I don't know how it works either but your assumption here makes logical sense: if both brakes were applied by the rider such that, say, the rear brake began to lock up, the ABS system would modulate only the rear brake to stop it from locking while leaving the front brake alone (and under the same [not yet to lock] braking force already being applied). Which effectively amounts to 'unlinking' the linked brakes.... sort of. But that would require two separate modulator pumps in the ABS module. ??

Interesting discussion and topic either way though.

Brian

I have found verbiage that states that K-ACT complements the standard ABS.

So, since the point is to provide optimum braking force without locking the wheels up, it makes sense that if the system senses wheel lock in only the front wheel, it would only modulate the front brakes to maintain maximum braking force.

Just read an article on the BMW ABS system, and it was noted that applying the front brake lever in an emergency situation activates both front and rear ABS simultaneously.  Didn't say what applying only the rear to lock up did.  Would go try my RT tomorrow to find out, but suppose to rain all day.

In a straight line on wet pavement would be the preferred way to exercise ABS. I'm not yet familiar enough with the ABS systems on motorcycles to have an intelligent opinion as to the need to "exercise"  the system.  25 years ago the automotive systems needed to be activated or "exercised" periodically to keep the valves from sticking due to non use. After several years the manufacturers realized that in order to minimize the sticking valve problems, a simple momentary activation upon start up eliminated the vast majority of their ABS related warranty claims.
 
We used to tell customers to go ahead and try the ABS in a wide open space (i.e. parking lot) to activate the system and to experience what it felt like when it was used
W

I don't know how it works either but your assumption here makes logical sense: if both brakes were applied by the rider such that, say, the rear brake began to lock up, the ABS system would modulate only the rear brake to stop it from locking while leaving the front brake alone (and under the same [not yet to lock] braking force already being applied). Which effectively amounts to 'unlinking' the linked brakes.... sort of. But that would require two separate modulator pumps in the ABS module. ??

Interesting discussion and topic either way though.

Brian

I think between the videos I posted and articles I have read that I have a pretty good understanding how the K-ACT ABS system works.  The ECU and control loop software are in control of what is happening when you brake and when the system determines front or rear wheel lock up.  The goal of the system is to keep the braking force between the front and rear brakes balanced to provide maximum stopping power so that you don't reach the point of causing wheel lock up as soon as you would on a non K-ACT bike.

The computer monitors the amount of braking pressure applied to either the front or rear brakes individually and applies the calculated solution force to the opposite brake, or when both brakes are applied the computer adjusts the pressure going to each brake to maintain the optimum balance point for braking.

Knowing that the computer can modulate the pressure in EACH circuit (front or back) then it certainly can modulate the braking pressure to only the wheel that is experiencing lock up. 

The brakes are always linked, but are individually modulated by the computer based on the inputs it receives.

The inputs are:
1. front brake fluid pressure caused by the rider pulling in on the front brake lever.
2. rear brake fluid pressure caused by the rider pushing the rear brake lever.
3. rear wheel sensor
4. front wheel sensor.
5. motorcycle speed.
6. there may be others but I have not discerned any additional information from what I have read.

These inputs go into the calculated solution to determine how to distribute the fluid pressure going to both the front and rear brakes.

I think between the videos I posted and articles I have read that I have a pretty good understanding how the K-ACT ABS system works.  The ECU and control loop software are in control of what is happening when you brake and when the system determines front or rear wheel lock up.  The goal of the system is to keep the braking force between the front and rear brakes balanced to provide maximum stopping power so that you don't reach the point of causing wheel lock up as soon as you would on a non K-ACT bike.

The computer monitors the amount of braking pressure applied to either the front or rear brakes individually and applies the calculated solution force to the opposite brake, or when both brakes are applied the computer adjusts the pressure going to each brake to maintain the optimum balance point for braking.

Knowing that the computer can modulate the pressure in EACH circuit (front or back) then it certainly can modulate the braking pressure to only the wheel that is experiencing lock up. 

The brakes are always linked, but are individually modulated by the computer based on the inputs it receives.

The inputs are:
1. front brake fluid pressure caused by the rider pulling in on the front brake lever.
2. rear brake fluid pressure caused by the rider pushing the rear brake lever.
3. rear wheel sensor
4. front wheel sensor.
5. motorcycle speed.
6. there may be others but I have not discerned any additional information from what I have read.

These inputs go into the calculated solution to determine how to distribute the fluid pressure going to both the front and rear brakes.

I'm with ya, the system likely does work the way you describe.

I wasn't really thinking of the locking up of the rear wheel affecting the front ABS...I didn't put much though into that, but no, you certainly wouldn't want that to happen imho. However, when considering heavy front braking....I would want my front and rear ABS to work together.
Keep in mind the ABS will become active long before the wheel actually locks up...even if we're only talking about milliseconds here, but still...the point isn't for the ABS system to sense a wheel locking up before it activates.

Under heavy front braking...and I mean not even touching the rear brake at all...you're still activating both brakes, and the bike knows you're in a panic situation. It would make sense to me if the ABS were activated on both wheels...they're both turning the same speed, and they're both in a situation where the ECU is sensing they may lock up. Now, even though the rear brake is activated via the front, it's still under a lighter pressure than the front...BUT, as the front dives and the rear of the bike becomes raised/lighter, the back wheel can lock up much easier with much less pressure. This is why vehicles used to have those mechanical brake proportioning valves.

Anyway, just food for thought is all. It would seem logical to me if there's an "ABS calculation" involved that activates both wheels under single front brake activation (when both brakes are actually activated).

That's all, nothing more. In my little mind, that's how I would want it to work. It would be the same as Tomp mentioned above about the BMW...that activating only the front brake operates the ABS on both wheels. There are likely calculations to make the ABS system work both ways...depending on the situation;).

At the end of the day, I have no idea...lol.

Rem

WOW, this is getting more confusing by the post.  Being handled by some form of computer, I guess it works with lightening speed and amazing accuracy, at least that's what a computer genius friend once told me.  He is now dead, but I believe his thoughts were correct.  RIP, Charles...