ABS - I'm afraid!

[Oil-Burner]

After many many years of riding experience, I have to admit I'm new to ABS and I have no idea what I'm talking about... which leads me to a question of ABS operation.

 

I've heard that below approx 5~10mph ABS stops functioning. I think I've heard this called the low speed threashold. So I'm thinking that before I take the advice of many here to go grab a handful on a gravel road, that I should find this out.... at what speeds does ABS really kick out (stop functioning) for you all on emergency stops? or is this just an urban legend?

[T__]

Oil-Burner, I’m not sure on the EXACT speed & it probably varies slightly by tire diameter & tire deformation but most ABS systems stop the ABS function at around 2-5 mph.. This is necessary on ALL ABS systems so the vehicle will come to complete stop.. If the ABS function didn’t do this you could never bring the vehicle to a complete stop as the ABS system would release all braking control as the tires stopped turning thinking there was a wheel lock up..

There are some other factors here also as the ABS system basis it’s speed input off of wheel speed input so the vehicle speed needs to be accurate & believable.. Therefore there are decel rate curves in the ABS controller that allow it to know possible from impossible..

 

In a very simple explanation-- if it saw 70mph then in less in than 1 second later saw 3 mph it would know that was impossible & know it was impending wheel lock up so would allow controlled wheel release to prevent lock up.. On the other hand if it saw evenly matched front & rear wheel speed decel at the rate of 10mph for every 2 seconds it would know non ABS braking & as it saw a smooth decel curve of 10,9,8,7,6,5,4 mph it could shut off ABS function around 2-3 mph to allow a complete stop..

 

When I do max braking on packed dirt roads I usually get a little front wheel slide for the last foot or so (I never measured it).. I might have rear slide also but never noticed it.. On loose fresh gravel I can’t remember doing a max ABS stop all the way to stand still as the stopping distance is long & I usually let off the brake before a full stop.. Loose gravel would not be the place to practice as there are other factors on gravel like maintaining bike balance as the tires walk sideways as they roll over movable gravel stones..

 

ABS systems on loose substrate (even snow) is a trade off (even in automobiles) as you trade off vehicle control & straight line stopping against overall stopping distance.. When stopping quickly on loose substrate you can get a shorter stopping distance by braking hard enough to allow material build up in front of the tires (material piling in front of the tires).. With (most) ABS systems they keep the wheel decel rate above that material piling point so do add stopping distance (can be considerable in some cases)..

 

On your 09 RT you might start out practicing on a dirt or sand covered road (no real large stone gravel) then practice using only the rear brake to begin with as that will only allow rear wheel ABS operation.. Once you understand rear wheel ABS feel then move on to the front brake,, even then to begin with just do short distance max braking until ABS release then let off the brakes to recover bike control.. I think you will find the ABS allows good bike control even at max braking..

 

 

Twisty

 

[Oil-Burner]

Thanks for the detailed reply Twisty, it makes alot more sense now. One followup question though... how abrupt is the transition when the ABS kicks off? I'm guessing that I will experience full wheel lockup for the last few feet be it asphalt or loose surface.

[Quinn]

Thanks for the detailed reply Twisty, it makes alot more sense now. One followup question though... how abrupt is the transition when the ABS kicks off? I'm guessing that I will experience full wheel lockup for the last few feet be it asphalt or loose surface.

 

The obvious answer is that yes you will--with or without ABS--unless you ease up slightly on the brake lever. Just like you do with a car's brake pedal coming to a smooth stop. You probably don't remember back to when you first started driving a car and almost put your father through the windshield when you just kept increasing brake pressure until the very end. It's now a natural proceedure to ease up slightly at the very end to counter the last second jerking rebound. The last second ease-up also lets the front wheel roll for balance and lets you plan which way the bike will lean over so you can get your foot down.

 

--

 

 

 

[T__]

Thanks for the detailed reply Twisty, it makes alot more sense now. One followup question though... how abrupt is the transition when the ABS kicks off? I'm guessing that I will experience full wheel lockup for the last few feet be it asphalt or loose surface.

 

Oil-Burner, I can’t speak of ALL road surfaces or traction conditions but on a hard packed dirt or gravel road with the gravel worn off or worn into the clay binder it will be pretty seamless.. You will already be on a fairly steep decel rate so as the last few mph are dropped it will just stop..

