Changing dynamics

Road crown can affect turning dynamics.” width=

A vehicle protruding into an intersection can force a biker
to take a path through an intersection with more road crown,
which can affect turning dynamics.

I take the same route to work most mornings. There is one intersection that continues to give me pause. One of the streets fronts Wadley Hospital and runs basically east-west. The other joins it from the south in a T. There was obviously drainage problems here at one time as the roads have excessive crowns and large drain openings. As I head west into the intersection, and make a left, turning south onto the other street, I notice problems holding the turn. Even at a cautious speed, I’ll sweep out much farther than I intend to. I often drag the pegs trying to stay out of the gutters. It took me a while to figure out that the extra angle of the road surface was what was causing the trouble. If I can hold a line close to the center line, where the surface is more horizontal, I have very little difficulty. It’s only when I drift toward the road edge, and the more steeply sloping surface, that I have problems.
This is actually counter-intuitive to me. A motorcycle turns by leaning. I had always assumed that the angle of the tire to the road surface was the determining factor as to the radius of the turn. But if that were true, the crown would make the turn easier as you got closer to the edge of the road. But I was experiencing the opposite.
One thing that is obvious is with the same lean angle relative to the horizontal, you will be much closer to the road. A lean of 45 degrees to the horizontal may feel like 60 degrees on a crowned road.
Whatever the cause, the way to avoid the issue is to stay as close to the center of the road as I can. That is what I usually do. But sometimes there will be a car waiting at the stop sign. The car will have the stop sign, but if it protrudes too far into the intersection I can’t turn close enough to the centerline. It forces me to take a line farther out where the crown is more pronounced. If that happens, I have to slow down to make the corner. But I’m doing so in front of a driver impatient enough to intrude into the street. I’ve got to keep an eye on the driver to be sure he doesn’t assume I’m going faster than he expects and run over me as I slow to negotiate the turn.
Just one more reminder that not all of the decisions about my safety while on my motorcycle are up to me.

- Guy Wheatley

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