Re: ABS brakes: How to use effectively and what not to do.

Before I even start to 'try to touch on the answer' to your question, motorcycle riding is a very complex procedure. And there is a reason why there's this quote 'it's like riding a bike. You never really forget'. Most of our motorcycling is done via intuition and muscle memory. An example could be counter-steering. We all do it and for the most part, we do not know what it is. At least not scientifically.

Coming back to your question, ABS and its benefits plus, its effectiveness in corners. Firstly, let's talk about a motorcycle without ABS. You are riding upright and for some reason you have to brake hard. Now, the retarding force or braking force is being fought by the traction from the tyres and the travel of the suspension.

In very simple terms, you have 100% of the traction available when you are upright and when you brake hard, you use that traction. Depending on the situation, if all of it is used, you slide. That is where suspension comes in. The force needed to break that traction limit is more than that needed to compress the fork. And so, the force takes the easy way out and compresses the fork instead of trying to break the traction limit. So the fork keeps compressing till there is no travel left, post which, if the braking force is still maintained at the level with which you started, you are awaiting a warm welcome from the surface because the the breaking of traction limit barrier comes almost instantly.

Now, ABS. From what I know, ABS, in the simplest terms, modulates the braking pressure. As soon as it senses the wheel locking up, it lets it spin for the tiniest fraction of a second to prevent traction loss i.e. it reduces the braking force just a tad bit. Then it comes back on. This cycle keeps repeats itself hundreds of times a second (I think) and you come to a stop. On a side note, in theory, it should also relieve the pressure on the forks but I am not too sure if the frequency or the duration of the brake pressure relief is enough to do that. Also, it should cause extremely mild skipping of the wheel if it does. But like I said, I am not too sure about that.

Now, coming to the answers to your questions, it is rather simple (I wish!). In terms of traction, it reduces when you lean over due to reduction in the contact patch between the tyre and the surface. So, the more you lean, the lesser traction you have. Let's say you are at a lean angle of 'x' degrees and on that angle, the available traction is 50 as compared to 100 in a straight line. Meaning, half of the force needed to make the wheel in upright condition slide is needed to slide it when leaned over.

Theoretically, ABS will keep modulating the braking force and reduce it significantly when you are leaned over and apply brakes. It will try its best to keep the wheel from sliding and if you are fortunate, all that happens is you lose your line and veer towards the outside of the corner. That is the best case scenario because even if you end up losing traction and slide, you will still slide towards the outside of the corner only this time, you'll be scraping some of your body (and soul) while that happens. Again, it depends on available traction which is dependent on the amount of lean you carry (size of the contact patch) and the surface (if it offers sufficient amount of friction).

Now, if that was not enough, you also introduced oil, water, or sand in the scenario.

Anyway, again, in simple terms, since the amount of traction available is also dependent on the surface, in this scenario we have even lesser traction. So the force required for the tyre to slide is even lesser and I believe that even the tiniest fraction of a second where the wheel is locked will be enough to induce a slide and some unwanted doctor time. Water is bad, sand is worst, oil is hopeless.

There are a few things that I'd like to mention at the end. If you apply brakes too hard in a corner (even with ABS) the tyre may still slide because it is already battling the forces trying to throw the motorcycle out of the corner (centrifugal force). So even on the best tarmac possible, if the lean angle is too much (traction is too less), the tyre may still slide as the force on the tyre in that split second where it locks before being released by ABS may be enough for a dirt trip. Also, the effectiveness of the suspension also decreases exponentially i.e. there ability to share the braking force.

And that is why... WE HAVE CHASSIS FLEX! That's why there are teams in MotoGP and not just riders...

While I tried to the best of my ability, there may be many others in our family who may know more and I request them to correct me if I am wrong and if not, add to it.

Re: ABS brakes: How to use effectively and what not to do.


As soon as I saw your reply, a Meme came to mind, this one:




I was already assuming the answers which you provided, but I didn't know the exact science behind it. Thanks a lot.

