What i meant is that if the magnet is at the rim, it will pass the sensor so fast, especially at high speeds, that it may not register every revolution. Thats what i've read, and made sense to me. I could see how that would be possible. But then again, i of course don't know this for a fact so i thought i'd ask and see how it works for y'all. Seems from the responses so far i don't have to worry about it tho.