Helmet camera,
no adhesive.

Half the frame is your handlebars.

A chest harness never touches the helmet, but the view comes from chest height: on rough trails the long, flexible strap bounces, and — more annoyingly — half the frame is typically your bike and bars instead of the trail. A chin mount keeps the camera at eye level: it shows what you're actually looking at.

The strap works loose.

A strap cinched around the chin bar is easy to move between helmets, but it's a hassle to get tight enough — and on rough trails it works loose and flaps while you ride. If the strap goes slack, the camera moves and shifts out of place. The angle is fine when the strap is tight; the problem is keeping it tight.

Adhesive is a commitment.

An adhesive mount's position locks to wherever you stick it — you can still adjust the camera angle from the GoPro fitting itself, but you won't move the mount again. A proper bond needs a cleaned surface, an adequate temperature, and about a day to cure before use. And when you eventually need to remove it, it doesn't come off quickly or cleanly.

A clamp presses on one point.

A clamp tightened onto the chin bar is removable, but it loads the helmet over a small area, and its hold depends on how precisely the clamp happens to fit your particular chin bar. The clamp's jaws can also press into the shell or the EPS foam — in my own case, a clamp took a chunk out of my helmet's EPS.

The tie spreads the load.

A Zipmount threads through the helmet's own vents with zip ties that spread the hold over a wide area — no adhesive, no cure time, no claws gouging the foam, no modifications to the helmet. Its shape is fitted to that exact helmet model's chin bar, so it sits tight and the camera stays put. UV-resistant zip ties are included, and the whole mount is light.