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Cobie's Deadly Sin


Jaybird180
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We've all heard about it. If you've looked at the pages of this forum you know that thing that he preaches about: Adding throttle and lean angle at the same time.

 

I'm beginning to wonder if my 2 mystery crashes aren't attributed to violation of the Cobie Commandment.

 

My question is: what would it feel like to lose the front in this situation? What does it look like to see a rider do it? Have any pics or videos to cite as a reference?

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Hi JB,

 

Yeah, we really try and pay attention to this, as its the single biggest cause of crashes, in the turn.

 

Did you see the race last year, when Marquez won the title, I think it was Motegi, Japan? In that race, both Rossi and Lorenzo crashed. I think they both added throttle and lean, mid-turn. Maybe you can find that video?

 

Doesn't really matter when in a turn it's done (although at turn in, it makes the bike run too wide). Normally happens later in the turn, rider keeps increasing the lean, and adding more throttle.

 

One can certainly lose the front this way, or even both ends. The point is the 2 actions together make it unpredictable and sudden, it overwhelms the tire. Even traction control won't save it all the time. That other thread you and I were on, that had the video link and you saw Stoner sliding the bike (front end turned out). That is the opposite of throttle and lean angle increasing. He was increasing the throttle, but bringing the bike up.

 

As for what it feels like is one is just down, often wondering WTF? Can be the front or rear or both, maybe even just the rear too.

 

CF

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Sometimes I wonder whether it's better to enter corners at higher speed than lower. For novice riders lower speed is the obvious choice but for advanced riders and racers low entry speed can hide this type of trap. High speed on the other hand can be corrected by trail braking with less risk.

 

Not obvious to fix habit and instinct in this case.

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Spaghetti (BTW, love your avatar picture),

 

If that entry speed goes too high, what's the likely result as far as when the gas can come on? If the brakes carry in too long, too late...gas has to wait. Some turns this has to happen (long, late apex, decreasing radius comes to mind). But in modern racing if you go in too fast, run a little wide, brake too much, too long, a bunch of guys go by. Also, from the traction standpoint, waiting late on the throttle...is that ideal traction distribution, front loaded? (based on tire contact patch, which is bigger?).

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I just had to explain why this is a sin. How did I do?

 

 

As you apply the countersteering action, the tire takes load which uses up some of its available traction. The further the lean angle the less traction is available at the same steering rate. With the application of throttle the front end is pushing while being asked to steer the bike. It's a very fine line as to where the limit is.

 

If you watch MotoGP, Lorenzo used to have this problem a lot; losing the front end on the early parts of the corner. That's what he was doing; countersteering and adding throttle.

 

If you need the performance, get the speed and the chassis geometry set with throttle, then get the bike rolled over to the required lean angle then roll on the gas steadily throughout the remainder of the turn. From the video it appeared the rider was hitting the gas just before deciding where to initiate the steering input, holding it constant and then relying on power to accelerate late in the turn. It's not ideal from a chassis, suspension and tire grip standpoint and you can get away with it many times and in fact, I used to ride this way myself, but you only have so much available traction on the tires until, you don't.

 

 

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In most turns the gas roll on is not begun, until after the steering is completed. That would affect what you have above.

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We've all heard about it. If you've looked at the pages of this forum you know that thing that he preaches about: Adding throttle and lean angle at the same time.........

When cornering per TTOAW2, we are adding throtle and lean angle simultaneously.

Rolling the throttle on constantly increases the speed (not much, just 2 to 4 mph per each second).

If the radius of the arc of your turn is constant, as it should be, you will see a light increment of the lean angle along the turn.

If you want your leaving speed/lean angle combination to be at the limit of traction, you need to moderate your entry speed accordingly.

 

Now, whenever you are close to the limit of traction, you will need to reduce lean angle (increasing the radius of turn) in order to safely increase torque load on the rear tire or to increase speed.

Because the same reason, if you need to reduce the radius of turn, you will need to slowdown some first.

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When cornering per TTOAW2, we are adding throtle and lean angle simultaneously.

If the radius of the arc of your turn is constant, as it should be, you will see a light increment of the lean angle along the turn.

 

Hm, I read it differently.

 

Have a look at TOTWII, Chapter 4 Throttle Control: Everyman's Ideal Line, the section called "Line Follows Gas", and also at Chapter 14, Steering:The Rules, particularly the section "Off/On + Lean". To me, these sections recommend NOT adding any more lean angle once the initial steering is completed.

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........Have a look at TOTWII, Chapter 4 Throttle Control: Everyman's Ideal Line, the section called "Line Follows Gas", and also at Chapter 14, Steering:The Rules, particularly the section "Off/On + Lean". To me, these sections recommend NOT adding any more lean angle once the initial steering is completed.

