Coming Unglued

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Yamaha Motorcycles Street Event - Skagit


Coming Unglued

By David L. Hough

My personal motorcycling hero from the good old days was Mike "the Bike" Hailwood. Mike is no longer with us, but in his prime he could ride a motorcycle around the tricky Isle of Man circuit faster than anyone else, back in the 1970's. He knew the 37-mile circuit like the back of his hand, and rode every race consistently, smoothly, and in absolutely in control, without every hanging a knee off the bike. It was like Mike the Bike was glued onto the saddle.

Well, sports fans, times have changed. Today, when you see roadracers in action, they all hang off the bike towards the inside of turns. They hang off so far they actually slide their knees on the pavement, which is why they have plastic "pucks" on the outside of their leathers. You may have wondered whether hanging off is something the street rider should even consider.

em>(above: Even large touring and sport-touring bikes can benefit from hanging off. It's important to feel what your bike is trying to tell you.)

"What's so important about hanging off?"

"Is hanging off a real advantage, or just a show-off gimmick?"

"Even if hanging off is an advantage on the track, is it a skill I should use on the road?"

In a nutshell, if you're riding a sportbike similar to those racetrack machines, hanging off in turns stabilizes the bike and reduces steering effort, while helping maintain leanover clearance. If that's all you need to know about hanging off, skip the rest of this and go riding. But if you're curious about why it works, or you're a little paranoid about trying it, get your head on tight, and stay with us.

One major difference between Mike Hailwood's style and that of today's roadracers is that motorcycles have been improved. Let's consider tires, for instance. Back in the 70's, motorcycle tires generally had round cross sections. Today's motorcycle tires are typically much fatter and wider, with oval-shaped profiles. Tire profiles and compounds contribute greatly to what happens as the bike is leaned over into turns. Not only do tire compounds provide better wear and better traction, but wide, low profiles have some advantages. First, the wider, flatter footprint puts more rubber on the road, and bridges across surface problems such as grooves or cracks. Second, an oval profile results in more consistent engine RPM as the bike leans over.

Tire Profile vs. Drag

One characteristic of a wider profile tire is that the contact ring shifts further towards the sidewall than a narrow tire as the wheel leans over (Figure 1). What's important about that? Well, it effects steering. The front wheel is being pushed down the road by its axles, but the tire is dragging backward down at the contact ring, due to it's rolling friction. As the bike leans over, the tire contact ring moves farther and farther from the centerline of the bike, so the drag on the tire has more torque to pull the wheel towards the turn. In other words, the tire's drag steers the wheel more towards the turn as the bike is leaned over.

em>(above: Figure 1. The greater the lean angle, the more the front wheel steers itself towards the turn.)

Be aware that a two-wheeler balances by countersteering. To lean the bike right, you momentarily steer the front wheel left, which forces the motorcycle to lean ("roll") towards the right. So, in a left turn, if the front tire steers itself more towards the left, the effect is that the motorcycle wants to roll itself upright, back into a straight line again. (figure 2)

(above: Figure 2. If the front tire steers itself more towards the turn, the effect is that the motorcycle wants to steer itself upright.)

To keep the motorcycle leaned over and continuing around the turn, the rider must maintain pressure on the low grip. Letting up on that low grip at the curve exit allows the front wheel to steer itself a little tighter, rolling the bike back vertical again. But you may have noticed that sometimes the bike seems to hold a lean with very little pressure on the low grip, and sometimes you've got to push hard on the low grip, or even pull on the low grip to maintain the same lean angle. What's going on? Why isn't steering effort the same all the time?

Part of the answer is road camber, the slant of the road in curves. Some roads slant toward the curve (positive camber), some slant away from the curve ("off-camber") Consider a bike leaned over to the same angle in three different curves, one with positive camber, one with the pavement level, and one off-camber. Notice that the lean angle of the bikes is the same in all three turns. (Figure 3)

em>(above: Figure 3. In a positive-camber turn, steering should feel very neutral. In a level turn, you may have to push on the low grip to maintain the same curving line. In the off-camber curve, a much stronger push on the low grip will be needed to hold the same line.)

In the positive-camber turn, the contact ring will be close to the bike centerline, so side drag from the tire will be minimal, and steering should feel very neutral. In a level turn, there will be a moderate amount of offset drag, requiring more push on the low grip to maintain the same curving line. In the off-camber curve, the tire will drag much more towards the inside, requiring a much stronger push on the low grip to hold the same line.

Changing Road Camber

If you think about how roads snake up and down hills and around corners, it should be obvious that road camber is constantly changing. Even on a straight road, the surface may stagger from a left slant to a right slant, and back again. Most of those twisty two-lane roads we like to ride have a crowned center to allow rainwater to run off, so where you position the bike in the lane makes a difference in the camber under your tires at the moment. If you follow our suggested "delayed apex" line, your tires will cross different cambers at different parts of the curve. That helps explain why the feedback from your handlebar grips seems to change from one moment to the next.

Back in the "good old days", road camber didn't have as much effect, because those old round-profile motorcycle tires didn't cause as much of a sideways shift in the position of the contact ring as the bike leaned over. There can't be much side drag on a 2.75-18": or 3.25-19" tire. Dunlop even designed a "Trigonic" front tire that had a triangular cross section more like a V than an O. The idea was to have maximum tire contact with the bike leaned over. But one result was that the contact ring remained close to the bike centerline right up to about 40 or 45-degree lean angles. And with the harder rubber compounds available in those days, riders had to be pretty nervy to lean the bike over that far. Those few riders who were adequately nervy discovered that when the tire suddenly made full contact on the flattish side of it's tread, a bike could make some surprising changes of direction, or produce some scary wobbles.

