Observations about aggressive body position

[csmith12]

Originally Posted by Falcor

I think it depends which brake you use, but the bike will stand itself up if you brake in a turn too hard. Braking should be done before entering a turn.

While on the street, setting your entry speed before turning is a great safety measure to take.

But.... There are exceptions to nearly every rule. On the track, there are pros and cons to completing all braking before entering the turn. But a spectacular part of trailbraking is the nail biting late brake passing that puts the fans on the edge of their seats.

[Falcor]

I've noticed that lightly using the rear when in a turn is sometimes very favorable in certain circumstances.

[Panda]

Originally Posted by csmith12

Yes, just like overloading the front tires traction with too much weight with braking, you can underweight the rear to initiate traction loss.

The intent of trail braking isn't really to scrub off large amounts of speed. Take this hypothetical example;
A right turn & rider with a an entry speed goal of 50mph and the bike is traveling at 100mph;
Before the turn in point, scrub off 45ish mph via heavy straight up braking from your brake marker
Just before the turn in point, begin gently, progressively and smoothly easing off the brake and continue to decel until you reach the goal speed of 50mph, then begin throttle roll.

In this example; per throttle control rule #1 and since the rider is still on the brakes, the rider is underweighting the rear tire from the turn in point until the bike reaches 50mph. This is the time where that bike/rider/tire combo runs the highest risk of rear tire traction loss.

What should the rider do in order to stabilize the rear tire under these conditions?

How many times have you seen a rider lose the rear in a turn under heavy front braking that causes an off? Most of the time somebody loses the rear is because they get too greedy with the throttle mid-turn.

The intent of trail braking on the track is to go faster. Any turn in which there is a displacement from the tip in to the slowest part of the corner trail braking will net the rider a higher average speed.

[csmith12]

I have seen it plenty and nearly done it myself many times, it's posted on video in a few threads here.

Loosing the rear from purely aggressive throttle, I would bet is more rare than you think. You can totally light up the rear and the bike will stay pretty stable, maybe a bit wiggly as it looses grip and then catches traction again. However, if you spin up the rear and add lean angle at the same time... I would render a guess that the most common rear traction issue is with chopping or rolling off the throttle mid-corner. The end result is the same as stabbing at the brakes or trail braking with to much brake pressure as the lean continues to increase, to much of the weight moves forward, the contact patches get smaller, the rear unloads and eventually looses grip.

Besides... you asked if it was possible and the answer is simply yes. The reasons why can be many.

[adouglas]

Originally Posted by csmith12

Take this hypothetical example;
A right turn & rider with a an entry speed goal of 50mph and the bike is traveling at 100mph;
Before the turn in point, scrub off 45ish mph via heavy straight up braking from your brake marker
Just before the turn in point, begin gently, progressively and smoothly easing off the brake and continue to decel until you reach the goal speed of 50mph, then begin throttle roll.

In this example; per throttle control rule #1 and since the rider is still on the brakes, the rider is underweighting the rear tire from the turn in point until the bike reaches 50mph. This is the time where that bike/rider/tire combo runs the highest risk of rear tire traction loss.

What should the rider do in order to stabilize the rear tire under these conditions?

Your example describes a done deal... braking is over and done with, bike is already at the apex and throttle is already being rolled on. What can one do other than follow throttle rule 1 (keep rolling on smoothly and progressively throughout the turn)? What are you asking?

If we back things up a bit... to reduce the risk of losing traction at the rear, I'd say you need to shift weight to the rear and get load back on the tire earlier. Which means going to maintenance throttle earlier. (i.e., you're going through the apex at 50 mph but under maintenance throttle, not making the transition from off-to-on at that moment).

That in turn means scrubbing off more speed before you reach the apex, which means getting more of your braking done before you tip in. Not all of it necessarily, but more of it.

Slow in... fast out....

This thread has win written all over it.

[csmith12]

I understand that you are trying to make sense of my post, maybe I wasn't clear, but also note that I didn't say anywhere in my comment about the apex. If the rider can get the bike to 50mph before apex, then fine enough... the roll starts before apex. And yes... that would be earlier and reducing risks AND.... going faster. Your not going faster if your on the brakes. ijs

[Panda]

So you can lose the rear by spinning it up and it's not a big deal. So if it gets light under braking it shouldn't be a big deal either.

The point I'm trying to make is that I believe the tire you should be concerned with is the front under braking and turning not the rear. Your focus should shift to the rear under acceleration.

[Motofool]

Originally Posted by tooblekain

Here's my thoughts on why it works. Most of your body mass/weight is your upper body. When you bring your upper body forward and down, you are essentially putting more weight on the front end. When you put more weight on the front end, it compresses the forks. It's very similar to trailbraking in the sense that you're not using the brakes...........

