can someone explain the theory/physics behind cadence braking? Bondurant's book goes over that for panic braking situations, which is alternating between maximum braking (just short of locking) and no braking, faster being better.

He likens it to ABS brakes, which doesn't seem like a good analogy. I thought ABS only kicked in once the wheels were already skidding? so you alternate between skidding and stopping. I've seen others on this board mention that they stop faster when threshold braking (just before ABS kicks in) than when they just mash the pedal and let the ABS do the work. my car doesnt have ABS so i can't test this.

anyway, why does Bondurant advise cadence braking (and even cadence throttle for FWD cars in other cases?!) the only thing i can think of is that by jumping on and off the brakes, you let the weight transfer to the rear of the car momentarily, which helps the rear brakes do a larger portion of the work. maybe i'll test this in a parking lot or something.

I've been through Bondourant's book 3-4 times, and don't remember anything about cadence braking. Can you post a quote from the section of the book you are referring to? I'm not even sure I understand what you mean.

just checked amazon, the book is called Bondurant on High Performance Driving. Go to This page on amazon (http://www.amazon.com/exec/obidos/tg/detail/-/0760306036/ref=lib_dp_TI01/104-9802768-3287145?v=glance&s=books&vi=reader&img=12#reader-link) then click the right arrow key to get the 2nd index page. Braking, Cadence, page 111, 112. The book on amazon has a different cover, maybe because mine was hardcover, or an older version?

I returned the book to the library yesterday, but i'll get it back and get a quote. It was in the section about getting into trouble, what do you do, etc.

--edit- I probably had the 2nd or 3rd revision, I believe it had the previous generation mustang on the cover.

I guess Bob wants you to manually replicate ABS. It wouldn't be nearly as effective as ABS due to the much slower cyclic rate of your leg. Stick with threshold braking.

ps- Ahh, emergency siuations. I've done something like a slow ABS simulation when brakes were cooking. I've also done something similar in icy/snowy road conditions on the street while sliding. Brake, try to steer, brake, try to steer, brake, steer.

Maybe he assumes that you will be locking up the front brakes, and the thing to do when locking the brakes is to let up on them until the tire regain traction, and then brake again.

the example he gives for cadence braking is when you can only go straight, and the brakes are your last effort to avoid a crash, so releasing pressure to allow for turning doesnt fit (in this example). he makes no mention of brake fade either. (oddly enough, i don't remember reading about brake fade in the entire book)

He did reference the panic of the situation ("Panic City" as he put it... ya, its an older book), so maybe he's assuming you're unable to concentrate and brake without locking them up.

I've been through Bondourant's book 3-4 times

What?? You know those sillly books with their useless racing theories are not going to make a bit of difference out on the track, don't you Bryan? REAL seat time is the only thing that can teach you how to drive! ;)

Can someone explain the theory/physics behind cadence braking?

I'd have to think he was referring to race cars without ABS and that this was his terminology for 'pumping the brakes'. ??? Either way, I don't think I'd be trying to learn it on the track.

What?? You know those sillly books with their useless racing theories are not going to make a bit of difference out on the track, don't you Bryan? REAL seat time is the only thing that can teach you how to drive!

Now I know you're just "pokin' fun" as they like to say in 'Bama - I've heard this many times before.

I actually think that with a very technical(geeky? :D) mind that reading and visualizing charts and graphs(Carrol Smith's books are great at this, since he was an engineer at one time, RIP :(). I find that I would actually recall the tire slip angle versus traction curve while in a long corner or series of corners and try to guess where I was on that curve based on feedback and noise. Found that helped me not overdrive my tires. Just a little example of how something disguistingly geeky to some would help out those "gifted" few of us. ;)

Originally posted by ceegeezM3
What?? You know those sillly books with their useless racing theories are not going to make a bit of difference out on the track, don't you Bryan? REAL seat time is the only thing that can teach you how to drive! ;)

I realize you are kidding, but the two aren't even close to the same thing.

Books are based on real world accounts, physics and engineering behind what makes a car go fast around the track. A book can tell you what "feelings" mean and how to prepare your mind/body to react to them.

