Hi and
to the forum.
The HBS motors are equipped with three 5V hall sensors just as described, but only the rear motor can be fitted with a brake disc as shown in the
User Guide.
I have no idea what the speed rating for these bearings is, but they are unlikely to be spinning above 500rpm on an ebike.
These hubmotors are designed for low rpm operation, and would probably not be balanced well enough to run at really high rpm, so I expect it would be the dynamic vibration from the motor that would limit the maximum rpm, rather than the bearings overheating.
Alan