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This question is not wrt. fully mechanical fly wheel based systems seen in a few cars back in the 60's.
This question is with respect to a few brands (among which are many no-name manufacturers) which manufacture a particularly peculiar type of add on ABS system for bikes
Here are two for reference -

  1. SAFERIDE
  2. MOTORINO

Initial impressions of the websites seem like a complete scam with utter lack of information on the system and content copied from regular closed loop ABS systems (particularly in the case of SAFERIDE).
Upon further investigation I was appalled to find the popularity of this system (also manufactured by a few other no-name brands as mentioned before).
So here's how they claim it works -
SAFERIDE ABS
The ABS system, the bronze unit seen above, is installed between the brake line and the calipers.
Another picture -
SAFERIDE OPEN

The rest of the details on how it works are a bit obscure, but here's an excerpt from MOTORINO which makes a similar system -

The all-mechanical ABS on MOTORINO™s uses sophisticated valves on each brake caliper to damp the hydraulic pressure spikes that occur as a wheel approaches lockup, slightly relieving the pressure and allowing the wheel to continue to rotate, which helps maintain steer¬ing and maximum braking traction. The rider should always bear in mind however, that, unlike the computer-controlled ABS used in cars, you can still lock the wheels by applying excessive brake input. The ABS on your MOTORINO™ can help you maintain control in marginal situations but does not do all the thinking for you. The front and the rear ABS valves are different and tuned given fact that approximately 60%-100% of the braking power of a two-wheeled vehicle is provided by the front wheel.

If I were to paraphrase the above, I believe they're claiming that the membrane absorbs any sudden spikes in the brake pressure (due to abrupt application of brake pressure?) which may initiate a premature wheel lock.
Now it is obvious that this system in no way monitors the wheel speed and hence there's no mechanical control system of any kind at play here.
I believe all this system does is introduces a certain amount of sponginess in the system, kind of like having a certain amount of air in the brake lines (albeit a calculated amount (?) intentionally introduced).

  1. Is there any substance to these scientific sounding claims?
  2. Is there any supporting evidence proving/debunking the above?
  3. Is there any benefit at all or are these potentially dangerous?

EDIT
I understand how ABS systems work, in principle at least. I also understand that this is not a replacement for modern day closed loop feedback based ABS systems which take multiple parameters into account including wheel speed trends apart from just comparing wheel-speeds to each other.
I want to ascertain if this BRAKING-AID is of any good at all even if it doesn't do what is advertised. :)

  • Interesting thread you've created here. I haven't seen these third party applications in the wild yet. Excited to see what the responses might be. – DucatiKiller Jun 3 '15 at 7:29
  • @DucatiKiller oh yes, me too. I haven't seen these either. Surprised at the lack of information on something that modifies a rather critical system. – chilljeet Jun 3 '15 at 13:04
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To answer these questions:

  • Is there any substance to these scientific sounding claims?
  • Yes there is and there is not, these kits simply reduce the total pressure applied onto the brakes by the user and are exactly not "ABS" or Anti-Lock Brakes.
  • Is there any supporting evidence proving/debunking the above?
  • I cannot Give hard evidence but these rudimentary systems were sometimes recommended by mechanics for beginners who drove Bajaj Pulsar bikes which were notorious for locking their front discs.
  • Is there any benefit at all or are these potentially dangerous?
  • These system are dangerous to life of rider and people around him.

DO NOT INSTALL THEM ON YOUR BIKES or your Friend's, People don't realise the seriousness of this issue.

In some website of the manufacturer you can see that they have mentioned that these do not act as replacements to the Electronic computer controlled ABS systems and that these ones can cause wheel to lock.

This is plainly a pressure valve that's all !!! it can in no way detect a wheel lock and act accordingly. These are clearly selling tactics and are not good.Most of the people who have fitted this contraception claim this to be useless.

EDIT: Practically, Some people have reported that this system works,It sort of does work if you are new to bikes with a Disc brake since on drum brakes you need to apply a lot of pressure to stop suddenly migrating to a disc will obviously make you lock them up.

When I purchased my first bike, the salesman was giving tutorial on how to use a disc brake since most bikes had a drum. So this might be useful for new riders who stomp on the brakes hard and lock wheels which BTW used to happened a lot when the first Bajaj Pulsars Came out in 2003.

That Said, they are pretty much gimmick now a days as people are aware of disc brake technology.