Any commercially available driving sim, on the other hand, is simply a game designed by a bunch of computer programmers, who have likely never actually driven a race car. It's designed to be fun and marketable...not to teach you how to drive a race car. It doesn't provide any of the feel and feedback necassary for developing driving instincts, and there's no guarantee that it's written in such a way that the inputs you are using in the game are resulting in a lifelike output on the screen. For all you know, what you do to "save" a car in a sim may result in your death in the real world.

Let's take your fighter pilot sim for example. When that sim was designed, they used gigabites of data accquisition from real world situations in order to build a simulation that is lifelike. How many video racing games are doing the same thing? None, because they are building the game to be fun and sorta lifelike, not to teach you how to drive a race car and handle situations that put your life and the life of those around you in jeopardy. In the end, it's just a video game with very little transferrable skill sets. The most you can pick up is better use of your eyes, quicker reflexes, and a decent idea of a track configuration...but not how to actually feel and drive a car at speed.

As I always understood it, cadence braking was what you did in a car that was not equipped with ABS...

Yes, I'm totally messing with you! But in good taste I hope.

Any commercially available driving sim, on the other hand, is simply a game designed by a bunch of computer programmers, who have likely never actually driven a race car. It's designed to be fun and marketable...blah, blah, blah, blah, blah, and there's no guarantee that it's written in such a way that the inputs you are using in the game are resulting in a lifelike output on the screen. For all you know, blah, blah, blah, blah.

My 10 year old cousin and all his friends can drive a race car on a simulation better than I can.

Judging by your statements I'll assume you've never driven any real sims. You also continue to insinuate that you are the only one who's ever driven a BMW on a track. I've been doing autox, open track days, DE instructing and sim racing for several years. Until you've done a fair amount of sims then I don't think your statement holds much water. (Basically, it's not even remotely true) In the research and development world, this is know as 'not having all the facts'.

I have spent years doing BOTH and can tell you from first hand experience that sims can and will help you learn a multitide of basic concepts about car control and race craft. (Either that or I am a prodigy race driver with an amazing talent for car control). :)

I've made my point and won't bother you with this subject again.

Originally posted by ceegeezM3
You also continue to insinuate that you are the only one who's ever driven a BMW on a track.

What the heck are you smoking?

BTW, name some of these "real" sims and I'll let you know whether I've played them.

Originally posted by ceegeezM3
Judging by your statements I'll assume you've never driven any real sims.

Name some.

I've been doing autox, open track days, DE instructing and sim racing for several years...

I have spent years doing BOTH and can tell you from first hand experience that sims can and will help you learn a multitide of basic concepts about car control and race craft.

So you've never been W2W racing, but you know that you have learned race craft on sims? Where did you put this race craft into practice? A DE? Wouldn't you agree that that sorta limits your credibility?

No offense, but there's no race craft to be learned by trying to out manuever a computer program written by some geeky computer guy. Race craft is the LAST thing I would give sims credit for teaching...I'd say there's a chance you could learn some aspects of car control WAY before you learn anything about race craft.

Until you've done a fair amount of sims then I don't think your statement holds much water. (Basically, it's not even remotely true) In the research and development world, this is know as 'not having all the facts'.

You act like you're the only one who has played a sim...afterall, I'm the only person that has ever tracked a BMW? :dunno

As someone who has limited professional W2W, auto-x, DE instructing, and W2W driving coaching experience, I have found almost no car control benefits from driving race car sims available on the market whatsoever. Even on the best sims, you can do some really dumb stuff and not lose the car...stuff that could get you seriously injured in a real race car. On some of the best sims on the market, you still aren't always properly rewarded for driving a correct line.

If you talk to any serious racing teacher, they'll tell you that the key to becoming a good driver is seat time, simply because there is no other way to develop the connection between your butt and the car. A sim (like you've described) cannot reproduce that in any way. Car control relies on balancing a car on the limits of the traction circle, which can't be duplicated on a 2D screen in your living room. You can't feel the car rotating around the front outside tire as you trail-brake into the turn with slight steering corrections to account for the changing balance. Car control is all about instinct, and instinct can't be learned if you can't "feel" the cues that trigger your instincts. Further, there's no guarantee of the authenticity of the limited (sight, sound) cues that you do receive from a sim...particularly sims that are marketing at kids age 12-18 for entertainment purposes (which is all sims that have been mentioned on other threads on this board).

