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Old 9th March 2011, 20:26   #16
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Default Re: ABS for bikes: How different from cars?

^^^
Hi,
As far as I'm concerned, yes, they are misrepresenting their product. It is like calling any pressure reducing/ limiting valve an antilock braking system.

Opinions please.

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Old 10th March 2011, 20:50   #17
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Default Re: ABS for bikes: How different from cars?

Hi,
With the experts lurking only, it's up to us amateurs to discuss.

Lets discuss the points one by one. Remember, these are my personal opinions only.

What does 'Brake Assist' have to do with motorcycle ABS?

When ABS was first introduced, it was found that many drivers were not pressing the brake hard enough. The idea behind ABS then was 'You stand on the brakes, ABS will take care of the rest'. But years of driving had instilled into many of us that one should not lock the brakes. Instinctively, we would release the brakes after some time to prevent wheel lock. The result was significantly reduced braking efficacy. In fact far worse than if wheels had been locked. A novice would extract better performance from ABS than an experienced driver. Thus was born Brake Assist.

From the engineering point of view, there was no need for BA. But ABS is a driver aid. Asking for wholesale driver re-education was not on.

Now in motorcycles, the rider experience is far more involved than in the case of a car. The rider becomes part of the machine. Things are learned which become part of our instinct. Any driver aid which causes a significant change in this relationship would be problematic. Maybe even downright dangerous. A driver/ rider aid should enhance, not significantly change the existing riding experience. This, I think should be a very important thought to be kept in mind when designing the ABS system.

Waiting for comments. All PoV welcome.

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Old 10th March 2011, 21:16   #18
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Default Re: ABS for bikes: How different from cars?

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Originally Posted by Sutripta View Post

From the engineering point of view, there was no need for BA. But ABS is a driver aid. Asking for wholesale driver re-education was not on.

Now in motorcycles, the rider experience is far more involved than in the case of a car. The rider becomes part of the machine. Things are learned which become part of our instinct. Any driver aid which causes a significant change in this relationship would be problematic. Maybe even downright dangerous. A driver/ rider aid should enhance, not significantly change the existing riding experience. This, I think should be a very important thought to be kept in mind when designing the ABS system.
Firstly I would separate Indian market bikes used a commuters and hi-power big bikes which sell in developed markets.
Latter is used for recreation by expert riders with good skill and fitness and tend to be fair weather/good mood machines on sticky tires. There is a huge priority for sportiness, low mass and with riders being experts, one would question the need for ABS in the first place.

In India commuter bikes are used by people who cannot afford cars (mostly). They many not necessarily have the skill, fitness and/or need to ride under all conditions.. rain or shine.

As far as the system itself, the primary difference is lack of booster and the fact that F/R are 2 independent circuits. (which necessitates 2 modules). Also rears are mostly drums and are cable actuated.

Also, on Indian commuter bikes, firstly the rider generally tends to use rear brake more often. In an panic stop again the rider may not be able to pull the RHS lever hard enough.

Therefore in my mind, the first requirement is a linked braking system with hydraulics on both F/R. Additional benefit is that you can get away with just 1 module (2 channels) and can avoid BA because the right foot can push much harder than fingers squeezing.

Last edited by Mpower : 12th March 2011 at 00:53.
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Old 10th March 2011, 21:50   #19
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Default Re: ABS for bikes: How different from cars?

^^^
Hi,
My bringing in BA was not to question its necessity, but to highlight the fact that a driver aid should help existing drivers and driving styles. Pure engineering itself is not enough.

Can those who have taken advanced riding courses/ track tuition fill us in on the braking methods taught. And whether it needs to be modified for ABS. And for different types of ABS.

@MPower, I think you agree with Honda's philosophy. What do you think of the (more conventional) TVS system?

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Sutripta
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Old 10th March 2011, 22:21   #20
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Default Re: ABS for bikes: How different from cars?

Understand. My thoughts on BA and why its more relevant on a bike

In a car, driver's posture is more conducive to apply large force on pedal by bracing oneself on the backrest. Driver also uses his foot which can exert a force almost 10x the fingers.

Not only is this missing on a bike, a rider has to balance himself on the bike in a panic situation. Balancing frequently involves sticking the leg out.

PS: will check out the TVS video later
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Old 10th March 2011, 22:29   #21
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Default Re: ABS for bikes: How different from cars?

^^^
Agreed. But two fingers are normally sufficient to lock up the front wheel.

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Old 10th March 2011, 22:32   #22
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Default Re: ABS for bikes: How different from cars?

