I'm thinking a fiber-glass, carbon fiber, or bamboo bike might be a good thing - but I don't have any direct experience but I think I would feel more comfortable riding one then a conventional metal tube frame bike with lightening around.

Also the danger of lightening varies greatly depending on where you are. On the east side of Montana its a big concern because that is flat land country with only very gentle hills, where as on the west side unless your standing on top of a mountain peak the odds of you being hit or incredibly low even if you stood in the middle of a puddle holding the bike up over your head trying to make it strike you because there are trees, hills, and mountains everywhere and with 10,000's of trees around your immediate vicinity all of which are taller then you some on hills that are way taller then you lightening strikes on anything man made except for power poles where it is a case of the charge in the electric wires attracting the charge in the sky are very rare. Basically on the east side of the state the flat land prairie side a lot of barns and silos and other man made tall stuff gets hit by lightening and burns down, on the west side of the state lightening usually hits trees and starts forest fires and then the forest fire burns down the man made stuff if it gets going well enough. Anyway, that's what I know about lightening strikes up in my area. On the west side of the state actually getting struck by lightening on my bike in a thunder storm would be the last thing I would worry about, other vehicle operators on the road hitting me because of the reduced visibility and me getting all wet and nasty from sloppy road goop would be what I was thinking about. On the east side, yes, in a bad lightening storm I would worry about it.