I would presume as that is happening you are already positioning your feet for the complete stop..

 

I seldom come to a COMPLETE stop even when practicing ABS or other high G decels as I guess I’m too lazy to put my feet down just for practice stops..

 

I probably should practice very high G stops till completely stopped on pavement as there is an art to getting your feet deployed as the bike stops very abruptly.. My old GoldWing is really bad in this area as my feet slide forward under the cylinder heads on high G braking so they are difficult to get to the ground in complete extreme decel stops..

 

As a rule in normal (even high G stops) most people let up on the braking as the bike rolls to a stop but that won’t happen if a collision is eminent as it will be max braking until the bike stops just short of the threat or there is a collision..

 

I would suggest you start your ABS practicing by just braking hard for short periods not all the way to a complete stop.. As you get used to the braking & bike feel then you can brake closer to a complete stop until you understand the abruptness near the end.. High decel on dry pavement you might slide forward on the seat if you normally sit back while riding..

 

Keep in mind things in the stopping path can upset the bike’s stability even with ABS (like round sticks from tree branches,, or large rounded stones,, etc) as they allow a sideways kick of the tires as the wheel brakes over it..

 

 

 

Twisty

 

[Oil-Burner]

Thanks for the response Quinn and Twisty for such detail, this has all been very very helpful.

 

Now to take all this new found knowlege and experience my first ever (bike or cage) ABS application...

[russell_bynum]

Further, with a good ABS system, and any ABS system on current Euro-spec bike is damned good, you can't "overwhelm" the suspension - the instant loss of traction approaches the brake pressure is automatically dropped for the minimum time required for re-gaining traction when maximum force will be re-applied until you either stop or chose to let off the brakes. The suspension charecteristics obviously determine how much traction is available but I have yet to read a verifyable account of anybody out braking an ABS equiped bike with a similar non-ABS bike on a one attempt stop! In an emergency you don't get a practice run!!!

 

It's good to hear that the Euro-spec bikes have finally gotten around that whole "laws of physics" thing. I'll have to buy one of those bikes next time I'm in the market. Do they also get 5,000,000mpg, do 0-100mph-0 in .01 seconds, and run on liquid pixie dust?

 

Physics is physics. ABS doesn't do anything until the wheel accelerates at a rate higher than the pre-programmed threshold. Which means that ABS doesn't do anything until the tire is already at the threshold of losing traction. That threshold is not a fixed point...it changes based on a number of factors...including how well the suspension is doing. Telelever helps, of course, but physics is still physics.

 

But even if the laws of physics are suspended while you are riding a modern BMW, they are resumed when you ride most other bikes...and when the technology on the modern physics-defying BMW fails (which has been known to happen from time to time)...so you would be best served developing good technique that will work well on every bike.

 

 

And I repeat the most important time to loose speed is while your are at high speed.

 

I completely agree...which is why it is important to get the whole system working at its max potential and efficiently as possible. Premature unnecessary ABS engagement due to "jamming on the brakes" is not the quickest and most efficient way to do that.

 

Of course like everyone else here I hope never to have to put any of this into use but you just never know when you might need to so as others have said practice.

 

Yup...but it helps if you're practicing the right response.

 

 

Safe riding in 2010.

 

Derek

 

Likewise!!

[sardineone]

Wow, lots of opinions here. I might get stoned for saying this. I'd say just ride your bike normally and you'll hardly know it has ABS. The ABS's best accolade is it helps cover your mistakes when you misjudge road conditions or panic. The purpose of the ABS is to turn off the brakes if you begin to lockup a wheel, right? That would lead to a safer but, longer stopping distance. So I don't ever try to lockup a wheel but, have the ABS in reserve if needed.

[russell_bynum]

Wow, lots of opinions here. I might get stoned for saying this. I'd say just ride your bike normally and you'll hardly know it has ABS. The ABS's best accolade is it helps cover your mistakes when you misjudge road conditions or panic. The purpose of the ABS is to turn off the brakes if you begin to lockup a wheel, right? That would lead to a safer but, longer stopping distance. So I don't ever try to lockup a wheel but, have the ABS in reserve if needed.

