Automatic stability Control (ASC) - BMW F800 Riders Forum & Registry



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  1. #1
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    There are several previous threads regarding ASC (some going back quite a few years). None adequately answer the the question I'm about to ask. First a little background. Several days ago while out for ride, I came around a fairly tight corner (advisory speed warning sign said 35kph), part way around the rear end slid sideways. Maybe a damp surface or perhaps a bit of oil, I didn't go back to look. It took all my 50 years of riding experience (many as a riding instructor) and a bit of luck to stay shiny side up. During the whole episode, neither the ABS nor ASC activated. Should they have? I can think of a number of reasons they may not have. 1. The ABS compares the rotational speed of both wheels, activating if it senses a difference. If the rear was sliding sideways, is it possible that both wheels were still rotating at about the same speed? And before anyone asks, I tend to drag the rear brake and keep constant throttle on entry to slow speed corners.....helps pull the bike into the turn. 2. The ASC was turned off. The ASC on/off is activated by the same rocker switch as the electronic suspension control. I had been experimenting with the suspension settings during the ride but I'd assume if I had accidently turned the ASC off, I'd have a flashing warning sign on the display. 3. I assume that the ASC uses the same comparative wheel speed as the ABS, so my number 1 reasoning would apply here too. When I arrived home I hooked up the trusty GS-911 and checked for faults and found none. Checked that the ASC was in fact "on".....it was. Am I expecting too much from the system or was the situation beyound the parameters of the system?

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  3. #2
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    By the sounds of it, the slide wasn't caused by power so the ASC wouldn't be activated.

    My guess is as you were dragging the rear brake is it was a small lock up, and you either slightly released pressure which allowed the wheel to start turning again or the surface became grippy enough for the tyre grip to overcome the force of the brake. Whcih is why the ABS didn't intervene - i find the ABS is not overbearing and does allow some lock up before it intervenes.
    BMW F800ST, 2010, Black, Fuzeblock, Sat Nav, BMW Tank Bag, Givi Touring Screen, Denali Spotlights, Denali CANSmart, Wunderlich Crash Bars, 55K Miles & counting 

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    Agreed , as the slip was likely caused by lack of grip rather than too much power its unlikely to intervene.
    Same with ABS, the wheel might have been slipping but likely it was still rotating sufficiently not to activate the ABS.
    One thing I have found while partaking in Slow Speed Skills day is that the ACS (traction control) can catch you out and stall the engine. If one is slipping the clutch and controling the bike with the back brake to get round cones the bike cant tell the difference between rear wheel slip and clutchslip if the clutch switch has not operated.
    During one session I kept stalling until I realised and turned ACS off. I had no further problems.
    The instructor cried "bollocks!" until he tried it and yes he stalled it with ACS on, ok with it off.
    The clutch adjustment and switch adjustment are correct but I dont know what version of ECU software the bike is running.
    I havn't noticed a problem "on the road" it only showed up during training manouvers.
    F800GT in blue known as "The Blue Bat"
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    Dave, how far were you leaned over in the corner? As far as I'm aware, the GT has straight line ABS/traction control only. More complex systems have an inertial measurement unit (IMU) which can detect angles of roll, pitch and yaw. Without the IMU, the traction control and ABS cannot detect and then intervene to arrest traction loss that includes a lateral slide. Last year my traction control intervened but the bike was upright. I was approaching a T-junction at moderate speed when a copper signalled me to slow down even further because there was a diesel spillage at the junction. At the junction I stopped and put my feet down but my feet started slipping, so I quickly put on power to pull away. The back wheel started to slip on the diesel and the bike commenced moving sideways. The traction control reduced power to the back wheel (big flashing light in the dash) and I was able to move away slowly without dropping the bike. It was a scary moment though.
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    Glad you stayed shinny side up. Moments like that are a little un-nerving when they occur, even small slips at relatively low speeds can feel like full on "speedway slides" when you're not expecting them.

    Not wanting to teach you to suck eggs here just curious. What condition are the tyres in e.g. tread depth, pressure and anything leaked onto the tyre surface?