Hey Matt and @Misti, would you mind explaining the change in position a little more in detail?

I ask you because it doesn't make sense to me (Physics-wise) and I would like to learn more about the position from which you are bringing your upper body forward and down.

In other words: You are cornering while normally hanging-off, with your upper-body in line with the bike and your inner leg out (your upper body is forward and down already, isn't it?).
Suddenly, you discover that it is a hook turn, and then..................?
No steering or counter-steering, the bike just follows the reduced radius?

[tooblekain]

Originally Posted by adouglas

Learning how to avoid charging the corner. Learning how to keep your average speed up. Learning that the chassis should be settled as early as possible so you can get on the gas sooner -- and therefore carry more speed out of the corner.

I prefer to ride in a manner that doesn't rely on heavy braking for much the same reasons that tooblekain cited. I've always been a fan of small, light, low-power vehicles that rely on momentum (I drive a Honda Fit).

What opened my eyes to just how big a deal momentum can be was driving on the track; years a go I did a season or two of time trials, mostly in old, very underpowered Saabs (if you're a geezer like me you might remember the Saab Sonnett). Those cars were a lot like the Ninjette. Very agile but little power. I could easily keep up with Vettes and Vipers in the corners but as soon as the road straightened… forget it. In a vehicle like that a loss of momentum COSTS so you learn how to use the brakes less.

My 750 is far and away the most powerful machine I've ever owned/operated of any kind… but a lifetime of habit is hard to break.

Dammit!!! You beat me to it!!! well explained!!!

[csmith12]

Originally Posted by Panda

The point I'm trying to make is that I believe the tire you should be concerned with is the front under braking and turning not the rear. Your focus should shift to the rear under acceleration.

Ah, I understand now and that makes logical sense. This is a statement vs. your other post was a question. No harm, no foul right?

[alex.s]

Originally Posted by Motofool

Hey Matt and @Misti, would you mind explaining the change in position a little more in detail?

I ask you because it doesn't make sense to me (Physics-wise) and I would like to learn more about the position from which you are bringing your upper body forward and down.

In other words: You are cornering while normally hanging-off, with your upper-body in line with the bike and your inner leg out (your upper body is forward and down already, isn't it?).
Suddenly, you discover that it is a hook turn, and then..................?
No steering or counter-steering, the bike just follows the reduced radius?

i, too, was completely bewildered by that statement. head down further compresses the front? it makes zero sense. then i figured they must have meant comparing straight up and down street riding, to an aggressive forward position...

i spent a good deal of time trying to understand how the difference between tuck center in the corner and tuck off the side of the tank could change the weight on the front (it doesn't as far as i can tell from sitting on the bike and measuring the front forks when straight up)

[Panda]

I think the move to the front is just a result of leaning off. The meaningful weight shift is to the inside/down which increases the effective lean angle which would tighten up the radius.

It's the same you do on the exit of the turn. You stand the bike up, lean off more to the inside of the turn, which helps keep your effective lean angle high but the actual lean of the angle of the bike decreases which gets you on the fat part of the tire.

[tooblekain]

Originally Posted by Falcor

I think it depends which brake you use, but the bike will stand itself up if you brake in a turn too hard. Braking should be done before entering a turn.

If you use the front brakes at a decent lean angle and the bike starts to stand up, it means you've used too much braking force. If you put a Gopro facing your front forks to see the fork action. Try entering a corner with no brakes. Then take that corner again and at that same reduced speed when you took it with no brakes and ever so slightly touch the front brake. Watch the video clip and see how much your forks compress. You should be able to see a difference.

Originally Posted by csmith12

Yes, just like overloading the front tires traction with too much weight with braking, you can underweight the rear to initiate traction loss.

The intent of trail braking isn't really to scrub off large amounts of speed. Take this hypothetical example;
A right turn & rider with a an entry speed goal of 50mph and the bike is traveling at 100mph;
Before the turn in point, scrub off 45ish mph via heavy straight up braking from your brake marker
Just before the turn in point, begin gently, progressively and smoothly easing off the brake and continue to decel until you reach the goal speed of 50mph, then begin throttle roll.

In this example; per throttle control rule #1 and since the rider is still on the brakes, the rider is underweighting the rear tire from the turn in point until the bike reaches 50mph. This is the time where that bike/rider/tire combo runs the highest risk of rear tire traction loss.

What should the rider do in order to stabilize the rear tire under these conditions?

Exactly...perfect as described. I couldn't say it better or add anything.

Originally Posted by csmith12

While on the street, setting your entry speed before turning is a great safety measure to take.

But.... There are exceptions to nearly every rule. On the track, there are pros and cons to completing all braking before entering the turn. But a spectacular part of trailbraking is the nail biting late brake passing that puts the fans on the edge of their seats.

