While you can use a headlamp as a bike light, the space you need to be illuminated for your bike may not be quite the same as the lighting you need for hiking or running in the dark. That said, a headlamp can be a great addition to a bike lighting setup, especially for night-riding mountain bikers who want to scan the trail.
You can use the headlamp to scan from right to left ahead of you while keeping your trail directly ahead lit up with your handlebar-mounted light. For which headlamp to choose, check out our Best Headlamps Round-Up.