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Old 07-03-2012, 09:07 AM   #16
RxZ
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Originally Posted by Donster View Post
OK, is there some rule of thumb that generally takes these factors into account?
No.

Tires are made out of different compounds, roads are made of different materials. Each has their own coefficient of friction differing from dry to wet. To have a rule of thumb, you would have to know all the variables as mentioned.

The only rule of thumb is, whatever traction you have when dry, there is less when wet.
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Old 07-03-2012, 11:31 AM   #17
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This should be a sticky.
Thank you for a great article.
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Old 07-03-2012, 11:34 AM   #18
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Thanks for cross-posting that. I just finished his book, was a really solid read. What a great guy!

I'm an inveterate trail braker. I just do it. It drove my riding instructor abso-fucking-lutely nuts until he realized that I just do it and if I could do it, good. He started to work with it more heavily (German driving instructor, so no racing allowed), and now, he is quite proficient and gets the point.

Once you learn to trail brake, you will see turns a whole new way. Decreasing radius turns no longer are scary, because so what? Just keep slowing gently. It works!
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Old 07-03-2012, 11:48 AM   #19
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Originally Posted by RxZ View Post
No.

Tires are made out of different compounds, roads are made of different materials. Each has their own coefficient of friction differing from dry to wet. To have a rule of thumb, you would have to know all the variables as mentioned.

The only rule of thumb is, whatever traction you have when dry, there is less when wet.
What about same bike, same tires, same everything, on the same road, only difference is the road is wet or dry. Could you assume 20% less grip? 50%?
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Old 07-03-2012, 11:52 AM   #20
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Originally Posted by RxZ View Post
No.

Tires are made out of different compounds, roads are made of different materials. Each has their own coefficient of friction differing from dry to wet. To have a rule of thumb, you would have to know all the variables as mentioned.

The only rule of thumb is, whatever traction you have when dry, there is less when wet.
You might want to think that you actually, on a clean wet road, assuming decent tires and a good rider, there is more traction there than you think. You really just have to be smoother and a bit slower in the rain. You don't do nothing sudden in the rain, be it steering inputs, braking or acceleration. I have seen good road racers only loose a second or so per lap on a 1.5 mile course in the rain. Slicks are another story.
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Old 07-03-2012, 11:56 AM   #21
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Originally Posted by Donster View Post
What about same bike, same tires, same everything, on the same road, only difference is the road is wet or dry. Could you assume 20% less grip? 50%?
I am not sure the numbers but someone who designs roads could give you the traction co-efficient for a given turn, all factors being equal. But the final outcome based on his numbers will be generic and may or may not work well for a bike since they do the numbers based on auto's etc.
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Old 07-03-2012, 12:06 PM   #22
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Traction is a transient condition. We in da biz will only commit to "more", "similar" or "less".
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Old 07-03-2012, 12:06 PM   #23
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Here's a dumb question.

First, a preface: I consider myself a very techno-friendly rider. Meaning, I'm not at all averse to whatever 21st century gizmo can be added to the bike to make it easier or safer to ride. No, I don't want the stuff legislated, and no, I don't want it on every bike. But I like having a marketplace that supports making all the nifty gizmos and doo-dads available to the riders that want them.

With that out of the way... I can't recall any training course / motorcycle expert / experienced rider tell me anything different from "always brake progressively." Holding a baby bird, cradling an eggshell, counting "one-one thousand"-- whatever you call it, everyone says the same thing: don't grab or slam on the brakes or else bad things can happen.

Now, maybe there are instances you need to grab or slam the brakes as hard as you can (on dirt, maybe? I don't ride dirt, I wouldn't know). But on the street?

So... where are all the electronic-assisted brake options out there? It seems to me that wiring the front and/or rear brakes on a street bike with a system that resists grabbing/slamming and progressively engages the brakes no matter how hard you yank on them would avoid go a long way to avoiding this problem, no?

Alright, what's wrong with this option? Fire away...
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Old 07-03-2012, 12:14 PM   #24
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Originally Posted by daveinva View Post
Here's a dumb question.

First, a preface: I consider myself a very techno-friendly rider. Meaning, I'm not at all averse to whatever 21st century gizmo can be added to the bike to make it easier or safer to ride. No, I don't want the stuff legislated, and no, I don't want it on every bike. But I like having a marketplace that supports making all the nifty gizmos and doo-dads available to the riders that want them.

With that out of the way... I can't recall any training course / motorcycle expert / experienced rider tell me anything different from "always brake progressively." Holding a baby bird, cradling an eggshell, counting "one-one thousand"-- whatever you call it, everyone says the same thing: don't grab or slam on the brakes or else bad things can happen.

Now, maybe there are instances you need to grab or slam the brakes as hard as you can (on dirt, maybe? I don't ride dirt, I wouldn't know). But on the street?

So... where are all the electronic-assisted brake options out there? It seems to me that wiring the front and/or rear brakes on a street bike with a system that resists grabbing/slamming and progressively engages the brakes no matter how hard you yank on them would avoid go a long way to avoiding this problem, no?

Alright, what's wrong with this option? Fire away...
Bikes are two wheels not four, and those systems are available, they are called anti-lock brakes but they only work well in a maximum braking straight line situtation and we are talking about braking in a corner here.
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Old 07-03-2012, 12:28 PM   #25
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awesome read, a reason why I hate linked braking but love abs
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Old 07-03-2012, 12:54 PM   #26
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Originally Posted by outlaws justice View Post
Bikes are two wheels not four,
Really?? Hadn't noticed.

Quote:
and those systems are available, they are called anti-lock brakes but they only work well in a maximum braking straight line situtation and we are talking about braking in a corner here
Sorry, I either mistyped or you misread (I'll charitably assume the former!).

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.

It seems to me, however, that there may be benefit to a system that engages the brakes progressively BEFORE wheel lock is achieved and ABS would be required. Perhaps (some) bike ABS systems do this already; I'm unaware of the technical differences between the various ABS systems out there.

Again, if the ideal is to brake progressively to avoid locking and losing traction-- yes, even in cornering, thank you very much-- why not have an electronic system that addresses this problem before it becomes a problem, versus after?
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Old 07-03-2012, 01:05 PM   #27
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Originally Posted by daveinva View Post
Really?? Hadn't noticed.



Sorry, I either mistyped or you misread (I'll charitably assume the former!).

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.

It seems to me, however, that there may be benefit to a system that engages the brakes progressively BEFORE wheel lock is achieved and ABS would be required. Perhaps (some) bike ABS systems do this already; I'm unaware of the technical differences between the various ABS systems out there.

Again, if the ideal is to brake progressively to avoid locking and losing traction-- yes, even in cornering, thank you very much-- why not have an electronic system that addresses this problem before it becomes a problem, versus after?
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.
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Old 07-03-2012, 01:16 PM   #28
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For the guy wondering about measuring traction changes as conditions change.

Go straight, pull in clutch, apply back brake until tire locks, unlock wheel get a feel for how much pressure it takes to do this.

Wait for conditions to change, repeat above.

I do that whenever I wonder what the actual traction of the road is. You do it enough you'll develop allot of confidence in shitty conditions.
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Old 07-03-2012, 01:19 PM   #29
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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.
Yes it's a sad world, Even in cars people have forgoten how to use brakes, now days its mash the pedal and thats it. Its sad for many reasons, we had to learn to use the brakes properly and having brakes that you could lock up helped in bad winter driving conditions when you could not make the hill and locked it up going backwards to allow you to flip ends and then get back down the hill.
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Old 07-03-2012, 01:19 PM   #30
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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.

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.
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