On Mon, 21 Jun 2004 17:57:44 GMT, Velvet
wrote in message :

I think we're kindof in agreement here. My point was that people aren't
all that likely to be braking as well as ABS would if you apply it
properly - people (myself included) either tend to overbrake (and skid
if no abs) or underbrake (abs or no, they'll not stop as fast as if they
overbraked with abs).

Indeed. That was my point: what ABS is doing is compensating for poor
technique, not helping you "stop quicker".

I don't drive any closer (or further away, it has to be said) than
pre-ABS.

You think. But on average, people do. That's what risk compensation
is about. It's pretty widespread - see Tony's comment re "childproof"
containers above.

Or read Risk - it's very interesting.

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington University

Just zis Guy, you know? wrote:
On Mon, 21 Jun 2004 17:57:44 GMT, Velvet
wrote in message :


I think we're kindof in agreement here. My point was that people aren't
all that likely to be braking as well as ABS would if you apply it
properly - people (myself included) either tend to overbrake (and skid
if no abs) or underbrake (abs or no, they'll not stop as fast as if they
overbraked with abs).


Indeed. That was my point: what ABS is doing is compensating for poor
technique, not helping you "stop quicker".

Whether it compensates for my technique or not is immaterial, in the
same given circumstance, with ABS I will stop quicker, in a shorter
distance, than without ABS.



I don't drive any closer (or further away, it has to be said) than
pre-ABS.


You think. But on average, people do. That's what risk compensation
is about. It's pretty widespread - see Tony's comment re "childproof"
containers above.

If I remembered I actually had ABS more than once a few months then I
might believe I drive closer/faster. But given I don't, I doubt it has
any affect. To be honest, since I've never been in a situation where
tromping the brakes has actually activated the ABS, it seems likely that
I'm not compensating for the percieved increase in safety.


Or read Risk - it's very interesting.

Guy

I'm sure it's fascinating :-)

--


Velvet

On Mon, 21 Jun 2004 19:55:05 GMT, Velvet
wrote in message :

Whether it compensates for my technique or not is immaterial, in the
same given circumstance, with ABS I will stop quicker, in a shorter
distance, than without ABS.

If you want to continue believing that "ABS stops you quicker" then be
my guest. But I refuse to indemnify you against any damage which may
result.

Angels dancing on the head of a pin notwithstanding, that is /not/
what it's designed for. Assuming that it is, will end in tears. As
the studies prove.

If I remembered I actually had ABS more than once a few months then I
might believe I drive closer/faster. But given I don't, I doubt it has
any affect. To be honest, since I've never been in a situation where
tromping the brakes has actually activated the ABS, it seems likely that
I'm not compensating for the percieved increase in safety.

So you say - now...

read Risk - it's very interesting.

I'm sure it's fascinating :-)

It is. Genuinely.

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington University

Just zis Guy, you know? wrote:
On Mon, 21 Jun 2004 19:55:05 GMT, Velvet
wrote in message :


Whether it compensates for my technique or not is immaterial, in the
same given circumstance, with ABS I will stop quicker, in a shorter
distance, than without ABS.


If you want to continue believing that "ABS stops you quicker" then be
my guest. But I refuse to indemnify you against any damage which may
result.

Look, I've explained how ABS could stop ME quicker, you'll note I've not
said it'll stop EVERYONE quicker.

Perhaps you overlooked that subtle point?


Angels dancing on the head of a pin notwithstanding, that is /not/
what it's designed for. Assuming that it is, will end in tears. As
the studies prove.

If I ever have cause to test it in that sort of situation then I'll find
out, won't I, one way or t'other.



If I remembered I actually had ABS more than once a few months then I
might believe I drive closer/faster. But given I don't, I doubt it has
any affect. To be honest, since I've never been in a situation where
tromping the brakes has actually activated the ABS, it seems likely that
I'm not compensating for the percieved increase in safety.


So you say - now...


read Risk - it's very interesting.


I'm sure it's fascinating :-)


It is. Genuinely.

Guy


--


Velvet

On Mon, 21 Jun 2004 21:10:50 GMT, Velvet
wrote in message :

Look, I've explained how ABS could stop ME quicker, you'll note I've not
said it'll stop EVERYONE quicker.
Perhaps you overlooked that subtle point?

Nope, not overlooked. You really do need to read Risk: John Adams
says it far better than I can.

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington University

All snipped, since replying to myself rarely makes sense.

I quote from a few websites...

Q. Does ABS reduce stopping distances?

A. Yes, in braking situations where the wheels on a non-ABS equipped
vehicle would lock up, ABS will generally provide shorter controlled
stopping distance. The amount of improvement in stopping distance
depends on many factors, including the road surface, severity of
braking, initial vehicle speed, etc. On some surfaces, such as gravel
roads, braking distances can be longer, but you will still have the
control benefits of ABS. The important capability of ABS is control. ABS
provides improved vehicle steerability and stability when braking.

(from the General Motors website gm.com, who, presumably, should
understand this concept of ABS)

Rotational-speed sensors continuously monitor each wheel. As soon as
incipient lock-up is detected at a wheel, ABS temporarily reduces the
braking pressureat the wheel in question to such a degree that lock-up
is prevented.

