Thinking in Vs-Dissecting Cornerspeed

Paul Duval thinking in Vs – otmpix.com

Guest writer Paul Duval shares his thoughtful observations about performance cornering based on electronic data gathering.
Corner speed. It is the holy grail of motorcycle road racing and track day riding alike. Knee down and railing, carving the corners like a snowboarder or giant slalom skier. It looks and feels awesome! Smooth technique pays big dividends and you can carry a lot of speed as your skills progress.
But how is it that you can be cranked way over thinking you have maxed your speed for a given corner and yet, some other dude comes by on the inside (or outside at a Tony’s Track Day!) and walks away from you before the bikes are even upright on the next straight bit?
And by the way, He’s not even leaned over as far as you are! There must be more to corner speed than meets the eye. Let’s take a closer look at the middle of a corner.

Corner Speed Perception

If we draw the arc of your path on paper it looks like a smooth outside-inside-outside line and it is easy to visualize maintaining a somewhat constant speed, decreasing and increasing in a smooth fashion, but overall steady. One could imagine their speed data trace looking similar or the same as the arc of their line through the corner. This is, in fact, how most riders perceive cornerspeed. They feel they can put a number on it.
For example, that’s a 70 mph sweeper, or a 50 mph hairpin. But something is wrong. How did that fast guy in the example above pass while you were dragging knee, elbow, boot, etc. with 57 degrees of lean angle? If he’s going faster, wouldn’t he need MORE lean, not less?

V is for Variable Corner Speed

If we look at GPS speed data from a corner, we can see the first flaw in our perception of corner speed. It is not constant. It is not even close. From the start of the arc that we drew with our bike, speed drops precipitously until it reaches a low point much slower than expected somewhere near the middle of the arc. If you perceive a 70 MPH corner, the chances are your slowest point of that turn is 50MPH. This rapidly dropping speed line doesn’t rest at the bottom for long rather it reverses course and quickly climbs out of the hole. The trace of your speed data doesn’t look like a U. Instead it looks decidedly like a V.   Our minds fill in the slow spot, and we perceive a 70 MPH corner.

In this image we see speed over distance data (kph) for Thompson Speedway turns 1-4.

The Pivot Point

The bottom of the V, or the slowest point of the corner is the important spot to recognize.   From here on out I will call this the pivot point. The pivot point should actually be part of your cornering plan. In other words, you need a reference point (or a few) for this spot on track. It is the spot at which your bike can change direction the most easily.
This critical moment in riding is often ignored, but it is where the real direction change happens. As you trail off the brakes, your hands get lighter on the controls until you have no weight on the bars and you allow the wheel fall INTO the turn. THIS is the spot where your grip needs to be as light as possible.
To be clear, you still need to countersteer to initiate lean. Countersteering is an important technique, but in this article, we are focused on the middle of the turn, the pivot point.

photo: otmpix.com

When and Where to Pivot?

Most of you are thinking, “we are talking about the apex, right”? I am avoiding the word apex on purpose. Many people refer to the apex as the point where you are closest to the inside of the pavement. This is often not the same place as the pivot point.
For example, double apex corners and increasing radius corners tend to have the pivot point in a different location than the “apex”. This concept applies to all bikes, big and small, and all lines, point and shoot, or fast and flowing. Different bikes may choose different pivot points to take advantage of the strengths and weaknesses of each platform.
Examples:

  • In a “fast exit” corner, the pivot point would be located earlier and you would get on the gas sooner to take advantage of that fast exit.
  • In a “slow exit” corner, the pivot point is located later to take advantage off all the possible entry speed.
  • In a “balanced corner” (equally fast entry/exit) you have a little wiggle room. If you need entry speed to pass a rider you can pivot a little later, if you want to out drive them on the exit then pivot a little earlier.
photo: owenstrackdayphotos.com

Similar Mid-Corner Speed

Interestingly, if you compare a fast lap and a slow one, you will often see that the mid corner speed (slowest point) of the faster rider is not a lot different from that of intermediate riders. Maybe just a few MPH, or maybe no different at all!
What you will see is that the slopes of the V in the speed data trace are steeper, usually on both sides. The faster rider is faster into and out of the corner. Understanding where your pivot point is allows you to plan the fastest way the get to it, and the fastest way to get away from it.
So here comes that fast(er) guy blowing by you on the outside into a fast corner. You already feel you are mid corner and cranked over good, but he knows that he has some yards to go before reaching the pivot point, and is taking advantage by carrying more entry speed, tipping in slower and braking later or longer.
You both reach the same minimum speed in this corner, and you feel like he’s in touch for a moment. You might even feel like your “corner speed” is the same as his, but he quickly pivots the bike and walks away on the exit because he can accelerate sooner than you. Sigh.
Time to start thinking in Vs.


otmpix.com

About Paul Duval

Paul Duval is the latest RITZ guest writer. Paul is a fellow track day instructor, former Loudon Road Racing Series 125 GP Champion, and professional educator. You can see Paul in action at most Tony’s Track Days events.


