Some throttle info/testing - YMMV, I made one test on one Photon motor, you're at your own risk and all of that.
In short, a generic "Bafang" throttle supplied as part of a BBSHD kit purchase seems to work just fine on/with my Photon motor.
CYC going off on their own with the throttle design and/or wiring standard made no business sense to me (no significant profit to be made or intellectual property to be protected), and I had one of those late-night thoughts that, screw it, I'll electrically compare a Bafang BBS02 bike throttle and wiring directly against the CYC equivalent. If all looked the same, then I'll plug in the typical Bafang generic throttle into the CYC Photon and give it a rip.
As I posted earlier in the thread, I've already run the "incompatible" (per CYC) 750C display on the Photon, and have been using the Bafang mechanical brake levers along with a gearsensor.com shift sensor - all without any apparent issues.
To make the electrical testing easier and somewhat short-proof, I chopped in half a short throttle extension cable. The cable wires happen to have the same color codes in the Bafang wiring diagram:
On the Bafang BBS02 bike, I verified that black pin 8 ground was 0 ohms to battery ground (just in case), then powered up the system and verified positive 5vdc (4.82vdc actual) between the ground and red pin 6 +5vdc (throttle unplugged). Then I plugged in and ran the throttle, measuring the voltage between the ground and throttle pin 7, and the voltage climbed up (between roughly 1 and 4 volts). The results were all as expected, and as reported on various forum threads as the typical throttle circuit behavior.
I repeated all of the individual steps and measurements on the Photon bike, using the CYC "compatible" Photon throttle, and got the same results. With a bit of confidence and only a slight hesitation, I plugged in the Bafang throttle, powered up, and the throttle worked. I did not go into the CYC app and run the throttle-autocalibration tool. The only difference I could detect was that the Bafang throttle is somewhat more abrupt in the range than the CYC, taking less thumb paddle throw - an ongoing complaint against this version of the Bafang throttle. I also dragged the rear brake and made sure the torque sensing still worked. No, I didn't test the bike out on the road - all measurements and tests were made on the stand.
In hindsight, there are more comparative tests I could have made (such as the pin 6 5-volt supply line current draw), but the throttle circuit design(s) are fairly simple and straightforward and I don't feel the need at this point to do so.
So, the cost appears to have been sacrificing a throttle extension cable and some wire ties to the DIY "knowledge base". My bet is that any throttle that is known to work with the Bafang BBS motors, be it thumb, twist, or whatever, will probably work just fine with the CYC Photon.
