De Puniet At 2008 Pre-season Sepang Test

[adamsys]

Hi All;

 

Randy De Puniet has reputation of being very fast but also for crashing often. At the recent Sepang Pre-season Test he was 11th fastest and was having front end problems.

 

Here is a quote appearing on the Speed VT website:

 

(http://www.speedtv.com/articles/moto/motogp/42696/?page=3)

 

Randy De Puniet, LCR Honda: 2m 01.873s - 56 laps “I worked on the range of tires that Michelin brought here for me to try then on the overall balance of the bike with suspension settings and a different off-set on the front forks. Then, when I was happy with the set up in the early afternoon I worked on front tires. I crashed today at the same place as yesterday, the same time and the same speed. The front turned in on me very quickly - very strange as I was of the gas. Maybe it was a combination of the high track temperature and a too soft front tire. I ran my race simulation test yesterday afternoon and it was very good. I am very happy I have been fast on every day.”

 

Let me bring attention to this bit:

"The front turned in on me very quickly - very strange as I was of the gas."

 

Doesn't backing off the gas put weight on the front end making it more likely to slide?

[racer]

Eee-yup.

 

That sentence caught my eye, too, Adam. Good point.

 

That said, however, I don't know what kind of turn it is and he didn't say what part of the turn he was in, ie. turn entry, mid-corner, etc.

 

I wonder what they did with the off-set insert in the gooseneck? More aggressive with the rake perhaps? Gives quick response but is less stable...?

 

It is hard to imagine that someone at his level wouldn't have a good handle on the basics, but ... ?

[littlefield]

Maybe in Randy's mind being 'of the gas' is like being one with the gas, i.e. in the gas. Or a typo, should have been 'on the gas'.

[racer]

Maybe in Randy's mind being 'of the gas' is like being one with the gas...

 

Or a typo, should have been 'on the gas'.

Good point. I didn't think of that. I just assumed it was a typo for "off the gas" from the context of his statement that the front turned in quickly combined with the inserts comment which led me to think he was turning in and "tucked" the front. But...he isn't really perfectly clear about that.

[adamsys]

Eee-yup.

 

That sentence caught my eye, too, Adam. Good point.

 

Yeah, I thought so. Last season, between track days, I was working on my body position by laying out a 50ft radius skid pad on a decommissioned Air Force base and doing laps every weekend. I was trying to "tune my tilt-o-meter" but way before I touched my knee down, the front tire would wash. The surface was poor and the radius too short because the tires really didn't get up to temperature. Still, it was my front that slide first instead of both ends together. At the time, I moved more of my weight forward and lower. After the 2nd chapter of Twist II, I realized I did the exact opposite of what I should have done. That made me very sensitive to the subject.

 

BTW: Am I right about my weight bias? If my front end is sliding at constant speed and constant radius then I should move my weight back?

 

It is hard to imagine that someone at his level wouldn't have a good handle on the basics, but ... ?

 

That's why I felt obliged to ask. He certainly would mop up my butt!

[racer]

BTW: Am I right about my weight bias? If my front end is sliding at constant speed and constant radius then I should move my weight back?

 

That sounds like a good idea to me.

[Cobie Fair]

One's body can effect the weight bias, but the biggest adjuster is your right wrist.

 

On another note, a comment I've heard from Keith more than once is he's surprised the things the top guys don't really fully understand. What to do with the bars when the bike slides is one.

[adamsys]

One's body can effect the weight bias, but the biggest adjuster is your right wrist.

 

First, thanks to you and "racer" both for the feedback. I definitely appreciate it.

 

But, in the totally clinical conditions of a 360 degree constant radius track, I would think that one would be locked into a constant speed: the throttle would be very nearly still. I'm guessing that its a "steady state" condition that tests weight bias in isolation, no?

 

I admit that this condition is never actually experienced on a race track, at least not exactly like this. When the Yoshimura team tested rain tires last season, Mladin requested a figure eight track instead of a simple circular skid pad. (http://www.roadracingworld.com/news/article/?article=29882) I'm certain the figure eight is much more representative of an actual race track and I will us this set up for my own training in the future. Throttle control will definitely be involved here.

