You are pedaling the Ginger Ninjas Sound System…

Coupling super efficient digital amplifiers with generators attached to working bicycles (as opposed to purpose-built stationary bikes), this system allows a band to play off-grid anywhere, wall outlet or no, and to carry the system to a gig on two wheels. The band calls up members of the audience to pedal, up to four at a time with our current configuration.

How it works

  • All of our rides are Xtracycle-equipped sport utility bicycles: like regular bikes except longer behind the seat to provide more room for and better handling when carrying gear.
  • The Xtracycle system also provides for a dual-sided heavy duty kickstand that gets the rear wheel off the ground for stationary generation.
  • A small DC motor with a 1” roller rubs on the sidewall of the rear tire, generating DC current. This motor is engaged and disengaged via a shifter lever, allowing for rapid setup of the band, and also enabling the rider to engage the motor while on the road (more on this below).
  • This varying voltage DC pedaling energy is stored briefly in supercapacitors (“caps”), which shoot out a more consistent 11-15V. The buffering and storage of the caps supply amplifiers with both constant power and bursts. Our system demands about 160-200 Watts steadily, and up to 1000 Watts peak.
  • An L.E.D. indicator on the handlebars tells the pedaler whether to pedal harder, keep ‘er steady, or STOP. Too little voltage will kill the sound and too much will actually ruin the cap.
  • Each bike has its own cap, and each cap feeds into a common inverter. The inverter changes the DC current into 120 VAC with regular electric outlets, into which we plug all of our equipment: 2 x 500W speakers, mixing board, effects pedals, laptop, Down Low Glows, and chargers for the small devices we have on tour with us.
  • Without efficient amplifiers, we would need 8 pedalers to get the same sound level!
  • Our complete touring system incorporates flexible solar panels, small, eco-friendly Lithium Phosphate batteries, and on-the-fly generator engagement for all of our electric needs.
  • We’re using bikes to power music, but you could use a similar generator to power most any household electrical device.

Equipment we use

We have a range of bikes from different makers, including Giant, Schwinn, Bridgestone, Trek, and Surly, all equipped with the Xtracycle FreeRadical, a frame extending “rack”. We also have a Surly Big Dummy ( a complete long-frame bike that’s compatible with the Xtracycle rack system.) We favor mountain bikes for their cushy fat ground-loving tires and relatively strong wheels (smaller wheels are stronger than bigger wheels, all else being equal). We use quick-release seatposts so seat heights can be adjusted for different riders. To improve: we often find that none of our bikes are small enough for little kids who want to pedal at shows.

We fabricated our dual-sided kickstands ourselves, though Xtracycle keeps threatening to manufacture one for sale. We also glued and screwed little blocks to the undersides of our SnapDecks for the kickstand feet to rest in. This keeps the bikes more stable for pedalers, and also enables us to play on the grass without the stands burrowing in. To improve: current stands need both hands to engage (not really kickstands at all) so are very inconvenient for casual stops. Also, they have no leveling capability if the ground isn’t flat. Hopefully the Xtracycle stand will address both of these weaknesses.

We mostly use Schwalbe Marathon XR 2.25 tires, because they’re really puncture resistant, have cool reflective sidewalls and are great rollers. On the other hand, they’re fairly expensive and don’t seem to offer any more resistance than average to sidewall wear. Any time your roller wheel is insufficiently engaged with the sidewall, the sidewall will suffer. An tire can be ruined in one generating use without proper attention. (If you see little black specs on the floor, adjust your roller immediately!). Lately we’ve taken to using the cheapest MTB tires we can find since we haven’t yet figured out how to keep them from wearing out. To improve: find a touring tire that’s made specifically for a dynamo rub wheel.
Tip: as you start to notice your sidewall wearing, rotate your tires. On a set of two tires you have 4 potential sidewalls to use and with good roller and rotation management might be able to use the tires until the tread wears out instead of replacing otherwise good tires b/c their sidewalls have failed or are about to fail.
Caution: don’t put a tire with a bad sidewall on your front wheel! A blowout on your front wheel will most likely be ugly!

We use a generic motor that we order from McMaster-Carr, part number: 6331K13. It’s kinda expensive and only rated at 5 amps (at 3456 rpm; we produce upwards of 10,000). We’ve calculated that our system produces 7-10 amps often, meaning that we’re overdriving this motor and it’s lifespan is decreased. We built a plastic housing around our motors to keep them dry while riding in the wet. To improve: find a widely available 7-10 amp motor, optimally a common auto part such as an electric fan motor.

