Google "light mounting fork knobs". I have 2 on our tandem. They work very well, better than bar mounts because they are lower and throw better shadows.
Also Peter White:
Mounting Lights from Peter White Cycles
Also
show me your fork light mounts
Also
Mounts for Bicycle Lighting
Also
Minoura Besso LH 50 Front Fork Mount Light Bracket 16mm 38mm | eBay
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