There are plenty of speaker systems for bicycles but the BoomBot Rex is one that looks like it could survive a ride through Jurassic Park, if there were really such a place. This ruggedized, hexagonal speaker features two 36mm drivers in the front of the oblong subwoofer. This makes for a compact speaker that is also waterproof and offers wireless operation just about anywhere.
It can be mounted on a bike, or just taken for a hike in the woods.
This speaker, which is in development via a Kickstarter campaign, has the promise to connect to a smartphone, tablet or computer or any other Bluetooth-compatible device. In addition to being a speaker for music it can take calls from a phone, Facetime or Skype. Just in case you need to have a conference call while out on the trails.
http://youtu.be/G3whKZsiLGs