Motor Mount
We custom built our mounts out of aluminum. They are designed to bolt into the bottom of a cantilever brake boss, enabling their use on most any modern adult bicycle without welding. They pivot in and out of engagement.

Engagement Lever
A cheap thumb shifter or downtube shifter (from a derailleur, often available from the old parts bin at your bike shop) mounts anywhere within reach of the rider and engages the motor against the tire. A simple, custom spring mechanism retracts it. To improve: optimally, the rub wheel would automatically engage the tire just the right amount always, so that there would never be too much pedaling resistance and never too little contact (and too much wear). This system would have to account for the likelihood of the wheel being somewhat out of true.

This custom made piece mounts to the handlebar. A small wire from the capacitor lights up either a yellow, green, or red L.E.D., letting the pedaler know whether to pedal harder, hold steady, or stop. To improve: our yellow L.E.D. doesn’t come on with super low voltage; if it did, you’d know that the system was working correctly even before you’d gotten it up to operating voltages. Sometimes people keep pedaling even when the red light is lit, either out of ignorance or bliss or both. The optimal system would have a safeguard that would not allow the cap to get overcharged (which burns it up). The catch is creating such a “shunt” or voltage regulator that doesn’t constantly draw juice. The mount could also be improved to be quicker and surer to attach to the handlebars.

58 Farad caps manufactured by Maxell. Part number: BPAK0058 E015 B01. To improve: as stated above, it would be nice to have some overload protection for these expensive beasties. It would also be nice to find a used or generic source for something a bit less expensive, though the investment isn’t bad if you don’t destroy them!

Voltage Drainer
When the system voltage (as determined by the highest reading cap in the chain) goes over 15 something, the inverter overloads and turns off the music. We have a little tool that plugs the offending cap into a resistor and sheds voltage down to the useable range. To improve: it would be nice to know which cap of the four was the offender. Sometimes you can tell be looking at each indicator, but sometimes you have to unplug each individually and check the voltage with Mr. Watty before draining the one that needs it.

Mr. Watty
A little electronic meter that connects, in-line if desired, into the wire coming from the cap to the inverter to tell you what the cap voltage (or current) is. To improve: the deluxe system would show you the digital voltage of every incoming line without needing a special tool and would have built-in voltage drain feature.

Power cables between capacitors and the inverter are varying lengths, from about 12 to 20 feet, since we want to minimize cable weight while allowing for bikes to be set up in different places. Heavier gage wire minimizes line losses, but it’s called “heavy” for a reason… Neutrik connectors are used on both ends. To improve: do some math or testing to optimize gage; Neutrik not always reliable; clean up cable routing to avoid accidental tire rub.

Our amps are rated at 1000 Watts peak (combined), so we thought we’d be fine using consumer-grade off-the-shelf inverters rated at 500 W continuous/1000 W peak. We tried lots of brands, Coleman, West Marine, Vector, etc, burning them all up in turn and deciding that our use demands something more robust. We settled on a 1000W unit from Xantrex, makers of professional grade alternative energy equipment. It lasted a couple months before becoming quirky; they replaced it on warranty with an 1800W model. We think that the 1000W unit was up to the task but just a bad piece, but haven’t checked another one. The 1800W model has worked flawlessly. It has the option of hard wiring in an additional cable or outlet, and we did. So our long amp/speakers’ power cables are wired right into the unit.

We wanted a system that would be loud enough for 3-400 people, carryable on two wheels over the long haul, and powerable with four generator bikes or fewer. We knew that we would be putting all the instruments and vocals through the mains: no bass amp, no guitar amp—everything direct. We spent a lot of time researching different speaker weights and looking at state-of-the-art amp technology. Most amps are Class A or B or A/B. These amps analog amps are about 60% efficient on average—the other 40% of energy in ends up as heat. Lately, a Class D amp technology has become digified and applicable to live sound reproduction. We had decided to have a Danish dude build us a custom DC (no inverter required) digital amp, when we discovered that JBL had just come out with a killer sounding cabinet that already had a digital Class D amplifier built into it. We bought two of these PRX-512s. Each is a two-way speaker, with a 12” woofer and a horn. They weigh about 42 pounds each and fit perfectly on the back of an Xtracycle. We had found lighter speakers, but none that had amps inside. If we weren’t using Class D amps of some sort, we need almost twice as many bikes to get the same volume! It’s a really good lesson in reducing your demand before you work on the supply side—even if you know the supply is going to be “sustainable.” As an analogy, you’d want to replace your incandescent bulbs with CFLs before trying to run your house on solar panels. To improve: it would be nice if amps didn’t draw at all when there was no signal, to minimize storage loss in the cap when the band stops. It would also be nice if the speakers weighed less! We’re thinking about trying to re-make the cabinets out of fiberglass.

