Friday, November 02, 2007

More on lines.

Bryce left a comment on the last post that got me to thinking I should add a little more to the subject of lines and apexes. He mentioned setting up to the outside, coming closer towards the middle, then exiting near the center of the road. There was also that question of what to do with those folks coming the other way who are over the yellow line and such similar things. I figured it was worth some more discussion.

The classic line through a corner is Outside-Inside-Outside. The picture below shows it for us.

I've written about this before but a short refresher is in order. Especially in light of looking out for bogies coming the other direction. Setting up outside allows a greater sight distance coming into the corner. We should be looking as far through the corner as we possibly can see. The outside entry position also increases the radius of the turn. In other words, there's less cornering forces exerted on the bike. Which, in turn, helps us keep ground clearance and traction in the bank. Just in case.

Going back to the visual aspect, I'm sure we all agree it's important to have as much information available to us as possible. It's the old "Forewarned is forearmed" thing. Just note that "outside" doesn't mean all the way to the edge of the road. A wise rider will leave a little room to move in response to something unexpected.

Now we move on tonthe part of the corner called "The Apex". Sounds exciting, doesn't it? We all love apexing. I think we like talking about it with other riders even more. The trouble is that there's a lot of riders who don't know fur sure what the apex really is. Take a second and see if you can describe it exactly.

You might be greatly surprised how many so called experienced riders tell me it's the center of the turn. Sometimes it is but mostly it's not in the center. Knowing what an apex is helps us to use it to our advantage. Bear in mind that this is motorcycling, not engineering or physics. I have these kind of folks in my classes who want to tell me it's something like the farthest part of an apogee or something. Maybe in their worlds, but certainly not in mine!

Simply put, the apex is the point where we're the closest to the inside of the curve.

This can happen early ( although it seldom does, at least not on purpose, as it can throw the rider way too wide ), in the middle, or late. In the real world late apexes will be the norm. Or should be as we'll see soon.

As we approach a curve we set up to the outside for maximum visibility. As a parallel thought, it also helps oncoming traffic see us better. If we see debris, tar snakes, gravel, or another vehicle close to the center line we simply change where we apex. I recently saw a guy in a track based cornering class have one of those "lightbulb over the head" moments. When I drew a picture and explained that a middle of the curve apex wasn't written in stone, the light suddenly went on. I could see a whole new understanding light up his face. It seems so simple a concept to just delay the apex as needed. Yet for this guy it suddenly explained why he'd had some previous problems and close calls.

Now that we've established that we're in charge of our own riding lines, lets explore a little more along the lines of when we should commit to our apex.

Here's a drawing of a classic situation. It's a decreasing radius curve.


Freeway on-ramps are something I deal with every day. They're not the only decreasing radius turns we'll find, though.

Notice how the apex comes way late in the curve. One reason is that it makes for far fewer transitions. Staying wide makes for one smooth turn instead of a bunch of little ones. A rider's eyes should be on the exit of the turn. Just for fun, imagine that this curve wraps around a hill covered in brush and trees. If the exit's not visible, we should be looking as far as we can see. It's obviously important to be smooth but there's a much bigger issue involved when deciding when to apex.

Here's another question to ponder: When should you commit to the apex?

Think about it. The apex of the corner is when we're using the most ground clearance because of the lean angle. It's also the point where we're using the most traction. If you want to be scientific about it, a lot of centripetal force is being used to fight centrifugal force. Simply put, physics makes the bike want to go toward the outside of the turn but we need the bike to turn towards the inside of the turn. Either way you look at it, that's when we're the most vulnerable. The apex is when there's the least amount of resources available for any sudden adjustments.

So when do we commit ourselves to becoming this vulnerable?

It's when we can see the exit of the corner. How can we commit without having all the available information? If we can't see the exit we need to stay towards the outside until the exit does become visible. Only then do we have all the information. Too many riders pay a high price for pulling the trigger before they can see the target. How many corners in the real world actually have clear visibility all the way through to the exit? You can see why I stated that late apexes will probably become the norm for us.

Keeping our eyes up and getting all the information before we make the decision to apex also helps link corners smoothly. Take a look at this drawing.


Notice how the apex of the first corner is late. The curve itself didn't require a late apex. It could have happened in the middle of the curve. If the rider had apexed there, though, the bike would have been way out of position to enter the second corner correctly. Our rider would have had to make a quick dart to the outside again to get ready for the next curve. Too many transitions and wasted traction would be the result. Besides looking way un-cool!

Instead, the rider kept their eyes up and saw the corner ahead. In order to be smooth, they chose to apex late in order to be in the proper position to enter the second curve. The goal is to make the exit of the first curve the entrance to the second curve. One smooth line. What I tell riders is to stay wide until you see the entrance of the next corner and then ride right for it.

The good news for those who might think being "safe" means not having fun is that the opposite is true. A safe line is also the fastest as far as street riding goes. It's the difference between carving corners and doing the slice and dice thing.

Hope this helps put the whole picture together. Cornering on a bike is so much fun. It's also the number one place that fatalities and injuries happen in our state. Riders are doing it to themselves without the help of other vehicles. It's critical to get cornering technique right.

Miles and smiles,

Dan




8 comments:

Bryce said...

Time for comment...
Dan in your classes, where do you advise riders to ride? Down the middle of the lane, or on the right of the middle of the lane or
to the left of the middle of the lane?
Because depending upon your reply, that in turn would explain in part where the motorcycle and rider end up
(poor choice of words I know) after completing the curve. In your examples, the machine ends up to the right of the middle of the
lane, which I have always tried
to avoid. Left of centre is preferable; the middle has the
lubricants and the right, well critters of both the four legged
and two legged variety are often
seen there.

