ABS off road??

Discussion in 'The Perfect Line and Other Riding Myths' started by Nevada, Aug 26, 2013.

  1. eatpasta

    eatpasta Lawnmower Target

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    its just as simple as when you want to stopoff road, the tires need to dig by locking up. Every time the tire starts to slow down or skid, the ABS kicks in a prevents the skid thereby making it nearly impossible to even slow down in the dirt or ice. just imagine applying the brakes and essentially nothing happening aside from the noise of your ABS cycling like crazy.
    If you're going down hill, this can become extremely dangerous, very quickly..... especially with a 750 lb bike
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  2. Bob59601

    Bob59601 Bob59601

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    Yep and it is simple to do. At least it was on the 990.

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  3. Andyvh1959

    Andyvh1959 Cheesehead Klompen

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    I used to work directly with Bosch ABS systems development engineers on heavy trucks back in the late 80s early 90s. Although it was on trucks, the control principles of ABS are fairly uniform for railway, airplanes, cars, trucks and motorcycles. It all has to do with how much predetermined slip/wheel lock is programmed into the ABS controller, how qucikly the system can "cycle" the brake on any wheel on/off, and how quickly the wheel/tire being braked can "speed up" after the ABS brake control is released.

    That last part is called hysterisis: the time delay for a slowed/stopped wheel to spin back up to vehicle speed before ABS control is applied again. A good comparison is a large truck wheel/tire assembly compared to a motorcycle wheel/tire assembly. Obviously, the truck wheel/tire has much higher hysterisis because of its higher mass.

    In ABS control, on loose surfaces the system expects the wheel assembly to spin up faster than it actually does (like a tire plowing into sand or gravel, creatng a "dam" in front of the tire). But the tire does not spin up to speed, and ABS control then holds OFF brake pressure until the tire spins up. Like shown on that video, the bike had little or no braking down hill. In the case of loose surfaces that can "dam up" in front of a tire it is better to turn off the ABS control so the rider still has braking control. Generally speaking, on loose surfaces the vehicle speed is lower than on paved surfaces. That is why it is best to turn ABS off, when going off road.

    ABS control on just the rear tire is also not a good idea on loose surfaces like sand, gravel etc. The downhil example on dirt is the best proof. Downhill on dirt is often best done by dragging the rear brake, sometimes to purposely lock the rear tire, to ride the dam of material ahead of the tire. Also, quite often on loose surfaces, its a good technique to lock the rear tire to bring the back end out or "back it in". With ABS control on the rear tire this can't be done either.

    Also, like I said earlier, ABS control expects a wheel to speed back up once control is initiated. If the tire on ABS control dams up material, and the ABS cycles the brake off, but the wheel delays in spinning up because the "dam" is restricting it, the ABS may sense this as a fault condition and shut itself off and initiate the ABS warning lights. Again, to avoid a false system error, it is better to turn off the ABS for loose surface conditions.

    To the comment "wire in a switch to turn it off", be careful how this is done. It "may" turn the system off. But it may also trigger an ABS fault mode. Then when back on the road, it would require resetting the system to clear the fault. Not as simple as just wiring in a switch on the ABS power lead.
    #23
  4. btao

    btao RIP Lilolita

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    Well said. That makes sense that part of the logic is to make sure the wheel is traveling at the speed of the ground before reapplying the brakes. If it doesn't happen fast enough, you simply won't slow down.
    #24
  5. OrangeYZ

    OrangeYZ Been here awhile

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    Chances are, turning off your ignition key will deactivate the ABS system and you can lock'em up all you want. Works for my Tiger 800XC.
    And if you're going down a hill like in the video, you don't need or even want the motor on anyway.
    #25
  6. Bob59601

    Bob59601 Bob59601

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    Indeed a fault code is thrown until I cycle the ignition off and then on. I fail to see the problem here. Am I missing something? :ear

    My bike does have an ABS overide switch, however if the bike stalls the ABS is reset and I almost never remember to hit the switch again. When using the bypass the ABS is off until I decide to turn it back on.


    #26
  7. jachard

    jachard Been here awhile

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    Someone posted earlier regarding washboard on dirt roads... This is a huge reason to turn ABS OFF. My 2012 BMW won't stop at all with the ABS on in washboard so that negates the old vs new ABS question.

    My simple rule is as follows:

    Pavement=ABS ON
    Fire road to singletrack=ABS OFF

    It's that easy.

    Cheers, James
    #27
  8. DAKEZ

    DAKEZ Long timer

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  9. DAKEZ

    DAKEZ Long timer

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    ^^^^^ This
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  10. tkent02

    tkent02 Long timer

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    Nope, the brakes don't work regardless of tire choice.
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  11. tkent02

    tkent02 Long timer

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    It works on the F800GS, too.

    The one time I needed to do this, I didn't have a spare hand to turn the key for a few seconds. Steep hill, got up quite a head of steam in those few seconds with absolutely zero braking....

