Gear shift sensor alternative

TwoTired

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My 7 speed ebike with a BBSHD and shift sensor worked OK down shifting, but when upshifting the motor turned back on before the shift was complete with the smaller sprockets. I think this happens because upshifting is done by spring action and so is slower than cable pull.

As far as I know the off interval of the gear shift sensor is not programmable so a few weeks back I decided to try something like the front freewheel system (FFS) Shimano made back in the 1970s. Shimano used a rear freewheel with increased friction that kept the drivetrain moving so shifting can be done while coasting.

The BBSHD has a chainring freewheel so all i needed to do was increase the friction in the rear freewheel. To do it I used a piece of cardboard wedged between the sprockets and the chain guard (see photo). The cardboard interfered with the large sprocket but I was careful not to use it during the first 20 mile run. It took a while to get used to shifting this way. Stop pedaling, shift and resume pedaling is something you just don't do with a BBSHD. Shifting went smoothly, without nasty sounds coming from the drivetrain. Since then I've replaced the cardboard with a piece of flexible plastic pushed farther down so I can use first gear.

To test the system, all anyone has to do is wedge a piece of cardboard as in the photo. For those who try it and decide it works for them I have set a web page with instructions and photos for a more permanent system at http://lce.org/ebikes/ebike-shift.html .
rear-freewheel.jpg
 
My 7 speed ebike with a BBSHD and shift sensor worked OK down shifting, but when upshifting the motor turned back on before the shift was complete with the smaller sprockets. I think this happens because upshifting is done by spring action and so is slower than cable pull.

As far as I know the off interval of the gear shift sensor is not programmable so a few weeks back I decided to try something like the front freewheel system (FFS) Shimano made back in the 1970s. Shimano used a rear freewheel with increased friction that kept the drivetrain moving so shifting can be done while coasting.

The BBSHD has a chainring freewheel so all i needed to do was increase the friction in the rear freewheel. To do it I used a piece of cardboard wedged between the sprockets and the chain guard (see photo). The cardboard interfered with the large sprocket but I was careful not to use it during the first 20 mile run. It took a while to get used to shifting this way. Stop pedaling, shift and resume pedaling is something you just don't do with a BBSHD. Shifting went smoothly, without nasty sounds coming from the drivetrain. Since then I've replaced the cardboard with a piece of flexible plastic pushed farther down so I can use first gear.

To test the system, all anyone has to do is wedge a piece of cardboard as in the photo. For those who try it and decide it works for them I have set a web page with instructions and photos for a more permanent system at http://lce.org/ebikes/ebike-shift.html .
rear-freewheel.jpg
You might try slightly activating one of the brake levers, assuming you have motor cutoff switches in your levers, this will cut the motor to allow the gear change to complete.
 
You might try slightly activating one of the brake levers, assuming you have motor cutoff switches in your levers, this will cut the motor to allow the gear change to complete.

Thanks, I was using that before adding the wedge. I still use it when I don't want to stop pedaling to shift, like halfway up a steep hill.
 
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