Why is it wrong to brake and down-change simultaneously?
Discussion
DaineseMan said:
I know about the saying 'brakes to slow, gears to go' and that, in line with IPSGA, speed and gears are separate stages - but can anyone actually explain to me why it is wrong to brake and down-change simultaneously?
So after three pages of some amazing debate, have we got any simple answers to this?Bert
BertBert said:
DaineseMan said:
I know about the saying 'brakes to slow, gears to go' and that, in line with IPSGA, speed and gears are separate stages - but can anyone actually explain to me why it is wrong to brake and down-change simultaneously?
So after three pages of some amazing debate, have we got any simple answers to this?Bert
DaineseMan said:
I know about the saying 'brakes to slow, gears to go' and that, in line with IPSGA, speed and gears are separate stages - but can anyone actually explain to me why it is wrong to brake and down-change simultaneously?
So after three pages of some amazing debate, have we got any simple answers to this?Bert
pthelazyjourno said:
Bit of a contradiction there, no?
You don't think anybody should be near the limits of traction, and haven't needed to change your driving style to avoid it, but you gave changed your driving style (presumably?) to accommodate understeer...??
If you're dealing with understeer surely you're near the limits of traction, otherwise your car would just be turning in.
Don't think so - understeer is just a natural characteristic of most cars and everything to do with steering geometry/load, not available grip. in the case of using weight transfer to the front to kill understeer, all you're doing is load the front end for turn-in. You don't think anybody should be near the limits of traction, and haven't needed to change your driving style to avoid it, but you gave changed your driving style (presumably?) to accommodate understeer...??
If you're dealing with understeer surely you're near the limits of traction, otherwise your car would just be turning in.
SVS said:
How sure are you about that? I ask because Motorcycle Roadcraft states: "Pass through any intermediate gears during the later stages of any braking by the block changing method or by systematically working through the gears, engaging the appropriate gear as speed is lost."
I'd say that's crystal clear guidance that you should change gear towards the end of braking (i.e. it advocates BGOL). And if that wasn't enough, then Motorcycle Roadrcaft goes on to specify quite clearly when and how to overlap.
Block changing: "During the later stages of braking, hold in the cluth lever and change down the gears until the appropriate lower gear is selected, then release the clutch."
Sequential changing: "As speed is lost during braking, work down through each gear, engaging the next lower gear as its optimum speed range is entered."
In conclusion, I'd say that Motorcycle Roadcraft is crystal clear that advanced riders should overlap. It specifies when they should overlap (i.e. the later stages of braking) and how to overlap.
It is and, to clarify there, when I'm teaching, I start with dissecting IPSGA with the Associate and ask them to see how their own riding style applies. The most usual outcome is them realising that they are either trying to do too much all at once, too late or have got Speed & Gear the wrong way around. Or indeed both. We then work on each component and then move on to the overlap of braking/changing & block shifting. That's in conjunction with using better forward planning to - where appropriate (natch) - using throttle sense for the Speed phase rather than, or as well as, braking. It is perfectly true that never showing a brake light has become a bit of a badge for so-called Advanced Riding, which is damn silly, as the brake, like all the other controls, is a tool for the job and should be used as such, but always for a reason. In group riding especially, I always show a brake light as a Ducati on the overrun slows down as much as most machines do on the brakes and I know of at least two examples of other bikes running into the back of Ducatis that weren't showing brake lights.I'd say that's crystal clear guidance that you should change gear towards the end of braking (i.e. it advocates BGOL). And if that wasn't enough, then Motorcycle Roadrcaft goes on to specify quite clearly when and how to overlap.
Block changing: "During the later stages of braking, hold in the cluth lever and change down the gears until the appropriate lower gear is selected, then release the clutch."
Sequential changing: "As speed is lost during braking, work down through each gear, engaging the next lower gear as its optimum speed range is entered."
In conclusion, I'd say that Motorcycle Roadcraft is crystal clear that advanced riders should overlap. It specifies when they should overlap (i.e. the later stages of braking) and how to overlap.
davepoth said:
I don't think you contradict me. 
The CofG for any moment in time might be anywhere in the car. All I was saying is that the car is in balance when the CofG is at a fixed point, no matter where it is in the vehicle. The 911 is probably a bit of a special case in terms of vehicle dynamics (I've not had the pleasure of driving one) but most vehicles, like your 4x4, respond well to shifting the weight around slowly and progressively, unless you're on a rally stage.