 

Having said that, though, it might be informative regarding the transition from entering on the brakes to neutral mid-turn to exiting on the throttle: That little bit of neutral... ...what do you think?

 

 

(BTW: really diggin' this thread!)

[racer]

But, in the totally clinical conditions of a 360 degree constant radius track, I would think that one would be locked into a constant speed: the throttle would be very nearly still. I'm guessing that its a "steady state" condition that tests weight bias in isolation, no?

 

 

Can you negotiate the same radius turn slow or fast? Is a closed circle not an endless turn?

 

More speed = more lean for the same radius turn.

 

 

(BTW: really diggin' this thread!)

 

Me too.

[tweek]

First, Mr. De Puniet drives me nuts. I'm trying my damnest to root for Kawi but he keeps going off and dual sporting in the gravel traps and taking other riders with him. That isn't fast - it's dangerous. Glad Kawi have moved on to find new riders. Hopefully, Mr. West will figure out where he is supposed to grid up and win a few podiums this year.

 

As for the front end sliding - funny, I'm rereading the books getting ready for another season and I just finished the section on throttle control.

[racer]

So, if Mr Du Puniet was in fact "on the gas" and losing the front, it would seem to be a problem of too much lean angle...eh?

 

So, Cobie.... if you are allowed to say ... what should a rider "do" with the handlebars when feeling the front start to slide in a corner?

[Cobie Fair]

So, if Mr Du Puniet was in fact "on the gas" and losing the front, it would seem to be a problem of too much lean angle...eh?

 

So, Cobie.... if you are allowed to say ... what should a rider "do" with the handlebars when feeling the front start to slide in a corner?

 

I can't answer these as well as Keith has in the books---particularly Twist 2, say chapter 8.

 

If the rider is doing something with the bars, and the bars will do the right thing by themselves (providing the throttle is used correctly), then what should the rider being doing? (gotta keep the thread going )

 

C

[adamsys]

I can't answer these as well as Keith has in the books---particularly Twist 2, say chapter 8.

 

Hey Cobie:

 

thanx for the response.

 

I bought the full package with the books, audio CDs, DVD and interactive CD. (such a deal!) Well, I've been listening to the audio CDs throughout my work day, over and over again. There is a wee bit of a contradiction regarding rider position and weight balance that has me a bit perplexed. There is the notion of force balance related to tire contact area that favors the rear tire over the front tire (approximately 40% front to 60% rear). This requires a small amount of acceleration to achieve balance. Very logical. But then there is another section where Keith describes his personal experience; he had his weight very far forward over the front end because he placed his chest on the tank, as I tend to do. He describes a tendency for the rear to come around on him. With more weight on the front, the front should have gone out first, no? ( I can cite this more rigorously if you wish.)

 

This reminded me of the "pony cars" that were very front heavy with those big V8's under the hood. The rear end smoked 'em all the time. They made great drag racers because the weight transfer under acceleration loaded the driving tires with the full weight of the vehicle in the case of a perfect wheelie with the just a bit of sunlight under the front tires.

 

But I also know when I WANT to break the rear end loose on the bike, I climb way over the bars and snap the clutch. It works like a charm and toasts the rear tire.

 

So my thinking, at this point, has been revised. There is some kind of relationship between traction and loading that is somewhat nonlinear. In pure cornering, both tires contribute to the goal of lateral acceleration. In pure straight-line acceleration, only the rear tire provides the drive so any weight shared with the front tire reduces the rear's potential to drive the bike. There must be some situations that lie between these 2 extremes in a road racing scenario.

 

I'm a major geek so I will explore this exhaustively but, I must say, this bothers me. Is this a De Puniet gotcha? I'm thinking more about this but I think I'll let this post go "as is."

[racer]

With more weight on the front, the front should have gone out first, no?

 

I think Keith was probably talking about breaking the rear loose with the throttle due to too much weight on the front.