 

Yup!

 

[Little_Brit]

Russell,

 

You are talking a whole lot of cods wallop. If you can stop more quickly with your controlled techniques than an ABS equiped vehicle I will eat my hat!!!!

 

Derek

[russell_bynum]

Russell,

 

You are talking a whole lot of cods wallop. If you can stop more quickly with your controlled techniques than an ABS equiped vehicle I will eat my hat!!!!

 

Derek

 

All I'm saying is that the best way to stop a bike is the best way to stop a bike and it doesn't matter if it has ABS or not.

 

I have done repeated tests with ABS disabled and with it functioning on my R1100RT...in all cases, the best way to stop was by using good technique rather than just "grabbing a handful". You may argue that this was in a controlled situation when I was expecting the stop. That would be a correct argument, but it does not change anything.

 

ABS is there for when your best isn't good enough due to you misjudging the available traction and/or other factors taking your attention. I like ABS...I think it's a "good thing", but it isn't magic and it can't defy the laws of physics.

 

If you act as if you don't have ABS (i.e. use good braking technique and strive to modulate the brakes to keep the wheels turning), and you practice that technique, the following will be true:

1. Your skills will work on bikes without ABS...or on your bike when your ABS fails on a long trip.

2. Your skills will work on ABS-equipped bikes

3. When you're riding an ABS-equipped bike and your skills fall short, ABS will be there to take up the slack and keep you upright.

 

Conversely, if you just "grab a handful" and rely on ABS to stop you:

1. If you are riding a bike without ABS (or your bike with the ABS failed), your skills will cause you to lock a wheel and probably crash.

2. Your skills will work on bikes with ABS, but you will have longer stopping distances than if you brake properly.

 

Doing it "right" is a win-win. There's no reason NOT to aspire to brake properly...and rely on your ABS to keep things sorted when you mess up.

 

 

[T__]

Derek, I doubt ANYBODY even Russell can out stop the integrated linked ABS system on an ABS equipped BMW bike.. Even the best rider in the world can’t hold both the front & rear wheel slip to edge of traction & keep it out of ABS as the ABS learns the wheel slip rates & will modulate those even prior to full ABS brake apply.. If the rider is keeping the wheel slip above ABS intervention he isn’t stopping quick enough to get minimum stopping distance.. As you noted in your first post ANY stopping distance given up in the first few milliseconds can never be made up during the rest of the stop as the bike just travels too far at speed during those first few seconds..

 

 

Now on a like bike without ABS or BMW ABS bike with the ABS disabled a real good rider might be able to slightly outstop the ABS system on a KNOWN good traction clean road surface using repetitive stops to learn maximum tire adhesion.. I know of no-one (I doubt even Russell) can out stop a well balanced learnable BMW ABS system on a “once only” max G braking event on a road surface unstopped on by the rider before.. If anyone knows of & can show any testing data that shows (ANY) rider that can out-stop a BMW I-ABS or New Gen I-ABS adaptive brake system on a ONE STOP application on an unknown clean road surface I sure would like to hear about it..

 

Now I’m not talking the early BMW ABS-2 (pre I-ABS/ New Gen I-ABS) as that early generation system was rather slow,, not adaptive,, & released way too much front brake to prevent rear wheel lift..

 

Twisty

 

[russell_bynum]

I give up. Just grab a handful and pray.

[tallman]

Russell,

I agree with the concept of practice, ride like you don't have ABS.

 

However, while your R1100 system may have worked that way for you, many riders will not have the same skill set, even with practice.

Also, new generation ABS systems, in particular the Honda product, have been tested by professional riders and motojournalists. These riders would have skill sets similar to yours.

In these tests (see May'09 Cycle World) the ABS system outperformed the nonABS bike, in some cases by huge margins, in others by small margins.

The only time the non ABS bike stopped in a shorter distance was a test on dry, smooth, pavement.

The distance was one foot shorter.

It took four trials to produce even this result.

Not all bikes are set up with these systems so practice is definitely one's first line of defense.

But, there are bikes out there, and there will be many more, where even the best riders will have difficulty getting better results than the ABS system will give, in almost every situation.