Indeed, and apologies - I was speed-reading the thread rather. I entirely agree that, in any vehicle, progressive control of shifts of the CofG are exactly what's wanted. In the 911's case, that's to avoid the back end suddenly deciding it wants to be the front end and, in the 4x4, to avoid massive lurching and GBH of the earhole from passengers. Racing and rallying are completely different cases, where the competent are deliberately using violent shifts in the CofG to creatively destabilise the vehicle. I do not have that skill and, much as I enjoy sliding around in the snow, the thought of chucking a 300bhp, 2-tonne X5 around like that does give me the heebies - that's a lot of mass to stop once it decides to depart from the norm.The CofG for any moment in time might be anywhere in the car. All I was saying is that the car is in balance when the CofG is at a fixed point, no matter where it is in the vehicle. The 911 is probably a bit of a special case in terms of vehicle dynamics (I've not had the pleasure of driving one) but most vehicles, like your 4x4, respond well to shifting the weight around slowly and progressively, unless you're on a rally stage.
MC Bodge said:
Technomad said:
However, my Multistrada has such an utterly ineffectual back brake that I usually end up overlapping braking with the front with gearchanges when decelerating.
I'm a bit confused. Why wouldn't you wish to do that through choice?Was specifically referring to the part of the conversation about low-speed control, where I'd prefer to work on just throttle and back brake, if I had one! At road speeds, I'd only ever use the back brake to balance the machine, not for speed control and, if I'm on it enough to be using a decent amount of brake, I'd certainly be shifting and braking at the same time.
Technomad said:
That's something I can carry out safely and tolerably smoothly, but I certain wouldn't be looking for a relatively inexperienced associate to be doing that
Why is that? What is difficult about braking with the front and changing gear at the same time? Is it the rev-matching element? Admittedly, to do it smoothly and sympathetically, blipping the gas whilst pulling the brake lever with two fingers takes a little practice, but it isn't that difficult to get the hang of. I doubt that most riders do it though.
They don't, believe me. And that's (as per other comment) a good reason for dealing with each aspect of IPSGA whilst teaching, before reassembling into a coherent whole.
Technomad said:
My 911 on the other hand has roughly 40:60 F:R static weight distribution so I'm using throttle and brake to manage CofG much more actively - turning in under trail braking when travelling at any speed massively improves the steering on the 911, followed by a rapid shift to the back under acceleration to nail the tail to the floor. So overlapping AND braking through turn-in massively improves feel, kills understeer and gives a smoother ride than a non-overlapping approach. The 911 is of course about the most extreme case you can get, but learning to drive one is hugely educational about the different needs and ways of managing CofG.
I would love to try driving a 911, especially an older one.Perhaps it's useful to stand back for a moment. The "system" we are talking about has a specific purpose. It has a basic premise, and objective and a scope.
The objective is to take any driver (perhaps specifically "average" types) and improve their driving performance to make a step or significant change in their safety (increased) and accident risk (decreased).
The basic premise for this is to devise a system and ask/train/coach/teach people to drive using that system. The core of the premise is that the system is easy to teach, easy to put it practice and easy to test. The premise has it that the objectives can be achieved by driving according to this system. The premise has it that the test is much more biased to the systematic method rather than judging the outcome.
The scope is contained within the system, not things that are not in the system (obvious really). But as an example, HnT, just out of scope. Not right, not wrong, not better nor worse. Those are the wrong words. Just out of scope. Complex (actually possibly, even simple) vehicle dynamics out of scope. Handling at the limit, skid control etc, out of scope.
So I hope that helps the debate. For the OP...braking and down-changing at the same time, not right nor wrong. The system says when to do it and when to avoid it.
One of the current reasons (as opposed to all that daft history stuff about cable brakes) in the system for separating is as a fail safe method for taking more time and space in the hazard approach sequence...starting the job earlier. A simple approach to increasing safety approaching and negotiating hazards.
Whoops written too much.
BB
The objective is to take any driver (perhaps specifically "average" types) and improve their driving performance to make a step or significant change in their safety (increased) and accident risk (decreased).
The basic premise for this is to devise a system and ask/train/coach/teach people to drive using that system. The core of the premise is that the system is easy to teach, easy to put it practice and easy to test. The premise has it that the objectives can be achieved by driving according to this system. The premise has it that the test is much more biased to the systematic method rather than judging the outcome.
The scope is contained within the system, not things that are not in the system (obvious really). But as an example, HnT, just out of scope. Not right, not wrong, not better nor worse. Those are the wrong words. Just out of scope. Complex (actually possibly, even simple) vehicle dynamics out of scope. Handling at the limit, skid control etc, out of scope.
So I hope that helps the debate. For the OP...braking and down-changing at the same time, not right nor wrong. The system says when to do it and when to avoid it.
One of the current reasons (as opposed to all that daft history stuff about cable brakes) in the system for separating is as a fail safe method for taking more time and space in the hazard approach sequence...starting the job earlier. A simple approach to increasing safety approaching and negotiating hazards.
