I have two bicycle-related projects running simultaneously right now. The first one is a small rack-mountable radiobox, shamelessly lifted from the BikeBoomBox, which was in turn shamelessly lifted from MOSFETgrrl’s bike stereo. My goals with this radiobox are to make it easily reproducible, cheap and effective.

The basic idea is to use 6″ sonotube as a shell, build an internal frame out of MDF and pine for strength, jam a large SLA battery and an inexpensive super-efficient class T amp inside, and put marine speakers on either end. The total outlay *should* be less than $100, it should be weather-resistant, mount on a standard bike rack, accept mp3po input and be rechargeable. It can also be disassembled if necessary.

Here’s some MDF marked up with the speaker dimensions:

And in the process of being cut with a jigsaw:

MDF produces lots of nasty dust. It’s not really sawdust — it’s much finer, and is really not a good thing to breath. I tied a wet rag over my face to keep the dust out.

After an hour or so of cutting up wood, all the parts were ready for assembly:

The speakers attach at one end. A solid piece of MDF seperates the speaker area from the battery compartment:

Here’s an end shot with foam padding attached where one of the speakers will sit:

And here is the 7.5 Ah SLA battery fitted inside:

Next I need to install the class T amplifier, which just arrived from parts-express this week. Thanks to Pywaket for introducing me to this neat device.

I’ve also been working on a swingbike. Designing a strong center joint that can be disassembled for servicing has been challenging, but with Skunk’s high quality welds in place I think this iteration is going to work out:

The top piece will get bolted in with a thick hardened steel bolt. Here’s a top-down view of the joint, showing the bolt hole:

And a side view of the two connected frames. I’m going to use different handlebars ultimately:

It still needs a lot of work: painting, rear wheel, new cranks and chainring… but the hard part is finished!

I’ve been having so much fun riding ARP Synesthesia around that I haven’t even blogged about it. Before I get into that, though, a word of caution: pay attention to dimensions when ordering parts! I thought I’d ordered a small waterproof power connector. The connector size I expected is to the left. That shiny circle is a quarter. The connectors that arrived were MUCH LARGER:

On to the project at hand. First off, I got the battery mounted extremely securely using some 3/8″ rod that was bent into a holder, and a 3/8″ threaded rod to yoink it down. Parts:

And installed on the rear rack:

I also had to rework the speaker mounts. A single conduit clamp wasn’t strong enough to prevent them from wobbling, which would eventually cause metal fatigue in the metal bowl enclosures. So I doubled up the number of conduit clamps:

And secured the speakers to the frame at two points instead of one:

I’ve also added several incredibly bright blue LEDs. Here’s one lighting up the beehive spring on the front fork:

WRT other projects, the swingbike has seen a few design revisions, and I don’t have photos yet but will post some soon. Also underway, and I’ll blog about this — a bikeboom-style bike radio using cheaply sourced materials and components.