The UE Roll straps on great right behind handlebars, on the stem ( St2). I got mine at Verizon $ 100. Comes with a nice strap and is weather resistant . I was to distracted by it, as it ate up my Bluetooth data minutes. I guess I listen to my chain to be in the right Gear. It's nice because you hear it easily mounted right in front of you. And it looks totally awsome. It has a cool girls voice that audibly tells you how much powers left in the speaker when you press up and down speaker buttons at the same time. USB charging, and comes with an app.
I was thinking about getting one but then changed my mind (my route is a beach bike path and is so nice, no music addition needed). When I was looking, the best value from my extensive research was the JBL Charge. There are a couple portable speakers that have better sound quality, but the price jumps up. The Charge is still at a good price point, while providing WAY better sound quality. Unfortunately however, they don't make a bike mount, so you'd either have to jeri-rig your own, or buy something like this - http://www.amazon.com/gp/product/B0...rue&ref_=ox_sc_sfl_title_6&smid=AYVBNZYUA1KRK
This one would do the trick, but it's WAY overpriced.