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Old 07-04-2012, 04:33 PM   #46
Jan from Finland
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Quote:
Originally Posted by crofrog View Post
Quote:
Originally Posted by daveinva View Post
ABS indeed works best in a straight line situation, but to my knowledge, works only when traction is lost, i.e. ABS kicks in the moment a wheel locks to release and re-brake.
Your understand of ABS is flawed, a good system detects that the wheel is slowing down faster than it can possibly slow down, and should start to release pressure before the wheel is actually locked.
True.

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Originally Posted by crofrog View Post
This is why with training a good person can outbrake ABS by a bit because the person can keep it right on the threshold of maxium braking about 5-10% slip depending on tires, meaning the braking tires are turning 5-10% slower than actual speed over ground, versus abs going from below maxium braking and 0% slip back to 15% slip and repeating.
Only partially true. Maximum braking is done as said, but the best ABS systems now outperform a good person's best efforts most of the time. And the ABS can do it repeatedly, regardless of traction. A person needs multiple trials on constant traction to get even close. It's very limited set of circumstances where the good person can outperform the good ABS.

Quote:
Originally Posted by It'sNotTheBike View Post
"A driver has the potential for exerting three forces. For any given situation, there is a level of friction (coefficient) available for exerting these forces, and therefore, maneuvering the vehicle. When a driver exerts either a braking or acceleration force while at the same time exerting a cornering force, you must add the forces when considering the available friction. In other words, the sum of driving or braking traction and cornering traction must not exceed the friction limit, or the vehicle will go out of control. Whenever possible, avoid braking or accelerating while cornering. This allows all available friction to be used in cornering."
The available friction for braking and acceleration is not a zero-sum game. (The thinking is a bit old school here. Even on Ienatsch writing. Or oversimplification I hope.) The reason why modern tires allow aggressive trail braking is that the contact patch between the tire and ground is not round. It's oval. Even if you are on the limit of sideways traction there may be traction available for braking (or accelerating).

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Quote:
Originally Posted by Luke View Post
Why do you think current ABS doesn't work in a curve?
Go take an ABS equipped bike and grab a handfull of brake while leaned way over. Then let us know how it worked out. Make sure you are wearing all your safety gear and there is no guardrail.
Some ABS systems now include a tilt/roll sensor. They estimate how much traction you should have. In most cases it won't brake much if you are leaned over. It tries to prevent the low side. If the system has no roll sensor you will go down - assuming you are close to the limit.

A great writing by Ienatsch. However, he didn't speak about dirt riding. There is a forth option besides standing the bike up, laying it down or trail braking. On dirt (or even on the pavement if you are pro) you can make the rear end slide and use the front brake without worrying about the lowside - even if you misjudge the traction. The bike won't go down when the front and rear wheel don't follow the same track. It behaves as a two track vehicle. See what supermoto and motocross riders can do. It won't add the absolute overall traction and shorten the absolute minimum brake distance but it allows you to make most of the available traction on variable surface conditions. The added bonus is that radius still equals MPH like Ienatsch said. You can adjust the trajectory by slowing down or accelerating.
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Jan from Finland screwed with this post 07-04-2012 at 04:38 PM
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Old 07-04-2012, 08:21 PM   #47
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Originally Posted by Jan from Finland View Post
Only partially true. Maximum braking is done as said, but the best ABS systems now outperform a good person's best efforts most of the time. And the ABS can do it repeatedly, regardless of traction. A person needs multiple trials on constant traction to get even close. It's very limited set of circumstances where the good person can outperform the good ABS.
You're talking about race quality ABS properly tuned _or_ an OEM system with OEM tires and brake compounds I agree.

You can really start screwing with ABS systems if you start changing brake pad torque or tire compounds. On a race system you just tune for it, on a street system you pull the fuse and manage the brakes yourself.
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Old 07-04-2012, 11:32 PM   #48
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Originally Posted by Luke View Post
My point was that a lot of people say ABS won't work in a curve.
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Originally Posted by Romulux View Post
I couldn't begin to calculate the thresholds, but at any reasonable lean, lateral traction loss will occur far sooner than in-line traction loss when braking hard.
The actual ABS pump and logic work fine in a curve, but you are rarely in a position to activate them. What people really mean is "ABS won't save your ass ina curve like it can when going straight."

