Looking for ABS wisdom

[jfstein]

This past weekend I was following about 100 yards behind my riding partner when suddenly someone cut in front of him and forced a full-on panic stop. My friend was successful, but it was exciting (scary) from my vantage. What I witnessed was the sudden appearance of huge clouds of tire smoke and my friend working mightily to stay in control. With a lot of body english he managed to stay upright, avoid an impact and ride on. Good work!

In discussing this later, I remarked that's why I am happy that my ST has ABS. He pointed out that his big Yamaha Roadstar DOES have abs and he had felt it working. This has me wondering... should abs allow for such tire sliding? Is this normal abs behavior in a panic stop at 60 mph? Do I need to rethink my own comfort zone? I would have thought there would be a very minimum of tire slide - this was substantial.

Any insights would be appreciated.

John S.

 

[RichKirk]

if ABS is working correctly tire will not stop turning, even if on ice much less pavement, unless the tire was moving perpendicular to the axle (sideways) on the ground , you should never see tire smoke when braking

 

[Snave]

Hmmm - I thought ABS makes the brakes pulsate on and off - so for the brief time they are "on" smoke could be generated if they are "on" hard enough to stop or slow down their turning...

 

[bobframe]

Don't know the answer to your question, but I'll share something I picked up during my son's (auto) driver training class. The instructor told us that ABS brakes will not stop you faster than non-ABS brakes. Their primary advantage, in his mind, was that it permits the driver to continue to have use of the steering wheel while in a panic stop.

This doesn't really apply much to a motorcycle, I guess.

To your question, I would not think that ABS brakes should ever lock up...whether on snow, ice, wet or dry pavement. But what do I know?

 

[sennister]

Keep in mind that every bike company implement ABS differently. What a Yamaha uses is different than a Honda. Heck between different models of Hondas you get different ABS so brand doesn't mean much. I have had my ABS kick in a couple times and didn't see smoke. Once was while doing drills when I hit a sandy spot in a parking lot, another under hard braking when someone made a left in front of me. It pulses but it is very smooth from what I noticed. Overall I am impressed with the system on the 1300.

Heck I have even activated it on my driveway beding in new pads. I say find a closed course and test it out.

 

[FJRHank]

John, why not do what we should all be doing? regularly? practice panic (emergency) braking? You know, if you practice it, you'll be a lot more likely to be able to accomplish it when needed? right?

the thing about hard braking is, if you don't practice it, you probably won't be able to squeeze those brakes as hard as needed to stop before the crash, you won't have the confidence.

my fjr has abs. I've practiced hard braking many many many times on dry pavement. that bike will stop on a dime, when it's dry, before the abs will engage. I've not yet been able to engage the abs.

all any of us should really be caring about is our own bikes, because they aren't all the same. the systems, how they work, tires, etc etc is different. practice practice practice!

okay, I just fell off my horse, I'll be okay though

 

[Blue STreak]

Sigh. Not this discussion again.

Rather than rehash the argument over ABS, just understand this: A motorcycle is not a car. Locking up the tires on a car may indeed stop you faster than ABS. Locking up the tires on a motorcycle will put you on your . Rapidly. Which, I guess, is one way to come to a stop, but probably not the preferred way.

As for the lockup, older technology ABS systems could only pulse the brakes maybe 4 to 6 times a second. You could get very brief periods of lockup during the cycles. But even then, not enough to generate huge clouds of smoke. Modern systems can pulse the brakes up to 100 times a second, and you shouldn't ever get real lockup.

Assuming that it really was working, I'm trying to think about what might have happened. Was he leaned over when he had to hit the brakes hard? A motorcycle ABS system won't keep the tires from sliding (sideways) if the ABS kicks in. It will keep the wheels from locking, but you can still exceed the limits of traction because of the lean angle.

 

[Mellow]

Sigh. Not this discussion again.

Nothing at all wrong with discussing this subject, it's very much on topic.

Perhaps, the system wasn't working very well. On my past wing, I could feel the system working when I used it on gravel.. it would cycle and skid-let loose-skid-let loose. Possibly there was some gravel or something on the road that overwhelmed the ABS on that bike? Or, it was actually malfunctioning? I don't know anything about the ABS for that bike, sounds strange but would it only be on one wheel?.. maybe a damaged sensor or sensor ring?

 

[jfstein]

My apologies if this falls in the category of oil threads. I do understand the technological evolution of abs from the various large aircraft I flew for 35 years - but that experience is not the same as for a skinny two-wheeler with my precious butt perched on it.

I really was looking for some practical considerations like I'm already getting:

All systems have somewhat different design features
Contamination on the roadway
Lean angles
Lateral motion
Continued control during the stop
Possible system malfunction
and of course, the great advice to practice more.

I have personally felt mine pulse on gravel stops at pretty low speed. I have made some very hard application stops on dry pavement in practice, but at 30 mph or less - not from highway speeds. Are there some cardinal dos and don't s? Apply max brakes and DON't let up in the middle? or use hard and THEN max? or are there other recommended variations? I just don't know. My inclination would be to remain in max apply and let the abs do its thing.

As for my friend's experience, I saw some wobbling and from what I've read above, maybe that caused all the smoke (lateral movement). If so, would you think wobbling was normal, rider mis-technique, or abs malfunction. Its probably hard to tell for sure.

Anyway, I appreciate the thoughtful responses I've gotten.

 

[sennister]

A gradual increase to max braking power is best and will result in a likelyhood that ABS won't even kick in. That is advisable non-ABS bikes as well. I wouldn't let up in the middle but that isn't to say that you should never do that. Talking hypothetically means you cannot cover every situation. Maybe there is a reason to release or lessen braking power mid stop. For instance on my non-ABS 1100 I had to brake hard when a car slammed on her brakes and stopped short for no reason. I couldn't stop quick enough so I released braking pressure to swerve to a position where I was lane splitting. Once repositioned I applied full braking power again stopping about even with the driver's door. With ABS on that bike I could have stayed on the brakes harder and would have stopped sooner. Though with the better brakes on the 1300 I wouldn't have had to swerve either.

Bottom line I don't ride my ABS much differently than my non ABS. The only difference is that I will brake using all 4 fingers on the ABS and only my index and middle finger on the non ABS as I don't want to apply as much braking power.

 

[wjbertrand]

Having witnessed and participated in a number of maximum braking tests with the MCN guys, I've never seen an ABS equipped bike do anything dramatic at all and never any tire smoke. Can you say boring? Even the original BMW systems with the slow 4 cycles/sec rate (I think most modern systems cycle between 15 and 20 cycles/sec) would not smoke the tires. Sounds like your buddy's bike does not have a properly functioning ABS system.