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Guest Writer: When Do You Lean?

The ability to lean a motorcycle with confidence is a fundamental part of riding. Unfortunately, humans do not come hardwired to lean much more than about 20 degrees, which is the lean angle where we start to lose traction  when we run in a circle on grass or dirt. Motorcycle riders must get beyond this lean angle limit for even basic maneuvers. This requires a leap of faith that the tires will grip. Practice is important to train your mind and muscles to lean beyond your comfort zone so you will be able to lean more if necessary. Once greater lean angles become more comfortable, the next skill to refine is timing so you reach maximum lean angle at the right point in the corner.


 
Paul Duval at full lean.www.otmpix.com
Paul Duval at full lean. www.otmpix.com

Meet Paul Duval

Paul Duval is the latest RITZ guest writer. Paul is a fellow track day and MSF instructor, former Loudon Road Racing Series 125 GP Champion, and professional educator. Let’s listen to Paul’s take on the importance of accurately timing maximum lean angle.


Timing Maximum Lean Angle

After many years of racing and instructing on the racetrack, there is one persistent mistake I see riders make when trying to ride faster: Using too much lean, too late in the corner.

Who is making this mistake?

Everyone is susceptible to this problem. Novice and intermediate track day riders often make the mistake of  increasing lean angle late in the corner in an attempt to get their knee down. Especially vulnerable riders are those with a lot of “natural talent” who got fast so much more quickly than everyone else. They end up riding fast, but without the knowledge and precision necessary to manage that corner speed.

What’s the Problem?

Adding throttle and increased lean angle at the same time is a bad idea.
Adding throttle and increased lean angle at the same time is a bad idea.

You may say, “What’s the big deal, I’m knee down and cranking?!” Yes, you may be fast, but this mistake WILL eventually lead to a crash, and probably a BIG one.
The problem with reaching max lean angle well after the apex of a turn is that this is precisely where you want to be on the gas.  Other riders will be already picking the bike up and driving hard.  This will encourage you to match their drive, but you are still adding lean angle.
Remember this:  Adding lean angle AND throttle at the same time is how high sides happen. The opposing forces of changing direction and accelerating can easily exceed available traction and will cause the rear tire to slide.   When this happens, slides are extremely quick, unpredictable, and hard to recover from.  All of your momentum is going exactly the wrong way.

Why do I keep doing this?

There are a few reasons people make this mistake.
Weak countersteering skills:  Newer riders haven’t yet mastered the “quick turn” technique of using counter steering to get the bike leaned over.  They bend their motorcycle into the turns gradually and often pass the apex entirely before the bike has changed direction.  Now they are running out of real estate and HAVE to lean it over to finish the turn.
Lack of reference points:Beginner and Intermediate track riders often use other riders as their reference points. This leads to a lot of crazy entry lines, none of which help the rider get the bike to change direction before the apex.  They commonly ride around the entry point as well as the apex, then crank the bike over to finish the turn.
Charging the corners:  Faster riders who make this mistake are at the most risk.  They rush into the corner at a pace that does not allow them to consistently hit their marks.  They will blow by a tip in point, drift wide past the apex, and then attempt to recover to get back on the “fast” exit line by adding a little more lean and a little more throttle.
Even with all this effort, they wonder why the faster guys are still pulling away.  They aren’t even cranked over like I am!!!  Hmmmm???  You may get away with late lean angles for a while, but eventually, you will push this mistake too far. Highside city.

The Solution?

The correction for all these riders is pretty similar.  And it’s not what they want to hear:  SLOW DOWN your corner entry to a speed that you can actually handle.  I mean a speed at which you can identify reference points, and ride an accurate line from tip in to apex that allows you to OPEN the corner after the apex, rather than tighten it up.  You need to learn to time your throttle inputs and your lean angle so that as you drive out of the corner and standing the bike up progressively as you roll on the gas.  BRAAAAP!  Wheee!


A quicker turn allows early direction change and less risk of an on-throttle highside.
A quicker turn allows early direction change and less risk of an on-throttle highside. copyright Riding in the Zone.

Ken:
Thanks Paul. Paul mentioned the importance of being able to turn quickly. By being able to countersteer with authority, you are able to get your motorcycle from upright to leaned so that the majority of the direction change is complete BEFORE the apex. With the change in direction mostly complete, you can reduce lean angle as you roll on the gas. Traction is managed and all is well. Post your comments below.


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