RE: [ST] ABS or not ABS, That is the question.

["Emile Nossin" <Emile@xxxxxxxxxx>]

>From: Masiak, Richard
>You can still skid without wheel lock-up.  Skidding is a 
>result of loss of wheel traction, and loss of traction
>can result from things other than just wheel lock-up.

But (a proper) ABS doesn't sense just lock up, it senses skid.
It can still slide sideways of course (on ice, you don't even
need to brake for that). But even if it would only prevent lock
up, wouldn't it be better to have it instead of not (looking at
the 2 previous experiences)? As long as you don't expect to become
immortal of course. The ABS sensors measure wheel speed acceleration
and speed difference, determining skid. 

>Although ABS can modulate the brakes faster than a human, the
>old school didn't really teach "modulate" the brakes. 

ABS modulates (again, a proper system) only when the wheel
is skidding. As a human you don't need to modulate because
you're not expected to skid the wheel. And if you would
sense a skid on a motorcycle, chances are that you are too
late when you finally sense it. Advantage of ABS is that it
can, so it enables you to brake right on that skid limit where
deceleration is really high. Even when the ABS modulates on-off
around that limit, it will brake harder than a human can without
modulating near to that limit. For this I refer to this test:
http://www.ibmwr.org/prodreview/abstests.html
Especially the result when slamming the brakes in wet weather
is striking, check out the last table (fig.4). And that's with
pretty old ABS systems, over 10 years old.

>After being on the track and learning to bring the brakes up to
>the maximum point of the break curve and trail brake through the
>turn.  IMO, ABS would really screw things up.

How's that? Do you trail brake while letting it skid? Basically,
do you let the rear wheel brake out by "locking up" the rear wheel?
If you are not, than ABS would do nothing either (a proper system
which doesn't intervene too early of course!).

>That's just an opinion, but I have the feeling this is a touchy subject,
>so let the flame war commence ;-)

Well, I think it can be handled pretty objectively. For instance on
off road vehicles ABS is not always an advantage. Reason for BMW to
make the ABS on the GS switchable on/off. And I can imagine your car
doesn't have a very good ABS system, or perhaps when the ABS would
be off you would have skidded all over the place when you wouldn't
expect it yet?

I've had ABS (and TCS) on my ST1100 and on my R1150GS. It was great
to experiment braking to see how hard it would be too lock it up,
something I normally would never try (well I did on my PC800 and
the same happened as with the 2 crashed Sprints, fortunately that
bike had 4 crashbars built in). Whenever I let friends try it out,
I asked them (usually in dry weather) to try and lock up (so activate
the ABS) on the front wheel. They are very experienced riders, but
the fear of sliding prevented them usually in the first few attempts
to get the ABS activated in the front. For me as well, it was amazing
how hard I could brake before it would activate. Similarly it was
great to just slam the brakes full power immediately when riding on
slippery cobble stones in the rain. I have to be a lot more carefull now...
fortunately the Sprint ST brakes are great on their own.

But having ABS requires training and knowledge of the system in a
different way than conventional brakes, to fully enable its potential
performance and to prevent misunderstandings about its abilities.

If the skid control on one of the F50's I fly fails (which is
basically ABS) we have to multiply braking distance with 1.5.
This is mainly because we would have to be relative easy on the
brakes to prevent loss of control during landing.

Emile
www.piloot.com

-----Original Message-----
>From: triumph1@xxxxxxxxxxxxx
>>where I braked was on a patch of damp oil/diesel.
>>Instant lockup and down we went on the right side
>I reacted by grabbing a handfull of front brake.
>Result, front wheel locks and it's goodnight 


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