    Ride safely.


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    Thanks for your opinions folks. DJ123, I agree with your summation. As it was afairly tight corner I only had very light throttle input, so unlikely enough to trigger the ASC. With any rear slide induced by braking when leaned over, letting the rear brake off gradually is essential if one wants to avoid a "highside". Years of practice have probably meant I did this more or less instincively.....hence no ABS reaction either. Bogbody, interestiing commment of the effect on low speed manoeuvers. I'm going to go out and try it. Right Hand Drive, that's the conclusion I've reached. Works as intended in a straight line, cornering and leaning are outside its parameters. I wonder though, would the ASC activate if,say, one had the power on UP a twisty road, and the rear stepped out going around a sharp corner? If it suddenly cut power (does it, or does it just reduce power), would one be likely to highside? Theoretical questions I know but ones to ponder.

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    My understanding is that BMW's traction control system, which I have on my R12RS, only helps with cutting power if the rear tire slips under acceleration. It will not help when cornering and the tire starts sliding sideways. However, the latest "Cornering ABS" systems will cut braking power if needed when trying to brake while cornering and one or both tires start to loose traction as the brake is applied. I am not at all sure that even that system will help if both wheels start sliding sideways and will not activate at all unless the rider is actually braking. The rider continues to be at the mercy of the elements and continues to need the use of his or hers Mark 1 brain cells and riding experience, no matter how many electronic programs are packed into BMW's expensive, extra-cost, firmware downloads on their latest models.
    Richard - Current bikes: 2016 BMW R1200RS, 2018 16.6 kWh Zero S, 2011 Royal Enfield Bullet 500 Classic, 2009 BMW F650GS, 2020 KTM 390 Duke, 2002 Yamaha FZ1 (FZS1000N) and a 1978 Honda Kick 'N Go Senior. 

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    Richard. +1 on the use of the brain cells. Although I've had the GT five years, it is the first bike bike I've owned with all the bells and whistles. I think over that time I've subconsciously started to rely on the ABS and ASC.....the old "she'll be right, if I stuff up the bike will save me" syndrome. The other day's ride was a bit of a wake up call to start thinking like rider again. Thanks for your input.

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    That is something that we all need to keep in mind while riding.

    One of the things that concerns me is the amount of information displayed on the new TFT TV screens that are now being installed on the latest motorcycle and car models. Looking at those things can be distracting, especially when they use small print and symbols. And adding the ability to receive and answer cell phone calls while riding also is likely to not help anyone's concentration and safety.
    Richard - Current bikes: 2016 BMW R1200RS, 2018 16.6 kWh Zero S, 2011 Royal Enfield Bullet 500 Classic, 2009 BMW F650GS, 2020 KTM 390 Duke, 2002 Yamaha FZ1 (FZS1000N) and a 1978 Honda Kick 'N Go Senior. 

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    The screens aren't 'in your face' so I don't mind. I have to actively look down at it for it to be a distraction, if I'm just riding along then it's out of sight, out of mind. As for the phone controls, devil's advocate here - People are going to put phones on handlebar mounts and F with them anyways, it can be argued that to allow them to do this without taking their hands off the bars is actually a safety feature.

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    Richard. I was driving my daughters late model car the other day and needed to turn the heater down. No tactile knob or slider that I could reach out and feel for while not taking my eyes off the road. Oh no....a tv screen way out my line of sight with, as you say, weird little symbols. Not wishing to be unsafe I pulled over to alter the heater settings. Such is "progress"

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    Quote Originally Posted by Redned View Post
    Richard. I was driving my daughters late model car the other day and needed to turn the heater down. No tactile knob or slider that I could reach out and feel for while not taking my eyes off the road. Oh no....a tv screen way out my line of sight with, as you say, weird little symbols. Not wishing to be unsafe I pulled over to alter the heater settings. Such is "progress"
    That is one thing that I really appreciate with my 22-year old Saturn. Everything is activated by either easy to reach buttons or sliders which don't need you to look at to operate once you get a feeling for where they are located on the dash. I might also add that my car has roll-up windows, so that is one more thing that won't break and then you find out that the electronic parts are no longer available. If the crank device ever does wear out (very unlikely), it is off to the junk yard for a replacement.
    Richard - Current bikes: 2016 BMW R1200RS, 2018 16.6 kWh Zero S, 2011 Royal Enfield Bullet 500 Classic, 2009 BMW F650GS, 2020 KTM 390 Duke, 2002 Yamaha FZ1 (FZS1000N) and a 1978 Honda Kick 'N Go Senior. 

