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The Value Of Anti-Lock Brakes


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Hello Wrist Twisters,

 

I recently tested two Harley-Davidson motorcycles. The big hog Electra-Glide Classic was surprisingly pleasant and easy to control with proper counter steering. The XR-1200 sport bike, on the other hand, scared the heck out of me when I locked the front brakes TWICE trying to get out of the parking lot! No, I didn't crash, but the bike tried hard to tuck under and throw me off. Yes, this was pilot error (I'm clumsy, I had just come off the Electra-Glide, I THOUGHT I knew what I was doing, I ride a Japanese bike with dual disks, I've got plenty of excuses), but still, it bothered me.

 

Soooo ...

 

... since I've done it in the parking lot, and I've seen Mat Mladin do it on the race track, why don't more riders use anti-lock brakes? I've heard people say, "The most dangerous thing you can do on a race track is brake for a corner." I've seen more crashes from over braking and leaning in than anything else. Would ABS help reduce this? I see why expert riders might turn the traction control off (they want to slide the rear end and have the finesse to get away with it). But with so MANY people toeing in and loosing it at corner entry, I just wonder why ABS is not more popular. Any comments?

 

Best wishes,

Crash106

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I've seen Mat Mladin do it on the race track, why don't more riders use anti-lock brakes? I've heard people say, "The most dangerous thing you can do on a race track is brake for a corner." I've seen more crashes from over braking and leaning in than anything else. Would ABS help reduce this? I see why expert riders might turn the traction control off (they want to slide the rear end and have the finesse to get away with it). But with so MANY people toeing in and loosing it at corner entry, I just wonder why ABS is not more popular. Any comments?

 

Best wishes,

Crash106

Crash;

We may have a number of different thread possibilities with this post. For starters not that many manufacturers offer ABS so that portion of your question may be limited but I may be wrong. Anyway I know that BMW does offer ABS and I believe that Honda has selectively offered it (don't quote me on that one) but most bikes leave it to their riders to figure out how to stop them.

Also Traction Control is another electronic enhancement that is different and separate from ABS. Traction Control measures wheel rotation speed against engine rpms (if I understand it myself) and makes an electronic adjustment to the ignition (similar to the rev limiter) if the differential in their relative speeds gets out of a predescribed range. You are correct that many pros dial down their TC but most who have it still use it.

The third piece of you post that I infer is a comment about trail braking - the process of tapering off the brake AFTER a rider initiates turn in. That one gets beaten around here and other Forums alot.

Now I may get clobbered for my complete misunderstanding of your post or the technical accuracy of my response but se la vie!

 

Rain

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For starters not that many manufacturers offer ABS so that portion of your question may be limited but I may be wrong. Anyway I know that BMW does offer ABS and I believe that Honda has selectively offered it (don't quote me on that one) but most bikes leave it to their riders to figure out how to stop them.

The "Big Four" (Honda, Kawasaki, Suzuki, and Yamaha) all offer ABS on some of their models - at least here in Europe.

While most of the bikes offered with ABS are in either the street/basic-bike or the super-tourer segments, Honda offers the CBR600RR and the CBR1000RR in both ABS and non-ABS versions.

Off the top of my head, I can only remember Triumph, along the other brands, as delivering ABS-shod models.

 

So yes, ABS is slowly being delivered on more and more bikes.

 

As to reasons: there are multiple, in my opinion.

* I read that BMW is now on their 7th generation of ABS. Up until the 2009 generation (or so), a good human operator could easily beat the ABS system on stopping distance, on dry pavement & good conditions. That applies for all the ABS systems more than two or three years old, actually (I've seen most of them as instructor at the DMC safety courses here in Denmark). With the latest generation, the ABS beats the human even on dry pavement (in the wet, ABS wins hands down).

*What we have also seen, is a reduction in weight: BMW's system on the S1000RR weighs in at 2.5kg (5.5lbs), whereas older systems would add up to 10-15kgs (22-33lbs).

* Conservatism within the rider community, and possibly a bit of unneeded heroism among the sports bike riders: "I don't want something between me and the bike", or even "I don't want X pounds of dead-weight added to my bike".

 

What I expect to see over the coming few years is that all the bigger brands will figure out how to deliver low-weight, "super-human" ABS systems, which will proliferate to most/all models.