 

The 40/60 formula is about creating conditions for maximum available traction. Breaking the rear loose with the throttle is really more about throttle control whatever the weight balance so, technically, a separate matter from having weight balanced for maximum traction per se. In other words, you don't have to be at the limit of traction at the front to break the rear loose with the throttle.

 

That said, I think Keith's point is that had he not been "riding the front" with his weight up on the tank, he would not have broken the rear loose as easily. With the proper balance, he might have been able to apply more throttle (go faster) without breaking the rear loose.

 

Does that help?

[Cobie Fair]

There are a few pieces to this, and we might need to get Keith over here at some point. I like to take one piece at a time, so here's one, but let's limit it (for sake of the thread at this point) to cornering, not straight line:

 

The front typically pushes with too much weight. The normal solution is to take some off with the throttle. The front can push too much due to too little weight. I lost the front on a 125 GP bike by simply coming into the throttle too hard, down I went. But that happens way less than the other--like rolling or snapping the throttle off in a turn.

 

Good so far?

 

C

[racer]

I lost the front on a 125 GP bike by simply coming into the throttle too hard, down I went.

 

I'd like to hear more about that.

 

 

Seriously though, I think the specific circumstances of just how and when the front might be "too light" are important, even if only rarely.

 

 

So, dish. What track, what turn... and whose bike was it?

[Rick448]

So how i see it is thus, too much weight ie. braking too hard into a turn or too much speed with not enough gas will lowside.

 

Too little weight, ie. on the gas too much and too fast on a good angle of lean will lowside.

 

In laymans terms it would seem that smooth throttle contol and braking, both on and off the brakes is the secret, plus rebound damping being not too soft, but i am only a novice at this stuff even though i have been riding over 25 years.. I never feel in danger of highside as i am cautious on throttle out of a turn, but i often worry about loading the front up too much initailly before getting back on the gas and hence balancing the bike. I think this is one of those things which cannot be answered by text and needs to be felt on the bike..

[racer]

I think this is one of those things which cannot be answered by text and needs to be felt on the bike.

 

I agree it is very difficult to verbalize or intellectualize about something that is so dependent upon "feel". And near impossible to grasp for the first time without firsthand experience. The books are an excellent place to start and an indispensable reference; but, there really is no substitute for doing a school with Keith Code.

[Rick448]

there really is no substitute for doing a school with Keith Code.

 

I know and i will be doing one later this year all being well. It is defenatatly top of my list. I'm not doing any more track days until i've done level 1 and 2.

[adamsys]

The front typically pushes with too much weight. The normal solution is to take some off with the throttle. The front can push too much due to too little weight. I lost the front on a 125 GP bike by simply coming into the throttle too hard, down I went. But that happens way less than the other--like rolling or snapping the throttle off in a turn.

 

Good so far?

 

Yes! One only needs to observe the antics of the stunters to see what happens at the extremes and there is plenty to learn from those guys even if its not "my trip."

 

I almost got into this deeper on my last post but waited. My thinking is this. The easiest way to "tune" the balance of rear and font tire force is a twist of the wrist (forgive the pun but it was me not Keith). No funky body positioning required so its doable for a mortal. But a circumstance like a top gear sweeper or a skid pad will not allow any acceleration. The rear tire normally has the components of acceleration as well as lateral load while the front only has the lateral thing to deal with. If acceleration is not possible then its a situation of pure lateral load. Then body position should be altered to match the tire patch difference between the front and rear tire, no?

 

Obviously, there is a sweet spot. I imagine that isolating that sweet spot in skid pad work might help with mid-turn cornering.

 

Maybe an upright torso is better in a high speed sweeper? That way you have your weight rearward and also get the benefit of wind loading the rear a bit, too?

 

Seems to me that the ideal is to have your weight back while on the brakes . Then move it forward to the 'sweet spot' in mid turn. Finally moving one's weight forward at the exit. However, one might need superhuman skill to pull this off without upsetting the bike.

