There are plenty of fancy portable speakers on the market but most of them are not designed specifically for cyclists. The JBL Wind 3 is a FM/Bluetooth speaker that mounts to motorcycle and bicycle handlebars. It also has a TF/MicroSD reader and aux-in function.
This speaker is IP67 waterproof and dustproof. It has Sport and Bass EQ modes for outdoor and indoor use. It has a 1050mAh battery that lasts up to 5 hours.