I recommend a chest mount if you're doing mtbing or bikepcaking. Helmet mounted is great for looking around and POV shots.

If you want super steady shots, you might want to invest in a gimbal. And I'd recommend a small, compactible monopod/tripod/selfie stick type device so you can hold the camera away from you. A little tripod can be handy if you want to mount the camera to something to get coming/going shots. I use one of those posable tripods, it's small at about 10 inches and light enough to carry in the back pocket.