BTW on the topic of CHASSIS flex, how much difference does a chassis make in handling and braking? Earlier I had a Karizma ZMR (which shared chassis design with a 100cc splendor) and now I have a Dominar 400 but I can't tell the difference because of a better chassis. I do feel the difference because of the beefy upside down fork setup while leaning and chicane maneuvers.

Re: ABS brakes: How to use effectively and what not to do.

Here is a good video that I found covering the exact scenario that you brought out. It is scary indeed and needs actions that are counterintuitive. While the entire reflex sense asks one to brake hard and brake fast, the correct actions are quite the opposite. It is better to learn before suffering a crash than to crash and learn. Here it is

Re: ABS brakes: How to use effectively and what not to do.

Really informative video. Thank you for sharing as I got to learn something new (scientifically) as well. More than the contact patch it is the load or the weight on the tyre that enhances grip. In a way, load increases the contact patch as well but all this is a tad too science-y for the day.

Motorcycling is just a whole lot of fun. I have been riding a non-ABS RTR 180 for quite a while now and I had known for a while that I need to load the front before going apesh*t on the brakes. In the beginning, I used to use the rear brake to load the front and then apply front. The typical knowledge giveaway that you use 20% of the rear brake and 80% front and so on...

I have outgrown that and now I do not use the rear brake at all when braking. I roll off the throttle to put some load on the front (engine braking by downshifting in more demanding cases) and then gradually grip the front brake lever. It is soft in the beginning and then transitions to grabbing it like I mean it. Helps a lot... But I have practiced this a lot and aggressive downshifting can lead to rear wheel hop or lock-up without a slipper clutch so one needs to be wary of these things.

Also, if you use engine braking, it is a continuous process in the sense that you have to keep downshifting for it it to work (and then it has to come to an abrupt halt by using the clutch). In essence, it is good for slowing down but not for coming to a halt. In fact, using engine braking in an incorrect way can lead to less efficient braking. The reason is that say your bike can do 20 km/h in the first gear and you are going at 30 in the second. Shift down and you start slowing down but the slowing down happens till 20 only, post which it does the opposite and keeps supplying power to the rear wheel. I have experienced that and I am still in the learning phase. But if done correctly, it can completely eliminate the use of the rear brake which I am not a big fan of because braking essentially unloads the rear and makes it more susceptible to losing traction and arranging a ticket to the moon aboard SS HighSide.

Agreed on the point of these kind of situations demanding counter-intuitive measures. Motorcycling needs a lot of that in a lot of cases. Another example that I have come to experience is to lean more if you think you have entered a corner too hot and start going wide. Intuition says brake but you should not do that and instead, lean more.

This is the case for most of the riders: Never in a lifetime do we use all the grip available (during turns executed well) and all the turning prowess of a motorcycle.

In simple terms, there is always more lean in store from the bike's end. The amount we lean is the limit of our own mind and scarcely, of the motorcycle. After almost grabbing the brake in a similar incident, I somehow got reminded of this and saved a very expensive crash. Entered too hot > started going wide > almost grabbed the front brake but didn't > leaned more while making sure that I rolled off the throttle very gently > got out of this situation unscathed. I was very lucky too as the other lanes were not occupied and there was no vehicle behind or in front of me.

Rolling off the throttle is important because it slows you down to tighten your line and the added lean leads you to the inside of the corner. It is also important because acceleration or applying the throttle tends to stand the bike up and therefore, sends you towards the outside of the corner. And it needs to be done gradually because if you let up the throttle suddenly, you upset the front by applying a lot of retarding force (engine braking) without loading the front gently. In essence, it is like braking without loading the front and therefore, the risk of losing traction increases.

Another nifty trick is to gently use the rear brake (very gently) to slow down and tighten your line. Again, something that needs a lot of practice.

Again, thank you for sharing the video @Chakrapani

I am thankful for the kind words but that meme is certainly not something I deserve. Too much to learn and ways to go still... But I am just glad that I am in the process and to be able to share that (and learn more) with you guys is a perfect add-on.