I think I'm becoming a Luddite. On with the Modern Safety Vehicles....
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Old 07-05-2012, 02:05 AM   #49
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How would it know?
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Old 07-05-2012, 02:29 PM   #50
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Interesting. At the beginning of this year I started experimenting with light trailbraking while initiating lean in/turn in. I've found that when done correctly the bike is much more settled going into the corner. I still try to get 80-90 percent of my braking done before turning, but trailing a little brake right as I put the bike into lean, and the smoothly releasing the brake right as the bike reaches the maximum lean (for that corner) just feels better than hammering the brakes on the straight, releasing, then initiating turn in. If I do the latter, the suspension "cycles" twice -- one compression and rebound for the brake/off brake, and another compression as the bike reaches full lean. Combining the two feels a lot better to me. Of course, a lot of that suspension "cycling" can be eliminated by being smooth with brake ON and brake OFF which I have spent years practicing...and still suck at

Someting else to note is that not every bike responds to this the same way. My EX250 just loves it. The VFR...not as much.
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Old 07-05-2012, 02:39 PM   #51
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Originally Posted by LuciferMutt View Post
Interesting. At the beginning of this year I started experimenting with light trailbraking while initiating lean in/turn in. I've found that when done correctly the bike is much more settled going into the corner. I still try to get 80-90 percent of my braking done before turning, but trailing a little brake right as I put the bike into lean, and the smoothly releasing the brake right as the bike reaches the maximum lean (for that corner) just feels better than hammering the brakes on the straight, releasing, then initiating turn in. If I do the latter, the suspension "cycles" twice -- one compression and rebound for the brake/off brake, and another compression as the bike reaches full lean. Combining the two feels a lot better to me. Of course, a lot of that suspension "cycling" can be eliminated by being smooth with brake ON and brake OFF which I have spent years practicing...and still suck at

Someting else to note is that not every bike responds to this the same way. My EX250 just loves it. The VFR...not as much.
The above is actually proper braking. The standard "brake before you turn" mantra is "safe" braking for noobs and those with less skill. You are doing a "higher performance" version of braking. What I define as "proper" braking.

Good on ya.

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Old 07-05-2012, 04:42 PM   #52
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At the beginning of this year I started experimenting with light trailbraking while initiating lean in/turn in. I've found that when done correctly the bike is much more settled going into the corner. I still try to get 80-90 percent of my braking done before turning, but trailing a little brake right as I put the bike into lean, and the smoothly releasing the brake right as the bike reaches the maximum lean (for that corner) just feels better than hammering the brakes on the straight, releasing, then initiating turn in.
This is how I ride when I'm in the groove & conditions allow. It does feel very smooth & secure with no dramatic weight transfer. It minimises the transition from brake to throttle (IMHO) but the side effect is you can end up riding rather quick. done right I think it increases the safety margin too.

Quote:
There is a forth option besides standing the bike up, laying it down or trail braking. On dirt (or even on the pavement if you are pro) you can make the rear end slide and use the front brake without worrying about the lowside - even if you misjudge the traction. The bike won't go down when the front and rear wheel don't follow the same track. It behaves as a two track vehicle. See what supermoto and motocross riders can do. It won't add the absolute overall traction and shorten the absolute minimum brake distance but it allows you to make most of the available traction on variable surface conditions.
I have had the dubious pleasure of doing this on the road due to my own inattention, entering a corner too hot with oncoming traffic & forced to stay in lane. It was only my experience riding dirt that allowed me to keep the bike up, purely instinctive when I locked up the rear & let it slide round while still on the brakes. No issue at the front, the opposite lock kept the front wheel upright & gripping & the bike was pointing in the right direction to make the turn without an off or collision. You would want big Cojones or a big budget to get good at it. I managed with pure luck
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Old 07-06-2012, 03:10 AM   #53
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Modern ABS works well in curves. At least it has been tested by a german motorcycle magazine up to 30°.

Older systems however reacted too slow and built up some kind of resonance oscillation in the suspension. So you shouldn't try to use a 20 years old mechanical BMW ABS mid corner, but you surely can use for example the CBF or VFR 1200 and all superbike/supersport ABS systems. Of course there are still limits and it might be a bad idea to try it at 45+° but than again it might be a bad idea to brake or drive with 45+° on public roads at all.

