Know your I-ABS II system

[Andy VH]

A unique aspect of ABS controlled BMWs recently came up on motorcycle-usa.com, a website message board on which I am a moderator, specifically in the Motorcycle Safety section.

Everyone should be aware of a control aspect of your ABS system that some people may misjudge as a fault of the system, when atually it is done purposely to help maintain bike stability. The sequence is: when during NORMAL braking, the bike drops over a pronounced crack or edge in the pavement, in such a way that the rear tire is momentarily airborne, the ABS senses this as a rear wheel lockup event. Rather than simply limit braking to the rear wheel, the ABS system momentarily releases FRONT brake pressure in order to limit the time the rear tire is in the air. In essence, with this system it is not possible to do a stoppie on BMWs fitted with either the ABS-8M system (F800 series) or the I-ABSII system (R's and K's). The R-GS model has a ABS-OFF switch to depower the ABS system, but it is the only BWM with this feature. Do not simply depower the ABS on your Can-bus equipped bike as it will cause a fault.

Again, this is done to maintain bike stability, not to produce a shorter braking distance. In terms of bike stability, unless you are a praticed stunter or very experienced rider, a stoppie type event can VERY quickly become unstable with a crash as a result. But as with any rider assistance system, the rider STILL must be ware of how the system works and practice with it to know how it acts.

The real caution here though, is you do not have to engage an ABS type stop (as in High-Effort braking) to have the system produce this reaction. It can and DOES happen under normal braking. What you will sense, is under braking when the rear tire goes momentarily airborne, the front brake WILL release and the bike will seem to surge forward and then immediately reapply the front brake. This is very easy to produce even on a K1200LT.

Here's a for instance. You are braking at 20 mph on choppy pavement where each edge in the concrete is like a small 1" drop. The rear tire goes airborne after the front tire has dropped the 1" and is still braking. The ABS system engages, and even if for a 1/4 second you have NO brake action, and the bike will have gone 7 to 8 feet , or about a bit more than a bike length. Just be aware this DOES happen and you really should practice it to be familiar with it.

If this were to happen at 30 mph, in 1/4 second the bike could go 22 feet without braking action until the brakes re-engage. All the more reason not to follow too close behind other traffic!

When we sell a K1200LT at Nick's BMW we actually train the new owner about this action of the ABS system. It really should be done as training for all new BMW owners.

[TomfromMD]

Thanks for the info, Andy. That would seem to present an interesting argument for a non-linked ABS system.
Tom

[deilenberger]

I'd beg to differ... there is no valid argument I can think of for not having ABS. IF you know what to expect and ride accordingly - ABS allows you to use maximum braking when needed - and that is why it's valuable. Many crashes happen when people ride right into the crash - when they could have avoided it if they used all the braking power available to them.

BTW - the newer ABS systems have a much faster cycle rate than the older ABS-I and II systems (and even faster than the EVO systems..)

Andy - any word on the recovery time involved with a new non-EVO system?

[hass]

I have a 07 R1200R with linked brakes. I have slammed on the brakes and really tried to activate the ABS but the traction never broke and the bike just stopped!

A in theory only non-issue if you ask me.

[Andy VH]

I will check on those values if I can find them in the BMW tech-training books.

Lets keep in mind that ALL ABS systems by thier very nature are "linked" in that the front and rear wheel sensors have to talk to the ABS computer at the same time, all the time. If either front or rear sensor fails the system shuts down. I doubt that any of the four ABS systems has provided will continue to work as a 1/2 system if one sensor has failed. In cars with front and rear ABS, if only one sensor in either the front or rear fails, the system records a fault but continues to work.

So in a sense there is no such thing as a non-linked ABS system, if you consider the "link" as being the front and rear ABS circuits.

But there are differences in ABS systems BMW furnished over the years. The old ABS-1 and ABS-2 systems were strictly ABS systems with no other integration into the bike. The I-ABS-II system is intergrated into the brake system more deeply than the ABS-2 system. Same for the ABS-8M system on the F series.

When referring to integrated-ABS systems it means the I-ABS-II and ABS-8M systems.

[JK]

In essence, with this system it is not possible to do a stoppie on BMWs fitted with either the ABS-8M system (F800 series) or the I-ABSII system (R's and K's). The R-GS model has a ABS-OFF switch to depower the ABS system, but it is the only BWM with this feature.

Hi Andy -

The R-12S also provides an ABS-OFF function feature.

Per Rider's Manual / Switch off ABS function (p 44/45):

o Switch on ignition or bring motorcycle to a stop.
o Hold down ABS button.
- ABS warning lamp "on."
o Release ABS button within five seconds after ABS warning light lights up.
> The warning indicator for ABS fault and ABS switched off are identical.
>> ABS function is switched off.
>>> ABS warning lamp continues to light up.

Switching on ABS function:

o Stop motorcycle.
o Hold down ABS button.
o ABS warning light goes out.
o Release ABS button within five seconds after the ABS warning light goes out.
o ABS warning light remains off.
o ABS function is switched on.
o As an alternate to pressing the ABS button, the ignition can be switched off and then on again.
> If the ABS light continues to light up after switching the ignition off and then on again, an ABS fault has occurred.


FWIW

J.K. :wow

[BubbaZanetti]

The R-12S also provides an ABS-OFF function feature.


interesting, i did not know that, just another + for me as i'm considering it as a future "possible" new bike.

is that you doing the stoppie:stick :D

[Andy VH]

Opps! You are right, and I now remember reading that in the tech training manual and also it is shown on the ABS system schematic.