 

That being said, I still believe that we, as riders, need to learn how to brake optimally, both with and without engaging the ABS system, since the ABS system CAN fail to provide the anti-locking effect - and that's where you really want to brake correctly.

 

Now, enough of my ramblings...

 

 

Kai

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Even on a dry road, without the ability to test for traction first, you will not find (m)any rider able to beat even an older ABS system during the first panic stop from speed. Especially under stress, that is in a panic situation. Add varying friction levels and even generation 1 ABS systems have clear benefits, although most experience riders could beat these in a controlled environment.

 

But as you mentioned, conservatism is probably the main reason why ABS hasn't begun to penetrate the market until recently. In Germany, however, I believe there are now more bikes sold with ABS than without - and within 5 years it will probably be very hard to find street bikes without ABS.

 

World class racers will, however, likely still ride and drive without this aid, although it's hard to see why - many current road bike ABS systems are set so that if there is grip, the bike can still flip over forwards with ABS interfering. Honda and several others have opted to prevent the rear from leaving the ground, helping the rider prevent the somersault at the cost of slightly longer stopping distances. BMW seems to be the current leader in the ABS technology war.

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Even on a dry road, without the ability to test for traction first, you will not find (m)any rider able to beat even an older ABS system during the first panic stop from speed. Especially under stress, that is in a panic situation. Add varying friction levels and even generation 1 ABS systems have clear benefits, although most experience riders could beat these in a controlled environment.

ABS systems surely have their benefits, but I fear you are putting far too much trust into the 1st and 2nd generation ABS systems. The first couple of ABS generations would not be able to save you from crashing, if you locked up the front wheel while leaning.

 

Trust me on this one, I have seen too many beemers with these systems doing braking exercises, and their owners will readily agree to the 1st/2nd generation shortcomings.

 

Regards,

 

Kai

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Oh, I agree with you that the early systems had their flaws, be that from BMW, Yamaha or Honda. Still, so does the majority of humans. Close to a decade ago, MOTORRAD compared riders of various levels of experience and skill to perform emergency stops on a test track. Not one got close to .8 g during their first stop, most were significantly worse than that. They also did a mountain ride and very few braked harder than .5g at any point, despite riding at a brisk pace, and .7 was the maximum reached. Hence even early ABS would assist most riders when under stress.

 

I remember Cycle magazine did a group test of ABS bikes around 1990. They rode back in the rain. Those riding ABS equipped bikes left the ones in the company without that aid behind, feeling confident that they would not risk a locked front as long as the bike was close to upright regardless of the road conditions. Current ABS systems are miles better, hard even to compare. For instance, a couple of years ago MOTORRAD failed to match the ABS stopping figures on the K1300R when they turned off the system, despite using their best rider and getting many attempts. But even the old ones would more often than not - in real road riding situations - beat their human operators.

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  • 3 years later...

Found the test, printed in issue 17/2009. And it wasn't the K1300R, but the K1300S. Here are the results, all averaged from 3 stops with ABS chattering.

 

Dry track

K1300S: 36.5 m = 10.6 m/s2

SL750 Shiver: 36.6 - 10.5

GSX650F: 38.9 - 9.9

XJ6: 39.7 - 9.7 (all 3 above better than 1G)

1400GTR: 40.7 - 9.5

Fireblade: 41.0 - 9.0

Tiger 1050: 44.0 - 8.8

 

 

Bad and bumpy track solo (two-up)

K1300S: 43.7 m (45.8) m

SL750 Shiver: 47.6 (47.6)

GSX650F: 52.6 (53.3)

XJ6: 53.7 (51.2)

1400GTR: 55.2 (56.0)

Fireblade: 48.7 (55.6)

Tiger 1050: 51.1 (53.2)

 

 

Wet track

K1300S: 41.0 m = 9.4 m/s2

SL750 Shiver: 39.4 - 9.8 (one G)

GSX650F: 42.8 - 9.0

XJ6: 43.5 - 8.9

1400GTR: 43.8 - 8.8

Fireblade: 41.8 - 9.2

Tiger 1050: 45.4 - 8.5

 

 

According to the article, when leaned over 35 degrees, you still have grip to reach 70% of upright braking performance.

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