For "average" riders, data I've found going back to the first BMW ABS systems show marked advantages in some riding conditions, small advantages in others (advantage being shorter distance/no wheel lock) and in some tests the ABS took longer to stop the bike.

Road surface, weather, riding experince, tires, suspension all factor in.

IMO, there is a new age coming.

One where technology will perform at a level that even the best riders can't duplicate.

Is there a reason some vehicle racers use paddle shifting?

Can't they do it better the "old fashioned" way?

Time will show us where this road leads to.

 

Stay safe.

Best whishes.

[russell_bynum]

Edit: Content deleted because it wasn't productive.

[big-t]

I give up. Just grab a handful and pray.

 

 

Thats a first..

 

 

..or are you just baiting the trap...

[Username]

I would tend to agree with Russell for the most part. Ride like you don't have it. If you need it, it will be there. And practice is supremely important.

I regularly practice things like emergency braking with both my car and bike. Just cause it's fun. I do find that I do not like ABS in my car. I can stop faster and "better" on snow and ice without it. I really don't like ABS fighting with me for control.

I have not had the experience of having it kick in on the bike. Which makes me happy, cause I know that it isn't overly intrusive. I also think it will be more useful than on the car if I actually do reach a point where I need it. Hopefully.

[Burt]

I give up. Just grab a handful and pray.

Is that you Foghorn?

[russell_bynum]

I give up. Just grab a handful and pray.

Is that you Foghorn?

 

Some fellas have to keep their tongues flappin' but not me. I was brought up right. My pa used to tell me to shut up and I'd shut up. I wouldn't say nothin'. One time darn near starved to death. WOULDN'T TELL HIM I WAS HUNGRY!!

[tallman]

How he feels about ABS

[pmdave]

Russell, I'm with you here. There are obviously others who believe so much in technology that they can't see any other outcomes than the technology saving the day while the poor unskilled rider goes along for the ride.

 

That's admirable faith in the engineers, but there are lots of situations where ABS--even the latest and greatest--won't save the day. For instance, if you're leaned over in a curve, encounter an Elk or a stalled logging truck, and grab a big handful of front brake, I suspect the ABS wouldn't prevent a crash. And if the statistics are anywhere near correct, a majority of motorcycle crashes are occurring in curves. I'd love to be proven wrong about this, and I understand BMW is working on a means to put lean angle into the braking equation. I don't think we're there yet. Which means the rider's technique is still a big part of the equation.

 

I've ridden various ABS-equipped machines, and some had very seamless braking, even on gravel. One was so herky-jerky it dumped me on my butt when I attempted to trail brake on the rear in a tight U-turn. One would fault (every other morning) and provide so little braking I would sweat the first stop, until I could reboot the engine. That was likely a failing battery, but it was something that could occur to any of us.

 

Fortunately, the engineers have recognized the issues, and have pretty much done away with ornery power assist modules. So, what we have today is better than what we had just a few years ago. However, today's engineers are mostly yesterday's engineers, right?

 

IMHO If you buy a late model BMW with ABS, keep it serviced every year, and trade it in within three years, you'll probably get the best braking system in the world, and have no problems stopping under most conditions. If all your emergency stops happen to be straight line, the latest systems will probably outstop most riders.

 

Just remember that the computers have their limits, and in the end the responsible party is not the engineer or the salesman, but whoever was holding on to the handlebars at the moment of the emergency. If you ride too fast into a blind situation from which you can only save yourself by violating the laws of physics, you're toast, regardless of the brake system. And if you freeze in panic and don't reach for the brakes, even the best system won't do you any good.

 

Bastardi non carborundum, Bynam.

 

pmdave

[Selden]

Granted, cars are different, but I went out this morning on ice-slick Atlanta roads (no salt or sand) to see how the Fit handled them. On patchy ice, the ABS was absolutely astounding -- I could feel each wheel behaving differently, depending on whether it was on ice or pavement. No human being could possibly do this, using any conceivable technique.

 

Re ABS on motorcycles, consider this article, now 17 years old: No Fault Braking : A Real-World Comparison of ABS Systems. Ideal conditions braking is one thing; real world braking is quite another. If a skilled race rider can stop 100 feet shorter in wet conditions using ABS, it takes a lot of hubris to think that a street rider can consistently beat the performance of ABS brakes.

