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BBS02 keeps rotating the crank arms by itself

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    BBS02 keeps rotating the crank arms by itself

    Hello,

    I have a BBS02 which I bought around a year ago. I have done just over 1000 kilometres without any issues, however now I have a strange (and quite dangerous) problem.

    The cranks keep rotating by themselves, seems like to clutch is not working properly when I stop riding. Currently I need to press slightly the brake levers to activate the magnetic switch whenever I want to stop rotating the cranks.

    Please refer to this video showing the issue.
    https://www.youtube.com/watch?v=nQFn...oDFLixlRTk4-aw


    What do you recommend? What spare parts do I require?

    Thank you.

    kind regards,
    John

    #2
    First check throttle connection, maybe it's 'sticking'.

    Comment


      #3
      Hello, I'm not using the throttle.

      Comment


        #4
        While the bike is stationary. can you back-peddle or is it "frozen"? If you tug the top of the chain backwards, does it move at all (making sure the rear sprocket/cassette isn't frozen).

        If you can't freely back-peddle (bottom bracket axle and pedals rotate backwards, chain ring stays stationary), it almost certainly must be the one-way or sprague clutch, as you surmised.

        On the BBS02 motor, replacing the clutch is involved - see instructions here. If the reduction gear is not damaged, you'll need the clutch and probably the special axle tool.
        BBSHD/BBS02B builds: IGH 1 2 3 4 5 6

        Comment


          #5
          Hello, thanks for the feedback.

          When bike is stationary, after having stopped the "hijacked" crank rotation using the brake lever, and having turned off the battery supply, I can back-peddle. The cassette is not frozen.

          Is it still the case to order the clutch and the special axle tool? Would you also recommend the reduction gear? Though it's quite strange to have such damage after 1.5 kilometres, isn't it?

          regards,
          John

          Comment


            #6
            Originally posted by jsammut View Post
            Hello, thanks for the feedback.

            When bike is stationary, after having stopped the "hijacked" crank rotation using the brake lever, and having turned off the battery supply, I can back-peddle. The cassette is not frozen.

            Is it still the case to order the clutch and the special axle tool? Would you also recommend the reduction gear? Though it's quite strange to have such damage after 1.5 kilometres, isn't it?

            regards,
            John
            I would think then that it is not the clutch.

            I watched your video again - when you hand-spin the pedals and the motor starts up, what happens if you try to stop the pedals by hand?

            I have a bike with a relatively new IGH hub that has some cog drag - it'll do the same thing, as in spin the chain once the motor is started up, which then, by the pedal axle drag in the motor, spin the pedals, keeping the whole thing going. But it'll stop if I stop and hold the pedal still.

            There is a PAS sensor, I believe, but it appears to be working in your case.
            Last edited by ncmired; 01-31-2019, 10:20 AM.
            BBSHD/BBS02B builds: IGH 1 2 3 4 5 6

            Comment


              #7
              Hello ncrkd,

              If I try to stop the "hijacked" pedals by safety shoes (won't dare by hands), it simply kicks hard and keeps rotating. I tried this while the rear wheel is suspended by about two inches from the floor like in the video posted originally. It only stopped when the impact with the safety shoes was hard enough to possibly cause an over-current or some other safety protection that is inbuilt.

              Upon trying again to back-peddle while motor is powered off, I noticed that it does back-peddle, but I can feel some mechanical engagement internally from the motor.

              What do you think?

              regards,
              John
              Last edited by jsammut; 02-10-2019, 10:09 AM.

              Comment


                #8
                Back to the clutch, is my thought.
                BBSHD/BBS02B builds: IGH 1 2 3 4 5 6

                Comment


                  #9
                  Have you checked to see if the chainring is making contact with the crankarm?

                  Comment


                    #10
                    So I finally dismantled the motor, and found a broken tooth in the reduction gear, and also broken pawl clutch. Photos attached.

                    I really surprised and at the same time let down by this as I read very good reviews on the BBS02 before buying it. I had only done just over 1000 kilometres and I really take care not to cause any damage by over stressing the motor. I'm always using maximum power level 3/5.


                    What's your opinion on this?

                    Comment


                      #11
                      Hi did you get your motor fixed? I have a similar issue, PAS would keep going after I stop pedaling, at first it only happened sometimes, then most of the time, now almost always. It only stops when I reduce the PAS to level 1-2. Also now my throttle stopped working and speedometer stays at 0mph with error 21h showing. Just ordered a new controller from Luna. Your post about the clutch concerns me, as I did initially ride the bike a bit hard while learning how to be more gentle with it.

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