Lightning striking humans is very rare and when it does happen people are usually in very exposed areas with virtually nothing around them or standing under trees.

Be reasonable when riding in lightning -- If you have to ride on high exposed ridges riding is probably a bad idea. Similarly riding across the wide open prairie could be a bad idea. For most of us riding on city or suburban streets or bike trails there are probably much better lightning targets Probably the biggest danger for most of us in a thunderstorm is not the lightning but high winds bringing down trees and/or power lines. And of course drivers driving too fast for conditions who can't see riders in heavy rain.