I agree; once they're fully matured after "hatching", they are most active up higher in trees.
There will always be some flying closer to ground lever but they aren't super fast fliers; kind of clumsy really. Sure, you could hit one while on your bike but whether it hurts or not probably depends on how fast you are going. You guys do all wear shades right? I wouldn't want to get hit in the eyeball by one.