Road Science

Cornering Control:
Part 2, Cornering Lines

By David L. Hough

...continued from Part 1

One of the advantages of a narrow 2-wheeler is that you can follow lines through corners that not only provide better traction, but also decrease the risks of a collision. Yes, you can just follow one of the "car" wheel tracks through a corner, but that doesn't necessarily decrease the risks. Riding a motorcycle, you can use the entire lane, "straightening out" curves. The straighter your line through a corner, the less the demand on tire traction, which helps avoid a slide-out.

span style="line-height: 150%; "> The best way to maximize the view is to enter corners from the "outside" of the turn. That is, approaching a right-hander, make your turn-in from a position closer to the centerline.

It's also important to improve the view ahead, because what you can see is a big factor in how fast you can corner. To avoid sticking your neck out too far, you always need to be able to bring the bike to a stop within the roadway you can see. You have to assume that there will be hazards in the road halfway around, even if you can't see them yet. And when you're rounding a right-hand corner, your sight distance typically gets shortened by the shape of the landscape.

For a left-hander, make your turn-in closer to the right edge of the pavement.

The best way to maximize the view is to enter corners from the "outside" of the turn. That is, approaching a right-hander, make your turn-in from a position closer to the centerline. For a left-hander, make your turn-in closer to the right edge of the pavement.

Sideswipe Zones

It's also a high priority to avoid getting sideswiped by oncoming vehicles. It might seem prudent to just stay away from the centerline all the time, but that's not necessary. Drivers tend to wander over the line in specific areas, and it's only necessary to avoid those areas. Consider how an oncoming driver sees the road. There is a tendency to enter curves too fast, cut toward the inside too early, then drift wider in the last half of the curve.

So you don't need to avoid the centerline all the time, you only need to avoid those "sideswipe" areas. As it happens, entering a curve from the outside allows you to cut toward the outside of your lane at the critical zones, increasing your distance from potentially wandering drivers.

Surface Camber

Those twisty secondary roads we enjoy typically have lots of crown in the center, with the pavement on either side slanting off ("cambered") toward the edges of the road. A steep camber in a right-hander works to your advantage, but a steep camber in a left-hander works against you, decreasing traction and eating up lean over clearance.

The "bike" line keeps the motorcycle more vertical, especially on crowned roads.

Consider one motorcyclist following the center of the lane (the "car" line) compared to another motorcyclist following a straighter line (the "bike" line) Not only does the bike line keep the motorcycle more vertical, it also places the bike in the lane to take advantage of a crowned road.

Entering a turn from the outside helps make the best of a well-cambered surface. Entering a right-hander, you can carve over toward the right edge of the pavement where the camber is steepest. Entering a left-hander, you can ease over toward the center of the road where it's more level.

The problem with an early apex is that it points the bike "wide" in the last half of the curve.

We often describe our cornering lines in terms of the "apex"--the imaginary point where the motorcycle passes closest to the inside of the curve. The location of the apex determines the shape of your line. If you turn in early and point the bike toward the inside of the curve too soon, you'll pass by an "early" apex. The problem with an early apex is that you're tempted to carry too much speed into the turn, and then halfway around, realize you're running wide.

Imagine a "delayed" apex somewhat farther around the turn. In a right-hander you'll need to make your turn-in closer to the centerline, and a bit later. In a left-hander, the turn-in point should be close to the outside edge of the road. The delayed apex (sometimes called a "late" apex) provides a better view ahead, conserves traction during the last half of the turn, keeps you away from those "sideswipe zones," and points the bike more around the curve. A delayed apex line is a good idea for riding public roads where anything can happen.

Let's imagine an ideal "delayed apex" line through a blind right-hand curve. You don't have to see the actual position of your imagined apex, just mentally slide it a little farther around the corner than where you think the actual road apex might be. A delayed apex line works just as well in a left turn, with your imagined apex along the centerline, a little farther around the turn.

To follow a "delayed apex" line, mentally slide the apex a little farther around the corner, even when you can't see the rest of the curve.

...continue to Part 3

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 two books Proficient Motorcycling and More Proficient Motorcycling , both published by Bowtie Press. He is also the author of Driving A Sidecar Outfit and a pocket riding skills handbook, Street Strategies .