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Testing out the ABS.

Discussion in 'General Motorcycling Discussion' started by minglis, May 16, 2011.

  1. I went down to our usual Saturday morning practice this week, and it was a nice wet day. This gave me the chance to do something that I'd been wanting to do for a while... test out the ABS in the wet. I thought I'd share some of my experience with whomever was interested.

    First, some context:
    Bike: CB400 (2010).
    Conditions: wet with large puddles
    Where: Marina car park (usual Sat morning practice location)

    So, after getting down there, I decided that with it being so wet, it was too good an opportunity to miss out on, so I saddled up, did a few laps of the car park, then decided to check out the brakes. At first, I did a simple E brake on the wet pavement, but next to a big puddle from about 40km/h. All went very smoothly, and this was just a test. The next was at 50km/h, then the rest after that were at 60km/h.

    I've often tested the ABS in the dry, so I knew what that felt like. First off, the REASON I know what that's like is because I deliberately tested it to check it all out. How does it feel, how hard do I need to brake to feel it etc... Once I had a handle on it, I've been using the ABS (dry) as a gauge for when a lockup would occur, and then doing a release, reapply. The goal is to know how to brake, whether I have ABS or not, not to just rely on the ABS.

    I found that in the wet, the ABS felt quite different. In the dry, the ABS would grab and release very quickly, giving you a fairly quick pulsing. In the wet, the release and grab was much longer, particularly when hitting the breaks as hard as I could from 60km/h in the middle of a big puddle. Depending on how I applied the brakes altered the feeling, and when it kicked in. Some of the tests were done as a hard grab, a "panic" grab so to speak. This caused the ABS to kick in very quickly, both on the pavement and in the puddle. Most of the tests however, were a setup and squeeze. I found with these tests that the ABS was less aggressive (at the start) but almost always needed to kick in at the end of the brake. (note, the back brake ABS kicked in most of the time, but that's common. This is because I tend to use both front and back break, and the back wheel has very little weight on it, so not much traction). So, the sensation was, breaking hard, all my weight going forward etc (into my knees on the tank) and about 1-2 meters before completely stopping, I could feel the front ABS let the wheel go, probably for about a meter (at a guess) then grab again. The bike would stop straight away at that point. While the question from you may be, would the bike have stopped a meter earlier if the ABS didn't do that, I'm 100% convinced that the answer is NO. Without the ABS, I would've lost the front end in a big mess.

    Probably the most notable thing about this test was this:

    Without the proper technique, I would most certainly have crashed. Let me say that again. Even with the ABS, if I didn't keep my head up, my weight on my knees etc, the ABS wouldn't have saved me. As I was hitting the brakes hard in the puddle, I could often feel when the bike started to loose traction, and the bike was begin to go out of shape. Then the ABS would kick in, and I could feel the bike straighten up again. This was while I was sitting upright, with my weight central and gripping the tank, so my body wasn't applying too much counter productive weight transfer on the bike. If you look down, you will always look down either left or right, and your weight will go that way. Had I done that, I think I would've gone down.

    So, in the end, I was really happy with the ABS. It was interesting, because I felt much more comfortable squeezing the brakes as hard as I could in a big puddle at 60km/h than I did turning the corner at the bottom of the car park to start my run back up again.
  2. Edit: double post
  3. I wonder if there are enough flameproof suits around here for this thread...

    This goes without saying. I mean if you line up for a brick wall and ride into it, ABS won't help there either.

    What you want ABS for is when the situation goes beyond the rider's ability at that point in time and the ABS can come in and help. That isn't to say it will help in all situations. i.e. mid corner but there are a few where it most likely will stop someone grabbing a handful resulting in them sliding down the road on their backside.

    I suspect this thread will reiterate a lot of the previous discussion, debate etc that has already been covered. It is almost a bit of a religious topic in some respects.
  4. I don't think it does go without saying. There are too many that think that having something like ABS means you don't HAVE to learn to brake correctly. There are others that think that anyone with ABS don't WANT to learn how to brake correctly. This statement lets both know that that isn't the case.
  5. I've never seen this myself, especially on a bike. It is certainly an opinion that is put forward however not one that I have ever seen verified.

    All that I have seen in research is with a particular segment of drivers (taxis) in cars (not bikes) potentially drive more aggressively knowing it is there - which is quite different different. Even in a car, I haven't come across anyone who engages ABS as a feature of regular daily braking.
  6. There was a video posted here of a guy on a bike while a reporter was reporting on all the safety gizmos the bike had in place and how unlikely it was to crash. Rider took off and you can guess what happened. If you don't know how to ride and brake properly in the first place you'll crash with or without abs. In the last 33000kms my abs has engaged 3 times (2 intentional 1 unintentional) What does that tyre ad say "if it only saves you once a year it's a good year"
  7. So before you were saying that abs would only kick in after lock up, now your saying it will stop a lock up?

