As this search engine result indicates, there are some people who actually search for information on “biker boots to wear with shorts.”
Here are two options:
1. If you want to wear a functional boot as a hiking boot, and confuse that with what some people call a “biker boot,” then get a boot that is about 6″ tall and has good tread — and go hiking.
2. If you possibly could have been considering wearing shorts while riding a motorcycle, all I can say is, “please don’t.” Wearing shorts while riding a motorcycle is silly, stupid, unsafe, and looks really dorky. Don’t wear shorts while riding a motorcycle — even if you choose to wear boots.
Life is short: wear long pants and boots while riding a motorcycle.