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