About chassis flex, it is a very, very vast topic like most of the science behind motorcycling. In simple words, the sad truth is that 99% of motorcyclists including us will never be able tell the difference between a decent and good chassis. And bad ones are rarely made nowadays.

Anyway, a stiff chassis is supposedly good for communication about the available traction and the road conditions. Ideally, a stiff chassis should transmit all the small details that you need for pushing harder and to explore the limit of the motorcycle. Something that 99% of us (including us) do not do. Racing at the highest levels is where all these things come into play. They need a stiff chassis that listens to everything the tyres and the surface has to say and transmits those to the rider.

Flex on the other hand comes into play when you are leaned over... a lot! As I said in my previous post, with increasing lean angles the suspension becomes more and more useless and it is obvious why. At 0 degrees of lean, when the motion of suspension is perpendicular to the road surface (not taking into account the rake angle), it work the best because when there is an undulation in the surface the tyre doesn't jump or drop, instead the forks compress or decompress to absorb those and the tyre maintains a more or less steady contact with the surface. So the suspension is able to keep the tyres planted despite the undulations.

Now imagine a motorcycle negotiating a corner with 50 degrees of lean angle. In that case, if you go over an undulation in the surface, the suspension cannot do its job because of the direction of the force generated by that undulation in relation to the suspension. And if there is no suspension, at great speeds even the smallest of undulations will make the tyre hop or lose contact with the surface for the smallest fraction of a second. And even the smoothest of surfaces have a lot of micro undulations so that results in micro jumps of the tyre or inconsistent grip.

So in racing, manufacturers have to develop the chassis in such a way that it is stiff enough to provide enough feedback to the rider and flexes just enough when leaned over fully to act as suspension.



Apologies for the hastily and shoddily made graphic. But I think it is easier to understand that flex is also just another form of suspension. So while the conventional suspension works in the direction portrayed by the arrows pointing up and down, flex in the chassis works along the direction pointed by the arrows going from left to right and right to left.

Again, this is a rough portrayal and the actual thing is much, much more complex. Luckily, if you ride long enough, you will be able to tell what a good chassis can do for you because gradually, we all learn to listen to the tyres and the road but the key, again, is riding a lot. Flex... sadly, we'll probably never see it in action much less, experience it.

Re: ABS brakes: How to use effectively and what not to do.

Extremely well explained sir. As avid riders we finally find our own ways and means to negotiate tough situations. And a lot of it is specific to our individual bikes. Hence we spend precious time looking at tyre tread wear, suppleness of suspension springs and are driven sleepless by the odd screeching sound or knocking that we notice. It is a riders instinct that tells us something is not right and also when developed over a period of time makes us perform counterintuitive actions in tight spots.

Chassis stiffness and suspension set up are indeed motorcycling dark arts which most of us road riders are neither required to know nor are exposed. Of late there is some interest in suspension upgrades since YSS and Ohlins have started offering kits for the RE Twins. Still the overall effect for the costs involved may not be immediately noticeable by the average rider. Motorcycle racing is a different ball game altogether. Your explanation of chassis flex is eloquent. Thanks for your efforts.

Re: ABS brakes: How to use effectively and what not to do.

Thank you for the kind words. Also, just like that meme, I am not worthy of the 'sir' as well. Too much to learn and ways to go still...

And I agree on the fact that we all find (and have) our own ways of seeing and negotiating different kind of situations. It is such a phenomenon that the one common ground between all of us is motorcycling and yet, we all have different ways of approaching it. Paradoxically, intuition contributes majorly to our riding skills and yet, counter-intuition is something the prevalence of which is more than what we believe it to be.

But then, our intuition has been honed after years of practice... and practices not all of which are conducive to good and safe riding. Some things and actions that oppose that preset of muscle memory or reflex, can be tuned and the newly acquired skills honed to further our collective cause of being better riders. In the beginning, you have to adopt these new practices consciously, but after a while, it becomes a part of your new intuition. I wish I was able to word it a little better to make it a little less confusing but complexities of nature often render language inadequate.

P.s. Dark arts is a very apt name for chassis and suspension setup.