I have a Hero session 5. (purchased a few years ago). Tiny cube. Press the button for a second to start capturing, press again to stop. Excellent image quality, waterproof, tons of accessories (many variants of handlebar/helmet mounts). Short battery life (but is probably true of alternatives as well).

You may also want to consider Garmin's VIRB. One nice feature is remote control via ANT+. You could mount your camera on your front hub and activate capture with your GPS.

Tons of alternatives. Really depends on what you want to do (cost/features/quality)