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Old 07-03-2012, 02:20 PM   #31
Luke
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Quote:
Originally Posted by klaviator View Post
Since we now have electronic traction control which helps control wheelspin in a corner, I'm sure ABS which works in a curve will come along before too long. The drawback of these systems is that once they become commonplace people will loose the ability to ride without them and will no longer even understand the dynamics of the bikes they are riding. Just look at all the cage drivers out there unable to drive with a manual transmission, and absolutely clueless on the dynamics of driving.

Of course, plenty of riders don't really understand what they are doing so more electronic safety devices may just save their asses.
Why do you think current ABS doesn't work in a curve?
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Old 07-03-2012, 02:45 PM   #32
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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.
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klaviator screwed with this post 07-03-2012 at 02:53 PM
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Old 07-03-2012, 02:57 PM   #33
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Originally Posted by klaviator View Post
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.
Already done. Except that there was a guardrail. It worked out just fine.

My point was that a lot of people say ABS won't work in a curve. I've never heard anyone say that it didn't work in a curve. And yes, I realize that there are several reasons that could be the case. :)
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Old 07-03-2012, 03:19 PM   #34
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Quote:
Originally Posted by klaviator View Post
Since we now have electronic traction control which helps control wheelspin in a corner, I'm sure ABS which works in a curve will come along before too long. The drawback of these systems is that once they become commonplace people will loose the ability to ride without them and will no longer even understand the dynamics of the bikes they are riding. Just look at all the cage drivers out there unable to drive with a manual transmission, and absolutely clueless on the dynamics of driving.

Of course, plenty of riders don't really understand what they are doing so more electronic safety devices may just save their asses.
Thanks for the response.

Yeah, I know there's the "this dumbs things down too much" factor in play-- comes out in EVERY thread here-- but not every rider out there is an expert on this stuff, and let's acknowledge that even the experts often appreciate the assist/margin of safety that tech can provide.

Besides, don't like the tech? Don't buy it. Or, buy more bikes, so you can choose which one you want to ride that day- the tech-enabled machine, or the pure classic experience. I'm a fan of the latter school
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Old 07-03-2012, 03:20 PM   #35
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Originally Posted by nwdub View Post
awesome read, a reason why I hate linked braking but love abs
Your hatred is misplaced. I have two bikes with linked, ABS brakes and both work beautifully. You don't have to think about the fact they're linked or ABS equipped, you just use the brakes and you stop.
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Old 07-03-2012, 03:20 PM   #36
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Already done. Except that there was a guardrail. It worked out just fine.

My point was that a lot of people say ABS won't work in a curve. I've never heard anyone say that it didn't work in a curve. And yes, I realize that there are several reasons that could be the case. :)
Everything I have read says that ABS is not designed to work in a curve. I never put it to the test on my R1100GS. The newer systems are more sensitive than the older ones. I guess it all depends on how far you are leaned over and how much brake you use. I'm sure it works just fine at a mild lean angle but if you're way over I wouldn't depend on it, especially on an older bike.
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klaviator screwed with this post 07-03-2012 at 03:27 PM
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Old 07-03-2012, 03:49 PM   #37
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Quote:
Originally Posted by klaviator View Post
Everything I have read says that ABS is not designed to work in a curve. I never put it to the test on my R1100GS. The newer systems are more sensitive than the older ones. I guess it all depends on how far you are leaned over and how much brake you use. I'm sure it works just fine at a mild lean angle but if you're way over I wouldn't depend on it, especially on an older bike.

Yup, I've read a lot of that too. I've also read that you can't use regular brakes in a curve. I've never read that anyone actually tried to activate ABS in a curve intentionally. Something about how ABS bikes are always too new and expensive to risk scratching up.

I was on a '95 1100GS. But I don't know that the newer systems are necessarily better. I don't have an ABS bike any more, so couldn't experiment myself.
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Old 07-03-2012, 03:55 PM   #38
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Yup, I've read a lot of that too. I've also read that you can't use regular brakes in a curve. I've never read that anyone actually tried to activate ABS in a curve intentionally. Something about how ABS bikes are always too new and expensive to risk scratching up.

I was on a '95 1100GS. But I don't know that the newer systems are necessarily better. I don't have an ABS bike any more, so couldn't experiment myself.
Were you leaned way over, or just a little bit? I regularly used my brakes in curves on my 95 R1100GS but in 87000 miles, I never had the ABS activate in a curve, and I never crashed except for an encounter with Bambi. Of course, I never tried to use the brakes hard while leaned way over.

