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Jaybird180

How Agressive Can The Throttle Be Rolled On?

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I'm familiar with what's in TOTWII however I think it would be helpful to have a clear example. I was watching a YouTube video the other day and on my drive in to work I began to rethink how aggressive the rider was rolling on the gas (and the mid-corner upshifts) and it got me comparing it to my anemic roll-ons that I'd rationalized as "smooth".

 

So really? How hard can you get on it at full tilt boogie? Have a video clip to share?

 

 

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Race bikes usually have a shorter throttle run than street setups: throttle input tends to open the butterflies slower at the beginning and then progressively faster as we reach the end of the run. Motion-Pro is one company that produces this kind of modified throttle cables. When I installed one on my bike it changed the engine feeling completely without compromising traction control at lower speeds (entering corners and at max lean angle).

 

So in the end traction control and smoothness are critical in some parts of the track, but when racing you need to be aggressive on the throttle on the exits, as allowed by the tire grip.

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I'm familiar with what's in TOTWII .........How hard can you get on it at full tilt boogie? Have a video clip to share?

 

 

The book recommends 0.1 ~ 0.2 g acceleration to balance the load on the contact patches.

That means that you should add 3.22 ~ 6.44 ft/s (2.2 ~ 4.4 mph) of speed for each second spent on the turn.

 

Please, see these:

http://forums.superbikeschool.com/index.php?showtopic=3645

 

http://forums.superbikeschool.com/index.php?showtopic=3665

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Thanks for the references. Now, can you tell me what that looks like? Or sounds like? Words often miss the significance of something that has to be experienced. That's the point of my OP.

 

And besides...it's fun to reverse engineer or redefine what "rolling on" means. Why does the book recommend 0.1 - 0.2g of acceleration? What happens if you apply 0.3g? Does the bike blow up? Does the rider highside himself to the moon? I'm not a spoon fed kinda guy. I have to understand why.

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Thanks for the references. Now, can you tell me what that looks like? Or sounds like? Words often miss the significance of something that has to be experienced. That's the point of my OP.

 

And besides...it's fun to reverse engineer or redefine what "rolling on" means. Why does the book recommend 0.1 - 0.2g of acceleration? What happens if you apply 0.3g? Does the bike blow up? Does the rider highside himself to the moon? I'm not a spoon fed kinda guy. I have to understand why.

 

The recommended acceleration achieves an optimal weight distribution (more or less 40% of total weight of bike and rider on smaller front contact patch and 60% on bigger contact patch) and an optimal position for the front and rear suspensions (about half of each stroke) and an optimal clearance of the chassis (higher position during moderate acceleration).

 

The increment of rpm's may sound different for each size and type of engine.

It feels like you are gaining around 3 mph per second, regardless of the speed you are traveling at.

Considering the gain of speed during the turn, you enter the curve as slowly as you need it to enter in order to leave it as fast as you want or can.

 

The 0.1 - 0.2g only means that the force accelerating the bike forward (in addition to the force needed to overcome aerodynamic drag) should be 10% - 20% of the total weight.

If that force is bigger, like the 0.3g of your example, then it is 30% of the weight; hence, the front tire and suspension are a little less loaded and the rear tire is a little more loaded than ideal.

 

Nothing catastrophic will happen..... if you are not riding at the very limit of traction.

Actually, you can wheelie out of a turn at a moderate angle of lean, in which case, 100% of the weight would be on the rear tire.

 

All the above (weight distribution, suspension position, etc.) is more critical for turns that require extreme lean angles and grip.

In order to understand the reasons to be precise and smooth for high performance riding, please, read this:

http://www.motorcyclistonline.com/leaning-bike-code-break

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How aggressive you can roll on depends on a variety of factors. But there are ways to tell if you rolled on too aggressively or are approaching the limit.

 

So, question to the group, what are some INDICATORS that you rolled the throttle on TOO aggressively in a corner?

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How aggressive you can roll on depends on a variety of factors. But there are ways to tell if you rolled on too aggressively or are approaching the limit.

 

So, question to the group, what are some INDICATORS that you rolled the throttle on TOO aggressively in a corner?

 

If I roll on TOO aggressively, I feel:

-I can't keep my line and start to run wide (missed apex)

-a sense of understeer, which may be the same as previous point (very easy to blame the bike/tires)

-when very aggressive, the rear tire skips and the TC warns me to calm down

 

And just a side note that may or may not be relevant. While doing level 1, Coach James observed that I was coasting into corners and told me that if I couldn't get on the gas immediately after completing my turn-in steering action, then I was entering the turn with too much speed.

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Good answers all--really.

 

The only dangerous no-no (a leading cause of crashes that we see) is increasing the throttle AND increasing the lean angle--that is the deadly no-no. Every school day we see it and have to get it cleared up.

 

CF

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Does anyone recall the videos of Kevin Schwantz wheeliing out of turns...and looked like he was still leaned over 35-40 degrees? Maybe we could dig those up and get them here.

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How does the video compare to the ideal roll-on? Too much, too little or "three little bears" just right?

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It'd be cool if we could find that...anyone up to that?/

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So back to the original reason for this post....

 

Is there enough information in the video to evaluate the rider's roll on?

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So back to the original reason for this post....

 

Is there enough information in the video to evaluate the rider's roll on?

 

It looks to me like in the first lap or two his roll-on early in the corner is too aggressive - he is missing the apex on many corners and you can see that although he gains on the other riders at the first 1/3 to 1/2 of the corner, they pull easily away from him later in the corner, totally smoking him on the exits. Missing the apex means he is not pointed properly to the exit and cannot drive as hard as the other riders. A little later when the riders are not right in front of him he calms down and his throttle control improves, he starts hitting his apexes and the exit drives improve. It sounds like he is spinning the tire a little on the exits on some of the turns, so he is at the traction limit; he might be able to get a better drive by being slightly more patient with the throttle mid-corner and using pick-up to get the bike more upright for improved traction (via more suspension efficiency) on the exits.