 

Wet Pavement Braking over Sewer Cover

(All measurements recorded with Yamaha FJ1200)

 

Racer

non-ABS 298 ft

w/ ABS 211 ft

Full ABS Control 193 ft

 

And that was using 1992 ABS technology.

[CoarsegoldKid]

...but there are lots of situations where ABS--even the latest and greatest--won't save the day. For instance, if you're leaned over in a curve, encounter an Elk or a stalled logging truck, and grab a big handful of front brake, I suspect the ABS wouldn't prevent a crash...

 

pmdave

...and I suspect non-ABS wouldn't prevent a crash either.

Handful is relative. I like many on this forum have cut our teeth on non-ABS brakes-drum through disc technology. I think for the most part we say "I had to grab a handful of brake when the cage turned into my lane". I've said it. I don't say "in the first 10 milliseconds I gingerly applied the front brake, applying a measured and calculated amount of lever pressure in proper time and rolled to a stop." Doesn't have the same ring.

By all means practice your skills of braking, throttle control, lane position, viewing the big picture and don't put yourself leaned over hauling ass when you come to a blind corner where that elk or a stalled logging truck can catch you off guard. Please.

[russell_bynum]

Granted, cars are different, but I went out this morning on ice-slick Atlanta roads (no salt or sand) to see how the Fit handled them. On patchy ice, the ABS was absolutely astounding -- I could feel each wheel behaving differently, depending on whether it was on ice or pavement. No human being could possibly do this, using any conceivable technique.

 

Re ABS on motorcycles, consider this article, now 17 years old: No Fault Braking : A Real-World Comparison of ABS Systems. Ideal conditions braking is one thing; real world braking is quite another. If a skilled race rider can stop 100 feet shorter in wet conditions using ABS, it takes a lot of hubris to think that a street rider can consistently beat the performance of ABS brakes.

 

Wet Pavement Braking over Sewer Cover

(All measurements recorded with Yamaha FJ1200)

 

Racer

non-ABS 298 ft

w/ ABS 211 ft

Full ABS Control 193 ft

 

And that was using 1992 ABS technology.

 

I don't know why I can't leave these alone. I keep telling myself I'm not getting into it anymore, but it's like watching a train wreck...I just can't look away.

 

1. Adverse and/or unpredictable traction conditions are where ABS really shines. That goes for bikes as well as cars. I've never disputed that.

 

2. ABS gives you the confidence to brake harder, especially over surfaces with unpredictable traction. That's a very valuable benefit. I've never disputed that.

 

3. I don't know about you, but for me, most of the time when I have to use the brakes, the conditions are more or less "ideal". I can probably count the number of times I've had to brake hard on wet pavement over a manhole cover on one hand...while wearing mittens. Most of the time it's clean, dry pavement with good traction. So...saying that "ideal conditions are irrelevant" doesn't make any sense. They're VERY relevant because they're what most of us experience most of the time. That doesn't negate the benefit of ABS in non-ideal conditions, but don't pretend that normal conditions are irrelevant.

 

4. None of this changes the laws of physics. The best way to brake is the same regardless if you have ABS or not. ABS can (and should) give you the confidence to brake harder, knowing that it will be there to bail you out if you brake too hard, but it does not change the laws of physics. Most relevantly it does not change how the braking force acts on the suspension and how that can reduce your available traction.

 

5. What happens when your ABS fails or you ride a bike without ABS?

[russell_bynum]

...but there are lots of situations where ABS--even the latest and greatest--won't save the day. For instance, if you're leaned over in a curve, encounter an Elk or a stalled logging truck, and grab a big handful of front brake, I suspect the ABS wouldn't prevent a crash...

 

pmdave

...and I suspect non-ABS wouldn't prevent a crash either.

 

If you've practiced threshold braking, you have some hope of being able to modulate pressure and maintain traction. If you have practiced "Just grab a handful and pray"...or more likely...not practiced at all, then you're right...you have no hope of avoiding a crash.

 

 

Handful is relative. I like many on this forum have cut our teeth on non-ABS brakes-drum through disc technology. I think for the most part we say "I had to grab a handful of brake when the cage turned into my lane". I've said it. I don't say "in the first 10 milliseconds I gingerly applied the front brake, applying a measured and calculated amount of lever pressure in proper time and rolled to a stop." Doesn't have the same ring.

