Originally Posted by
hotbike
Speed sensor on the front wheel, cadence sensor on the cranks. You need two sensors, because the computer doesn't know what gear you're in.
Am I failing to grasp the question?
Well, no. You're right. Some cpus however, use one sensor for both. Meaning it takes the speed off the rear wheel and then another little arm of the same sensor reads the crank cadence.
Now, what's the gear got to do with anything?
Thx