# avih

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Cornering Apprentice

## Previous Fields

• Have you attended a California Superbike School school?
no

Noticed that factor myself too. My solution though is to "turn" the helmet upwards (as if it rotates on an axis that goes between your ears). Your chin might stick out more than usual but it does the trick when you put your head down. From a safety perspective, I initially thought it would be less safe since you can hit your chin during a crash, but on 2nd thought, it would take quite a coincidence for that to happen. You will have to be flat out on your belly on the track, while your head is backwards for your chin to hit the track. Also, I think I saw Pedrosa using the same "trick"...

In mid turn, the tire that lose traction 1st is the one which has more centrifugal force to hold than traction available by load+CP size (that's not a direct algebraic sum but rather a combination of both parameters) . The theory is that the optimal balance is about 60% on the rear and about 40% on the front such that lean angle and (momentary) cornering speed is maximized. To achieve this balance you usually have to apply a little throttle while turning. If you apply some more throttle then more weight goes backwards, let's say to a balance of 25-75, at which case your optimal cornering speed is compromised. If you try to stick to optimal cornering speed though, the rear will lose traction because it'll have to provide more traction than it can (75% of the bike's weight instead of it's maximum 60% for maximum overall centrifugal force), while the front will hold less than what it can, so the front will not wash out. Imagine a wheelie while exiting a turn. The bike is still somewhat turning, 0% weight is on the front yet the front doesn't wash out (and the rear also doesn't wash out because the centrifugal force is lower than in mid corner and so it can hold). Generally speaking, while at maximum lean/cornering speed, the tire that will lose traction is the one which you request to hold more than it can (40% weight for the front, 60 for the rear). If you apply more throttle then it's the rear (usually high side), if you close the throttle or apply some brake, it's the front (low side). The reason people trail brake is not to keep the weight on the front during maximum lean, but rather to brake later than otherwise and to keep the weight on the front while applying the turning command (which requires much traction from the front). As long as the turning has not started, optimally 100% of the weight is on the front while braking. While during the turn, the front holds only 40%, which leaves the rider to handle the transition from 100-0 in a straight line to 40-60 balance at the apex. Optimally, and taking the turning command into account, this is achieved using trail braking.
3. ## Cornering: Body Weight Distribution

Hi, After my previous discussion here http://forums.superbikeschool.com/index.php?showtopic=1098 , I figured two things about my body position: - My abdomen is facing straight forward, while in most pics of pro racers it's directed somewhat towards the bike itself (body is a bit twisted). - My inner ankle is too bent instead of "open", and it carries most of my body weight. It both limits me and not very comfortable. I'm trying to use calf raise, but I still somehow put much of my weight on the inner peg. Also, when I try to take my body out a bit more, I'm losing the calf raise lock of the outer leg and put even more weight on the inner peg. I'm opening a new thread here because my question is very specific and different than my general previous post: While you hang off the bike, how is your body weight distributed? i.e. what points of contact would be the hardest to "take apart"? Do you put much weight on the arm resting on the fuel tank? do you feel much weight on the inner peg (i.e. can you take it off the peg relatively easy and still keep the BP)? do you try to put most of the weight on the outer leg? maybe the thigh on the seat? etc. I figure the handlebars carry as little as no weight at all. I'm guessing this subject has been mentioned, but I couldn't find relevant posts. If someone would be able to point me to some, I'd appreciate it, if not, answers are welcome here too thx
4. ## Body Position - Help (pics)

That's why I said accelerate slowly. Let's say, 1MPH more on each lap. For the sake of the weight balance, the acceleration is negligible and therefore we're very close to 50-50 at a constant speed. This ratio prevents us from utilizing the full centrifugal traction potential of the bike (more weight on the front than the optimal balance), hence, we will lose the front before we reach max possible lean angle.
5. ## Body Position - Help (pics)

Ahh.. new term is coined, neglectible Indeed, I have not estimated this "40-60 acceleration" in practical terms. It could be interesting, I'll put some time into it a bit later, and try to put it into more accessible terms of percentages/lean angle/etc. IIRC, in TOTW2 there's an estimation of this amount of acceleration in a straight line. BTW , Interesting corollaries of this conclusion are: - By riding round a fixed circle at a constant radius while very slowly increasing speed, you cannot reach maximum lean angle, since as you get close to it, the 50-50 (appx) weight balance of fixed radius/speed with no acceleration prevents you from taking advantage of the maximum centrifugal traction the bike can offer. You will lose the front 1st because it would have higher centrifugal load than it can bare, while the rear will keep tracking perfectly. - If cornering without accelerating, you're at risk of losing the front, especially if you're close to the max lean angle. Even more so if you shut the throttle off or even just ease it while turning. If indeed this conclusion and corollaries are of non-negligible proportions, then this theory of maximum traction availability only in an ever widening arc goes very nicely with late apexing.
6. ## Body Position - Help (pics)

Take your time racer, though If I were you, I'd get right on with this post.... There's no need to try and contradict every single sentence of mine, you can do that in a general manner

8. ## Body Position - Help (pics)

