jateureka said:
I stumbled across product news of this switch that attaches to shift cable outer to detect inner cable movement and cut the throttle based on the shift.
More info on that gear sensor here
http://gearsensor.com/
Good to get some more information on this device. Interesting that they are relying on activating existing brake switch inputs, both Hall and straight switching to kill the throttle while shifting.
This works OK but after quite a bit of riding using a "hack" version of the theme, I have become increasingly less tolerant of the inherent delay in throttle recovery associated with brake switches. The delay is acceptable for general commuting, but with more spirited riding, the delay in throttle after shifting gear is simply too long.
So decided to rethink the concept and come up with a delay fee gearshift throttle kill hack.
As most are now aware, the throttle arrangement on BBS drives has the characteristic of killing the PAS as soon as throttle is applied. It then has quite a wide dead band before the thumb throttle starts to react.
The PAS kill is close to instantaneous when the throttle is applied and close to instantaneous recovery of PAS when the throttle is released. Just the conditions we are looking for when changing gears. Now with a bit of practice, you can use this throttle deadband as an area where you can safely change gears in. I personally suspect this deadband has been specifically engineered into the drive by the Bafang Engineers.
So with the above in mind, the solution for the perfect shifting system is to mimic this throttle action when change gears.
I use a button throttle rather then the standard thumb throttle and came up with the following simple circuit to kill just the PAS when shifting gears.
This arrangement sends a 1.5V signal to the controller when the gear selector is activated which in turn places the throttle in it's dead band / no PAS range. However, this arrangement has no effect on the button throttle which is OK, but not ideal.
This next schematic use both the normally open and normally closed contacts of the Micro switch and is designed to kill both PAS and the button throttle when the gear selector is activated. Basically the micro switch now switches between two voltage ranges.
This last schematic is similar to the above schematic but this time is designed to use the original thumb throttle.
Making the loom was quite straightforward with the voltage divider resistors just hidden under the heat shrink.
The Mirco switch is mounted onto a flat plate with high strengh double sidded tape and the plate then screwed to the shifter mechanisum. Yo can see in the pictures how the micros sits in both at rest and gears activated.
And the results.
Finally gear shifting is smooth and delay free. Only negative is that you can beat the derailleur shift with the drive reactivating if you shift too fast. However, it only takes a few shifts to figure out how fast you can shift and keep it smooth.
