For most people using the PAS system on the BBS02 they have had to get used to just barely pulling in the front brake (enough for the motor to disengage) in order to up shift without putting serious strain on their chain and risking breakage. Paul from em3ev is now selling a Giant Green Button™ (thank god it’s not red or I’d HAVE to press it) for $6 that connects to the ebrake sensor and shuts off the PAS while the button is held down to facilitate up-shifting without risking a damaged chain.
There is a real need for this in the BBS02 community as it is annoying and awkward to have to slightly pull in the brakes to disengage the motor to shift. Although you can downshift under load (one gear at a time) without busting chains, trying to upshift under load puts your chain at serious risk of breakage.
Kepler from ES built a nice system with an automatic micro-switch for shifting with his singletrack weapon found here which is far nicer than anything I have ever built. For all intensive purposes the Giant Green Button™ will work about as well and be much easier to install. I recommend installing it on the left side so your left thumb can hold it down while your right thumb shifts. I also recommend hooking it up to the front ebrake connector and leaving your back ebrake sensor connected. I always favor the rear brake and anytime I hit the front brake I always hit the back brake as well.
If you use a throttle only system and have removed the grey wire as shown in step 3 here then you really don’t need this button at all.