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.
 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 leanover 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. |