As for using regular brakes in a curve, trail braking has been a common and well know technique for a long time even if there are some who say not to do it.
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Old 07-03-2012, 05:13 PM   #39
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Everything I have read says that ABS is not designed to work in a curv.
How would it know?
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Old 07-03-2012, 06:31 PM   #40
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I'm not great at physics and this may be totally wrong, but my understanding of ABS & curves is as follows:

The ABS system is measuring wheel rotation in line with the bike. That is, no lateral component of motion or force comes into play in ABS calculations, strictly wheel rotation in comparison with speed.

In a curve, if you hit your brakes, you are unlikely to be able to slow the tire quickly enough to engage ABS without lowsiding.

You have extreme lateral forces when cornering that are NOT taken into account by ABS. Any lateral sliding beyond the traction of the tires obviously can't be compensated for by the ABS.

If, in some impossible situation, in-line traction loss could occur due to hard braking while cornering without lateral traction loss, ABS would kick in just fine.

But I think that's an impossibility at anything but shallower lean angles. 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.
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Old 07-03-2012, 08:22 PM   #41
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Excerpt from a vehicle dynamics course :

The use of available traction for braking or anything else can considered in terms of "available budget".
The portion of the budget which can be spent on braking without causing a loss of traction varies depending
on what the vehicle is being asked to do. The complexity of this in the real world is one reason why some of us
call the top MotoGP guys "aliens" ; the aliens have the ability to maximize the use of available traction in a way
which is so superior it almost seems superhuman.

The paragraph below is a nice summary of the use of available traction, from a web-based course on vehicle dynamics :


"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 above is from this page, which is part of a class on vehicle dynamics :

http://ritzel.siu.edu/courses/302s/v...ledynamics.htm

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I dislike linked brakes myself because there are times I want to be able to lock the rear wheel in order to
make the bike do something. I usually use a lot more front brake than rear brake on the street, and I prefer
to be able to choose the differential between front and rear brakes myself. I would choose ABS brakes on a
bike only if the ABS had a defeat switch. But I will never own a bike with linked brakes. All of which is
my personal preference only.

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Old 07-03-2012, 08:49 PM   #42
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Interesting thoughts on ABS & linked brakes, never had the pleasure of living with either.
Recent experience implies to me that a bike would need very sophisticated electronics to maximise braking in a corner, possibly the latest offerings from Ducati, Aprilia & BMW which are basically track focused & at the cutting edge have that sophistication.
I'm only postulating this because I recently did some training to learn how to brake in a curve, not trail braking but hazard avoidance. Fried my mind to begin with, their is a lot to think about & modulate with braking, steering, grip & observation.
I found it was possible to haul a bike down at speed cranked fairly hard over & still be able to control the direction I want the bike to move in. I've recently plucked up the courage to practice this in the rain
I think it's a big ask for a black box to monitor & assist braking in this situation, the physical variables are huge & changing constantly.
I would certainly like to know if manufacturers have designed this into their systems, it would be a real help.
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Old 07-04-2012, 02:12 AM   #43
Luke
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Quote:
Originally Posted by klaviator View Post
Were you leaned way over, or just a little bit? I regularly used my brakes in curves on my 95 R1100GS but in 87000 miles, I never had the ABS activate in a curve, and I never crashed except for an encounter with Bambi. Of course, I never tried to use the brakes hard while leaned way over.

As for using regular brakes in a curve, trail braking has been a common and well know technique for a long time even if there are some who say not to do it.
I probably wasn't leaned over that much, but it was enough that the bike stepped out and caught itself every time the ABS cycled. It certainly would have been a crash -either high or lowside- without the ABS.

It only happened once, I either got better at braking or better at not needing too. Probably a bit of both.
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Old 07-04-2012, 08:11 AM   #44
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I liked it. As usual all the theoretical crap gets in the way. Folks, it's all about practice and experience. There are no numbers when you're there doing the task. The only computer working is your brain. Your brain can only compute what you have experienced and take action from there.

When you realize that, you will start to see - It isn't numbers and science, it is the idea that it is possible and that you need to learn how. That is true in many areas of motorcycles, not just braking in a corner or countersteering or any of the other practical riding requirements.

Learn that it is possible, then learn how to do it. In this discussion that involves realizing road conditions, what your situation is on the motorcycle, what you can try to do, then doing it. That is all computed by the human mind in a fraction of a second based on learned experiences, the action is the solution derived by that human mind. The sad part is... GI=GO

If you never develop the input you can not deliver the output. And I'm not talking knowledge, I'm talking action.
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Old 07-04-2012, 10:39 AM   #45
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ABS will not save you while leaned over for the same reason(s) you can low-side by tucking the front without being ON the brakes at all. Sensing wheel rotation and lateral friction, ABS does only 1 of these...

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