 

 

I just did read those portions of the book again: :)

- Ideally the bike should accelerate in a turn = The speed of the bike increases some after rolling-on of throttle begins (as soon as possible).

- A good and constant line through any turn allows the application of the golden rule: Once the throttle is opened, it is rolled on constantly throughout the remainder of the turn = The goal is to obtain the ideal 40/60 weight distribution.

- One steering action is ideal = The radius of the trajectory of the bike should be constant (up to the moment to pick up the bike to exit).

 

It seems that my choice of words was not the best: it is not that we want to increase the lean angle, it is that the lean angle becomes a little steeper naturally while we apply these rules.

Trying to explain to Jaybird180 that "Adding throttle and lean angle at the same time" sometimes occur, not causing a slide when the combination is moderate.

 

The lean angle is not something that we can select at will, at least not directly.

The lean angle is the balancing reaction of the bike to the lateral (sliding) forces of cornering, which are the consequence of speed and radius of turn.

 

More cornering speed

} = Higher sliding forces = Steeper lean angle

Tighter cornering radius

 

It seems to me that in track talking, "adding lean angle" refers to counter-steering in order to quickly reduce radius of turn, which induces higher lateral forces and naturally a greater lean angle.

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The radius of the trajectory of the bike should be constant (up to the moment to pick up the bike to exist).

 

 

I do follow your path of logic, but where are you seeing the statement in Twist II that the radius of your arc should be constant? It talks about getting the bike to hold a "predictable line" and says that "line follows gas" but I do not see anything that says you must maintain a constant radius arc.

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The radius of the trajectory of the bike should be constant (up to the moment to pick up the bike to exist).

 

 

I do follow your path of logic, but where are you seeing the statement in Twist II that the radius of your arc should be constant? It talks about getting the bike to hold a "predictable line" and says that "line follows gas" but I do not see anything that says you must maintain a constant radius arc.

 

As you accelerate by rolling on the gas the radius of the arc opens (widens), no?

 

 

 

 

........Have a look at TOTWII, Chapter 4 Throttle Control: Everyman's Ideal Line, the section called "Line Follows Gas", and also at Chapter 14, Steering:The Rules, particularly the section "Off/On + Lean". To me, these sections recommend NOT adding any more lean angle once the initial steering is completed.

 

 

I just did read those portions of the book again: :)

- Ideally the bike should accelerate in a turn = The speed of the bike increases some after rolling-on of throttle begins (as soon as possible).

- A good and constant line through any turn allows the application of the golden rule: Once the throttle is opened, it is rolled on constantly throughout the remainder of the turn = The goal is to obtain the ideal 40/60 weight distribution.

- One steering action is ideal = The radius of the trajectory of the bike should be constant (up to the moment to pick up the bike to exist).

 

It seems that my choice of words was not the best: it is not that we want to increase the lean angle, it is that the lean angle becomes a little steeper naturally while we apply these rules.

Trying to explain to Jaybird180 that "Adding throttle and lean angle at the same time" sometimes occur, not causing a slide when the combination is moderate.

 

The lean angle is not something that we can select at will, at least not directly.

The lean angle is the balancing reaction of the bike to the lateral (sliding) forces of cornering, which are the consequence of speed and radius of turn.

 

More cornering speed

} = Higher sliding forces = Steeper lean angle

Tighter cornering radius

 

It seems to me that in track talking, "adding lean angle" refers to counter-steering in order to quickly reduce radius of turn, which induces higher lateral forces and naturally a greater lean angle.

 

Isn't adding throttle and lean angle a deliberate act? Inducing a slide is nice, if it were controllable and 100% predictable everytime, all the time. If that were the case, then the thread would be moot.

 

Could it be argued that if someone on the levels of Rossi and Lorenzo were unable to do this, it might be prudent to consider it a danger zone, no?

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Even they (Rossi and Lorenzo) need to pay close attention.

 

I think I stated this in another thread, but they both crashed in the race Marquez won the title (Japan I think). Looks to me that they both added throttle and lean...not sure if one can find that footage or not.

 

And yes, above when you add throttle the line will widen.

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And yes, above when you add throttle the line will widen.

 

Just to clarify, when adding maintenance throttle to achieve the desired 40/60 tire loading, you are in a state of acceleration. Not only are you accelerating fast enough to counteract the slow down from the bike being leaned over but your speed will increase; however not by much. So your line widens but not significantly. Is that correct? And this widening line should become part of your "expected" line through a corner.

 

I don't know if there's a drill to simulate to students on a stationary bike what maintenance throttle roll on should look like under different conditions or speeds.

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Bashir, that is correct, regarding the line. The term "maintenance throttle" can mean to some, just holding, not continuing the roll on (used more in cars I think). So, like you have done above, good to define it.

