Kevin Schwantz Suzuki School - Defining Corners

Text: Kevin Schwantz, Lance Holst • Photography: Kevin Schwantz, Lance Holst

Most street riders have favorite roads and favorite corners, and if they're honest they'll admit that they also have roads and corners that they just don't feel comfortable riding. Ask them why and many won't be able to tell you, but a number of aspects determine the average rider's confidence level in corners.

We're going to take an in-depth look at corners and break them down in terms of radius, camber, elevation change, visibility, and pavement surface. These are the characteristics that make corners comfortable or uncomfortable for the typical rider, and defining them in these terms helps riders better understand them. With a higher level of understanding, riders can overcome the portions that make them uncomfortable and eventually master all types of corners and ride with complete confidence.

The dictionary defines radius as "a straight line extending from the center of a circle or sphere to the circumference or surface." When we motorcyclists talk about a corner's radius, we're actually referring to a section of a circle's circumference or the arc of the turn. Corners are either constant radius, increasing radius, decreasing radius or, in some cases, a combination of the above.

Most public roads feature constant radius turns, or corners, which carry the same arc from beginning to end. What you see entering is what you get all the way through. We're comfortable because we know what to expect and there are no surprises. An increasing radius corner actually opens up as the corner progresses, which may be more or less confidence inspiring, depending on the individual rider. Decreasing radius corners tighten up as you continue through the corner, forcing one to either lean over farther or decelerate while in the corner. Either of these actions tends to make riders uncomfortable and robs them of confidence.

We typically refer to camber as banking. A corner can feature flat camber, positive camber, negative camber or, as many public roads feature, a crowned camber. Flat camber is straightforward and gives the rider exactly what is seen. In positive camber or banking, the outside surface of the corner is higher than the inside, which helps turn the motorcycle into the corner, which in turn inspires confidence in most riders. With negative camber corners, the inside surface of the corner is higher and the pavement slopes away from the corner, which makes the corner effectively tighter than it looks and undermines rider confidence. Most public roads are crowned (with a high point in the center and downward slopes on either side) to allow water to run off rather than puddle. Turn five at Road Atlanta is an example of crowned camber and as students go from the apex to the center of the track it's banked, only to turn immediately into negative camber, which sets up the feeling that it's pulling the bikes wide toward the curbing at the exit of the corner. And until they understand it better, it's a corner most students feel uncomfortable confronting.

Elevation sounds straightforward enough but while traveling at speed around Road Atlanta, for instance, you'd be surprised how many riders estimate it incorrectly. Obviously riding uphill helps slow the bike down and inspires confidence while downhill makes the bike more difficult to slow due to gravity, and saps the courage from most riders. Another aspect related to elevation change is visibility, particularly at the crest of hills as experienced at Road Atlanta in turns two, three, five, nine, and especially under the bridge in turn eleven. Anytime a rider can't see what's coming up next, that rider's poise suffers and that's where reference points (which we'll concentrate on in the next issue) become particularly important.

Pavement surface determines traction and should be a top priority for all riders. On the track, where riders lap continuously throughout the day, the pavement surface (and traction) is predictable, changing only under extremes in temperature and in inclement weather conditions. This allows track riders or racers to ride much closer to the limit of adhesion in relative safety. Street riders don't have this luxury, however, and it's one of the main reasons why riding on the street is more difficult and dangerous than riding on the track. On the street it's best to ride with what we call a 'reserve' of at least 20 percent additional lean angle and traction to allow for unexpected variables intrinsic to street riding. Failing to do so might not bite you every time, but eventually it will catch up with you and a price will be paid.

Breaking down each corner in the terms we've covered will allow you to better understand how corners affect your bike and you. In the next issue we discuss finding reference points and using them to give your riding more predictability and precision.