches” on the throttle will always have grip issues if he/she must hold or add lean angle on the exit.
And a little hint for the car lovers: “Go to Power” works with slow cars driven slowly or with the traction control (TC) in full-on mode. Fast cars or less electronics will punish this practice. Oh, and every time your car or bike is in TC, it’s cutting horsepower, that’s why the MotoGP boys hang off so far and point the bike so well: Get it out of TC and into full-power mode ASAP.
Final Thought: As you pick-up (initiate) the throttle to exit the corner, all that matters is your line and rear grip. Focus relentlessly on your right hand and the rear tire, that’s what counts. If your radius is opening, you can increase throttle. Radius staying the same you must hold throttle. Radius needs to tighten? You must reduce throttle.
Below, friend-of-BikeMinds, Trever kindly demonstrates what loss of rear grip looks like – and how it can quickly get expensive.
Nick Ienatsch (@NickIenatsch) is chief instructor at Yamaha Champions Riding School, For more than 18 years, he has provided motorcycle instruction rooted in his own successful professional racing career, which includes two AMA SuperTeams national championships, four top-three annual finishes in AMA 250 GP competition, two #1 plates from Willow Springs, three WERA Grand National Championships, and top-three finishes in AMA 600 SuperSport. Author of “Sport Riding Techniques,” Ienatsch has been a motojournalist since 1984 and currently writes for Cycle World.
Cover photo courtesy of 4theriders.com
What's Your Take?
Did you learn something about rear tire grip that you can apply to your own riding?
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