You simply can't compare a video game available at Best Buy to a simulator that fighter pilots use to learn to pilot F-18's. A sim that could absolutely duplicate lifelike situations and provide spot-on feedback would take far more lines of code and a much bigger processor than your CD-ROM and PC can handle. Outside of such a device, you're better off buying a yard kart for $100 and driving it around your front yard (that's where I first learned about counter-steer and power-on oversteer) or spending $30 to drive a kart at the local amusement park or indoor karting facility. Honestly, I believe there's much more to be learned there than from a sim.

Originally posted by ceegeezM3
You also continue to insinuate that you are the only one who's ever driven a BMW on a track.


Wow. I've never seen Bryan insinuate anything like that.

Originally posted by ceegeezM3
I've been doing autox, open track days, DE instructing and sim racing for several years.


Michael Schumacher beware.

You wouldn't happen to post on Rennlist as Ghettoracer would you?

You wouldn't happen to post on Rennlist as Ghettoracer would you?

Now you're going to insult me? Geez, try and offer some advise and you get labeled as a Frank Lin. Oddly enough, we were talking to him about coming out to a DE we're putting on in a couple months.

From the rennlist forum

Geo31 says... Hey, looks like Ghettoracer has a long lost brother. From the Bimmerforums Race, Track, Autocross forum:

"BTDT... yawn.

You're guys are still totally missing the point. Because of the time I've spent on a sim, I was able to keep my car under control when I got that first wiggle into T1 at 120mph. Without some offline practice, I'd have probably been in the wall. "

Hehe. Too funny.

Do I have to insult people if I want to be a real racer?

Just another small difference between flight and driving/racing sims(and actual operation).

Pilots are trained NOT to fly by feel...in instruments they trust! "Feel" has no place in an aircraft!

Quite the opposite for cars and/or racing.

Originally posted by BMWRacerITS
Name some.
You simply can't compare a video game available at Best Buy to a simulator that fighter pilots use to learn to pilot F-18's. A sim that could absolutely duplicate lifelike situations and provide spot-on feedback would take far more lines of code and a much bigger processor than your CD-ROM and PC can handle. Outside of such a device, you're better off buying a yard kart for $100 and driving it around your front yard (that's where I first learned about counter-steer and power-on oversteer) or spending $30 to drive a kart at the local amusement park or indoor karting facility. Honestly, I believe there's much more to be learned there than from a sim.

Actually from 1991 through 1998 I took a bunch of people every year to Sky Warriors to play laser tag with real airplanes with real fighter pilots teaching. It started with wondering how someone flying your basic computer sims you buy at Best Buy (although when we started Best Buy wasn't around) would do in a real airplane.

And what we found (I am a former fighter pilot) is that the sims can teach you situational awareness. They don't teach feel and Gs, and such, but they teach where you want the airplane to go, and the basics of how to get it there. They teach you the concenpt of manuevering for the shot.

The sims used most often for fighter pilots are mainly to teach you where and how to throw the switches (LOTS of them) and fly intruments, not air combat. There are the full dome sims that can be used for air combat training, but they are not common.

Oh, and BTW most PCs have more computing power than the sims used by the military (excluding the dome sims). The sims are old technology in most cases. Figure most of the sims were made when the airplanes were new.

WRT to the subject of this thread.

I just grabbed my copy off the shelf and read the section. At this point I think Bondurant is an idiot. OK, not totally.

His point seems to be that pumping the brakes like that is better than locking them up. And I have to agree with that.

But the fastest way to stop is to quickly apply the brakes to the point of incipient lockup and then modulate the pressure to maintain the braking at just below the lockup point. This does require training and practice, and thinking while the panic is happening.

I think he is basing on the fact that most people when faced with a panic stop will hammer the pedal and slide into whatever they were trying to avoid.

Also most people release brake pressure at some point in the panic stop and then still hit whatever they were trying to avoid. This is why MB has come up with their braking system that if you hit the brakes HARD, the ABS takes over and does a max performance stop, no matter what you do to the brake pedal.

OK, so he does have a point. But I still prefer to try to max brake.

Originally posted by ceegeezM3
Now you're going to insult me? Geez, try and offer some advise and you get labeled as a Frank Lin. Oddly enough, we were talking to him about coming out to a DE we're putting on in a couple months.

Run away, run away!