Quote:
Originally Posted by Mpower View Post
...primary difference is lack of booster and the fact that F/R are 2 independent circuits.
...the first requirement is a linked braking system with hydraulics on both F/R.
Sorry, but one query from a semi- AFA bikes are concerned: Are there any bikes at all, which have a single brake circuit transferring braking force applied at a single point, to both front and rear wheels (the way a car's braking system does)? If not, why not? And why, in any case, did motorcycle brakes continue to be operated by separate limbs, through the last century (is it just force of habit, or does riding dynamics have anything to do with it)?
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Old 10th March 2011, 23:11   #23
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Default Re: ABS for bikes: How different from cars?

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Sorry, but one query from a semi- AFA bikes are concerned: Are there any bikes at all, which have a single brake circuit transferring braking force applied at a single point, to both front and rear wheels (the way a car's braking system does)? If not, why not? And why, in any case, did motorcycle brakes continue to be operated by separate limbs, through the last century (is it just force of habit, or does riding dynamics have anything to do with it)?
Nothing comes to mind. In the Honda linked system foot is a single circuit which operates F+R but there is an additional circuit (RHS lever) which operates front only.

Reason, I'm not sure..riders like to have independent control over F and back. IMO scooters should all be linked.
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Old 10th March 2011, 23:46   #24
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Default Re: ABS for bikes: How different from cars?

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IMO scooters should all be linked.
Are they? Not the Bajaj, LML, Kinetics I knew a little bit of. No idea about innovations in scooter design in the last 10-15 years. And do scooters also carry an ABS system? My take on this is - they'd benefit more with ABS because of the smaller wheels that tend to lock up more easily.
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Old 11th March 2011, 06:54   #25
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Default Re: ABS for bikes: How different from cars?

Quote:
Originally Posted by Sutripta View Post
Hi,
What does 'Brake Assist' have to do with motorcycle ABS?

When ABS was first introduced, it was found that many drivers were not pressing the brake hard enough. The idea behind ABS then was 'You stand on the brakes, ABS will take care of the rest'. But years of driving had instilled into many of us that one should not lock the brakes. Instinctively, we would release the brakes after some time to prevent wheel lock. The result was significantly reduced braking efficacy. In fact far worse than if wheels had been locked. A novice would extract better performance from ABS than an experienced driver. Thus was born Brake Assist.
Sutripta
I think we are mixing ABS & BA are entirely two different usage. ABS as we all know is for braking without locking the wheels. Where as BA is more a collusion prevention technology in which the ECU decides depending speed vehicle and force applied on brake paddles, a large amount of pressure is applied to bring the vehicle to a stop. BA comes to play only in emergency braking and not under normal braking conditions.
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Old 11th March 2011, 15:49   #26
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Default Re: ABS for bikes: How different from cars?

Quote:
Originally Posted by SS-Traveller View Post
Are there any bikes at all, which have a single brake circuit transferring braking force applied at a single point, to both front and rear wheels (the way a car's braking system does)? If not, why not? And why, in any case, did motorcycle brakes continue to be operated by separate limbs, through the last century (is it just force of habit, or does riding dynamics have anything to do with it)?
Moto Guzzis had a halfway system, much like Honda's C-ABS (without the ABS).
I think we'll wait for the experts to chip in regarding motorcycling dynamics, and rider involvement. My feeling is that motorcycling ABS systems have to be designed ground up. And is rather more problematic than the automobile case. Removing two channels from a car system absolutely will not do. It is exactly this that I'm trying to explore.

Quote:
Originally Posted by v&v View Post
I think we are mixing ABS & BA are entirely two different usage.
For clarity, preface the discussion on BA with 'In an emergency situation'. Major percentage of ABS invocation is also under emergency braking conditions. Don't think we're mixing up ABS and BA. And the topic on BA came up to illustrate user behavior differing from what the engineers foresaw.

Could the experts chip in with recommended braking techniques for commuters, and for advanced riders.

In the meantime, lets move onto another aspect: How does one detect an about to lock wheel?

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Old 11th March 2011, 16:57   #27
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Default Re: ABS for bikes: How different from cars?

the abs equipped bikes have sensors on the rim , when one wheel is moving slower then other its about to lock . just at that point the abs system releases the hydraulic pressure in the brake line and prevents wheel lock .the rtr 180 has just been launched with a 9000 rs extra price over non abs version .
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Old 11th March 2011, 19:56   #28
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Default Re: ABS for bikes: How different from cars?

I have never ridden an ABS bike, but cannot resist adding my two cents worth of opinions:

I think the linked combined braking sytem of Honda is essentially designed to be safer for newbies. On operating the rear brake lever both the rear as well as the front brakes are actuated, effectively increasing the braking power (the front brakes generally being much more powerful than the rear). Most riders are much quicker at applying the rear brake, and also apply it harder, because of our most powerful leg muscles. [Newbies generally haven't mastered the art of using the front brake hard without locking the wheel, so the linked braking system is safer for them. Moreover, in an emergency even an experienced rider may not find the front brake lever in time, unless he has it covered with his fingers already. It has been found in studies that in a significant number of cases of collision, motorcyclists did'nt even apply the front brakes before crashing]. However, applying only the rear brake is dangerous, because locking the back wheel will make the motorcyle lose its balance in about two seconds. ( A front wheel lock-up, of course, will topple you in a second!)

