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In a modern (<10 year old) car I question the "pro driver" result. I've been looking for data on this, and haven't seen anything that says this is true, but hav

by tass 3y ago

In a modern (<10 year old) car I question the "pro driver" result. I've been looking for data on this, and haven't seen anything that says this is true, but have seen the opposite. In the past, this was likely true when ABS systems weren't able to control individual wheels. They can do that today, can check for wheel lock-ups and react dozens of times a second, and can therefore compensate for changing grip at different parts of the road during the entire stopping process. In formula 1, where ABS has been banned, drivers have the capability to manually adjust brake balance (front/back and left/right) which they can do for each corner - so in this scenario it is true but only because they are given an advanced control, practice it over and over for the specific corner, and aren't allowed to use ABS to begin with.

iokanuon 3y ago
This video is about motorcycles, not cars. Also, the data on this is in the linked video - the author demonstrates you can do a controlled stoppie to decelerate faster without ABS, because that's its main feature - preventing you from flying off the bike.
- tass 3y ago
  I've seen the video, but the comment I'm replying to seems to be referring to a car driving course. I'm a little surprised there's no "pro ABS" for motorcycles which allows you to do a stoppie if you enable an option, and/or are keeping the bike perfectly straight.
  - sudosysgen 3y ago
    There is, that specific bike has it and it's really close to the best performance you can get as an expert. But it's not very common
labcomputer 3y ago
> In a modern (<10 year old) car I question the "pro driver" result. I've been looking for data on this, and haven't seen anything that says this is true, but have seen the opposite. There is an old SAE paper published by Chrysler that I can't find at the moment. IIRC, it was published in 1968 or 1969, and evaluated their new all-wheel[1] ABS system (later to be sold on the 1969-1973 Imperial). The gist of it is that on most surfaces relevant passenger cars, ABS gives somewhat ~shorter~ [Edit: longer ] stopping distances but the difference is minimal compared to a trained professional driver, and both are significantly shorter than locking the wheels (what a non-pro is likely to do in a panic situation) On ice, locking the wheels produces stopping distances that are several times greater than threshold braking. Wet pavement (especially asphalt) is better for ABS, too, though not as extreme as ICE. Importantly, threshold braking also enables the driver to maintain directional control on all surfaces, especially when the left and right wheels have different amounts of traction. ABS enables the driver to concentrate on steering while the computer adjusts the brakes. However, on dry concrete, as well as gravel or snow, locking the wheels does produce somewhat shorter stopping distances. (Concrete tends to be aggressively textured, almost like sandpaper; gravel and snow can build up a "ramp" ahead of a locked wheel) The only problem with locking for emergency stops is that 1) you wear the tires down to the cords after about 10 such emergency stops from 60 mph on dry concrete; and 2) the vehicle tends to spin. If the driver should happen to back off the brake pressure while partially spun, the vehicle will depart the road before they can react... so if you're going to lock the wheels, you have to really commit to it. [1] Chrysler had 4-wheel ABS 10 years before Mercedes' "first car in the world with 4-wheel ABS", but Chrysler had computer logic to release brake pressure on both rear wheels if either one slipped (it had sensors in both rear wheels), which is how Mercedes was able to claim a "first" with their system that simply treated both rear wheels independently.
- pdonis 3y ago
  > on most surfaces relevant passenger cars, ABS gives somewhat shorter stopping distances but the difference is minimal compared to a trained professional driver* Hm. This [edit: the "shorter", which has now been corrected] doesn't fit my experience when I took advanced driver training years ago (I was a GM employee at the time). The training vehicles could have ABS enabled or disabled by a switch on the dashboard. The instructor first disabled ABS and had me practice threshold braking, until I reached the point where I could negotiate a setup with cones where you had to swerve left, then swerve back right, all while braking enough to not overshoot. I was able to do that several times with threshold braking after some practice. Then the instructor turned the ABS on and had me try the cones again. I overshot every time. Of course this was some 20 years ago, and more recent ABS systems might do better. But the SAE paper you refer to was even earlier.
  - labcomputer 3y ago
    > Hm. This doesn't fit my experience when I took advanced driver training years a Yup, that was a typo, see edit.
- darkerside 3y ago
  Depart the road means flip?

by tass 3y ago

iokanuon 3y ago

This video is about motorcycles, not cars. Also, the data on this is in the linked video - the author demonstrates you can do a controlled stoppie to decelerate faster without ABS, because that's its main feature - preventing you from flying off the bike.

tass 3y ago
I've seen the video, but the comment I'm replying to seems to be referring to a car driving course. I'm a little surprised there's no "pro ABS" for motorcycles which allows you to do a stoppie if you enable an option, and/or are keeping the bike perfectly straight.
- sudosysgen 3y ago
  There is, that specific bike has it and it's really close to the best performance you can get as an expert. But it's not very common

labcomputer 3y ago

> In a modern (<10 year old) car I question the "pro driver" result. I've been looking for data on this, and haven't seen anything that says this is true, but have seen the opposite. There is an old SAE paper published by Chrysler that I can't find at the moment. IIRC, it was published in 1968 or 1969, and evaluated their new all-wheel[1] ABS system (later to be sold on the 1969-1973 Imperial). The gist of it is that on most surfaces relevant passenger cars, ABS gives somewhat ~shorter~ [Edit: longer ] stopping distances but the difference is minimal compared to a trained professional driver, and both are significantly shorter than locking the wheels (what a non-pro is likely to do in a panic situation) On ice, locking the wheels produces stopping distances that are several times greater than threshold braking. Wet pavement (especially asphalt) is better for ABS, too, though not as extreme as ICE. Importantly, threshold braking also enables the driver to maintain directional control on all surfaces, especially when the left and right wheels have different amounts of traction. ABS enables the driver to concentrate on steering while the computer adjusts the brakes. However, on dry concrete, as well as gravel or snow, locking the wheels does produce somewhat shorter stopping distances. (Concrete tends to be aggressively textured, almost like sandpaper; gravel and snow can build up a "ramp" ahead of a locked wheel) The only problem with locking for emergency stops is that 1) you wear the tires down to the cords after about 10 such emergency stops from 60 mph on dry concrete; and 2) the vehicle tends to spin. If the driver should happen to back off the brake pressure while partially spun, the vehicle will depart the road before they can react... so if you're going to lock the wheels, you have to really commit to it. [1] Chrysler had 4-wheel ABS 10 years before Mercedes' "first car in the world with 4-wheel ABS", but Chrysler had computer logic to release brake pressure on both rear wheels if either one slipped (it had sensors in both rear wheels), which is how Mercedes was able to claim a "first" with their system that simply treated both rear wheels independently.

pdonis 3y ago
> on most surfaces relevant passenger cars, ABS gives somewhat shorter stopping distances but the difference is minimal compared to a trained professional driver* Hm. This [edit: the "shorter", which has now been corrected] doesn't fit my experience when I took advanced driver training years ago (I was a GM employee at the time). The training vehicles could have ABS enabled or disabled by a switch on the dashboard. The instructor first disabled ABS and had me practice threshold braking, until I reached the point where I could negotiate a setup with cones where you had to swerve left, then swerve back right, all while braking enough to not overshoot. I was able to do that several times with threshold braking after some practice. Then the instructor turned the ABS on and had me try the cones again. I overshot every time. Of course this was some 20 years ago, and more recent ABS systems might do better. But the SAE paper you refer to was even earlier.
- labcomputer 3y ago
  > Hm. This doesn't fit my experience when I took advanced driver training years a Yup, that was a typo, see edit.
darkerside 3y ago
Depart the road means flip?