I'm not sure how it is on smaller motorbikes but on motorcycles there is usually a smaller, slotted disc (partially highlighted in yellow) inside of the brake disc. Mounted above the smaller slotted disc is usually a sensor that measures rotation of the wheel (circled in red). You might be able to tell from the VIN as well.
It must be me.... My experience with Grab over the last two months has been mediocre to bad. On my last ride the driver was apparently trying to get out of the ride by stalling - parking about 0.5km up the road from where I was. After 7-8 minutes of waiting I finally texted him to say "Where are you?". After that he quickly moved to pick me up. Beyond that Grab has given me the opportunity to interact with what must be some of the dumbest people on the planet. Most of the drivers that I've had did not know their way around BK or how to use Grab's built-in mapping function. I got used to