[racer]

I'm not sure I've ever encountered a sweeper so long that I reached the limit of acceleration here in the US. Some long carousels like Putnam Park and Nelsons, but they tend to tighten up and most guys seem to trade off some entry speed for max accel at the exit. But I can see your point about the skidpad now, ie eventually a limit of speed/lean/acceleration will be reached and what do you do then?

 

Moving the bodyweight toward the rear combined with a constant throttle sounds logical to me. I'll have to think about that in relation to the longer carousels, too.

[adamsys]

I'm not sure I've ever encountered a sweeper so long that I reached the limit of acceleration here in the US. Some long carousels like Putnam Park and Nelsons, but they tend to tighten up and most guys seem to trade off some entry speed for max accel at the exit. But I can see your point about the skidpad now, ie eventually a limit of speed/lean/acceleration will be reached and what do you do then?

 

Yeah, it might be no more than an intellectual curiosity without any practical application. What can I say, I'm a curious guy.

 

Moving the bodyweight toward the rear combined with a constant throttle sounds logical to me. I'll have to think about that in relation to the longer carousels, too.

 

anybody else with an opinion?

[Cobie Fair]

The front typically pushes with too much weight. The normal solution is to take some off with the throttle. The front can push too much due to too little weight. I lost the front on a 125 GP bike by simply coming into the throttle too hard, down I went. But that happens way less than the other--like rolling or snapping the throttle off in a turn.

 

Good so far?

 

Yes! One only needs to observe the antics of the stunters to see what happens at the extremes and there is plenty to learn from those guys even if its not "my trip."

 

I almost got into this deeper on my last post but waited. My thinking is this. The easiest way to "tune" the balance of rear and font tire force is a twist of the wrist (forgive the pun but it was me not Keith). No funky body positioning required so its doable for a mortal. But a circumstance like a top gear sweeper or a skid pad will not allow any acceleration. The rear tire normally has the components of acceleration as well as lateral load while the front only has the lateral thing to deal with. If acceleration is not possible then its a situation of pure lateral load. Then body position should be altered to match the tire patch difference between the front and rear tire, no?

 

Obviously, there is a sweet spot. I imagine that isolating that sweet spot in skid pad work might help with mid-turn cornering.

 

Maybe an upright torso is better in a high speed sweeper? That way you have your weight rearward and also get the benefit of wind loading the rear a bit, too?

 

Seems to me that the ideal is to have your weight back while on the brakes . Then move it forward to the 'sweet spot' in mid turn. Finally moving one's weight forward at the exit. However, one might need superhuman skill to pull this off without upsetting the bike.

 

Not to sound like a lame ad, but that is exactly one piece of what we sort out on the lean bike (in a skid pad). How much one can really effect the bike with adjusting their body weight, and compare that to say being able to stay loose on the bars (Twist 2 has lots on this for anyone not having done the school). Being loose on the bars (when one needs to be), is a vital, vital skill. If the wind pulls on you in a fast turn...and the rider is up, what's is he going to hold on with?

 

C

[adamsys]

Not to sound like a lame ad, but that is exactly one piece of what we sort out on the lean bike (in a skid pad). How much one can really effect the bike with adjusting their body weight, and compare that to say being able to stay loose on the bars (Twist 2 has lots on this for anyone not having done the school). Being loose on the bars (when one needs to be), is a vital, vital skill. If the wind pulls on you in a fast turn...and the rider is up, what's is he going to hold on with?

 

Don't worry, I've already made up my mind to take the classes. Although I haven't signed up yet, I'll be at the May Pocono event. Might try to hit the NJ Motorsport Park event late in the season, too. Which class in the sequence has the lean bike?

[Cobie Fair]

Don't worry, I've already made up my mind to take the classes. Although I haven't signed up yet, I'll be at the May Pocono event. Might try to hit the NJ Motorsport Park event late in the season, too. Which class in the sequence has the lean bike?

 

Level 1 is the steering exercise, pretty critical for many riders. Level 2 we'll get you on the lean bike, we need to cover some of the later techniques in Level 1, to really have the lean bike be of maximum benefit. 2-day camps we can sometimes get it in later in the first day, but normally it happens on the 2nd day there too.

 

C