For quite some time I've wanted to build a portable speaker I could carry in my bike's water bottle cage. I've also wanted to build a bluetooth speaker--that is, I wanted to see if I could hack a cheap, crappy-sounding bluetooth speaker & turn it into a decent-sounding portable speaker. It has taken some months to scrounge up all the necessary parts, but now I've combined both projects into one successful build.
First, I picked up this hard plastic tube, about the right size to fit snugly into a water bottle rack. Don't laugh…the tube originally came with a toilet brush in it! Then, I came up with this 4" speaker driver, rescued from an old bookshelf-type speaker…it fits into the tube just about perfectly.
Next…I found this little Wireless Bluetooth Speaker. These usually sell for around $20, but a local retailer currently has 'em on sale for $9.99.
The speaker driver that's inside isn't worth a hoot, but the enclosed electronics are sufficient to power a bigger, better speaker at reasonably loud volume levels. This speaker came apart fairly easily, and all of the electronics are conveniently housed in the base of the device. I did have to lengthen the speaker wiring a bit.
The rest is pretty straightforward…drilled a small hole in the bottom of the tube to run the wiring through, affixed the electronics to the bottom of the tube with some wood screws...
...and secured the speaker driver with hot glue.
As a finishing touch I added a grippy rubber thingy from a travel coffee mug to the bottom of the construction, to help keep the slippery plastic tube from sliding out of the water bottle cage.
Although I could certainly use this as a stand-alone speaker via bluetooth connection, my plan is to use it in combination with an earlier project, my backpack subwoofer (details on this build mentioned HERE). This sub is a 4.5 inch driver in an 8" x 8" x 4" bass reflex enclosure, also powered by an internal rechargeable battery. Anyway, I'm using my iPod classic to play music while biking, & it's not a bluetooth-enabled device. It's a relatively simple matter to wire all of the devices together on the bike. Whenever I need to park & lock up, I can remove all of the vital technology from the bike & carry it with me…no worries about potential theft or vandalism.
This bike/music idea started when I got a Jawbone Jambox & wanted to find a way to mount the speaker on my bike. Now that I have the other speakers up and running I probably won't bother to use the Jambox while cycling any more...but for the curious, I've documented my Jambox bike mount project HERE: http://jrsprintsofdarkness.blogspot.com/2013/07/the-jambox-project.html
Update, 3/14/14 - I added a protective cover with metal grill to the bike speaker.
More modifications (3/24/14): The electronics from the original bluetooth speaker I hacked gave me some grief (mini USB charging port broke off, etc.)...so I decided to swap everything out, rebuilding the electronics with the guts of another (non-bluetooth) portable speaker. I also added a bass reflex port tube, made out of a plastic pipe elbow from a hardware store.