Mic Stands
We use straight tripod stands for lightness. Though accustomed to boom stands, we’ve gotten used to the straight ones and like the couple pound weight savings. Roland used to make one out of aluminum, and we have on of these, but it’s been discontinued. It weighs half of what the steel ones do. We considered using headset mics (Madonna style) to save on both mic and stand weight, but if you sing with a lot of dynamics, you pretty much need a dedicated sound engineer to monitor your levels since you can’t vary your position from the mic. We tried making our own out of bamboo, but didn’t like the lack of adjustability of the first batch. To improve: get aluminum stands or make nice ones out of bamboo (renewable!).

Speaker Stands
We made some super light stands out of old carbon fiber windsurfer poles. They got the speakers up high but had to be tied to a bike for stability. We didn’t use them much, accidentally left them behind in Baja, and have been just setting the speakers on the backs of bikes since then—either horizontally or vertically, with some sort of tiedown. Horizontally seems to be stable enough that the bike can also be used as a generator bike, minimizing the total number of bikes on the stage.

We don’t currently have monitors. We position the mains a little bit behind the frontline and do our best. Some of us think this is ok, some of us think it sucks. To improve: We’re going to experiment with wired in-ear monitors and might try some small powered mic-stand speakers, too.

Soul Cycle
One of the speakers has a 500/1000w West Marine inverter built into it (by us). This enables us to plug it directly into a 12V battery and have iPod music while we’re riding, a truly bomb element of being a mobile musician. The generator doesn’t spin fast enough while tooling around town to produce the current needed by the big speaker, which is why we must use a battery. To improve: wirelessly connect both speakers (on separate bikes) so we could roll in stereo.

In addion to the primary power out, the caps also have a jack for plugging in a Down Low Glow, these lights make the pedal powered spectacle even more dulce. Also, they can be charged continuously while riding (like the dynamo-driven lights of the old days excpet way cooler) and give an amazing amount of side visibility. To improve: the lights would go out when the indicator was yellow, letting full power go to the inverter until the pedaler gets up to green. Also seriously lacking from our setup is real stage lighting.

The caps are built into little plastic boxes (made out of a section of square gutter downspout—for protection and water resistance). Also in these boxes is a charge controller so that the generator can be used to charge a battery instead of feeding into the inverter. To improve: a kick-ass charge controller would allow you to engage the generator at the top of a really big hill and use 10 amps or so to charge a battery. As it is, our charge controller is not robust enough to use this much current, and the capacitor doesn’t have enough capacity to store it, so most of the downhill potential goes unused. Building this would be one of the top 3 improvements to the system.

We have 6 amp-hour 12V lithium ion phosphate batteries, primarily for running the Soul Cycle, though they could also run laptops and charge other devices. Lithium ion phosphate is a chemistry that is supposedly very eco-friendly, very simple to charge (doesn’t require a smart charger), and relatively lightweight. It is also expensive. We ordered these directly from a Taiwanese manufacturer as a sample. It looks like Brunton is getting ready to sell something similar, in a really robust package, and we hope to try them out. To improve: 6 amp hours isn’t really enough for a bangin’ soul cycle session. We want to try 12.

Solar Panels
We have folding 26 Watt solar panels made by Brunton. They can charge our Lithium batteries, AAs, or iPods. If you daisy chain a couple-three together, you can run a laptop directly.

SHOUT OUT to the self-powered pioneers: SHAKE YOUR PEACE!, Fossil Fool, Nate Byerley, Jeremy Fisher, bicycle the band, Xtracycle Inc, and the Bicycle Music Festival. And big ups to our main man, the engineer and whirlwind tour de force behind our system: Dante Espinosa, now selling this stuff and providing even more detail at his site, economadica.


Can you do it without an Xtracycle?
There are a gazzillion ways to carry cargo on a bike: from jury-rigged rack to kid trailer to home-built hauler. A lot of this stuff is easier to find used than is the currently-in-high-demand Xtracycle, and therefore likely cheaper. Xtracycle is generally lighter, faster, nimbler and more adaptable to a wider variety of cargo than other options: we don’t think any other means of cargo carrying is as suited to the bicycle musician lifestyle, especially if you plan to tour out on the open road. And we are certainly biased (one of us co-founded the company).