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    Quote Originally Posted by Redned View Post
    Richard. +1 on the use of the brain cells. Although I've had the GT five years, it is the first bike bike I've owned with all the bells and whistles. I think over that time I've subconsciously started to rely on the ABS and ASC.....the old "she'll be right, if I stuff up the bike will save me" syndrome. The other day's ride was a bit of a wake up call to start thinking like rider again. Thanks for your input.
    The bike with the bells and whistles is the new model F800GT...... which is made by Yamaha rather than BMW. The Yamaha 9GT has a 6-axis gyro which really will do something, within its limits, when you are not going in a straight line. The system in the F800GT is quite unsophisticated in comparison.

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    You're describing the new F900XR and F900R bikes too, the Riding Modes Pro option includes an IMU.

  18. #15
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    I'm no luddite, and like of most advances in car/bike technology. But there always seems to be a situation that the programmers/designers missed or didn't think about. All these ABS, ASC, Cruise control etc tends to make riders/drivers mentally lazy (as I was). As Richard says, there really is no substitute for brain cells when the s**t hits the fan.

  19. #16
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    My thought is that all of the electronic bells and whistles are nice, but your best bet is to pretend that they are not there and ride accordingly. If you make a mistake and the electronic programming and safety technology corrects the issue then all is good and you are fortunate that your new bike has them. But if you ride like you are on an old-school motorcycle like an old BMW air-head you might never need those safety enhancements.
    Richard - Current bikes: 2016 BMW R1200RS, 2018 16.6 kWh Zero S, 2011 Royal Enfield Bullet 500 Classic, 2009 BMW F650GS, 2020 KTM 390 Duke, 2002 Yamaha FZ1 (FZS1000N) and a 1978 Honda Kick 'N Go Senior. 

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  21. #17
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    Again, devil's advocate - Until a deer runs out in front of you

  22. #18
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    It did bring up a theoretical question in my mind. If you are on both the brake and the throttle...and the rear wheel slips...which would activate? The ABS or the ASC?

  23. #19
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    Swamp Fox. My guess is that if you were travelling upright in a straight line, it would depend on which control was delivering the most control. By that I mean, if the trottle was delivering enough power to overcome the retardation of the rear brake (causing the wheel to rotate faster than the front wheel, then I assume the ASC would activate. If the brake was being sufficiently applied to overcome the drive imparted by the engine (slowing the rear wheel relative to the front), then I'd assume the ABS would activate. In the case of my original post, I was lightly dragging the rear brake and applying light throttle at the same time. There was therefore a "balance" of inputs and the ECU (or whatever unit works these things out) felt no need to intervene. Add to that the bike was sliding sideways, which from most of the advice posted here, is beyond the system's parameters. I'll stick to using brain cells in future, and hope that should I get into a situation that is beyond my ability to cope that all the "bells and whistles" do their job!

  24. #20
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    The newer BMWs having both ABS and DTC 'on' and trying to push them against each other will result in an ABS error, it's mentioned in the user manual. For the sake of this discussion, DTC is ASC with the addition of the IMU functionality. The error won't clear until you power cycle the bike and I'd suspect that ABS will be disabled while the error lamp is lit. Furthermore, if it's detected that you are 'emergency braking' and accidentally twist the throttle, or are holding the throttle open more then 5% during emergency braking, the throttle input will be ignored until the emergency braking condition is no longer detected. I'm not sure what the threshold is for this, but I know that the IMU does monitor braking G's

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