Originally posted by Kenzo
Pilots are trained NOT to fly by feel...in instruments they trust! "Feel" has no place in an aircraft!

Tell that to a fighter pilot.

Originally posted by ceegeezM3
From the rennlist forum

Geo31 says...

I stand by that.

The sims used most often for fighter pilots are mainly to teach you where and how to throw the switches (LOTS of them) and fly intruments, not air combat. There are the full dome sims that can be used for air combat training, but they are not common.

Interesting thing those domed, accuator driven flight sims. I sat in on a PhD disertation about shaped input commands. Basically, the input shaping to the accuators can be used to produce a realistic and equal in magnitude force for transitional manuevers. This kinesthetic(sp?) learning process is MUCH more useful than just the visual process of watching things happening on a 2D screen, with you sitting in your lazy boy. Of course, you can't reproduce the G's felt in long cornering manuevers, but the cost of trying to recreate that would cost more than all the flighttime a pilot could stand in his lifetime. :D

BTW - no need to get snippy here folks. You know, it IS possible to have an intelligent discussion on this topic without resorting to the "my ass has been in a racing seat for X number of years." Quite honestly, it doesn't mean yo' shit don't stick to put it bluntly. More experience, maybe, more value to your opinioni - debateable.

So play nicely children. ;)

alright, here's a few selected quotes from the third edition (i think 4th is the latest?) of Bob Bondurant on High Performance Driving w/ John Blakemore (c) 1993 (emphasis added):

If there's no place to go and it's either stop or crash then you'd better know how to stop: cadence brake. ... Using cadence braking you'll stop in half of distance of normal. Here's how it goes: Put the brakes on full, just to the locking point, then rapidly come clear off of them, then on again full, [etc] ... Those cars equipped with an ABS braking system do this for you...
I think those are the key phrases, and what confused me was the part in bold. It would seem that in this context, "normal" is going full on brakes and locking them up. For an inexperienced driver in a panic situation this is probably true. In drivers school for 16 year-olds, thats the kind of instruction i would expect, but not in a book on high performance driving.

Also, when braking "just to the locking point," i took that to mean threshold braking. so if you haven't locked up the tires, why get off the brakes? hence my earlier comment on trying to transfer the weight to the rear and even out the brake load.

IMHO, he didnt clearly state that in an ABS car you would just mash the brake and let the ABS do the cadence braking. He also didnt explain what ABS stands for (keep in mind, published in '93). I guess i'm a young'un, because i don't know when ABS started becoming standard on street cars. I know my '93 eclipse isn't, but i thought that was kind of odd. Anyway, just a little confusion. Overall it was a pretty good book, quick to read. It would be a good intro to fast driving, but i prefer a bit more detail in the physics behind it.

*flamebait- I should have known better than to pick up a book with a mustang on the cover. Speed Secrets has a widebody E36 M3 on it! :devillook

From reading your quote above, go back and read my post...

You other guys in this thread, keep it civil... :cop:

Originally posted by BMWRacerITS
Any commercially available driving sim, on the other hand, is simply a game designed by a bunch of computer programmers, who have likely never actually driven a race car.
Uh, not all of them. Sure, there are stupid driving games aimed at the mass market that are totally unrealistic. But there are also driving simulators out there that are actually based on real physics. Companies have used data acquisition, gps mapping, etc., to accurately model the dynamics of the car, and its reaction to driver and road inputs. The ones that come to mind are Grand Prix Legends, and that old Atari arcade game, Hard Drivin' (I think - it was a long, long time ago...). I'm sure that there are others that are more current, but I haven't messed with that stuff in quite some time.

Now, I won't debate whether or not they actually teach you anything. All I'm saying is that there's a lot more physics and realism in them than you're giving the "bunch of computer programmers" credit for....

Jim

Originally posted by Kenzo
Pilots are trained NOT to fly by feel...in instruments they trust! "Feel" has no place in an aircraft!

Quite the opposite for cars and/or racing.

I quess from that statement you don't fly. Or if you do, I don't want to ride when you are flying.

The ONLY time where a pilot flies strictly by using the instruments is when he can't see outside the aircraft. And at that point the body feelings can mess you up greatly. The body senses only work properly when you can see outside references.