As far as generating electricity goes, you can buy a ready-made stationary power generation station on the internet for less than $400 bucks that you can plop most any regular bike into and start making juice. These systems have big motors and heavy stands to hold the bike upright. This means they can likely generate more juice than can our system and that they are much much heavier, to the point wheree you wouldn’t want to tour with them. But if you want to make a system for local use that you can haul around in a trailer (or even leave in place) and use with a wide variety of bikes, this is a cheaper option than building a bike-mounted system.

For bike-mounted, mobile systems, the Xtracycle or another kickstandable longbike platform makes the most sense.

Do you generate while riding and then use the energy to power a show?
No. The capacitors can only store enough energy for a couple of minutes of performance, which is why the audience must (gets to!) pedal throughout the whole show.

Do you store the pedal energy in batteries?

No, we use supercapacitors that only weigh about a pound. Batteries are generally too heavy for bike touring and not as good at rapid charge/discharge. There is still research to do in this area. Some folks are saying that they think we could use batteries instead of capacitors.

Did you guys invent this system?
Most of the elements of the system were developed by Nate Byerley (the Juice Peddler) and Paul Freedman (aka Fossil Fool, of Rock the Bike) for/with Gabe Dominguez (SHAKE YOUR PEACE!) for Gabe’s bike tour of Utah in the Spring of 2007. Gabe’s completely DC system uses the same generator (mounted to the SnapDeck) and capacitor as ours, in a homemade speaker cabinet with a T-amp (a proprietary Class D amp). We wanted a motor mount that could bolt to any bike, a system powerful enough for a whole band playing for 400 people, and a variety of charging capabilities, so we developed these features (with Dante Espinosa, our team genius hurricane loco engineer). In reality, none of this technology is cutting edge (except for the digital amp); it’s just the mobility and application that are our collective contribution to this work that many others are also engaged in. People have been using bikes to power things for a long time.

Where can I buy one?
Dante Espinosa, our system engineer, at his new company economadica, and Rock the Bike both offer various standard and custom elements for human powering music and other things.

Where can I find out more?

There’s a community of interested tinkerers and noisemakers forming at

How much power does each rider produce?
You produce 30-120 Watts continuously on our system, depending on effort (and fitness!). If you’re like Lance, you can probably peak out at 400 or so Watts.

How much energy do you “save” this way?
We powered 98% of our shows in the past year with the audiences’ legs. It would probably be more accurate to say “they powered.” No nukes, no coal, no dams, no pollution. The saved electricity from the whole tour is roughly equal in energy content to about 10 gallons of gas. For comparison, by using bikes to get to our gigs, we saved about 3000 gallons of gas!

Also, because our total electricity is in limited supply, we are forced to conserve it. This means that we use hyper efficient amplifiers, efficient stage lighting, and don’t plug in a lot of extra junk. The scarcity of a resource makes you think way more about how you use it. People who live off the grid in solar-powered houses never forget to turn out the lights because they know if they do their whole system might be completetly dead in the morning! In our modern homes, the “wall” seems like a limitless supply of electricity and we therefore have to “remember” to think really hard in order to conserve it.

Our shows consume about 200W (1/4 the power of a toaster) of continuous human power (we think of it as “burrito power”) to run our 1000W sound system. A typical band our size, playing for a similar number of people (200–800), uses in the neighborhood of 1000–4000W of wall power, not counting lighting. “Wall power” is a euphemism; it means “screwing things up over there where you can’t see it happen.”

This energy saved is literally a drop in the bucket compared to how much energy is saved by touring by bicycle. The point of not plugging into the grid is more a show of independence and self-reliance and a way of helping people get excited about possibilities while connecting some of the mysterious sustainability dots than it is a bona-fide way of severely limiting our impact on the planet.

Can you generate power while riding to store in a battery to turn the motor to make it into an electric bike and make you go?
Yes, if you pray to the something for nothing gods, and are willing to ignore the laws of physics and/or pretend they don’t apply to you!

One comment to “our system”

  1. [...] out over the water, Michael and I mused for the river folks through the Ginger Ninja’s pedal-powered sound system.  The acts that followed us included Ruby Turple with Cedar • Bear Dyken with Summer Moon • [...]

Leave a comment