I am a simple, classic style sort of person, but those look fantastic whether MTB, motor cycle or car. Knowing how people's interests and tastes change over a lifetime (marriage?), they would probably be a bit much for a wedding ring, but would be great as dress rings.

DrPete, should the worst happen, would good old-fashioned bolt cutters do the trick with tungsten rings? Just in case I need to inform the emergency room staff...