All other times you fly by a combination of feel and vision. Landing is a prime example. Yes, you can land strictly by instruments, but it will not be a smooth landing. A smooth landing comes for having a feel and touch for the wing as it enters ground effect.

In a dogfight, if you look at your instruments you will not win the fight.

Truly flying (as opposed to driving one) an airplane is a lot like driving a race car. Getting the aircraft to the endges of the performance envelope and holding it there. Using the maximum performance without going past the edge, time and time again. The difference is flying a dogfight is more like rallying as you don't really know what will come next. You don't get to practice exactly the same course over and over. :)

And before you start questioning my qualifications in flying, I am a former USAF Mission Ready A-10 pilot. I hold civilian ratings to fly airplanes (single and multi engine, and single engine seaplanes), gliders and helicopters. I hold an instrument rating. I am also a rated flight instructor in Airplanes, Instruments, Gliders and Helicopters. And I currently teach formation flying for the T-34 Association. I have flown over 40 different makes and models of aircraft from ultralights to supersonic jets.

On the driving end, I mess with cars, autocross, and am qualified to obtain an SCCA Regional racing license. (just got to fill out the paperwork).

Originally posted by black_b[ ]x
I think those are the key phrases, and what confused me was the part in bold. It would seem that in this context, "normal" is going full on brakes and locking them up. For an inexperienced driver in a panic situation this is probably true. In drivers school for 16 year-olds, thats the kind of instruction i would expect, but not in a book on high performance driving.

Also, when braking "just to the locking point," i took that to mean threshold braking. so if you haven't locked up the tires, why get off the brakes? hence my earlier comment on trying to transfer the weight to the rear and even out the brake load.


I agree, the more I thought about it, the more I decided he was talking about the difference between the common panic lock them up versus any form of braking with the wheels rolling.

And due to the rapidity of the motion he is preaching, hitting the brakes quickly to just before lockup isn't going to happen. You will overshoot and lock them up, then come off them to get them rolling, the back on them hard.

I agree that I find it hard to believe he is teaching that in a book on High Performance Driving.

I need to sit down and read his whole book.

Originally posted by Def
Interesting thing those domed, accuator driven flight sims. I sat in on a PhD disertation about shaped input commands. Basically, the input shaping to the accuators can be used to produce a realistic and equal in magnitude force for transitional manuevers. This kinesthetic(sp?) learning process is MUCH more useful than just the visual process of watching things happening on a 2D screen, with you sitting in your lazy boy. Of course, you can't reproduce the G's felt in long cornering manuevers, but the cost of trying to recreate that would cost more than all the flighttime a pilot could stand in his lifetime.

They are awesome sims. I have not had a chance to fly the, but have flown other motion based sims. The level and accuracy of somatic sensations they create is amazing.

The long duration G forces are hard to do without a centrifuge, and a centrifuge can't react to the potential G force changes of a combat aircraft.

The funny thing is pilots tend to be more sensitive to oddball motion that normal people. I just about fall out of my seat watching a good Imax flying movie. First time I saw "To Fly" when the Air and Space Museum opened, I must have been funny to watch and I banked, climbed, and dove, sitting in my seat. :)

And those theme park rides where you watch a screen and they use similar motion bases to sims to provide somatic sensations drive me nuts. The motions don't match what the screen is showing.

Wow, such hostility.... :(

Can sims help learn basic driving skills... YES Then can teach car placement, the concept of driving a line, stabbing the gas is not good, .... Things that don't require the full recreation of a real driving enviroment.

They cannot teach a feel for the cars limits. They don't really teach you to transisiton a car. They don't convey the sense of speed.

They are another learning tool that is improving. Not a replacement for the real thing but still a tool that can be used when the real thing (seat time and instruction) is not available.


Oh, Bryan there is no need to insult computer people. There are some of us that DO both enjoy driving and work on sims and understand both.

Actually some time back in a week of frustration with my performance at an autoX divisional I wrote a quick and dirty sim of the previous autoX course. I drove through it on the computer and then looked at the plot of the line I took. Suddenly it was apparent what I was doing wrong. To bad it hasn't help me fix that bad habit just yet but it did make me very aware of it.

Early apex is not the fast line, early apex is not the fast line, ....

Originally posted by Enigma
Wow, such hostility.... :(

Honestly, where's the hostility? It seems you can't disagree on this board, or hold a discussion where two people have very different opinions without someone complaining about hostility or a flame fest.

