Rock The Bike

El Arbol: The Bike Tree

This custom art bike, made and based in San Francisco, rides through the city at 12 feet tall, then sprouts roots, branches, and leaves at events, where it becomes a 2500-Watt double-stack main speaker at our Pedal Powered Stage. Integrated LEDs look stunning at night. The Tree has two seats and creates all of its own power using an integrated One Bike / One Speaker circuit.

el arbol bike powered tree


Above, El Arbol in action as a Aerial Dance rig at Gaia Fest in 2012.

Shredder performs on hoop from El Arbol
Aerialist Shredder performs on hoop from El Arbol’s trusty rear branch. 
Tara performs on El Arbol at the start of the SF Marathon
Tara performs on El Arbol at the start of the SF Marathon
El Arbol without its Canopy of Leaves.
El Arbol without its Canopy of Leaves.

The sound quality is incredible. By using the audio elements from 2 Modified JBL PRX loudspeakers, it has the ability to get music out at festival levels with very low distortion. We use El Arbol as half of our Pedal Powered Stage at the San Francisco Bicycle Music Festival. The height of the upper loudspeaker (9′ up!)  helps the sound spread out easily out above a crowd, without requiring deafening volume levels for those in the front.

bike powered performance on el arbol

It’s fun and expands the notion of ‘Stage’ to include the pedalers.

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Crew of Junk Raft to rock a Soul Cycle on their ‘Junk Ride’ West Coast ocean advocacy tour.

Junk Raft.

The name alone arouses curiosity. A Junk is a type of Chinese sailing vessel that dates back to the Han Dynasty. And they were used for extensive ocean voyages.

But what is a Junk Raft? In the case of eco-mariners Dr. Marcus Eriksen and Joel Paschal, The Junk Raft is an ocean vessel crafted from junk plastic bottles, a Cessna 310 airplane fueselage and various other ‘junk’ materials.

The Junk Raft recently sailed from California to Hawaii to protest the growing pile of trash in our oceans. These plastics end up in the bellies of Albatrosses – things that really shouldn’t be floating out there, like lighters and toys. They don’t break down, not in the albatrosses and not in the ocean itself.

And it’s that very durability of plastic that has made the Junk Raft’s courageous voyage possible. Marcus and Joel literally netted up 15000 bottles from the waste stream of Los Angeles, forming two pontoons that floated them all the way to Hawaii. And what a journey it was.

Now Marcus and Anna Cummins, another plastics crusader, are teaming up, in more ways than one, and hitting the road, biking from Vancouver to Baja on the Junk Ride. To help them tell their story, we created Bike Speak.

Marcus and Anna wanted a small, self-contained thing they could carry with them on their tour, that would allow them to host cruiser rides, and do pedal powered slideshows and presentations at schools and parks. At the same time it had to pack enough punch to address a reasonable size crowd both indoors and out. They already had a Fender Blender X, so they we made an Xtracycle-compatible cabinet and a generator attachment that can be used with the Fender Blender base, without requiring tools to switch back and forth to smoothie mode.

With the human power module, a volunteer can pedal the system to run the amplification while Marcus and Anna give their talk. And with the Fender Blender bike blender system, they can serve up fresh smoothies to the crowd after the talk while enjoying great sounding music pumped out by the system’s internal rechargeable NiMH battery, good for an estimated 14 hours of light and music.

With each custom Soul Cycle that comes out of Rock The Bike, we try to push the envelope a little further. A few of us had been sketching hinged cabinets with two modes: stereo for cruising, and unidirectional for public address. Hence the flip-up action. We followed the snapdeck aesthetic, following the curves at the head and tail. The curve at the tail is functional. It matches the Fender Blender base. We used an ultra efficient amplifier for amplification and four Pro Audio full-range speakers. These speakers are small and extremely lightweight with alloy housings and neodymium magnets, weighing only 1 lb each! A crossover protects the tweeters. The entire finished cabinet, with speakers, amplifier, battery, mixer, voltage regulation system, microphone, and integrated lighting weighs in at a only 12 lbs! By far our lightest Soul Cycle to date.

A two-channel mixer is built into the controls. This stereo mixer will enable Marcus and Anna to play background music from their laptop’s slideshow program, while speaking through a lightweight microphone we provided.

We came up with a custom voltage regulation circuit to protect the internal battery, mixer, and amp from the motor. The circuit also taps a little power to trickle charge the battery. We also added a separate noise suppression circuit to mute static from the generator.

When the cabinet is flipped up, the user has access to a small “cubby” door. Inside the door is a small storage compartment where the microphone, cords, and handlebar mount can be stored when not in use.

The handlebar mount will accommodate an iPod or other mp3 player and features a battery fuel/voltage gauge. This gauge will tell the user the current charge state of the battery while also giving the human power pedalers an indication of how their pedal power is affecting the system.