I would guess the switch is included on the R1200S as it is a bike more likely used for club racing. In most cases, ABS is not a desired feature on a bike used for road racing.

By the way, that is a KILLER STOPPIE! Wow! Left handed no less! Left handed brake control on the right lever is in itself quite a trick to avoid any form of steering input.

[TomfromMD]

I'd beg to differ... there is no valid argument I can think of for not having ABS.
Don, I wasn't suggesting getting rid of the ABS - only the front-rear linking. Andy suggests that the ABS systems must be linked in that front & rear must "speak" to one another, but isn't an ABS system possible where the lever activates only the front and the pedal only the rear? (Especially since so many riders seem to use the pedal with the lever, apparently so that they won't forget how to do it on another, non-linked bike.)
Tom

[deilenberger]

Don, I wasn't suggesting getting rid of the ABS - only the front-rear linking. Andy suggests that the ABS systems must be linked in that front & rear must "speak" to one another, but isn't an ABS system possible where the lever activates only the front and the pedal only the rear? (Especially since so many riders seem to use the pedal with the lever, apparently so that they won't forget how to do it on another, non-linked bike.)
TomTom, sorry - I misunderstood. I still don't think this a better idea then what BMW is now using.

The current (2007) linked system I believe is designed to avoid this sort of thing happening. The linking isn't a fixed percentage - the proportioning front/rear is dependent on how hard you're using the front lever, and I believe from what I've read in tests of the bikes - it's about impossible to get a stoppie going on the linked system.

The trick will be teaching old dogs new tricks.. getting people to forget about the brake pedal.

I've actually gotten (after 10,000 miles) really good at JUST using the front lever, with the very rare exception of cases where I want some very light braking control at very low speeds in parking lot situations... then I'll use the rear brake alone.

I really like the new partial linked brakes. I didn't mind the partial linked servo-EVO brakes on my R1150RS - although they were rather abrupt at low speed.. but the new non-servo linked brakes are simply wonderful, and give a real feeling of confidence in braking the bike. The ABS being there gives the option of doing maximum braking without loss of control.

And to answer your question - up until the linked and partial-linked EVO brake systems - all BMW ABS systems used separate modulation circuits and separate front/rear control circuits. EDIT - additionally - in these systems, sensing locking on either wheel released both wheels AFAIK... so no advantage to the non-linked design vs a linked design.

[JK]

interesting, i did not know that, just another + for me as i'm considering it as a future "possible" new bike.

is that you doing the stoppie:stick :D

One day, in my wildest dream, maybe. For now, just using stunt images off the internet to do the depiction. Stunt bikes and sport bikes are two different animals. Did that sort of foolishness in my squandered youth on dirt bikes, when I healed faster.

In short, silly wabbit, tricks are for kids.... :deal

[FredRydr]

I wonder if the R1200S method of turning ABS off would work in the R1200R? I sure wish I could have when I was trial-riding on Friday. Steep downhills in the mud and leaves, in ruts with flowing springwater, on Line Mountain in central Pennsylvania. My poor Roadster. The ABS was kicking in non-stop and fighting back at me all the way down. But the DL650 I was with (no-ABS) was doing no better.

Fred
'07 R1200R

[deilenberger]

I wonder if the R1200S method of turning ABS off would work in the R1200R? I sure wish I could have when I was trial-riding on Friday. Steep downhills in the mud and leaves, in ruts with flowing springwater, on Line Mountain in central Pennsylvania. My poor Roadster. The ABS was kicking in non-stop and fighting back at me all the way down. But the DL650 I was with (no-ABS) was doing no better.

Fred
'07 R1200RFred - it might if you could find an ABS button to push.. :D

[Andy VH]

One thing for certain, BMW is trying to appeal to a larger, younger audience (but, aren't WE the ones with the discetionary income?). If you haven't seen or picked up the BMW "This is the Edge" CD at your dealer, make sure you see it. Some really cool riding on it.

Some great stunt riding by BMW sponsored rider Christian Pfeiffer on a BMW F800. He does a variety of wheelies, stoppies, locked rear wheel sliding turns, burnouts, etc on the F800. So obviously he has a bike without ABS or any type of intervention system to allow him the option to do stoppies. So if a young rider wanting to mimic him gets his F800 out and finds he can't do stoppies, what's he to do?

So perhaps a new breed of rider is coming into the BMW fold (though I doubt there will be many if any). A rider more liek some of the sport-bike/stunters we see on YouTube and unfortunately on our local roads.

I actually kinda like his stunt bike, a stripped down F800. Maybe mount the "Bender" headlight module from a K1200R on it, leave the frame exposed. Maybe BWM could make a street hooligan bike to go against the likes of a triumph Speed Triple.

[FredRydr]

Fred - it might if you could find an ABS button to push.. :D!

Oh. <sigh> Yeah, good point.

I was thinking of the ABSII on my '99 R1100R. It could be turned off if specified switches were held down in certain sequence when the ignition was turned on. It was not something made available to the consumer, but was for the mechanic. Hmmmm, I wonder....

Fred
'07 R1200R

[AZ-J]

Andy HV;

I suggest you start at page 1 and read all the way to page 16 to see how you and your theories are being viewed on a "worldwide" basis.

Please start here:

http://f800riders.org/forum/topic.asp?TOPIC_ID=2872&whichpage=1