Exactly. With track riding and racing. There is no absolute right way. I like to think of trailbraking, hook turning, etc...and all the skills of riding is like your tool belt or tool collection. The more tools you have, the better. I always have this saying. You can drive a nail into a board using so many different types of hammers...the question is do you use a sledge hammer, mallet, ball and pein hammer, framing hammer. Just like riding--you can take a corner multiple ways using different lines, corner entry, trail braking, hook turning, no brakes, point and shoot. Its a matter of choice.

Originally Posted by csmith12

I have seen it plenty and nearly done it myself many times, it's posted on video in a few threads here.

Loosing the rear from purely aggressive throttle, I would bet is more rare than you think. You can totally light up the rear and the bike will stay pretty stable, maybe a bit wiggly as it looses grip and then catches traction again. However, if you spin up the rear and add lean angle at the same time... I would render a guess that the most common rear traction issue is with chopping or rolling off the throttle mid-corner. The end result is the same as stabbing at the brakes or trail braking with to much brake pressure as the lean continues to increase, to much of the weight moves forward, the contact patches get smaller, the rear unloads and eventually looses grip.

Besides... you asked if it was possible and the answer is simply yes. The reasons why can be many.

Exactly. I have learned the hard way that if you're in a deep lean angle situation and running wide, it is better to stay on the gas and hook turn than to let off the gas. If you let off the gas too much, it overloads the front and most likely lose the front and crash (it happened to me on a slow turn). If you're at maintenance throttle, keep it there, the bike should tighten it's arc. If you've already committed to rolling and you're running wide, hook turn it.

Originally Posted by Motofool

Hey Matt and @Misti, would you mind explaining the change in position a little more in detail?

I ask you because it doesn't make sense to me (Physics-wise) and I would like to learn more about the position from which you are bringing your upper body forward and down.

In other words: You are cornering while normally hanging-off, with your upper-body in line with the bike and your inner leg out (your upper body is forward and down already, isn't it?).
Suddenly, you discover that it is a hook turn, and then..................?
No steering or counter-steering, the bike just follows the reduced radius?

Motofool, do you mean me? Because my name is Matt...or do you mean someone else. I'm assuming me because my post was quoted.

Funny you mention that it doesnt make sense to you. I though it was total utter bullshit too because for the longest time I couldnt figure it out and kept trying. I then just chalked it up to inadvertent steering input...and it worked mind you until I actually got the front end to shake...luckily I didn't crash or run off track, but I realized that it wasn't working because of my body position.

I worked on my body to position to not be so far off the seat and to emphasize having little to no weight on the clip ons. I first practiced the seat by making maximum butt off the seat was just 3/4 of one butt cheek. Once I was comfortable at that pace with that, I then did an exercise where if I passed someone in a corner at a very steep lean angle going right, that I would pass the person and give them a thumbs up with my left arm. I then lengthed it by once setting my lean angle to go through the corner with just my throttle hand and let my left hand/arm hang, wave, relax etc.

I then got into a situation where I was doing that and noticed I was running slightly wide. Instead of bringing my left hand back to the controls to correct, I brought my upper body down and forward while keeping throttle still pinned. I was in a pretty deep lean angle and pinned...I know if I added more steering input to make it lean further, previous experience showed that the front end would shake and I would feel chatter and the front grip struggling. I knew I did this right when grip felt good, lean angle from a visual standpoint didn't change and yet my turn arc was tightening.

I then started experimenting thinking this hook turn should be the new body position. I rode a couple laps doing nothing but hook turns, but realized there is no reserve with regards to if you need to make lean angle adjustments and it was actually starting to feel uncomfortable. I realized that the hook turn is your last resort

When doing trackdays, I realized that you shouldn't ride max out because you will be more prone to mistakes. The same thing applies to body position. You shouldnt be so far stretched out that you cannot make slight adjustments with your upper body.

Hopefully this makes sense to you

[Motofool]

Originally Posted by tooblekain

...........

When doing trackdays, I realized that you shouldn't ride max out because you will be more prone to mistakes. The same thing applies to body position. You shouldnt be so far stretched out that you cannot make slight adjustments with your upper body.

Hopefully this makes sense to you

Thanks, Matt; great post

Yes, I was asking you for a more clear description of the initial and final body postures for the discussed techniques.

It seems like an over-reach of the hanging-off position.

Our upper-body can only pivot around our hips-lower vertebrae and wrists; hence, any attempt to hang-off more makes it lower (side is down at high lean angles) and more forward, ................ if I have understood correctly.

The only way to reduce the radius of the trajectory once leaned is counter-steering some and then increasing the angles of steering and actual lean (combined CG respect to vertical).