  • I understand that these definitely do not fit the definition of ABS as we know it. And from what it seems, I do not think there'l be a reduction in the TOTAL braking force available as after the plunger depresses all the way, there is nothing reducing the total force being applied. Granted, that this will require one to depress the brake lever/pedal a little more to compensate. Where I presume this will interfere is during the application (transient) phase. I would like to know the effect of that interference, conclusively. – chilljeet Jun 3 '15 at 11:08
  • Ok , Think of trying to push a flat bottom rod through a tube filled with oil , When you push it very fast it will not go in and after like a second gradually sink in.. You are correct, this does not reduce the total force but it dissipates that instant surge of pressure thus "PREVENTING WHEEL LOCK" at least thats the theory – Shobin P Jun 3 '15 at 11:12
  • Still, its not even 50% effective at preventing wheel lock , its a market trick sadly people fall for it. – Shobin P Jun 3 '15 at 11:16
  • The product does seem like a complete gimmick. Let's see if even 'that theory' has any scientific backing at all. :) – chilljeet Jun 3 '15 at 11:19
2

enter image description here

My guess on how the system works is explained in the picture. in normal condition, the flow of the brake fluid is shown using the pink arrows. during the locking condition, the spike in hydraulic pressure pushes the spool valve against the spring force(green arrow) opening the chamber that stores some of the brake fluid, thus relieving the pressure at the wheel brakes.

  • I would assume that upon wheel lock, there should be a slight reduction in the holding pressure required. Where I see it could plausibly help is easing out the initial application of sudden brake pressure which, due to it's impulsive nature, could initiate a wheel lock. I maybe going out on a limb here. – chilljeet Jun 3 '15 at 9:45
  • Normally in ABS, the cycle is as follows. when there is a wheel lock, pressure is held. if the wheel is still in locking condition, the pressure is reduced. if the wheel tends to accelerate again, then pressure is increased. so the cycle is hold,reduce,increase. in this case, looks like pressure is mechanically reduced. – knocksAndMisfires Jun 3 '15 at 9:52
  • 1
    Yes, correct. But, I don't see how this mechanical system is able to ascertain a wheel lock. – chilljeet Jun 3 '15 at 9:57
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What this thing basically does is prevent you from applying too much brake pressure. Sure, it's a gimmick, but it does seem plausible and the little I know about hydraulics suggests it should work. It seems to work a lot like a wastegate (but with fluid, not air).

But it's not an active ABS system that will modulate the brake pressure to keep you right on the edge of traction. This thing will make your brakes squishy at (hopefully) the right moment.

I suspect you'd have to do lots of fine-tuning to get it just right. And it certainly won't perform nearly as well as real ABS.

As an aside: this thing has better reasoning behind it that those "vortex generators" that supposedly improve your car's performance.

  • Exactly, I dont think a squishy brake is a good brake:) – Shobin P Jun 3 '15 at 12:38
  • Yes, this is the primarily reason why I asked the question. I guess I should have just omitted the word ABS. I know that incorrect (sudden/impulsive) application of brakes can cause premature whee lock. A real ABS system would take corrective action of course. The theory that this thing could, could dampen the initial impulsive pressure sounds plausible. And this wouldn't be a reactionary system, it would prevent such spikes to begin with. – chilljeet Jun 3 '15 at 12:46
  • Racing cars without ABS are normally set up so that their wheels don't lock up. – Captain Kenpachi Aug 13 '15 at 10:25
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I have got this Mechanical ABS from Shopclues.com at 549 rupees including shipping charges. I installed it and checked. Found it to be good enough, but doesn't work when applied full sudden brake and that is what is said by many dealers online. Proper electronic ABS with speed sensors and ECU cannot be installed manually in most bikes, atleast in india it is not possible, forget about the cost. And this atleast works in my observation 80%. After few days of observation I have ordered one for the other disc also.

And for the ones suggesting better riding technique and control, please try to understand human psychology. The techniques and control will not be of any use in a panic situation when you would have applied the brake abruptly even before your brain analyses the situation, since as you know these riding things (applying brakes, holding clutch, reducing accelerator) are all done automatically even when our mind and brain are somewhere else. In panic scenarios, it is even worse. I personally was a victim of such panic situations and also seen few such instances). And finally the golden work 'Something is better than nothing'. Especially for the price. And you are not going to lose anything out of it.

And this Mechanical ABS has been tested by few companies and personals. So it is not some fake business. There are people who just assume and talk/write and there people who just do the analysis/testing/checking and come to a valid conclusion. I have done the later part. Please do your homework.

Please forgive me if my writing sounds hurting. Not intentional. I just feel sorry for the people who are ill-informed and over-confident with their half-baked knowledge and assumptions.

  • " Found it to be good enough" for doing what? Preventing wheels from locking? – Shobin P Aug 13 '15 at 14:56
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As i see this product, This system was never made to replace the original abs system which has sensors and wires and computers doing the thinking for the rider. As i see this product is an option available for the riders who des not have abs in their bikes and which can be fitted on the bikes already on road. So it can not do the work which an actual abs system does but 30k and 1.2k thats the diffrence in thier cost, and thats a bargain for the riders who doesn't have any saftey net on their bikes presently riding with no abs. Yes i agree it is not as effective as the original abs but it was never its purpose to replace that system. So even if it is 80% effective it is better than having no abs at all.

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Yes, good enough in preventing wheel lock about 80% while applying only back brake and have not seen any lock while using both brakes.

It is particularly very useful because wheel lock skid can possibly happen also at speeds of 30-40 kmph even when the brake is not applied abruptly depending on the road, wetness, gravels (small stones/sand), etc.

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