Billy the Boombox (Custom Music Bike Trailer)

Our fellow bicycle trailer enthusiast, Ryan Cooper, contacted us about a custom music bike trailer that he cooked up. We decided to post up his words and photos about his project. Also, check out another music trailer we reviewed.

The Origin of The Project:

“The local Critical Mass group completed their May ride and pedaled over to a local, bike-friendly watering hole for post-ride refreshments. As we sat on the patio, the discussion of music for the rides was brought up. My background includes work with car stereo systems and I felt that a car stereo modified for use on a bicycle would offer superior performance to the small, battery powered boom boxes we had previously used. After some discussion about how to make it work, I decided to give it a try.”

Custom Music Bike Trailer

Technical Requirements:

“There are a few things to consider when building a car stereo without the car- First, car stereos are terribly inefficient when it comes to power consumption. Cars use alternators to provide a constant source of power. Using only a battery would require some self restraint with wattage and volume levels. Next is the batteries themselves. Car batteries are quite literally filled with lead and they weigh between 25 and 55lbs! Finally, where to put all this stuff? I decided a trailer would be the best solution because it would allow me to keep the weight low and provide space for all the components.”

Let the Building Begin (The Stereo):

“First I had to design the stereo system. I had an old 2 channel car audio amp laying around the garage. I purchased some 6.5″ speakers from Wal-Mart. They are not fancy but I they do the trick. I also got some wires and a switch to use as an amp turn on. A fellow Critical Mass rider contributed a car battery. She also provided use of her iPod. With the stereo designed, it was time to start thinking about trailers.”

Bike Trailer Stereo DiagramBuilding Continued (The Trailer):

“A local rider learned about the project through a bike forum and donated a commercial kiddie-trailer arm for use. This was awesome because the attachment point is the hardest thing to ‘make’ in my garage. The trailer was built with a plywood base with wood and fiberglass reinforcement. The wheels are ball-bearing utility cart wheels mounted with custom steel axles that I welded on. The “body” of the trailer is made of polyester impregnated fleece stretched over MDF and welded steel forms. It is hard like plastic and works really well for this type application.”

Additional Thoughts:

“My total build cost was about $300. If someone wanted to replicate this trailer exactly the cost would likely be much higher because I did not factor in parts and supplies I already had at my home or the specialized skills such as welding and composites fabrication that I used. This trailer, as cool as it is, was really a proof-of-concept for me and in the future I would like to build version 2.0 including a deep cycle battery for improved play times, an integrated FM tuner so the iPod could control the stereo from a handlebar mount, and I’d use a 3 or 4 channel amp and a subwoofer to improve bass response.”

Trailer Stats:

Name: Billy the Boombox
Manufacterer: Ryan Cooper email: Ryan{at}thecooperproject{dawt}com
Build cost: apx. $300
Weight: apx. 50lbs. with the battery installed
Sound System: iPod head unit drives a 75watts x 2ch amp pushing 6.5″ three-way speakers.
Runtime: 3+ hours under normal playing conditions [depends on volume and gain settings]

In Conclusion:

“The trailer was a huge success. It was pulled at the June Critical Mass ride and met with a fantastic reception from participants and onlookers alike. It was used again for a patriotic-themed ride on July 4th where it again exceeded my wildest expectations.”

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