 

If people are actually braking properly, but they're just too lazy to articulate what they're doing here, that's one thing. If they're actually "grabbing a handful", then that's something else.

[pmdave]

Obviously, the skill to brake while leaned over is dependent upon extremely smooth throttle-to-brake and brake-to-throttle transitions--with or without ABS. After all, dumping the throttle applies sudden engine braking to the rear wheel that can't be controlled by today's ABS systems.

 

One difficulty with learning the skill is that racers use braking for a much different purpose than those who ride public roads, and often we look to the track schools for skills that we hope will apply to riding public roads.

 

A racer might think of trail braking as a means to getting a quicker turn-in to a fast corner.

 

A road rider might need aggressive braking to avoid a hazard, or to quickly reduce speed for a rapidly closing sight distance.

 

But both situations require skillful control of both throttle and brake, and so far the engineers haven't figured out how to provide a computer that's better at this than the human brain. Perhaps one day they will.

 

pmdave

[russell_bynum]

Obviously, the skill to brake while leaned over is dependent upon extremely smooth throttle-to-brake and brake-to-throttle transitions--with or without ABS. After all, dumping the throttle applies sudden engine braking to the rear wheel that can't be controlled by today's ABS systems.

 

It also applies a sudden load to the front tire, often resulting in the front washing out. ABS ain't gonna help you there, either.

 

One difficulty with learning the skill is that racers use braking for a much different purpose than those who ride public roads, and often we look to the track schools for skills that we hope will apply to riding public roads.

 

A racer might think of trail braking as a means to getting a quicker turn-in to a fast corner.

 

I know that this is what Freddie Spencer says, but honestly, I think he's wrong. Yes...when the forks are compressed (as they are under braking), the steering geometry up front is tighter and that should result in the bike being less stable...i.e. it should respond quicker to steering inputs and be more willing to change direction.

 

But...at the same time, when the front brake is applied while the bike is leaned, the bike tries to stand up. This is easy to feel for yourself...just go to a parking lot and get the bike into a corner, then gently apply the front brake...the bike will try to stand up.

 

I think these two forces fight each other and I'm not convinced that the end result is that the bike changes direction that much faster. I think the decision to trail brake into a corner has more to do with making the best use of traction and the ideal line through the corner than affecting the bike's geometry so it turns faster.

 

There's also the issue of suspension load and traction...if you brake coming up to the corner, that compresses the front end. Then you release brakes before you turn in...the front rebounds. Then you turn in and load the front...it compresses again. Then you start getting on the gas and standing the bike up...weight transfers back and cornering force is reduced...the front extends again. In an ideal world, you would remove braking force at the same rate that you add cornering force...eventually at the apex you have no braking force and max cornering force. Then you start standing the bike up and opening the throttle, extending the forks. This way, the forks only compress and rebound once.

 

 

On the road, that technique isn't the best way to go because it keeps you close to using 100% of your available traction at all times...which means you don't have anything left over to deal with the unknown.

[ShovelStrokeEd]

But both situations require skillful control of both throttle and brake, and so far the engineers haven't figured out how to provide a computer that's better at this than the human brain. Perhaps one day they will.

 

Well said, Dave, but I almost hope not. I have to work on my braking on an almost daily basis as I switch between my Tuono Factory (fantastic 2 finger brakes) and my Triumph Sprint (quite a bit weaker brakes). Actually, a mistake there, the Triumph will lock the front wheel, it just needs much different control input.

 

Needless to say, this keeps my on my toes so to speak. There is also a big difference in character with the rear brakes, this time with the Triumph having the more powerful brake and thus the need for more modulation of that brake during a hard stop.

 

Neither bike is equipped with ABS and, for the most part, I don't miss it. I do work both bikes to the point of lockup in my weekly drills to keep myself sharp. So far, there has been very little confusion on the rare occasions I have had to really get on the brakes in a street riding situation.

 

I would suppose that the engineers could build an adaptive system that would compare rider input to available traction and build a stoppie eliminator in as well. My local dealer just took in a CBR1KRR with the new ABS on trade. If the bike is still there in 2 weeks when I'm home again, I hope to ride it and see how good those brakes really are.