But let's get back to the future. Consider a contemporary bike leaned over into a curve, with the rider seated exactly on the centerline. The bike has its center of gravity ("CG"), the rider has his CG, and we can assume the two have a combined CG. With the rider sitting balanced in the saddle, the combined bike/rider CG is close to the centerline. Gravity is pulling the bike into a lean towards the curve, balanced against centrifugal force pulling outward. The rider controls balance and direction by slight adjustments in the position of the contact ring.

Shifting weight towards the inside of the curve (hanging off) allows the bike to hold the same line at less of a lean angle. The bike/rider combined CG is now in a slightly different position, but the bike can follow the same curve at the same speed at less of a lean angle. (Figure 4)

em>(above: Figure 4. Hanging off shifts the position of the combined CG, which allows the bike to corner at less of a lean angle, adjusting how the bike steers itself.)

It's obvious that the bike will have more leanover clearance with the rider hanging off towards the inside. What's not so obvious, but just as important, is that it moves the contact ring back towards the centerline of the tire, reducing that off-center tire drag, and therefore reducing steering effort. If the rider has to maintain a strong push on the low grip to keep the bike leaned over, that really means the bike wants to countersteer itself upright. In other words, the contact ring is too far from the centerline to allow the bike to stabilize itself at that particular speed or road camber. Hanging off doesn't change the traction equation very much, which means you don't increase the risks of a slideout by leaning your body to a different angle than the motorcycle.

If your machine makes sparks too easily, or keeps bending the sidestand lever, or requires a lot of steering effort to hold your intended line, hanging off might give you better control. You may discover that hanging off a few inches makes a big difference in steering effort, or allows you to follow a smoother line. And regardless of the good or bad manners of your machine, hanging off may be a smart idea for a severely off-camber surface, or a steady crosswind. The point is, don't throw away better control of your bike just because your habits have you glued to the saddle.

Get Some Exercise

The first step in learning to hang off is to get yourself unglued. Many of us are paranoid about moving around in the saddle, because we've noticed that wiggling around on the bike does strange things to the handling. Rather than live in fear of things we don't understand, let's get a handle on what's happening, so we can use our weight to advantage when it's appropriate.

Perhaps the first place to start would be to try some exercises with your bike. As with any practice exercises, you'd be smart to wear your crash padding and find some unused parking lot away from traffic.

Try riding the bike in a straight line while standing on the pegs. Get the bike up to 25 mph or so, and then lift your butt off the saddle, placing your weight equally on both footpegs. When that gets familiar, try loading more weight on one peg, and then on the other peg. To keep the bike in a straight line, you'll have to lean it bike away from the peg you're standing on. Remember, you control lean angle by countersteering—to lean the bike left, push on the left grip.

Once you're comfortable with standing on the pegs, try lifting your weight slightly, and sliding your butt to one side of the saddle. Then shift your butt to the other side. Try sliding over further and further, while holding the bike in a straight line. Keep your "outside" knee against the saddle to help keep you from sliding off. That is, when hanging off to the left, hook your right knee over the right edge of the saddle and tank. See if you can relax that death grip on the handlebars, and make small steering corrections by pushing on the grips without pushing your body around. And see how smoothly you can shift your weight around to avoid wiggling the bike.

While you're shifting your weight around on the bike and leaning it to compensate for your different body positions, try to figure out what sort of feedback you're getting through the grips. For example, as you lean the bike left, do you have to push harder on the left grip, does steering stay very light, or do you have to pull on the left grip to keep the bike from falling over? Does the bike try to turn left or turn right when you place most of your weight on the right footpeg?


Of course, your ability to move around in the saddle depends on the ergonomics of your bike. Ideally, you should be able to move your body around in the saddle independently of the handlebar grips. That means that most of your body weight should be balanced over the footpegs in your normal riding position, and your arms should be slightly bent reaching for the handlebar grips. If you have to brace yourself against the handlebars to move around or hold yourself on the bike, you will be making steering inputs whether you intend to or not.

There are lots of bikes around with ergonomics that severely limit a rider's ability to move around while riding. "Cruisers" tend to have forward-mounted footpegs that prevent standing on the pegs at all. Some handlebars are so low, or curve back so far, that it's impossible to stand on the pegs and still reach the grips. The ergonomics of your machine may be so awkward that you can't move out of your assigned spot and maintain a grip. Touring bikes are more likely to have footpegs and handlebars in the right positions, but the trend has been towards deep bucket saddles that pretty well lock the rider's butt into a single position. This isn't just a comfort thing—if the ergonomics of your bike are awkward, you can't expect good control in situations such as crosswinds or off-camber turns. You'll have to decide for yourself whether style or long-haul comfort is more important than better control.

On The Road

Assuming your bike has tolerable ergonomics that allow you to move around, it's time to try sliding your weight in the saddle. First, try to feel what the bike is telling you as you negotiate a few turns. Is steering light and responsive while the bike is leaned over, or does it require a stronger and stronger push on the low grip as you lean over more? Does the bike have lots of leanover clearance, or does it make sparks frequently at the middle of the corners? If steering is neutral, and you don't have a touchdown problem, hanging off is probably a waste of time for you. But if you are riding a sportbike with wide tires and quick steering, you'll probably discover that you can really fine-tune your cornering control by shifting your weight.

I suppose even Mike the Bike would be hanging off his machines these days, if he were still around.

David Hough is a long-time motorcyclist and journalist. His work has appeared in numerous motorcycle publications, but he is best known for the monthly skills series "Proficient Motorcycling" in Motorcycle Consumer News, which has been honored by special awards from the Motorcycle Safety Foundation. Selected columns were edited into a book "Proficient Motorcycling" published by Bowtie Press. He is also the author of "Driving A Sidecar Outfit". A pocket handbook, "Street Strategies" is also on the market now.

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