In this paper, a bicycle light-emitting diode (LED) headlamp is design for the purpose of meeting the regulation and removing the unwanted reflection of some specific parts. In addition to the optical design of the headlamp, a three-dimensional mask is designed to block the LED light source to remove the specific unwanted light on the front tyre of the bicycle and then reduce the glare effect to the rider. The experimental results show that the 3D mask can effectively eliminate 97.7% of the unwanted light on the wheel of the bicycle and keeps 98.6% of the original illuminance at the A point of the K-mark regulation. The proposed mask approach will be helpful to the design by using LED as a light source.