    Plowing a dam of dirt in front of the tire isn't it, at least not always. It happens in solid rocks as well as hard packed washboards. It's just that the tire is not contacting the ground firmly, like in between rocks or washboards, the ABS detects this lack of traction and releases the brakes completely. You feel it in the levers. Like I said, ZERO brakes at times.
    #31
  12. Icecold Dan

    Icecold Dan Been here awhile

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    I skimmed and didn't read through all the posts, but I can tell you that I spent the last 4 days riding over 400 miles of gravel is the Cherokee, Nantahala, and Pisgah National Forests on my Super Tenere, and not one time did I wish I was able to switch off the ABS. It worked flawlessly in every situation I asked it too. Steep up and down hills, loose gravel, hardpack, mud and wet clay. Don't listen to the BMW crowd. Maybe theirs doesn't work, but Yamaha nailed it.
    #32
  13. DAKEZ

    DAKEZ Long timer

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    Turn it off and it's even better. :deal
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  14. Jacl-Kampuchea

    Jacl-Kampuchea Booze Merchant

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    I'm biased. I don't like my CAR to have ABS. All of us have a built in ABS system, called our brain. Learn proper braking and practice regularly, then it gets better.

    I probably wouldn't buy a bike that I could not permanently disable the ABS on. I have driven a number of bikes with ABS, and I do not like it, as it's very tricky to find a braking limit when a computer decides where it is for you.
    #34
  15. Animo

    Animo Been n00b awhile

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    Have you tried the Tenere off road with the ABS on as well as off?
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  16. Pantah

    Pantah PJ Fan from Boston

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    I can't imagine wanting a system that can automatically turn off my brakes. Certainly not trail riding. I've never had a motorcycle with ABS but I would never pay extra for an ABS system. I like working my brakes on and off road, track or street. It's part of the fun of riding a motorcycle. Maybe if I rode a Gold Wing or something, but my bikes are all sporting machines.
    #36
  17. NateLePain

    NateLePain Long timer

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    I've ridden many dirt road miles with my ABS on and many miles with the ABS off. I've been riding with a group and just simply forgot to turn the ABS off but I've learned to adjust. I found myself engine braking more often to help control my speed. My brakes worked fine for most of the stuff, so long as I wasn't running excessive speeds. For me, killing the engine is a last resort. I have 61K miles on my '06 F650GSA.

    If you want an unsolicited opinion, read the "Angola It's Not Like They Said" ride report. Some of these guys grew so tired of turning the ABS on/off of their BMW Dakars, that they just left it on. It's a fascinating ride report and well worth read.

    As an aside, a simple way to "turn off" the ABS, on an F650, is to move the sensor away from the wheel. The ABS light will glow but the ABS won't kick in. I did this on my last DS ride and it worked great. I zipped tied the sensor to behind the fork leg, pretty much out of harms way. I know, it's not a perfect solution but neither is my well ridden F650.

    nlp
    #37
  18. DAKEZ

    DAKEZ Long timer

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    Yes. Granted it was not for very long but you can trick the Super Tenere into the ABS off mode. If only they had put a proper Chain final drive on the thing I may even own one. :1drink
    #38
  19. Icecold Dan

    Icecold Dan Been here awhile

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    Do you know why people stopped wiping their asses with the Sears & Robuck catalog?
    I'll tell you why, they found something that works better, that's why.
    #39
  20. Andyvh1959

    Andyvh1959 Cheesehead Klompen

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    Its not that the ABS is turning the brakes "off" at any given time, it depends on what the ABS system is sensing with info from the wheel speed sensors. Putting it real basic, ABS tries to keep the wheels turning at all times within a speed differential thresehold, some wheel speed percentage slower than the actual bike speed. When I was working with Bosch, the differential was 20%, meaning for a wheel with the brake applied, if ABS sensed that wheel going more than 20% slower than the vehicle speed, ABS brake control is engaged until 1)the wheel speed matches the vehicle speed, or 2) the operator realeases the brakes.

    So, any situation, WHILE braking, if a wheel remains turning slower than the thresehold value, ABS will engage/maintain control. A wheel sliding on pavement, asphault, concrete, dirt, gravel, sand, mud can cause ABS to engage. But moreso on a bike than a car, a wheel in the air, while brakes are applied even minimally, can slow the wheel beyond the thresehold very quickly and ABS will engage to release that brake. As long as the wheel does not speed up to match the vehicle speed, ABS control is engaged/maintained.

    It gets real interesting if the bike also has ABS integrated into stability control, like it does on the later model GS. Stability control means the ABS is used to maintain tire contact, inhibit stoppies, etc. If the ABS senses the rear wheel is going slower than the thresehold value due to that wheel being in the air, ABS stability control releases the FRONT brake to bring the bike down. That is why ABS on a bike with stability control, in areas that can cause the rear wheel to go airborne (like over rocks) should also be shut off.

    Perhaps the Yamaha Tenere doesn't have stability control and that may be why it works better off road.
    #40