Sometimes the machine and rider
can't avoid finding themselves
in the right of centre lane
however I try to follow the line
as suggested.

Now those on and also off ramps
from multi-land carriageways
that's a whole different aspect. The curve is usually plotted for
a four-wheel vehicle doing the
posted limit or less. And as we
all know nobody does the posted
limit unless it's a driving school
instructor and student.

The white line on the right, designating the "edge' of the
asphalt is there only as a suggestion and over time said line
disappears indicating the numbber of vehicles which blatently ignore
the line. Problem is though that line is also slippery when damp and
if a gendarme is following you
when you do cut the corner,so to speak, here in Ontario it's three points and a $250.00 fine.
Yes they can do it but not you.

The police here use the police model Harley-Davidson, a physically small (far too small for me as are most machines) and even they cross
the line on the inside of the curve. Now granted the only encounter anybody is going to have doing either a left or right tight
curve is the four foot high concrete barrier on the actual edge. Come winter, well actually right about now those H-D's go into winter storage as we do get winter
here, with a vengance.

I'd expect your horses for courses don't have highway riding or curve placement
as part of the program. Most courses I expect are slow-speed in
nature, more in ensure the rider
operator has control over the machine.

Sunny here in southern Ontario
this first Saturday in November,
heavy frost last night and as I type this it is just after 11:00 and the outside temperature is
a balmy 12 degrees Celsius. I should go riding however garden work calls first. On my hands
and knees knocking down deceased foliage, running it through the mulching machine and placing it in the compost, that's my weekend,
sadly.

Allen Madding said...

Dan...
Amen on paying the price for pulling the trigger and committing to the apex before we see the exit. A decreasing radius turn will spit you off the side of the road if you make this elementary mistake. Its impossible to visualize your path exiting the turn if you can't see the exit of the turn!

Thanks for a great article! Wish I had read that several years ago :)

Godspeed

Heinz & Frenchie said...

Hey thanks for dropping by. Although we won't be entering I95 anytime soon, we will make good use of the knowledge.

Steve Williams said...

I always enjoy the chance to improve my mental library by reading these kinds of posts Dan. After reading this and the last post I have been paying close attention to my lines and do recognize something. I ride so slowly a lot of the time, perhaps most of the time, that I have way more options in curves. The curves might has well be straight.

That said there are times I am moving faster and following lines like these and making decisions about the apex. You posted a long ways back about keeping your head up and looking out as far as you can in the turn and I try and do that everytime. Except when I am looking for pictures and putting along.

Anyways, thanks for the instruction!

Steve Williams
Scooter in the Sticks

krysta in milwaukee said...

I learned something today. Thank you, Dan.

"What's an apex"?
Like others, my first thought was 'the middle of the curve'... But the middle of the action doesn't always have to be the physical middle of the curve in the road. I knew that.

To be a bit more refined about the answer, it's where you stop going into the curve and start coming out of it.
Also where the sideways friction is most in use.
Also the point where you can finally really see the exit (or the entrance to the next curve) & have a fairly straight shot at it.

The last few days I've been paying more attention to how I set up for curves. Interesting to observe myself...

-

Kano said...

Thanks for the reminder to pay more attention to how I am cornering. Some of my closest calls have been from hitting a corner too hot. Now days I tend to slow down a lot more on curves than I used to.

Conchscooter said...

This is a brilliant exposition of the inexplicable. I've been doing it all my life but by instinct not by MSF. Most enjoyable to read more than once.

irondad said...

Bryce,
I tell students to think in thirds. Left third, center third, right third. Use the part that best suits the situation at the time. For a single curve to the left, the typical scenarion would be:

Enter from the right third, apex in the left third, exit towards the right third.

In linking corners it will vary. For example, I regularly ride a left / right combination set of curves. The left curve requires a late apex. When I exit this curve I hold the press and stay in the left third, which sets me up for the quickly upcoming right curve.

Wild critters are one reason I say not to go clear to the edge of the roadway when setting up for a curve.

As to lubricants, I don't find they're a problem for me except for spills, of course. The place they're heaviest is at intersections. People feel like they should position the bike to the right of center. Guess where the rider has to put their foot down, then?

I prefer to try to keep the bike wheels in the center and brake more gently. Success depends on getting information as early as possible and making sound judgements.

Allen,
It's amazing how many riders commit without enough information. I think it's just poor habits. Most riders I see don't look nearly far enough ahead even when riding in a straight line.

That's exactly what we see that tells us riders don't have enough visual information. They leave the road or cross the center line in the last third of the corner. In other words, they've been greatly surprised by what the road does.

Experience is a great teacher if we survive the lessons!

Heinz & Frenchie,
Hello, yourself. It will be interesting to see what develops over on your site!

Steve,
The good news about looking farther ahead even when riding slowly is that you'll see photo opportunities earlier!

Glad the informatin is useful.

Krysta,
Thanks for the honesty in telling me you learned something new. Makes me feel like I'm doing something worthwhile. It is always interesting to spend some time analyzing our own riding. We can all make improvements, no matter how long we've been riding. Sometimes we just get lazy and re-acquire bad habits.

Kano,
I should write about options for when we accidently enter a corner too hot despite our best intentions. I corner shall we say, briskly, but do it under control. Love to have fun, you know!

Conchscooter,
Thanks for coming by and commenting. I used to see you comment frequently on Gary's blog. It's an honor to have you over here. I think you've read a while, but I appreciate the comment.

Take care,

Dan

P.S. I'm going to slow things down, so to speak, for the next post. Time to visit slow speed stuff in response to a request from Dan earlier.