    Question for both of you. Why are you grabbing a handful in the first place. Minglis, granted you were just testing the abs, but do you do the same on road?
  8. yeah, that's probably a fair statement. While there may not be people who specifically say that having their ABS means they don't need to learn, there are PLENTY of riders out there who don't know how to e brake. There are even some out there who state that they don't need to learn (yes, I know of some who've said it) as they will never be in that situation cause they have good road craft etc. Regardless, I wanted 2 things clear... Despite the ABS, LEARN TO BRAKE and people with ABS still want to learn to brake (maybe not all, but at least I do).
  9. As soon as a loss of traction is detected, the ABS kicks in, so in essence, the lockup causes the ABS to stop the lock up :)

    absolutely NOT.
  10. No, it will kick in after a lockup.... It will prevent you remaining locked up, and decreasing the chances of going down and sliding down the road.

    Under normal conditions I haven't. There is only one situation where it has happened in an emergency situation and it kept me upright.

    ABS isn't there for the 99.99% of the time that everything goes according to plan, it is for that one time when things don't and invariably, if people are overwhelmed by an impending collision etc, tense up and grab the brakes - in an uncontrolled environment.

    Practicing normal braking is good. Sometimes its fun with the ABS somewhere quiet, maybe if there is a puddle to get it activated and feel it work. Amazing how quickly it can pull you up on some wet roads. On dry roads, it has always been roughly the same as my proper braking technique.

    Either way, when absolutely required it gives you the confidence to more aggresively brake in the knowledge things won't go all pear shaped if you misjudge, or if the surface changes slightly or any other one of 1000 variables that are happening (we are talking straight line braking here - I don't think anyone expects it to make a difference in a corner).
  11. Flame war in 5, 4, 3, 2.....

    Anyway, got my new bike the other day, gave the ABS a bit of a go on the way home the other day (in a car park, not on the road). Have to say, I was amazed at how hard I could squeeze the front brake without it kicking in (rear was a piece of cake), in fact, I still haven't managed to get it to kick in on the front wheel...

    It got me thinking that perhaps, all this braking practice I've been doing (including that through HART) was very much on the safe side of the traction limit.

    I'm looking forward to giving it a go in the wet when I get a chance....
  12. What bike is it?

    The "E Braking" that is normally done in the HART license courses are really just quick stops. Not too sure about some of their other courses, like the intermediate and advanced rider courses. Pulling up quickly from 20-25 just doesn't constitute an e-brake, as you are much less likely to get the things occurring that would normally occur in a proper e-brake (significant weight transference, wheel lockups etc...) While you CAN lock up a wheel with a full on panic grab of the front brake, I think you'd have to be looking down to really have an issue. They are a good place to start, assuming that you do them using the correct technique. Once you have the technique, I think it's important to understand how to apply that at faster speeds. I don't think you need to do it at 100+km, (I'm sure some will disagree with that) but I think that at around 60km, you get all the key inputs and sensations that you need to understand. While it might be nice to also practice at 100+, getting that kind of speed in a car park is not easy. ;) Once you get the technique right, and understand how your body/bike react at 60 or so, the concept is about the same from 100.
  13. Glad to see I'm not the only crazy one. ;)

    When I got my Tiger 1050 ABS one of the first things I did was set aside some time to test the ABS in different conditions, never having had any vehicle with ABS prior to that point. I wanted to see how it would respond, partly so I knew what to expect and partly to give myself the confidence to trust in the system.

    Dry stop from way north of 100, wet stop from 80, gravel stops from 60, and so on.

    In summary, the Tiger 1050's works well, even on a gravel road. I was particularly curious about the gravel-road performance because of how much toxicity and bile and rumours and misinformation are levelled toward the performance of ABS on unpaved surfaces; wild stories of bikes exploding or never slowing down at all, like that bus in the Keanu Reeves film. I have a suspicion that ABS might misbehave in 'real' offroad conditions, steep rough descents, but for graded roads and paved roads it's fine.

    And I'm not ashamed to say that it gives me the confidence to brake a LOT harder in the wet if I have to, even with how religiously I practiced emergency stops on my VTR250 in all conditions. Dry stops I was pretty good (IMHO), but wet stops were always filled with such trepidation.

    I've posted articles/papers to Netrider illustrating that even the best riders can't stop for shit in the wet, but the anti-ABS brigade seems to focus on the bit about that 1991-vintage ABS stopping 1 metre longer from 70mph in the dry compared to a race rider rather than discussing how even racetrack-bred humans stopped 32 metres longer than ABS in the wet. Lesser mortals took >45 metres more (the length of the test area was 350 feet, 106m; they didn't even stop before leaving the test zone!). That sort of selectivity kinda confuses me, 'cause it ain't the dry stops we have troubles with.

    I think the best part about ABS is giving riders (and car drivers) the confidence to brake as hard as they have to in emergencies rather than pussy-footing around at 50% brake application in fear of a lockup. But I digress.