 

There was a thread a long time back now on proper use of the brakes. Might have been by RD Franz, I know Russell participated. Taught me a whole bunch about how to properly brake and why the technique illustrated works so well. A search on Ta Dummmmm might find it.

[pmdave]

I'm a believer in practicing throttle-to-brake and brake-to throttle transitions, so that the muscle memory is there to be absolutely smooth. And I believe that the same techniques apply to all single-track motorcycles, regardless of the brake systems.

 

Let's note that Nate Kern (BMW racer) brakes with the three outer fingers, not the two inner fingers. He suggests that applying pressure further out on the lever provides more accurate brake control with less muscle power. In a race he wants to conserve energy wherever possible.

 

pmdave

[pmdave]

Would it be helpful to start a new thread about "Braking Practice"?

 

pmdave

[russell_bynum]

Would it be helpful to start a new thread about "Braking Practice"?

 

pmdave

 

You could try. Every time we have a braking thread, a bunch of yahoos come out of the woodwork and say that it doesn't matter because:

1. Only professional racers are capable of developing that level of skill

2. I have ABS, so I don't need braking practice

3. In an emergency situation all of that training will go out the window and you'll just "grab a handful"

 

It usually ends with me slamming my head repeatedly against the desk...or doing Foghorn Leghorn impersonations.

 

 

 

Personally...I would find a thread about braking practice to be tremendously valuable.

[T__]

Would it be helpful to start a new thread about "Braking Practice"?

 

pmdave

 

Dave, yes a new thread about “BRAKING PRACTICE” would be great as usually some yahoo hijacks the original post about

[“I know the ABS system is supposed to keep the front wheel (both wheels, actually) from locking up, but I foresee trouble if the front wheel should stop turning and start sliding. Is the ABS actually able to adapt to slippery roads, and can I forego testing this (I hope)?”]

& tries to turn it into some sort of “my way of braking is best” thread instead of answering the OP’s original question..

 

Maybe a new thread will not result in someone hijacking the original intent..

 

Twisty

 

[russell_bynum]

Would it be helpful to start a new thread about "Braking Practice"?

 

pmdave

 

Dave, yes a new thread about “BRAKING PRACTICE” would be great as usually some yahoo hijacks the original post about

[“I know the ABS system is supposed to keep the front wheel (both wheels, actually) from locking up, but I foresee trouble if the front wheel should stop turning and start sliding. Is the ABS actually able to adapt to slippery roads, and can I forego testing this (I hope)?”]

& tries to turn it into some sort of “my way of braking is best” thread instead of answering the OP’s original question..

 

Maybe a new thread will not result in someone hijacking the original intent..

 

Twisty

 

What hijack? Many of us believe that the answer to the OP's question is "no." (or...the _best_ answer is "no")

 

I suppose we could have left it at that, but that's not of much value. So you elaborate. "Here's the sort of testing that you could do." Etc.

 

That's the whole point of this forum.

 

 

 

 

[Morrie]

Now I’m not talking the early BMW ABS-2 (pre I-ABS/ New Gen I-ABS) as that early generation system was rather slow,, not adaptive,, & released way too much front brake to prevent rear wheel lift..

 

Twisty

 

Twisty,

 

I know the K75s, K100s and first year K1100s had ABS-1. I think the second through the last model year K1100s had ABS-2 which is what I think I have on my 97 R1100RT. (unlinked.) I think this is essentially the same system I had on my 1150RT with the added power servo and fully linked. My 1150R, I believe, also had ABS-2 with power and partially linked. I thought that was a good system but I didn't care for the power assist. I'm having to adjust to using the rear brake more, after riding the linked systems for many thousands of miles. I guess my question is: If I engage front and rear to the ABS activation point on the 1100RT, am I getting basically the same stopping assist as on the later bikes?

 

 

[russell_bynum]

I know the K75s, K100s and first year K1100s had ABS-1. I think the second through the last model year K1100s had ABS-2 which is what I think I have on my 97 R1100RT. (unlinked.) I think this is essentially the same system I had on my 1150RT with the added power servo and fully linked. My 1150R, I believe, also had ABS-2 with power and partially linked. I thought that was a good system but I didn't care for the power assist. I'm having to adjust to using the rear brake more, after riding the linked systems for many thousands of miles. I guess my question is: If I engage front and rear to the ABS activation point on the 1100RT, am I getting basically the same stopping assist as on the later bikes?

