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I have a 2008. This is probably a dumb question but here goes. When I apply the front hand brake does ABS apply equal pressure to the front and rear?

The pedal is rear brake only.
The hand lever is front and rear equally.

Damn, they sure work well!

silvermcoupe wrote:I have a 2008. This is probably a dumb question but here goes. When I apply the front hand brake does ABS apply equal pressure to the front and rear?

Not equal - proportioned pressure, ie - as much as is needed to balance the braking. I don't believe it's a fixed proportion - I believe it is related to speed and the amount of braking called for, but I could be wrong on that.

silvermcoupe wrote:When I apply the front hand brake does ABS apply equal pressure to the front and rear?

I don't believe ABS is involved in the proportioning of front and rear brakes; ABS is an Antilock Braking System.

- Dad

The owner's manual suggests that the linked braking function is only included with ABS. That is, the discussion of the "partially integrated brake" is only included under the ABS heading. This makes sense, because many bikes with linked brakes have two hydraulic lines to the linked wheel(s), with hand lever pressure on one line, activating one set of pistons, and rear pedal pressure on the other line, activating a second set of pistons. Ours don't, of course.

From the manual: "The ... ABS adapts the braking force distribution between the front and rear wheel brake to the loading of the motorcycle during braking."

The manual also supports Don's practice of braking with the hand lever only. Under "How is the shortest braking distance achieved": "To achieve the shortest possible braking distance, the front brake must be applied quickly and with increasing force. This optimally utilizes the dynamic load increase on the front wheel. At the same time. he clutch should also be actuated." There is no mention of what to do with the brake pedal.

This is contrary to what we teach in the MSF courses, where we say all stops should be made with both brakes. But this may be a case where BMW's technical sophistication goes beyond what the MSF course-designers had in mind.

It also suggests that those of us who habitually practice hand-and-foot braking may be over-braking our rears, which is why we see excessive brake dust on our rear wheels and unreasonably short lifetimes on our rear pads.

NeilS wrote:It also suggests that those of us who habitually practice hand-and-foot braking may be over-braking our rears, which is why we see excessive brake dust on our rear wheels and unreasonably short lifetimes on our rear pads.

Neil,

I tend to agree (as is somewhat obvious..) On the few instances where I have tried using the rear brake along with the front brake, it felt as if I activated the ABS in the rear, with a rapid buzz sort of feel to the rear brake pedal. This is a case where I'm fairly certain BMW has it figured out pretty well, and I'm willing to do what they suggest. Luckily - I never ride any other bike, so forgetting the rear pedal use isn't a real problem for me.

Thanks guys! I appreciate the help. I usually only brake with the front level. I wanted to gather opinions on whether I was doing it right. Thanks again.

Don,

I've also noticed that rapid buzz in the rear brake pedal. I mentioned it to my dealer when I brought it in for the break-in service, and they said they couldn't reproduce it. But when I feel it, I know I'm nowhere close to locking the rear tire, so I wonder if it's an artifact of the electro-hydraulic linkage algorithm.

Neil,

I'm sure it is - but I'm not so sure about not coming close to locking the rear wheel.. since the proportioning system should be trying to maximize brake power - it should bring it close to whatever maximum the rear can handle without locking.

It does remind me "Oh - don't do that.." quite effectively.

Well, I'd hope not. Certainly, when making a maximum-effort stop, the system should try to keep the rear tire just short of lock-up. But on a routine stop, when you're only asking the front brake for a fraction of its capability, it makes no sense to make that kind of demand on the rear.

A couple of lessons learned the hard way (broken shoulder blade, etc.) Don't lock the brakes! If you lock the front brake, let go immediately whereas keep the rear wheel locked till you stop and engage the clutch. I was practicing on a bike with conventional brakes at over 40 MPG and I did both types of lockup up a few times. The last try, I didn't get off the front brake quick enough...

http://en.wikipedia.org/wiki/Lowsider
http://en.wikipedia.org/wiki/Highside

In some ways this is like the problem of patting your head with one hand and rubbing your stomach with the other only you don't a second chance in an emergency. ABS reduces the number of activities you have to get right - just apply the brake, pull in the clutch, (get off the gas), figure out an exit strategy e.g. do you have a hard stop approaching quickly, and check the review mirror for on coming vehicle that may not be slowing down at the same rate you are doing.

In the class I was taking, 1 of 7 students (was a MSF insturctor) figured this emergency stopping with exit after about 23 attempts before the others in the class. The "exit" was a simulation of driving around stopped car using the "free space" between the cars with out hitting "the cars" The remainder of the class was around 40 trys minus the two of us who crashed. This portion of class was well worth the price of the course.

General thinking is ABS takes a bit longer to stop then an expert using conventional brakes. I'm not convinced this saving is acheivable without hours of practice on a bike I don't care about crashing.