Be sure to check the Junk Ride schedule for news about Marcus and Anna’s latest educational adventure and the Bike Speak system. During the Spring and Summer of 2009 Marcus and Anna will be touring the West coast. SF-Cruisers can expect a Junk Ride social ride with Anna and Marcus when they come through San Francisco. Like the Junk Raft’s epic sail to Hawaii, the Junk Ride mission is not easy. At last check Marcus was mentioning that he intended to tow a raft so that the pair could ford rivers. Rock on! Send them fanmail on their blog, and please stay tuned for more on that social ride.

Carbon Neutral press conferences

SHAKE YOUR PEACE!’s Gabe Dominguez pedal powers a press conference of Salt Lake City’s mayor Rocky Anderson, opening their Live Green festival. May 2007.

Below: Rock The Bike’s Paul Freedman pedal powers a press conference for San Francisco’s Wade Crowfoot, announcing the city’s endorsement of pedal power.

A bicycle may be the perfect place to listen to music. But you have to think big.

Soul Cycle Slim at Halloween Critical mass

Soul Cycle Slim in action at Halloween Critical mass in San Francisco

Many have tried putting speakers on bicycles. And there are even a couple handlebar-mounted products on the market that amplify an FM radio or an MP3 player. The difference between a Soul Cycle and those other products is sex appeal and sound quality. The sound quality of these handlebar mounted units is always compromised by forcing full range music out of tinny sounding speakers in tiny plastic enclosures with no capacity to reproduce bass frequencies. They sound no better than listening to your music on a laptop at full blast from across the room.

So music lovers turn to headphones, which, in theory provide perfect stereo separation and plenty of bass. But in practice, the wind seems to whip between the headphones and your ear. The wires are constantly getting caught on your brake levers and yank your earbuds down into your aural canal when you rise to climb a hill. And you take a real hit on safety by isolating yourself from the noise of approaching vehicles and pedestrians.

But none of these annoyances even approach biggest problem of headphones — that you can’t share your music. How awesome is it to drive a car to the beach with four friends, all singing along to Hotel California? Those social experiences are not only possible on a bike; indeed they’re even better than they are in a car. Because there is so much engine, wind, and road noise to overcome, most car stereo systems can’t match the clarity and presence of music on a Soul Cycle . In fact, one of the most common reactions bystanders have to a Soul Cycle is “That sounds better than my car!”

Soul Cycle Slim at a recent Mission District Party

Soul Cycle Slim at a recent Mission District Party

On a bicycle, the listening environment is much more favorable than in a car. The background noise is 100-1000 times lower than a car, creating a black velvet background for your favorite music. And because the background noise level is so low, you don’t have to turn your music up very loud to experience the immersive effect of hi-fi stereo. You’ll be listening to music in a volume range where your speakers can show the true clarity.

Soul Cycle Slim -- immersive mobile audio for bicycles.
Soul Cycle Slim is lightweight enough to carry up a flight of stairs to a train platform unassisted.

The volume will be just perfect for conversation, either with your passenger or with a friend alongside you. But when you want a little extra power to enter a barbeque (or just a bar) in style, it’s there.

Fossil Fool teaches workshop on Hi Fi Bicycle Cruising Systems at Maker Faire May 20, 21

Fossil Fool teaches bicycle audio workshop at Maker Faire


At the Maker Faire ( May 25 and 26, Fossil Fool taught a workshop on how to make a one-of-a-kind bicycle audio system.


Topics included:

– Overall concepts

– Picking amps and speakers and batteries.

– Designing a wiring harness and front mounted controls. Jacks, connectors, wire gauges, switches, etc.

– Building a music cabinet. Overview of the different cabinet making options — wood, fiberglass, etc. How to deal with ports, calculate speaker volumes, and make airtight cabinets for good bass response. Also, a few topics on 3D design.

– Picking a good base bike (no, not bass bike). What makes a bicycle suitable for a Soul Cycle mobile audio system? We’ll review the options: Xtracycle Sport Utility Bikes, Side By Sides, Commuters bikes, etc.

Fossil Fool vs Kool Herc

I rigged my favorite speakers to my new Soul Cycle Chopper, to prototype the sound of my new custom cabinet. To power the speakers, I used a small digital amplifier similar to the ones in our Soul Cycle Head Unit.

Above: Fossil Fool’s new ride — the Soul Cycle Chopper.


This shot reminded me of the classic image of New York’s first hip hop DJ, Kool Herc.

Kool Herc, pioneer hiphop DJ

Kool Herc, pioneering hiphop DJ’s classic convertible

Kool Herc was the first to introduce the spoken word (rap) to dance parties, and the first DJ to play just the breaks, or sweet moments of a song, instead of the whole songs.