    You pays your money and makes your choice. I have found that severe road corrugations tend to confuse and enrage ABS on downhill braking areas, which is a point of concern IMHO, but they're not too common thankfully.
  14. hmm. Interesting point about gravel. I hadn't thought about testing that out. I shall give this a go when I get the chance to do so.
  15. Yeah. Gravel has (historically) been an Achilles heel for early-generation ABS, which was very swift to react to a detected wheel slip by releasing the brakes immediately and completely. That's all fine and good on wet asphalt, except braking on loose gravel pretty much involves wheel slip all of the time, and therein lied the problem.

    Newer systems are much much much improved in interpreting the slippage detected and acting accordingly.
  16. Good onya for posting up your experiences Minglis.

    Minglis, just want to zero in on a concept you've repeated several times:
    This is a worthy and commendable goal. Just be aware, if your ABS isn't a slip system, and I don't think it is, then you are NOT reaching the intent of your goal. The ABS is most likely operating BEFORE slip. That means you are not getting a good indication of what it feels like when a bike's tyre begins to slip because the ABS kicks in BEFORE slip. This was shown most clearly in a Canadian ABS bike study where they got ABS'd decelerations to -0.87G's whilst skillful riders exceeded this and got as high as -1G.

    I'll cut Adporm off at the pass, not every rider is capable of the higher decelerations, but the points are: with skill it's possible (and one of your key thrusts is that you still need to be skillful even with ABS) and two, by design, simple ABS isn't designed to provide maximum braking - it's designed to stop a slide.

    That doesn't surprise me in the least. A shocked wheel locks rapidly. What was the braking distance like with these panic grabs?

    In an emergency brake, the amount of required pressure on the rear brake is equivalent to taking a step forward with the right foot, then pressing down with the right big toe. Any more and you're likely to lock the wheel.

    That's a set up and squeeze with proper weight transfer occurring. The ABS should not be activated in this phase. The last bit of your process is a failing in your technique. Your applied pressure is providing more braking than is required for the speed, hence the ABS kicking in. At some point you need to taper off.

    There's rarely ever a need to STOP following an emergency brake. What's more typical is to get down to a maneuvering speed and avoid the hazard. A good ebrake allows for this.

    Couple of excellent points here. Skill and technique is still needed.

    The sensation of falling with the loss of traction is real - how long can you keep a bike vertical while stopped with feet on pegs? 1sec, maybe 2secs when really concentrating? ..when you lose traction, the bike is going to lose it's balance in about the same length of time, but usually less because of the factors you've highlighted.

    You had a fundamental lack of trust in the traction when turning the bike around. You're not alone. Since my wet road spill, I'm way more conservative in the wet.

    What you've JUST DEMONSTRATED (Adprom, take note) is the almost exact embodiment of the Peltzman principle - you have now gained greater confidence in your braking in the wet (a riskier environment) as a result of the technology. There's a good chance you'll ride with less caution or higher speed (in a straight line at least) as a result.

    There are several insurance references I've come across that show cars today have a HIGHER MEDIAN speed in the wet than they used to, and that's been laid fairly and squarely at the technology and safety of modern cars. Adprom is happy to ignore this, but it doesn't change the reality. Pelztman effect.

    Mate, to really round out the picture, if you could repeat the experiment, properly recording distances based on different braking techniques, and then redo on a non ABS CB400 bike (don't do the snap on panic brake though... that will end in tears) we'd have some genuine data... but I know, you were just sharing your experience in the context of your bike and it having ABS.
  17. Good to see some reality in your ABS verbage Adprom. That's almost a back flip.

    Why do YOU need to verify it? There are plenty of references around, even a huge one in the middle of a study you held up to prove your point!! Why are you still denying this effect??

    For someone professing high intelligence, that's a rather obtuse comprehension of the topic.
  18. it's probably terminology, but as written, not quite right. ABS cannot detect a loss of traction. It detects an impending lock up. They are different things.
  19. No, I don't ignore any of it. I just point out that most of the "cons" are overstated. That isn't to say not to be mindful of them, but you have to be pragmatic when you consider real life situations.

    A theoretical best braking distance on a flat dry road which the rider knows well is the absolute best that could happen, and in a panic situation is unlikely to happen.

    P.S. Feeling more confident braking more firmly isn't the Peltzman principle - the Peltzman principle only applies if the rider uses this knowledge and counters it by riding more aggressively. There is no evidence on motorcycles to suggest this is or isn't the case.

    P.P.S - As pointed out previously ABS is a slip system and usually allows up to 20% of differential between wheel speeds before activating. It is simply impossible for it to activate before some slippage occurs given the only data is wheel speed - and it only activates when there is a difference in wheel speed, by which point ABS is activated. I'd like to know how it can detect an impending lockup without wheel slip on the data it has...