Whoops written too much.
BB
The people who prefer being out of scope & those who see no good reason to move into scope will stay away.
Those who may be tempted in will turn away if they find that they aren't regarded by the observer/examiner as being 'just' different (or out of scope), but told they are actually doing it wrong.
Admittedly that won't be huge numbers, because most just don't care or give it a second thought, but that's from the enthusiasts pool.
Those who may be tempted in will turn away if they find that they aren't regarded by the observer/examiner as being 'just' different (or out of scope), but told they are actually doing it wrong.
Admittedly that won't be huge numbers, because most just don't care or give it a second thought, but that's from the enthusiasts pool.
Edited by vonhosen on Tuesday 8th October 17:48
Why does IPSGA separate braking from changing down? I've no evidence but I've often thought it must reflect the characteristics of cars at the time the system was developed; cars with large steering wheels positioned close to the driver's chest for leverage and gearboxes where double declutching was often the norm. At the same time tyres offered comparatively little traction by modern standards. Also, brakes were more likely to be grabby and out of balance (adjusting each brake was generally a 3,000 mile service job) meaning that the driver needed to steer while braking to maintain a straight course. In that scenario it makes perfect sense to keep both hands on the wheel while braking and then, separately, to focus on changing down.
These days, unless the conditions are treacherous or the car is being driven very aggressively, there is so much surplus traction available, while gearboxes require so little thought to operate and power steering makes one handed operation a doddle that brake/gear overlap is completely irrelevant 99.9% of the time. Of course, that leaves .01% where it might make a difference but that is not enough to persuade most people to change their habits.
Personally, I try to be as smooth as possible for all the stability reasons described at length above and don't worry about ovelapping.
These days, unless the conditions are treacherous or the car is being driven very aggressively, there is so much surplus traction available, while gearboxes require so little thought to operate and power steering makes one handed operation a doddle that brake/gear overlap is completely irrelevant 99.9% of the time. Of course, that leaves .01% where it might make a difference but that is not enough to persuade most people to change their habits.
Personally, I try to be as smooth as possible for all the stability reasons described at length above and don't worry about ovelapping.
gdaybruce said:
Why does IPSGA separate braking from changing down? I've no evidence but I've often thought it must reflect the characteristics of cars at the time the system was developed; cars with large steering wheels positioned close to the driver's chest for leverage and gearboxes where double declutching was often the norm. At the same time tyres offered comparatively little traction by modern standards. Also, brakes were more likely to be grabby and out of balance (adjusting each brake was generally a 3,000 mile service job) meaning that the driver needed to steer while braking to maintain a straight course. In that scenario it makes perfect sense to keep both hands on the wheel while braking and then, separately, to focus on changing down.
These days, unless the conditions are treacherous or the car is being driven very aggressively, there is so much surplus traction available, while gearboxes require so little thought to operate and power steering makes one handed operation a doddle that brake/gear overlap is completely irrelevant 99.9% of the time. Of course, that leaves .01% where it might make a difference but that is not enough to persuade most people to change their habits.
Personally, I try to be as smooth as possible for all the stability reasons described at length above and don't worry about ovelapping.
I'm happy to be wrong, but having spent some time teaching youngsters using the system its all about getting it done early. Nothing to do with vehicle dynamics, brakes, steering, balance, traction, power steering and all that jazz. Just get it all done early. And seeing the difference between the people who rush the whole thing at the end and those who get it done early, it's a good discipline.These days, unless the conditions are treacherous or the car is being driven very aggressively, there is so much surplus traction available, while gearboxes require so little thought to operate and power steering makes one handed operation a doddle that brake/gear overlap is completely irrelevant 99.9% of the time. Of course, that leaves .01% where it might make a difference but that is not enough to persuade most people to change their habits.
Personally, I try to be as smooth as possible for all the stability reasons described at length above and don't worry about ovelapping.
Bert
BertBert said:
gdaybruce said:
Why does IPSGA separate braking from changing down? I've no evidence but I've often thought it must reflect the characteristics of cars at the time the system was developed; cars with large steering wheels positioned close to the driver's chest for leverage and gearboxes where double declutching was often the norm. At the same time tyres offered comparatively little traction by modern standards. Also, brakes were more likely to be grabby and out of balance (adjusting each brake was generally a 3,000 mile service job) meaning that the driver needed to steer while braking to maintain a straight course. In that scenario it makes perfect sense to keep both hands on the wheel while braking and then, separately, to focus on changing down.
These days, unless the conditions are treacherous or the car is being driven very aggressively, there is so much surplus traction available, while gearboxes require so little thought to operate and power steering makes one handed operation a doddle that brake/gear overlap is completely irrelevant 99.9% of the time. Of course, that leaves .01% where it might make a difference but that is not enough to persuade most people to change their habits.