ABS repeats this monitoring and control cycle in rapid succession for
each wheel. This form of electronic wheel-slip control ensures optimum
braking distances while at the same time maintaining full steerability
and stability.

“ABS substantially improves driving stability and usually shortens the
brake path as well,” says Wolfgang Drees, member of the management board
at Robert Bosch GmbH and head of its Chassis Systems division.

(From bosch.de, who designed ABS)


The only data I can find (and I can find no actual study data on any of
this) indicates that ABS when incorrectly used leads to longer stopping
distances (user pumps brakes when ABS is fitted - bad!), and that ABS on
loose surfaces can lead to longer stopping distances.

However, everything I'm reading says that in most situations because it
can keep the car on the limit of skidding more accurately than a driver
(who physically can't pump the brakes 15 times a second, for example) it
will perform at least as well, and even on dry roads where the friction
coefficient is greatest, normally slightly better. On wetter roads, or
differing surfaces, it greatly outperforms the driver with no ABS.

I'm now bored of this and have realised that I've spent a good half an
hour looking stuff up to find out if what I've believed is correct
(which it seems to be) so now I'm off to get on my bike and burn some
more calories, though of course, I'll be making sure to find out if it's
got ABS on before I decide how I should brake in an emergency, of course ;-)

--


Velvet

Velvet wrote:

Q. Does ABS reduce stopping distances?

A. Yes, in braking situations where the wheels on a non-ABS equipped
vehicle would lock up, ABS will generally provide shorter controlled
stopping distance. The amount of improvement in stopping distance
depends on many factors, including the road surface, severity of
braking, initial vehicle speed, etc. On some surfaces, such as gravel
roads, braking distances can be longer, but you will still have the
control benefits of ABS. The important capability of ABS is control.
ABS provides improved vehicle steerability and stability when braking.

In other words, yes and no, but for practical purposes no, unless the wheels
would be locking up. Which they generally don't. And, as stated, "the
important capability of ABS is control."

--
Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

Just zis Guy, you know? wrote:

Velvet wrote:


Q. Does ABS reduce stopping distances?


A. Yes, in braking situations where the wheels on a non-ABS equipped
vehicle would lock up, ABS will generally provide shorter controlled
stopping distance. The amount of improvement in stopping distance
depends on many factors, including the road surface, severity of
braking, initial vehicle speed, etc. On some surfaces, such as gravel
roads, braking distances can be longer, but you will still have the
control benefits of ABS. The important capability of ABS is control.
ABS provides improved vehicle steerability and stability when braking.


In other words, yes and no, but for practical purposes no, unless the wheels
would be locking up. Which they generally don't. And, as stated, "the
important capability of ABS is control."


Interesting that you made no comment on the second snippet I posted,
which came from the designers of the ABS system themselves...

Given the amount of people who know skidding = longer stopping
distances, they almost certainly will attempt to err on the side of not
inducing a skid, thus they will be braking less effectively than if they
had ABS and knew it would stop the skid.

I also uncovered some very interesting studies which showed that brkae
assist (something different to ABS) stops the problem of a driver
lifting the braking force to start the foetal curl reaction - again,
tends to indicate that in amny situations the car will not be travelling
at the point of skidding, and that again, would would take longer to
stop than if it *is* on the point, and has ABS, and they are, therefore,
engaged. Brake assist, in case you're unfamiliar, is where the car
takes over and KEEPS the pressure on the brakes even if the driver lifts
it off. Obviously, tends to be used in conjunction with ABS. WHich
tends to suggest that ABS is misused by quite a few people who've never
tried it to feel what it is like through a pedal, or who default (quite
dangerously) to pumping the brakes even though they have an ABS equipped
car.

The solution to the dirver confusion would seem to be to either fit all
cars or no cars with ABS, thus in the instant where you have to decide
if you tromp or pump, you get it right, and given the benefits of ABS on
mixed-surfaces/low grip etc, I think ABS on all is the way to go.

And it still stops me in a shorter distance on dry roads. And I'm sure
I'm not the only one who'll err the less-pressure side of the line in
that situation to avoid the skid. Which means that ABS does stop you
quicker, in that situation. If you've got excellent braking control
then granted it's probably not going to make a lot of difference, but
lets face it, how many people have - should we be devoting our sunday
afternoons to go do emergency stops repeatedly on the public roads, once
a month, just so we can claim we can stop in the same distance with a
non-abs car as we can with an abs one?

I think not.

--


Velvet

On Tue, 22 Jun 2004 09:21:13 +0100, "Just zis Guy, you know?"
wrote (more or less):

Velvet wrote:

Q. Does ABS reduce stopping distances?

A. Yes, in braking situations where the wheels on a non-ABS equipped
vehicle would lock up, ABS will generally provide shorter controlled
stopping distance. The amount of improvement in stopping distance
depends on many factors, including the road surface, severity of
braking, initial vehicle speed, etc. On some surfaces, such as gravel
roads, braking distances can be longer, but you will still have the
control benefits of ABS. The important capability of ABS is control.
ABS provides improved vehicle steerability and stability when braking.

In other words, yes and no, but for practical purposes no, unless the wheels
would be locking up. Which they generally don't.

You don't drive in the wet much, do you Guy?

And, as stated, "the
important capability of ABS is control."

--
Cheers,
Euan
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