 

Once you go to power-assist, that's not ABS-2 anymore, that's i-ABS.

 

I'm not sure when ABS-2 came out, but I know that's what is on the R1100RT. The K75 (and presumably the K100) were ABS-1.

 

To answer your question: No. i-ABS cycles faster than ABS-2, so if you are braking to the point where ABS takes over, you will take longer to stop than an i-ABS bike...all other things being equal, of course.

 

One other thing: I believe Twisty misspoke. The early versions of the i-ABS was known for overreacting and releasing too much front brake to keep the wheel from lifting. ABS-2 doesn't do that. ABS-2 will let you stoppie the bike if you want to. One fun thing to do with an ABS-2 bike, is while braking hard up front, just stand on the rear brake. Rear ABS will kick in, but by that point the rear end is so light that you lose yaw stability and you can slide the rear end around a bit with body english and handlebar inputs. Not recommended, and not the best way to stop, but it can be fun.

[T__]

Morrie, the system you had on your 1150RT was not the ABS-2 it was the later I-ABS system (completely different systems) ..

 

As far as your question-- within reason the earlier ABS-2 system acts the same as the later systems but it doesn’t have the learnability or adaptive aspect of the later I-ABS servo assisted brakes.. The early ABS-2 had a slower pressure build rate,, had a fair amount slower baud rate (pulsed slower),, had a fairly crude front/rear antilift linking,, & had a slower recovery response..

 

On a smooth paved road there is a difference when approaching or in ABS but not a whole lot.. On very slippery or choppy road surfaces I think you would find the later system much more responsive especially on anticipating impending wheel lock.. The newer I-ABS system would have a shorter stopping distance on a slippery or choppy road while under ABS control..

 

The new late 1200 ( late non servo hexhead) “new generation” I-ABS uses a valve type ABS controller with a very fast cyclic rate (valves vs pistons with accumulator ) & still has a servo powered rear brake when linked from the front.. This system is very dynamic in both adaptation & controlled decel curves so this system is light years ahead of the older ABS-2 system..

 

We’ll have to wait to see if the 2010 RT’s have a more advanced system yet..

 

Twisty

 

[russell_bynum]

The early ABS-2 had a slower pressure build rate,, had a fair amount slower baud rate (pulsed slower),, had a fairly crude front/rear antilift linking,, & had a slower recovery response..

 

 

Out of curiosity...in 10 years here, you're the only person I've ever heard say that ABS-2 has anti-stoppie capabilities. Do you have technical documentation or something to back that up? (Note: I'm not saying that it doesn't...but this would be the first time I've heard of it.)

[T__]

Russell, yes, I have a BMW document FULLY explaining the ABS-2 system & function.. I promised the engineer I got the info from that I wouldn’t publish the document (so no-one PM me asking for it..

 

I will post the part that applies to the anti lift though..

 

 

 

“Based on the rotating-speed information coming from both wheels, this system is also capable of detecting lifting of the rear brake when the brakes are fully applied and preventing this by correspondingly regulating the pressure in the front wheel brake circuit.

Owing to the fact that this system employs a plunger piston, the brake pressure can be decreased to 0 bar, thus ensuring dependable control behavior on difficult riding surfaces, e.g. black ice, gravel etc.”

 

There is no doubt in my mind that you can/could lift the rear wheel on the ABS-2 system.. That system was slow & the plungers were slow so if you spiked the front brake without applying the rear brake so the rear wheel was lifted but still spinning on engine power the ABS system would have no idea that was in or approaching rear wheel lift..

 

That system was rather crude & assumed for rear wheel lift detection that both front & rear brake were applied so the rear wheel decel rate would be steeper than the front during rear wheel lift..

 

Even on the later I-ABS system without linking you could do the same (shorter duration wheelie though)

 

Even on the linked I-ABS system I could lift the rear wheel (for a very short distance) if I braked hard with the front lever while keeping engine power going to the rear wheel..

 

Twisty