So Honda's linked braking system makes sense. With ABS being added it becomes even better. For now neither wheel can lock, so you get hard braking without the chance of wheel lock-up. Very good!

The problem come when a rider who is used to the Honda C-ABS rides another bike which has no ABS. He might have gotten habituated to braking with his rear-brake alone (why would he use the front brake lever, when the rear brake lever acutates both brakes?), and he will also be used to braking hard -- as the ABS would always save him from wheel-lock-up. Now, with these habits, when he rides a non-ABS bike disaster will follow! He will get poor braking (as he uses only the rear brake) and will lock up his rear-wheel (as there is no ABS) and fall.

SO the problem with the Honda system is that it spoils your riding style, unless you are aware of this problem and actively try to avoid it. So if you get the Honda C-ABS, train yourself to use the front brake progressively and hard and use the rear-brake moderately, which is good braking practice on all bikes ( including non-ABS ones). And also practice emergency braking so that you can brake effectively without having the ABS system kicking in to save you every time.

The more conventional ABS used by the Apache RTR will avoid the problem of over-dependence on the rear brake, but it might still create an over-dependance on the ABS to save you-- which might get you into problems if you later ride a non-ABS bike. Here too practicing emergency braking as above would help avoid getting into bad habits.

Last edited by Rollin' Thunda : 11th March 2011 at 20:10.
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Old 11th March 2011, 22:09   #29
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Default Re: ABS for bikes: How different from cars?

Although I'm no expert in this but I do have experience in Honda's CBS as I've ridden a Blackbird which used to come with CBS (but no ABS back then).
To me it did make a considerable difference as the stability of the bike under hard braking was phenomenal.

Also, I don't think the ABS systems on the latest high end bikes would be too basic as they are all filtered down from MotoGP which has one of the most complicated and detailed electronics in Motorsports.
Yes MotoGP bikes don't run ABS but they do run a lot of sensors etc. to monitor wheel movement and I think the same kind of technology is being used in the latest road bikes.

I think the CBS on the Honda is something similar to what we call EBD on cars.

Not sure about the ABS on the Apache though. It may not be as advanced as the Honda system but I don't think it is that Rs XXX ABS add-on either.

Last edited by goingout : 11th March 2011 at 22:10.
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Old 11th March 2011, 23:14   #30
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Default Re: ABS for bikes: How different from cars?

My 2 cents:

Quote:
Originally Posted by Sutripta View Post

A) How do we brake a car? A bike? Any differences?
For a car we apply pressure on a single pedal which is distributed over the four wheels. For bikes, since there are two circuits, we have to apply pressure separately (one through our leg and one through the hand).

The major difference I can think of is the pressure distribution. For the car this will be more or less even (provided the vehicle is in good condition and has not been modified). For the bike, it all comes down to the skill of the driver. Many people jam the rear brakes alone during panic situations. Many (who have not been trained properly) never touch the front brakes even during regular braking.

An ideal braking for the bike will be similar to the car, where both F & R brakes are applied with the same pressure. This is tricky since R brake is controlled by the foot where it is only natural that more pressure is applied. I think this is one of the main reasons why they set different "play" levels for the foot pedal brake and the hand lever brake. Also, in Indian bikes we find disc brake option mainly in the front. This makes the F brakes more efficient.

On a personal note, if I have to choose between a locked front wheel or a locked rear wheel on a bike, I would go for the locked rear wheel. It is easier to balance the vehicle when you have rear skid. You get some more time to react with a rear locked wheel as compared to a front lock.

Quote:
Originally Posted by Sutripta View Post
B) Car ABS systems have BA (Brake Assist) built in nowadays. Why is it necessary? Would the braking system not function to its full potential without it?
The brake assist as the name suggests is only an assist. This helps in balancing the distribution more efficiently. The braking system can function to its full potential even without the BA but in such cases the dependency on the driver is increased.

Quote:
Originally Posted by Sutripta View Post
A) How do we detect an about to lock wheel? On a car? On a bike? Any differences?
I don't know how you can detect an "about to lock" situation in a car. I guess maybe the moment you hear the screech you know the wheels have been locked.

For bikes, the about to lock sensation for front wheel would be when you realise a slight imbalance between the front and rear of the vehicle (the feeling you get of being lifted from the bike). For rear, I guess you can detect it only with the wobble. But here again it happens when the wheel has already been locked.
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