They cannot teach a feel for the cars limits. They don't really teach you to transisiton a car. They don't convey the sense of speed.

Which is all I've said.

They are another learning tool that is improving. Not a replacement for the real thing but still a tool that can be used when the real thing (seat time and instruction) is not available.

Which I haven't disagreed with.

Oh, Bryan there is no need to insult computer people. There are some of us that DO both enjoy driving and work on sims and understand both.

Honestly, if you took that personally, I apologize, but would warn against taking any generalized statement personally. I was simply drawing a distinction between a sim that might actually be designed by a ME who actually understands the physics acting on a race car, and a computer programmer who can't really interpret data acquisition correctly, even if it's layed out in front of him because he has no actual experience doing so...i.e. the average video game programmer.

Actually some time back in a week of frustration with my performance at an autoX divisional I wrote a quick and dirty sim of the previous autoX course. I drove through it on the computer and then looked at the plot of the line I took. Suddenly it was apparent what I was doing wrong. To bad it hasn't help me fix that bad habit just yet but it did make me very aware of it.

Excellent example of where a sim COULD be helpful. I have done a similiar thing using data acquisition, combining G-Forces, Speed, and GPS data to accurately map my line and figure out where I could improve...it's really helpful to be able to compare your results to other drivers who may do things differently as well. It becomes even more helpful when you can add in steering, throttle, and brake inputs. Start adding suspension sensors, and someone who knows what they are doing can look at the data and tell you exactly what is wrong, and how it might be improved through a combination of setup and driving technique. An accurate sim could take all that data and actually show what changes in line and setup would mean...I have no problems with that, though doubt that a sim designed for general consumption is going to offer that much accuracy because high quality graphics and cool extra features are factoring into how much data can be dedicated to making it realistic, and it's entertainment purpose and price restraints limit how much programming time will be dedicated to making it perfectly accurate.

In short, anything on the market is designed for entertainment first and foremost...and a game that was absolutely realistic would liekly be too hard to drive to be entertaining.

Originally posted by BMWRacerITS
Honestly, where's the hostility? It seems you can't disagree on this board, or hold a discussion where two people have very different opinions without someone complaining about hostility or a flame fest.


No kidding. It's amazing, of all the people who have expressed an opinion on the subject of sims, I think Bryan and I are the only ones who have raced W2W (but I'm not 100% positive and don't have time to look back through the threads). Interestingly enough, we are in near 100% agreement with each other. That doesn't make us elitest pricks. If you don't like the answer, don't ask the question. We're only trying to give honest answers.

The closest thing to a flame that I've seen on either thread is the BS flag I threw up. I stand by it. If that's a flame war, y'all are pretty sensitive.

Originally posted by BMWRacerITS
Excellent example of where a sim COULD be helpful. I have done a similiar thing using data acquisition, combining G-Forces, Speed, and GPS data to accurately map my line and figure out where I could improve...it's really helpful to be able to compare your results to other drivers who may do things differently as well. It becomes even more helpful when you can add in steering, throttle, and brake inputs. Start adding suspension sensors, and someone who knows what they are doing can look at the data and tell you exactly what is wrong, and how it might be improved through a combination of setup and driving technique. An accurate sim could take all that data and actually show what changes in line and setup would mean...


Which is what 7 post shaker rig does for set-up. I've never heard of anything like that for driving.

Originally posted by BMWRacerITS
In short, anything on the market is designed for entertainment first and foremost...and a game that was absolutely realistic would liekly be too hard to drive to be entertaining.

Indeed.

I think ive posted this in a previous post about driving sims, but these seem to be of interest here too.

check out the 3 year old game now, SPORTS CAR GT.
The game actually has the GTP BMW and Porsche (f thats what the class was called, sorry). I must say, I was 15 when I first played this game, and I played time trials against my dad, and this was the only game IN HISTORY he has ever beaten me at. Maybe because I had no real driving experience, and he had 20 years, and even some amatuer racing in Poland.

Really, find this game somewhere, itll be about $10 now. Its great. And there are A LOT of addons online, that work to even enhance the physics of the game. It really built up a reputation online for being accurate. And I must say, like others said, I think the game taught me a GREAT DEAL about knowing where cars are around me.