You can't just think "biker" here, also think "collector". Like salt and pepper shakers, postcards, and miniatures, there are folks who collect magnets. Let me rephrase, there are LOTS of folks who collect LOTS of magnets. Why send off a mere greeting card when you can add a little something extra without appearing overindulgent. I never had that luxury. My best friend collects toasters! Really. I wouldn't make it up.
Magnets measure 2" across and come in a set of four assorted: Be, Fly, Explore, Live. American. Handmade. Recycled.