By the way, ABS is a GREAT tool to learn braking. You can use your brakes as hard as you dare and when the ABS kicks in loose your grip only a little bit. After some time of training instead of the constant pulsating lever you are able to get two to three single ABS releases per braking and know you're operating at the limit as you would on a bike without ABS - only difference you're never in danger.
Oh and you CAN make your tires squeak even with ABS, some ABS bikes do that quite regular by themselves. But you WON'T outbrake a modern ABS.
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Old 07-06-2012, 03:29 PM   #54
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So older versions of ABS could be detrimental braking through a turn or in a hazard swerve?
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Old 07-06-2012, 04:05 PM   #55
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Originally Posted by Harvey Krumpet View Post
So older versions of ABS could be detrimental braking through a turn or in a hazard swerve?
If you were relying on the ABS I would think so. Otherwise the same rules of braking without ABS apply.
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Old 07-06-2012, 08:02 PM   #56
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So older versions of ABS could be detrimental braking through a turn or in a hazard swerve?
No, they just might not save your butt if you use too much brake when leaned over.
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Old 07-07-2012, 09:15 AM   #57
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This was such a nice thread before it became the new ABS argument thread.
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Old 07-07-2012, 09:41 AM   #58
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This was such a nice thread before it became the new ABS argument thread.

Yup! Ian, Iowa
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Old 07-07-2012, 10:28 AM   #59
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I think ABS discussion misses the whole point

I think the whole point of the original post was to say there are no simple rules to advanced riding - i.e. making the motorcycle do everything it can do at whatever your level of skill development happens to be.

ABS is great (and getting better) but it is a technology version of "never use your brakes in a corner" It is for using your bike as a transportation device where you are thinking about how to pay your mortgage.

I am not a pro rider and I am just amazed at what some people can do with a motorcycle.

If it can help anybody let me share my thoughts. If you are riding the bike correctly, and this is largely a mental thing, (bu t you need proper technique) you can feel what the bike is doing and you can feel how it is responding to your inputs and you can adjust your inputs accordingly to get the desired results.

In my experience, everything goes, brakes and throttle all at the same time. If the last thing that will save you is putting your foot down - done correctly this can save your ass too. I would even agree with "sometimes you need to crash the bike" and even this has a technique.

You need the right technique, with the right mental attitude and practice, practice, practice! I am not a pro or an instructor and all the technique stuff is available from much better sources but here are some personal thoughts and experiences.

First of all technique just makes it possible to do what needs to be done it does nothing by itself.

Sit on the bike properly, elbows bent, knees bent, weight on your feet, head up, look where you want to go. Practice standing, moving your weight forward and backward, side to side on all types of surfaces. Hold the bike with your legs/knees whenever you can. Mostly practice having the lightest possible grip on the bars. When you sit feel the bike under your but and how it is moving. The bike needs to move under you without upsetting your relaxed posture on the bike. The actual inputs to the bike are actually very gentle with a few exceptions, low speed and intense windy conditions.

Mentally the challenging part is that you are actually putting the bike into a unstable (will crash) condition to get it to change direction. The greater the instability you can create (and control) the greater you can influence the bikes direction (and speed)

Simple riding involves temporary and slight instability that you correct immediately to a stable condition. Advanced riding involves putting the bike into continuous instability that requires continuous input to correct. Controlling the bike at speed in this situation means accounting for and taking advantage of momentum.

That is why the original post is absolutely correct. If your inputs are too abrupt you can't explore this area of instability where same or other inputs can correct the instability after you have gotten the desired result out of the motorcycle.

Brakes are a huge part of controlling the bike - it is just unimaginable you would not use your brakes whenever they can help at any time.
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Old 07-07-2012, 04:24 PM   #60
Jan from Finland
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Originally Posted by crofrog View Post
You can really start screwing with ABS systems if you start changing brake pad torque or tire compounds. On a race system you just tune for it, on a street system you pull the fuse and manage the brakes yourself.
No doubt.

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Originally Posted by Harvey Krumpet View Post
I have had the dubious pleasure of doing this on the road due to my own inattention, entering a corner too hot with oncoming traffic & forced to stay in lane. It was only my experience riding dirt that allowed me to keep the bike up, purely instinctive when I locked up the rear & let it slide round while still on the brakes. No issue at the front, the opposite lock kept the front wheel upright & gripping & the bike was pointing in the right direction to make the turn without an off or collision. You would want big Cojones or a big budget to get good at it. I managed with pure luck
The reason why it was so violent is that you locked up the rear. If it's done the right way the rear never locks and keeps spinning.

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You would want big Cojones or a big budget to get good at it. I managed with pure luck
Start with a cheap bike or... http://i250.photobucket.com/albums/g...0r/61nuekw.jpg
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