Everything you say is correct, but Mr. Mountainbike never said that he locks the brakes up on his non-ABS cars. If you know what you’re doing, there’s no reason you should be locking the brakes. ABS was mainly invented because most people don’t bother to learn how to drive properly, and so when they press on the brake and the car isn’t stopping, they simply press harder. . Which of course is the exact opposite of what you should do, since if the car isn’t stopping on ice, it’s because the wheels are locked up, at which point you’ll stop faster with less braking power.
If you know how to threshold brake properly, you can stop faster than an ABS-equipped car. You never build up the water layer you talked about because your wheels aren’t locking up to provide the required heat.
We’ve been there done this and even the most experienced race car driver CANNOT modulate brakes as successfully as ABS. Had a student now on the professional race circuit…and I trust what he had to say about what he wants on his family cars. This all assumes that Mr. Mountain himself, fully trained will react properly and at the same time the “other guy” on an undivided highway with a closing speed of 110 MPH in the rain will as well.
The problem in emergency stopping with abs is many people don;t try to use the steerage they retain and freeze up…even the experienced drivers. Hit the brakes hard and steer out of danger; give yourself two chances to avail collisions.
A tire sliding on wet ice still has more stopping traction than a tire that doesn’t stop rolling at all. A tire that keeps rolling allows you to maintain steering, but does not shorten stopping distances on any surface including ice. The slipperier the surface, the more it lengthens stopping distance.
ABS does not shorten stopping distance, it lengthens it. While it allows you to keep steering, how often in these situations do you have somewhere to steer to other than into whatever is in front of you.
Wet ice is much slipperier than dry ice. But if the wheels won’t stop rolling that doesn’t matter.
The assumption in your example is that there will be someplace to steer to. That is often simply not the case.
I should clarify…I know how to use ABS properly…and the only accident I’ve ever been in in over 40 years was on dry highway and totally unavoidable by me. A van with migrant workers tried to go suddenly from the left lane to the exit ramp…except that I was in the right lane.
But there’s this hill by my house from which I make a left turn onto my street. When it’s slippery I have to slow almost to a stop to make the turn safely. With my non-ABS vehicles I was always able to do so. With my current vehicle, with ABS, the brakes pulsate (as designed), the wheels just keep turning, and I keep rolling right past the turn. Yes, it allows me to retain steering…all the way past my turn and around the block.
I’ve known others who have gotten into accidents because of the ABS, There was simply no place for them to steer to except into the car in front of them. And I believe what they’ve said.
Having experienced the downside of ABS, I don’t think the tradeoff is worth it.
“ABS does not shorten stopping distance, it lengthens it. While it allows you to keep steering, how often in these situations do you have somewhere to steer to other than into whatever is in front of you.”
Unfortunately you’re locked up in the locked wheel always produces the shortest braking distance…wrong ! For reasons I’ve mentioned before and don’t want to go into again. It’s surface dependent.
Secondly, all the wheels do not often contact the exact same braking surfaces all the time. Only ABS can modulate the differences and maximize control and minimize stopping distance for each individual wheel. You don’t have 4 brake pedals and 4 feet.
You’re missing the point. ABS will not make braking distance short; but can make them shorter on most conditions including ice with the exception being loose sand and certain types of snow …and then the slight distance loss is well worth the control gained.
ABS can only do so much; it’s not a miracle worker (often due to poor tires for conditions) and because it isn’t, it’s dissed by the non scientific approach, hear say “evidence”.
You’re correct in that it’s surface dependent. Driving through a deep puddle it helps, primarily because it allows the tires to continue rolling, cutting through the water reducing hydroplaning. On regular wet surfaces and especially on icy and slippery roads it lengthens stopping distances, sometimes severely. Where I live, icy snowy surfaces are far, far more a part of our normal driving environment than driving through deep puddles.
I’ve seen these deep puddle films before. Using them as evidence that ABS shortens stopping distances on icy surfaces is bogus.
One of the tenants of good science is to find out what actually happens in the exact conditions that the theory suggests should produce a given result. As regards evidence, the AAA Foundation for Traffic Safety, NHTSA, and other reputable resources agree that it’s purpose is not to shorten stopping distances, all agree that it lengthens stopping distances under some common road conditions, and disagree as to exactly under what conditions it does so. I’ve attached some links for you.
ABS was not designed for people who don’t know how to drive properly. ABS was designed to do what the human body can’t do, no matter how well-trained. Pump your brakes as fast as you can, and you will still be doing it slower than ABS can. On wet ice, no matter how lightly you touch your brakes, you will lock the wheels.
A tire sliding on wet ice still has more stopping traction than a tire that doesn’t stop rolling at all.
I don’t think that is true. The best friction point for stopping occurs just before the wheels lock. You will achieve the shortest stopping distance if you are capable of finding that point without locking the wheels at all. Since, on wet ice, that point is extremely difficult to pinpoint, I think ABS does a better job. People just expect too much from ABS on wet ice with all-season tires. It may not stop you in what you think is a shorter distance, but it will do better than you could have without it.
We’re clearly not going to agree on this issue. I think we need to agree to disagree. The debate could go on until we both become well-aged fogeys.
I stand by my statements, as you stand by yours. And I stand by my belief that ABS is highly overrated and can actually allow crashes in circumstances where crashes could have been avoided, particularly on icy roads. I know you stand by your beliefs also.
I think one point we can agree on is that there are differing opinions of the value of ABS, even among knowledgable people.
We can agree to disagree on opinions, but the fact that you don’t get maximum traction while sliding with the wheels locked is not an opinion. It is a scientifically verifiable fact:
“A skidding wheel (where the tire contact patch is sliding relative to the road) has less traction than a non-skidding wheel.”*
“Due to a number of force interactions when the tyre rubber and the tread flexes, the maximum traction force occurs when there is 10-20% slippage.”**
In addition, the one remaining, irrefutable fact is that each tire has it’s own traction requirement in real life. One or two side wheels hit snow or slush or just one hydroplanes because of less tread. These real life situation cannot be addressed by one brake, brakes all…only abs addresses this real life situation. Some can keep complaining about abs; I’ll not own a car (and fortunately I won’t have to) w/o it. The system is not static and I suspect each generation will show improvements. They’re good now and will get better.
For what it’s worth, I’ve been able to get around okay the past two winters with summer tires on a RWD car, in the snow once the plow made a pass. Granted we don’t get tons of snow in central VA.