How to generate a clock for my ring counter?
You appear to be somewhat confused about cause and effect. The ring counter needs to be going to get the motor to turn. That would be the cause. The sensors that detect some aspect of the motor rotating are the effect. Trying to devise some means to generate the cause from the effect will normally not work as there would be nothing to get things started from time zero.

Generally it would be way better to generate the CLK signal independently from some circuit that produces the rate that you want the ring counter to operate. The sensor outputs would then just follow the driven behavior of the motor in a cause and effect relationship. 

If you applied some intelligence to the interpretation of the sensor outputs, such as by using a microcontroller, you could possibly have that modulate the behavior of the standalone clock generator to increase or decrease the clock frequency to accommodate load changes on the motor that cause its operating speed to change.