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-   -   Does ABS matter? (https://www.horizonsunlimited.com/hubb/which-bike/does-abs-matter-35049)

AliBaba 8 May 2008 19:44

Quote:

Originally Posted by Threewheelbonnie (Post 188559)
I'd have ridden on, there is no ABS failure that results in loss of brakes, that isn't just a normal brake failure (like a leak).
Andy

Im' afraid that's not correct for the integral-ABS, or do you know something we don't?

oldbmw 8 May 2008 22:46

Quote:

Originally Posted by mollydog (Post 188590)


Your right about BMW ABS. We have seen a GS with ABS trouble that had ....NO BRAKES! ..... and God forbid if you start to roll backwards on a steep hill next to a cliff! In the case of Long Way Round, the bike would no longer run at all. (fried ECM?)

Patrick

Nope, look again at the video, Charlie is riding it around the garage yard saying it has no brakes.

Personally In Europe and most places I would like to have abs, especially a linked system, as it would alleviate the problem I have with having the brake pedal on the wrong side :) I am happy to accept if it does break get tow truck home. But I disagree with the inference that all things modern are infallible. Generally speaking the more complicated things are the less easy they are to repair.. Eventually it gets impossible. I am sure E & C had a good ( official BMW) mechanic in one of the vans together with more spares than most of us can afford. But still they had to abandon the bike. So what chance mere mortals? The less afluent have to really think what could be the repair cost of this or that feature as high repair costs can easily prematurely end a bikes working life.

Threewheelbonnie 12 May 2008 10:06

Quote:

Originally Posted by Flyingdoctor (Post 188567)
Threewheelbonnie, it's nice to have someone You meant on 4 wheel systems (or 3 wheels!) I'm sure but there is some confusion. IMHO ABS on a bike is only of any use when braking in a straight line as soon as you lean the bike over to steer you will have to come off the brakes or you'll lowside. .

The same is true for a bike, it's just very wierd to do it. ABS works on slip, which you can oversimplify as the speed of the wheel versus the speed of the axle. So, a rolling wheel (50 kph tyre/50 kph axle) has zero slip, a locked wheel 100%. Depending on the (Hard) road surface, a wheel at 10-70% slip produces a proportional brake force and a lateral/steering force at 50-100% of the zero slip condition for that tyre surface combination. A locked wheel produces about 10% of the brake force and a very low number for the side force, hence you stop long with the back end out, or short because the front end went under!

It does work, but the natural reaction we all know is to release the controls, go round the obstruction then go back on the brakes. If you release the controls, the brakes of course come off, EBA on a bike could be lethal if you vered onto a loose surface. If you stayed on the brakes and lived with the off geometry due to compressed springs etc. you would be better off.

I've done this once. A leraner car driver pulled out, saw me and stopped dead. I braked, realised I was going into the side of the car, went for the gap round the front, onto a wet painted area and stopped with the R1100R's front axle about a foot away from the nose of the car, inline with the badge on the grill. I'd braked all the way through an S at 40-0 mph over a lane change of about 3 meters on a surface that had a Mu value (grip level) about the same as ice.

Not using your rear brake looses you about 25% of what's available. Seems to make no sense to me.

The integral system on some BMW's is power assisted. An ABS failure leaves you with uncontrolled, over powerful brakes which is bad. A power assistance failure leaves you with a basic set up that needs the strength of three people to operate. Both will ruin your day, unlike an unpowered system that 99 days out of 100 will get you a long way home with the light on so long as you don't try the emergency stop on the wet paint!

The solution off road should be a Mu selector. This is what 4x4's have. The switch doesn't turn the ABS off, it increases the allowed slip before it acts. Hence you get the debris built up to brake on, plus the control when you really need it. I guess BMW will go this route next.

Andy


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