RIDING IN THE GREAT
NORTH"WET"
In an effort to help all the riders
out there in our wet part of the country I would like to post the following
article so that all may take a moment to stop and read up on wet road riding.
Most of us are pretty good at this because we get so much of it, but I know that
some of us could learn just one item that might save a life…maybe your own….
Hydroplaning
Water escapes from under a tire by
squishing out sideways along lateral grooves in the tread. A good rain tire will
have deep angled grooves that point out towards the sides of the tread. The good
news is that narrow motorcycle tires have a relatively long, narrow contact
patch that slices through puddles. The bad news is that today’s wide, low
profile motorcycle tires (which handle so much better in the dry) are more
likely to hydroplane over standing water. Roughly speaking, the typical low
profile radial car tire will start to hydroplane in 1/2" of standing water at
about 60 mph. The wider your tires, the more likely they are to hydroplane at
the same speed-something to consider when you’re thinking, "Hey, maybe I could
fit a 170/60-17 on the back instead of that old-fashioned 140/80-17"
And while we’re talking tires,
remember that a worn tire has shallower grooves which won’t let the water out as
easily. One of the advantages of a new tire is deeper grooves, and therefore an
increased hydroplaning threshold.
It’s also important to keep your tires
pumped up to correct pressures. An under inflated tire encourages a big ripple
to form ahead of the contact patch, and traps water at the edges. A properly
inflated tire has a better chance of pushing down through the water and
maintaining a grip.
Traction Control
Once you’ve had your tires do
the moonwalk on a rain-slicked off ramp, you can get pretty paranoid about a
fall down every time it starts to pitter patter. Obviously, there are many areas
of relatively good traction, and a few rally slippery areas. That’s a clue that
the slipperiness is caused by something more than just rainwater. The truth is,
clean wet pavement has something like 80% of the friction of clean dry pavement.
Of course, the critical word is clean, and
Of course, the critical word is clean,
and pavement rarely is that. Passing vehicles drip all sorts of lubricants on
the surface, including diesel oil, antifreeze, chassis grease, brake dust and
rubber particles. Note that antifreeze is so slippery that liquid cooled race
bikes must use only water in their radiators. In addition to those slippery
vehicle droppings, people toss, dribble and spit a variety of lubricants out the
window, including cigarette butts, hamburger wrappers, french fries, ice cream,
pizza, soda pop, snooze juice and used diapers, to name just a few. That road
glop doesn’t simply evaporate. Most of it gets squished into particles and
mashed into the pavement. A little moisture mixed with that glop can create a
slippery emulsion which is what really reduces traction. That’s why the road
seems so treacherous after just a little mist or morning dew. It’s the sloppery
goo, not just the water. Now, think about this: the only really good pavement
cleaner is a steady downpour that lasts longs enough to float that accumulated
slimy stuff into the gutters. That offers us two lessons: First, the longer it’s
been since a good rainstorm, the more slippery the pavement is likely to be. If
it’s been dry for awhile, you can actually see the slime floating away during
the first half hour or so. Secondly, the pavement will be most slippery when it
first starts to rain, especially if it’s just a little sprinkle or some morning
mist. Those lessons are especially important for riders who live in "dry" areas
and don’t get a lot of rain riding practice.
Once the road glop gets washed away,
both asphalt and concrete paving can have relatively decent traction in the
rain, with some obvious slick exceptions. Shiny spots such as plastic arrows,
steel plates, grated bridge decks or railroad tracks will be treacherous when
wet. Loose objects such as leaves, cardboard or flattened pop cans will be even
more hazardous when damp. And trucks or busses that dribble oil will continue to
dribble fresh supplies of oil on tip of the rain water.
So, take extra care when the rain
starts, don’t let your guard down for a second…it could be your last.
Thanks,
see ya down the road
Jim Townsend
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