I tried to compare Ben Spies' pic (good one sleeper ) with a pic of mine from a similar perspective. Had to flip my pic horizontally to make it easier to compare (mine is originally a right turn) and I can see few noticeable differences: - Obviously, he has a much steeper lean angle than me - He hangs off way more than me - His butt is completely out of the seat - His upper body "plane" is diagonal to the bike (vertical to earth), while mine's parallel. Probably an outcome of hanging off more? - Similar outer foot position on the outer peg - I think his outer knee doesn't touch the tank, mine does. I don't want to change that for now as it feels comfortable to me to be locked to the tank. - His inner ankle position is very different than mine. His is almost vertical, mine is almost horizontal with the ankle bent a lot. I think the last point is what I was looking for. The other points are clear and I'm mostly aware of them (whether they're OK or need improving). The last point about inner ankle position is something that I wasn't aware of. It always felt a bit strange to me that I have to bend the ankle so much to be able to keep my toes (and not the middle of the foot) on the peg, but I thought it's due to my height. Maybe it is and maybe it isn't, but it's definitely something I should spend some attention at. I know that it feels to me that I have much weight in the inner peg, and now that I think of it, maybe it's due to the stress on the bent ankle. But if the ankle is more "open" and the foot more vertical, how does that supports my weight? bahh.. gonna have to experiment with that. Good me for noticing something new and thanks again for the pic sleeper!
9. ## Body Position - Help (pics)

Apology accepted. IMHO, that post does include some interesting issues for discussion, on topic.
10. ## Body Position - Help (pics)

Racer, as you've managed to forget by now, I have read those books and I do have them. In case you haven't noticed, I added "IMO" to many of my points, which clearly states that this is my personal opinion and not some facts from heaven (the same applies to Keith's books and teaching BTW, with the advantage of his great experience). You asked twice for my opinion about your thoughts and I gave it, with much details. I had the feeling we're having a discussion about body position and weight transfer before turning, during and on turn exit. I've posted my thoughts on the subject and my interpretations. If you think it's worth commenting, pls do so. If you don't find it interesting, or you think it's not worth reading because you interpret it as contradicting to CSS methods, just skip it. 'nuff said.
11. ## Body Position - Help (pics)

It does, to a degree, because the 60/40 rule of thumb applies IMO only when the bike is at it's max lean angle and the acceleration/deceleration is neglectible. In that case, the only force that applies is the centrifugal/pital one which is applied evenly to both wheels, and the weight/traction have to match it. This phase is usually quite short except for very long turns. While breaking, I think we need the bias to the front since that's where the main steering action takes place, therefore, we need as much weight and traction as possible there to steer the bike effectively. The rear traction plays a much smaller role in this phase. On the exit (which is a relatively long process , starting probably just before the apex) when we progressively accelerate, the rear tire needs more traction than the front beyond 40/60, because the rear tire needs the extra traction to support both centrifugal force and acceleration. If we're at 40/60 and at the traction limit and we apply more throttle, the rear will beak loose IMO because it was at the limit already and can't support the extra force from acceleration. In general, the harder the acceleration, the more weight we need on the rear to have the traction needed. On corner exit process, few things happen gradually: - The turning radius increases - The bike straightens up - We apply more acceleration. The front traction is only needed while leaning (and initiating a turn) as it gives nothing on a straight line (I don't count steering correction as relevant for this discussion). Therefore, as we exit the corner, more and more weight should and can move rearwards to support acceleration. As acceleration increases beyond a certain limit where 100% of the weight is on the rear, the body should be forward to prevent the the front from coming up, allowing to accelerate even harder (as long as the tires are good and the asphalt grips well). All these processes are, naturally, gradual. It's all about balancing the traction needs at each phase. On entry we need mostly the front therefore it's probably 80-20 or more biased forward, while leaning we need both so that's the classic 40-60, on exit we need more and more of the rear, ending in 0-100 towards the straight when we only need the acceleration. And all gradually, smoothly and fast
12. ## Body Position - Help (pics)

Sounds about right to me On entry you have weight forward due to breaking, so you keep your body backwards. On exit, while the weight shifts backwards due to acceleration, you move your body forward to keep it from wheeling and balance the weight shift. If you shift your weight forward before accelerating, you might not have enough weight on the rear for the traction required for acceleration and you might spin it.
13. ## Body Position - Help (pics)

This can be endless. I'm out, and back on topic, if it ever surfaces again. peace.
14. ## Body Position - Help (pics)

racer, pardon me sticking my nose where I maybe shouldn't, but IMHO, it's hard to politely request something from someone while describing his posts as "self-centered, egotistical and narcissistic", and expect him to honor your request or otherwise treat you respectfully. It just wouldn't work. IMO your cynicism doesn't help the situation either. Apparently, we're all engineers here (myself included) and intelligent enough to maintain a civilized discussion. FWIW, I don't consider his posts on this thread as attacks on you or on anyone else, nor in any way inappropriate. It might be a good time now to get back on topic
15. ## Body Position - Help (pics)

racer, yes, I've read the Twist Of The Wrist books (1 & 2). The CBR is 2K4 I think (previously a Ten Kate SBK bike) and the tank is quite wide, at least wider than other bikes I've ridden. It's not my bike and the feedback I was hoping for was more general (which I got plenty of thus far, thank you). Regarding weighting the pegs, I didn't intend to start an off topic discussion and I mostly agree with you. I don't try to put specific weight on either peg, but I did notice that I put more weight on the inner peg while inside a turn and that putting weight on the inner peg during steering action makes the steering faster. I can also try the calf raise (mistakenly referred to by me as "California raise") which I don't currently practice. I had the impression it is used for locking the leg onto the tank, and since I feel pretty planted and comfortable as is, and I saw that many (most?) pro riders use similar foot position to mine, I didn't feel a need to try it. It would indeed require stompgrip or a similar product as my tank also doesn't have a sticking tank edge. hubbard_28, I'm at the back of the seat, as far as I can tell, but I can check it out again next time. In this regard, the CBR's seat is shorter than my bike's (GSXR1000 2K4), so the freedom to move backwards is somewhat limited. So if I try to summarize the tips so far, here they are: - Move further back on the seat, if possible - Hang off more - Lower upper body and head, towards the mirror - Try the calf raise to see if it makes a difference - Go faster, lower Right? Thanks again for the help so far, your feedback is valuable for me. Don't stop with the tips if you have more
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