 

That's what I think. What do YOU think?

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"Considering that most machines in a static or constant speed situation have a 50/50 weight distribution (+ or - 5.0 percent) front-to-rear. We begin to calculate the guidelines of correct acceleration through a turn. By the numbers, we want to transfer 10 to 20 percent of the weight rearwards, using the throttle. Technically, this is 0.1 to 0.2 G of acceleration. Simply put, it's the force generated by a smooth fifth-gear roll-on in the 4000 to 6000 rpm range on pretty much anything over 600cc."

TOTWII

 

Missing from this statement is the component of time. The statement clearly tells what is occurring but does not indicate over what period of time the RPM has been changed from 4000 to 6000 RPM. If we knew for example that it occurs over 23 seconds, that might be too anemic, likewise if it occurs in 0.068 seconds it might be too aggressive.

 

Can someone fill in the gap of time?

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"Considering that most machines in a static or constant speed situation have a 50/50 weight distribution (+ or - 5.0 percent) front-to-rear. We begin to calculate the guidelines of correct acceleration through a turn. By the numbers, we want to transfer 10 to 20 percent of the weight rearwards, using the throttle. Technically, this is 0.1 to 0.2 G of acceleration. Simply put, it's the force generated by a smooth fifth-gear roll-on in the 4000 to 6000 rpm range on pretty much anything over 600cc."

TOTWII

 

Missing from this statement is the component of time. The statement clearly tells what is occurring but does not indicate over what period of time the RPM has been changed from 4000 to 6000 RPM. If we knew for example that it occurs over 23 seconds, that might be too anemic, likewise if it occurs in 0.068 seconds it might be too aggressive.

 

Can someone fill in the gap of time?

 

This is not saying that you need to GET from 4000 RPM to 6000 RPM. It is saying that if you do a smooth roll-on in fifth gear and your RPM is somewhere around 4-6000 RPM the bike will GIVE you the about the right amount of acceleration to hit the desired 0.1 to 0.2 G. Keith is just giving an example of what an approximate 0.1 G to 0.2 G acceleration force FEELS like to the rider, so the rider has a simple way to try it, experience it, and know what it feels like.

 

(As a comparison, think of how the bike would feel if you rolled on the gas in second gear at 12,000 RPM - it would launch forward much more aggressively, producing MORE acceleration and weight shift than the desired 40/60. The fifth gear 4-6000 RPM roll is a much gentler acceleration and is automatically in the approximate 0.1-0.2 range.)

 

What RESULT are you looking for, when you have excellent throttle control? How you YOU judge for yourself if you got your throttle control right in a corner?

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A stable and predictable line. Better tire traction with both tires giving decent feedback. No SR inflammation. A satisfying engine crescendo.

 

All of these things are products of good throttle control and indicators that it is correct.

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A stable and predictable line. Better tire traction with both tires giving decent feedback. No SR inflammation. A satisfying engine crescendo.

 

All of these things are products of good throttle control and indicators that it is correct.

 

Sounds like you got it down cold. :)

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........... Missing from this statement is the component of time........

 

Can someone fill in the gap of time?

 

What transfers some weight onto the rear tire is acceleration, which only depends on mass (the weight of rider plus fluids plus bike) and force pushing forward (torque to the rear wheel).

 

Acceleration = Force / Mass

 

By rolling the throttle open, we are feeding the rear wheel with the torque that is needed to achieve the recommended rate of acceleration (0.1 to 0.2 G).

 

The statement of the book is only an example; you can feed similar torque or force in second, third or any gear that conditions dictate.

 

Being G = 32.2 m/s^2 (acceleration of gravity), the recommended 0.1 to 0.2 G means that the rate of cornering acceleration should be in the range of 0.1 x G = 3.22 m/s^2 to 0.2 x G = 6.44 m/s^2.

 

The above is hard to "feel" while cornering; which is the reason for the more practical reference in the book.

 

Three more hints that may help you "fill in the gap of time":

 

1) The proper acceleration feels like you are gaining around 3 mph per second, regardless of the speed you are traveling at.

 

2) During that acceleration, you should feel a force pulling your body backwards.

That force is the inertia of your body resisting the acceleration of the bike.

The magnitude of that horizontal force should be around 10% to 20% of your own weight.

 

3) This video:

 

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One of the things I got from that video is that my roll-on rates haven't been consistent. If I worked on that primary thing it should allow me to stabilize the other aspects of cornering.

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Inconsistent roll on rates...yeah, many, many have to pay some attention to that.

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Good close up footage of Johnny Rea's right hand during Race 1 of the Thailand WSBK race. He was on it pretty aggressively. And the new rules means they have to use stock throttle bodies, so no trickery except for Traction Control. IIRC the 2017 Kawi has ride by wire throttle (Grrrrrr).... which means no learning value for me.

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But traction control, that's a big deal...

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On 3/12/2017 at 0:14 PM, Jaybird180 said:

 ride by wire throttle (Grrrrrr).... which means no learning value for me.

There is much more there to be learned than meets the eye! A lot depends on the twist grip angle vs throttle plate(s) opening angle.

What is the ratio? How could this be changed to improve or impede your lap times?

 

Jeff

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So if Throttle Control Rule #1 were to be updated for the modern era, would it say that 'it should be rolled on to the limits of rear traction as moderated by TC'?

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