 

There are different levels of throttle needed, for different bikes, and cornering loads. If I recall data I heard from a factory 600 bike, at full lean it required 42% throttle to just get the bike to stop slowing down. That's a pro rider, factory bike, top-level tires (greatest cornering forces). On a liter bike it would be different levels of throttle, on a Ninja 300 it would be different. You are quite right, not so easy, it would take a heck of a simulator to duplicate the effects.

 

Through the heart of the turn, max lean angle, if one could get a little acceleration...

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Even they (Rossi and Lorenzo) need to pay close attention.

 

I think I stated this in another thread, but they both crashed in the race Marquez won the title (Japan I think). Looks to me that they both added throttle and lean...not sure if one can find that footage or not.

 

And yes, above when you add throttle the line will widen.

I did verify that was the correct race.

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The radius of the trajectory of the bike should be constant (up to the moment to pick up the bike to exist).

 

 

I do follow your path of logic, but where are you seeing the statement in Twist II that the radius of your arc should be constant? It talks about getting the bike to hold a "predictable line" and says that "line follows gas" but I do not see anything that says you must maintain a constant radius arc.

 

 

I don't see such statement either. :)

May be I am reading it wrong, but it seems to me that other statements in the book lead me to believe that keeping a constant radius is a desirable thing:

 

The book refers many times to decreasing radius turns as a bad situation to foresee; hence, constant or increasing radius are better situations.

It also advises about using standard 40/60 throttle control as "the only reliable way to hold a constant line through any turn." (Chapter 4 / Hold it).

It teaches that when using standard throttle "the only things that will change the lean angle of the bike to any great degree are a slide/catch action or steering input." (Chapter 13).

I understand the rule number one for steering (Chapter 14) as no reason for the bike to deviate from a circular trajectory after we counter-steer to achieve the proper lean angle: "one single steering action per turn", that is it.

 

Again, I may be reading all these statements incorrectly.

I understand that the conditions of the road, or track or a race may force a rider to trace a line that is far from perfectly circular.

To me, quick-flick, out-apex-out, 40/60 throttle control and hanging-off, are all techniques to make that radius of turn as big as possible, the suspension as stable and efficient as possible and to keep the lateral loads/stress on the tires as small as possible.

 

Accelerating or coasting during the turn, any steering input to decreasing the radius increases the lateral load/stress on the tires and the lean angle must get bigger.

Not combining that with strong acceleration is the point of this thread, IMHO.

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Seems like you do have this. One thing that sometimes comes up is with the throttle being rolled on, and 40-60 weight bias, there is some widening of the arc. Just to look at one more piece of this, if the rider gives the bike too much throttle, where will the line of the bike go?

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Seems like you do have this. One thing that sometimes comes up is with the throttle being rolled on, and 40-60 weight bias, there is some widening of the arc. Just to look at one more piece of this, if the rider gives the bike too much throttle, where will the line of the bike go?

 

Cobie I think you're opening up another can of worms here :)

 

Ideally with a more aggressive roll on whereby front loading is less than 40% and rear is more than 60%, the bike (and line) should run wider.

 

The complex side of this is that tires (both front and rear) slip as you ride/accelerate through a corner. But with an increased amount of throttle and rear slip can lead to a power drift thereby pointing the bike in a tighter line. Kinda like a controlled oversteer.

 

I think it was in the movie "Faster" where they talked about Gary Mccoy winning a motogp race by sliding around so much whereas theory dictates that drifting shouldn't be the fastest way around a racetrack!

 

As if this isn't complex enough, different electronics regulate the rear wheel speed differently. As speed increases, one has to understand how electronics are limiting wheel spin and cutting drive through and out of a corner. And personally, I still don't fully understand how slick mode on the S1000RR works!

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When you get to a point where you are adding enough throttle to start sliding the rear, that changes the dynamics but fortunately THAT scenario is covered in TOTWII Chapter Three in Rear Suspension and Gas, and also in Chapter Ten: RIder Input, Riding and Sliding.

Who can identify who said this, and where the quote can be found?
"Some guys slide the front and some the back. I like to get both ends going and play with traction at the end of the turn. To me that's the most fun. But sliding isn't bravery, its an extension of your skill and ability to control the bike with throttle."

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Who can identify who said this, and where the quote can be found?

"Some guys slide the front and some the back. I like to get both ends going and play with traction at the end of the turn. To me that's the most fun. But sliding isn't bravery, its an extension of your skill and ability to control the bike with throttle."

 

That's a good one! There's some Bayliss in there, some Mladin and seems like a third (maybe 4th) rider.

 

Ya got me.

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Bashir,

 

Quite right, another can of worms :D .

 

But up to the point of sliding, the arc will widen as more throttle is added.

 

Sliding is entertaining, no doubt.

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