The cadence + speed/distance sensors/magnets will attach to the rear wheel, the chain stay and the crank arm. Suggest you download the manual before you buy. Some of the manuals are impossible to figure out literally.

I bought a new model of my old cheap Cateye as the wiring harness gave out. After studying the manual for a while, I threw the cyclometer in the spare parts box and just used the new harness. I have two engineering degrees!

When my grandson needed one, I didn't buy Cateye.

Al