Large Forces Are Necessary To Go Fast On A Motorcycle

[Hugh Janus]

Up close, controlling and harnessing the full potential of a racing motorcycle is an exhausting workout. (MotoGP /)

Watching roadracing from spectator distance it looks precise, graceful. Sometimes writers get sufficiently carried away to use the word “balletic.”

But up close it is a high-effort, hammering, exhausting gymnastic workout on a hot, vibrating 250-hp side-horse. Look at how quickly riders change position on their bikes as they change direction. Yes, they do have to do it precisely because so much of their effort passes through their hands—which remain dedicated to the task of staying precisely on-line.

The handlebars on roadrace bikes are usually so-called “clip-ons,” separate right and left stub bars that are clamped by pinch-bolts to the two fork tubes. And despite those pinch-bolts being tightened close to yield, the bars can slip on the tubes, or are bent by the rider’s efforts to turn the bars against the powerful gyro force of the spinning wheels and the inertia of the whole bike and its fuel load, resisting efforts to throw it as quickly as possible from one direction to the other.

When one of my former riders, Nick Richichi, made the step up from a TZ250 Yamaha to a 325-pound 120-hp TZ750, after a couple of practices at Loudon, New Hampshire, he said to me, “I’m using all my strength to get this thing to change direction from turn 2 to turn 3. And I’m never quite sure I’m gonna make it.”

And if the rider isn’t strong enough? He/she doesn’t get turned soon enough and runs wide or off the track. What is the remedy in that case? To slow down enough to provide more time for the direction change. Strength is speed.

Steering precisely while fighting the forces of acceleration takes tremendous fitness and strength. (Monster Energy Yamaha/)

Why do modern racebikes have forged magnesium or carbon fiber wheels, with the lightest brake discs possible? Because a lot of a bike’s resistance to turning is in the gyro stability of its front wheel. Erik Buell, during his time as a sports motorcycle manufacturer, used mass properties apparatus—one for the bike as a whole and another for wheels alone—to measure that resistance so his engineers could reduce it in every possible way. The goal was more rapid and easier response to steering.

At Laguna Seca I watched Wayne Rainey and others at turn 11, a slow left. As he finished braking each lap I could see him pull himself forward as much as possible to put weight on the front wheel for the hard acceleration up the hill. When the front wheel lifts, that’s all there is—adding more throttle just adds to the lack of control. Keeping Rainey from sliding back was just the strength of his arms. That is like hanging from the high bar with arms bent at the elbows, while “weighing” 140 percent of normal (1.4G is a fair estimate of maximum lower-gear acceleration). And steering precisely at the same time. 

I also watched one rider who later went on to a distinguished career in World Supers remain all the way back in the seat through turn 11. As he throttled-up to accelerate, his front wheel became lighter because his body weight was maybe 4 inches further to the rear than Rainey’s. And his bike drifted wide despite his efforts to “dig in” the front wheel with extra steer angle. To avoid running off the track he had to reduce throttle. Slow lap times were the result.

This is why top riders today are all in heavy physical training programs—to give them the strength and endurance to quickly put their weight where it has to be: right, left, forward, back—and still retain the precision required to hold the line.

When bikes misbehave—weaving in the motion riders call “pumping,” or jerking sideways as tires slip and then grip again—rider control is threatened. At a recent MotoGP Ducati rider Jack Miller stood up on the pegs to let his bike go nuts. Rainey, launching off T11 all those years ago, had carefully moved his knees and elbows away from the tank, knowing that otherwise the bike’s violent slip-and-grip motions would compromise his ability to steer.

The ability to move instantly to wherever on the bike is needed comes from strength and endurance. (MotoGP/)

Maybe “balletic” is in one sense a good word to describe racing. When you get up close to the dancers you can hear the grunts of effort and see the large muscular forces required for the lifting, heaving, and whirling that from a distance look so graceful.

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