does it need to spin in both directions? If it only has to rotate one way, no need for an h-bridge. A single mosfet/switch would work.

 

If the output of the gear detection is a square wave pulse, you can detect the rising and falling edge to increase the resolution x2 if needed.
Max.

Turns out that the sensor is Hall Effect Proximity Sensor that is reading the gear and providing an unconditioned signal to the board.

 

does it need to spin in both directions? If it only has to rotate one way, no need for an h-bridge. A single mosfet/switch would work.

Are you sure it will work, besides I considered mosfets the reason why I chose the optoisolators were because the mosfets are gonna get pretty hot operating for a longer period of time, I can probably find better ones, but the optoisolators should provide the same function.