Personally, I try to be as smooth as possible for all the stability reasons described at length above and don't worry about ovelapping.
I'm happy to be wrong, but having spent some time teaching youngsters using the system its all about getting it done early. Nothing to do with vehicle dynamics, brakes, steering, balance, traction, power steering and all that jazz. Just get it all done early. And seeing the difference between the people who rush the whole thing at the end and those who get it done early, it's a good discipline.These days, unless the conditions are treacherous or the car is being driven very aggressively, there is so much surplus traction available, while gearboxes require so little thought to operate and power steering makes one handed operation a doddle that brake/gear overlap is completely irrelevant 99.9% of the time. Of course, that leaves .01% where it might make a difference but that is not enough to persuade most people to change their habits.
Personally, I try to be as smooth as possible for all the stability reasons described at length above and don't worry about ovelapping.
Bert
vonhosen said:
Yet classically the system wants you to finish the braking before getting the gear, which is delaying it if you could have taken it whilst braking (further away from the hazard).
I thought the idea was to bring your speed down to the point of having the sight line to decide if you must continue to stop or go. You either continue braking or change into an appropriate gear to go. Where bgol is useful is where you can see you will be able to go, but need to adjust your speed a little further downwards to time your entry into a gap in the traffic. You can do this using separation, however you are pretty much committed at that point with no option to continue to stop. Overlap increases your options.
Edited by Toltec on Wednesday 9th October 09:11
MC Bodge said:
...
You should do they are a blast, no power steering, no ABS and little servo and no electronics, just you three peddles and a steering wheel, add in sounds and smell to get drving heaven. The notion of the car trying to kill you by going backwards into any and all available hedges is largly just pub talk.Technomad said:
My 911 on the other hand has roughly 40:60 F:R static weight distribution so I'm using throttle and brake to manage CofG much more actively - turning in under trail braking when travelling at any speed massively improves the steering on the 911, followed by a rapid shift to the back under acceleration to nail the tail to the floor. So overlapping AND braking through turn-in massively improves feel, kills understeer and gives a smoother ride than a non-overlapping approach. The 911 is of course about the most extreme case you can get, but learning to drive one is hugely educational about the different needs and ways of managing CofG.
I would love to try driving a 911, especially an older one.To me advanced driving is all about using ones brain and so to follow a system without questioning it seems to go against the system itself.
As an example as to why separated braking seems pointless on the road, my first track day in the 911 was at Croft and during my instuction session it started to rain quite a bit, so having already been taught to do amazing things I thought we would be slowing down, no way no need. So blasting down the main straight and then braking HARD into the tight bend at the end whilst changing down (overlapping) not once did the car twitch or show anything that felt like it might want to do something horrible. This was a valuable lesson as to how capable the car is compared to the driver (me) and I got out at the end of the session tired and sweaty but with the biggest grin ever
Given that there is NO way you should be driving like this or even close to it on the public road, how exactly unbalanced and out of control is overlapped braking going to make you???
Toltec said:
vonhosen said:
Yet classically the system wants you to finish the braking before getting the gear, which is delaying it if you could have taken it whilst braking (further away from the hazard).
I thought the idea was to bring your speed down to the point of having the sight line to decide if you must continue to stop or go. You either continue braking or change into an appropriate gear to go. supersport said:
Given that there is NO way you should be driving like this or even close to it on the public road, how exactly unbalanced and out of control is overlapped braking going to make you???
And I think there you have the mis-conception. If you thought that the "IAM System" or even the "Roadcraft System" was a finely optimised tool for the very best of advanced driving, you would be completely wrong. It's a set of systematic, low-technology, sub-optimal steps. Made so anyone can do it to make a big improvement in safety.Specifically, the idea of IPSGA and non-overlapping has nothing whatsoever to do with vehicle dynamics, stability, control, braking or any of those things. It's a way of getting the hazard approach sequence to happen early and systematically. So add in the observation and limit point techniques and you have a system which is a big step up. We'll find it a lot easier if we stop discussing it as the pinnacle of advanced driving. It's a million miles away. It's a system for getting Joe-ordinary to be a lot safer.
Bert
BertBert said:
Specifically, the idea of IPSGA and non-overlapping has nothing whatsoever to do with vehicle dynamics, stability, control, braking or any of those things.
...but there are some people, albeit very few on this thread, that appear to think that it does. BertBert said:
It's a way of getting the hazard approach sequence to happen early and systematically. So add in the observation and limit point techniques and you have a system which is a big step up.
....It's a system for getting Joe-ordinary to be a lot safer.
....It's a system for getting Joe-ordinary to be a lot safer.
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