[Motofool]

Originally Posted by tooblekain

...........I know if I added more steering input to make it lean further, previous experience showed that the front end would shake and I would feel chatter and the front grip struggling..........

Regarding moving the body only without steering inputs:
It is possible, and may be desirable for extreme leans, to use the body only in order to induce a little change without overwhelming that front patch.
A little into-the-turn displacement of the CG could push the bike up some (by reactive forces), which will induce a microscopic counter-steering quickly followed by a little additional steering to tighten the turn.

Although minimum, the forward transfer of weight seems like a necessary evil (as explained in previous post) that goes against the 40-60 rule.
Additional weight on the front patch can never be good at extreme lean angles.
It may help on making the steering infinitesimally more sensitive and responsive to that small upper-body adjustment, but I am not sure about that.

[Misti]

Originally Posted by Motofool

Hey Matt and @Misti, would you mind explaining the change in position a little more in detail?

I ask you because it doesn't make sense to me (Physics-wise) and I would like to learn more about the position from which you are bringing your upper body forward and down.

In other words: You are cornering while normally hanging-off, with your upper-body in line with the bike and your inner leg out (your upper body is forward and down already, isn't it?).
Suddenly, you discover that it is a hook turn, and then..................?
No steering or counter-steering, the bike just follows the reduced radius?

As we explain at CSS, the hook turn is a slight movement of the upper body forward and down. So, yes you are already in a turn hanging off with your upper body inline with your bike, and your leg out. Your upper body is forward and down already but when we want to get the bike to hook a little you move your body further forward and down.

The key here is that when you get in your hang off position you don't want to be stretched out hanging off and as far forward and down as possible. You want to be in a good cornering position with a little reserve left to be able to lower your upper body MORE if you encounter the need to tighten your line a little without adding extra lean angle. The forward and down motion does not add input into the bars or change the lean angle of the bike. I'll see if I can dig up pics that show the differences in body position.

Misti

[Motofool]

Originally Posted by Misti

........I'll see if I can dig up pics that show the differences in body position.......

Thanks, Misti; please do !!!

[Misti]

Pictures

OK here are a couple pics that illustrate the subtle change in body position that creates the hook turn.

First pic is me and another CSS coach- he is more in the hook turn position than I am, his upper body a little further forward and down over the inside/front than mine.

Second pic is me racing AM Canadian Nationals and I'm in my regular riding position, you can see that there is some reserve left and I could move my upper body further forward and down if I needed to tighten my line a little bit.

Third pic is me racing AMA at Daytona and I'm hooking it here I'm further forward and down than in the other pic.

Hope these help!!

[choneofakind]

Great example pics misti!! The hook turn is a great tool for every rider to know. I've used it at the track on technical turns, and on the street when I had to avoid a lane-challenged driver mid-turn.

It's kind of fun too

[lgk]

i'm guessing the opposite applies as well.

if you are already in a tight corner and need to go wide, you could change bp and go wide slightly with no steering input.

[alex.s]

Originally Posted by lgk

i'm guessing the opposite applies as well.

if you are already in a tight corner and need to go wide, you could change bp and go wide slightly with no steering input.

no. doing the opposite simply makes you crash.

if you want to go wide, do an on-gas pickup maintaining current body position (you sink even lower vs the bike)... that way you can put the bike back down when you need to

[lgk]

Originally Posted by alex.s

no. doing the opposite simply makes you crash.

if you want to go wide, do an on-gas pickup maintaining current body position (you sink even lower vs the bike)... that way you can put the bike back down when you need to

Thanks for clearing that up

[Misti]

Originally Posted by alex.s

no. doing the opposite simply makes you crash.

if you want to go wide, do an on-gas pickup maintaining current body position (you sink even lower vs the bike)... that way you can put the bike back down when you need to

Well, let's take a look at this a little further. How would lifting your body up "simply make the bike crash?"

What would happen?

[alex.s]

Originally Posted by Misti

Well, let's take a look at this a little further. How would lifting your body up "simply make the bike crash?"

What would happen?

oversimplification on my part.

it wont, actually. but thinking about what happens when you do it... unless you were being very slow and smooth, moving your body up wrenches the bike down a little. you would have to have some kind of steering correction (which would be automatic due to the trail of the front wheel) to accommodate the change in CG vs centrifugal force which when at the limit of traction pushes things even harder. if you need to avoid someone and go wide because they did something unexpected, you won't have very much time. doing things slowly is out of the question. so we are talking about quickly raising the body up and causing the bike to wrench down, before the centrifugal force pulls the bike up out of the lean. so if you are on the very limits of traction, at worst it can cause a slide. or at best, its the slower alternative to doing a standard on-gas pickup.

which situations would this be useful in? situations where your front wheel is already past its limits and is not useful... where your front tire is no longer influencing the bike: corner exit wheelies