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Will a fixie wheel damage my BBSHD or batteries?

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    Will a fixie wheel damage my BBSHD or batteries?

    I have a big heavy Burning Man art bike fitted with a BBSHD that uses a cheap fat tire wheel off a Mongoose Dolomite. When I apply throttle, no matter how gentle I twist the throttle, there is a loud thunk sound from the wheel hub as the motor puts torque on the chain. I think it’s because the wheel hub has a simple 2 paw freewheel clutch with a small number of ratchets. As a load is put on the chain, a bit of momentum is built up on the paws before they slam into engagement. Since it's only 2 paws and a cheap wheel, I’m worried about an eventual failure of the 2 paws after repeatedly slamming them into engagement.

    Starting off with the peddles to initially and gently engage the paws before applying throttle is not an option. The bike is just too big and heavy to start off with the peddles. Also, the slamming of the paws happens if I get off the throttle and coast which causes the chain to stop even while the bike is rolling, then when reapplying throttle, the chain starts up and the paws slam into engagement.

    I tried programming the controller to apply initial torque from the motor as gently as possible. Didn’t help.

    What I’m considering doing is bypassing the wheel’s 2 paw hub clutch by packing it with JB Weld to make it a “fixie” hub. This should be a perfect solution when starting from a dead stop – the paws will be permanently engaged and the BBSHD won’t know the difference. But, what about when coasting? When off throttle while moving, the chain will continue to roll and the BBSHD will keep spinning even with no throttle input. Will this cause any mechanical damage to the BBSHD? If the BBSHD is turning a “fixie” wheel, it seems this will create a regenerative braking system when off throttle coasting. I'm worried about causing damage to the controller or batteries by pumping electrons into the system in the wrong direction.

    Will a fixie wheel hub damage a BBSHD (mechanical or electrical) or my batteries?

    #2
    There is a 1 way clutch between the motor and the pedals to allow the motor to go faster than the pedals. The fixie hub will drive the pedlas at all times and this will drive the motor. The rear freewheel is why mid drives don't have regen. Hub motors over run all the time. Whether regen will "just happen" or not IDK. My advice would put a 3 speed Sturmey Archer IGH in it and make it better.

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      #3
      It won't spin the motor, though, right? Just the gears, as if pedaling with motor off. A one-way bearing clutch in the nylon gear will allow the gears to go faster than the motor, as I understand this drive. I think it would be OK.

      Do note that with a solid rear hub, if that pedal clutch locks up then they could become "feet scramblers". Spinning as with a fixie, perhaps real fast.
      Last edited by JPLabs; 12-10-2019, 10:45 AM.
      Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

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        #4
        I think JPL is right about a 2nd 1 way clutch.. I got it wrong. The 1 way clutch in the pedals will let the chainring run ahead of the pedals. I think all 3 1 way clutches work in the same direction. Axle,pedals, and motor. Shouldn't make much difference. But an old SA 3 speed IGH should be easy to find cheap and willl make the bike 100% better as a bike.Vvery strong hub.

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