Spring is coming, and there's nothing more fun than a group ride through town with 10, 100 or 1,000 of your closest friends.  I've been on a lot of group rides and if there is 1 thing that really ads to the event its COSTUMES.  and if there is a 2nd thing, its MUSIC.  having a good sound system really ads to any bike event - both for riders and spectators.  I have several friends that consistently bring the music to local events, but its hard going.  Most of them have a trailer with a huge DJ speaker, weighty amp, maybe an inverter, and a car battery to power it.  Here in San Francisco that means a squat team has to help push them up the hills to keep up with the ride!  Today's project uses high efficiency components to make a much more convenient 25 pound (10kg) setup that mounts on any rear rack and gives the 150 pound (60kg) sound trailers a run for their money.

This setup is easy to build and if you buy all new parts will cost about $150.  The main cost is the speaker and you may be able to re-use one you have around.

If you need a more complete reference on off-grid party sound systems, check out my other article.


This article is sponsored by Momentum magazine and MonkeyLectric.  The article appears in Momentum Issue 45.  Here on Instructables i've posted an expanded build section that has tons more inspirational photos annotated with building tips.

Step 1: What you need

The basic stuff:
  • rear bike rack
  • mp3 player with belt clip/holder
  • small wood screws
  • mount from an old bike light
  • mp3 player cable and speaker cable
  • tupperware box
  • 4 bolts around 3" x 5/16"  (80 x 8mm) with 8 washers and 4 nuts
  • about 2' (70cm) of wood around 1" x 5/8" section (25 x 15mm).
  • if you want 2 speakers instead of 1: a piece of plywood to mount them on
The key components:
  • Amplifier
  • Speaker (1 or 2)
The key to this project is efficiency.  Home and car sound gear is not designed to be efficient or light - it just isn't a concern in those applications.  Low efficiency means you need lots more power to make the same amount of sound, and lots of power means a big heavy amp and a big heavy car battery.  An efficient speaker can produce 5x the sound volume from the same amount of power.  An efficient amplifier is 2x better than a standard one, plus its far smaller and lighter.

Efficient speakers:

PA and DJ speakers are the best place to look for efficiency.  Auto and home speakers are usually poor.  Large speakers are nearly always more efficient than small ones - this is one of our real tradeoffs because large speakers also weigh more.  

The smallest speaker I recommend is the Gemini RS-308, you can get that at Amazon and other places for $70.  It fits into a milk crate and weighs 15 lbs.

For the current project I used a somewhat larger Behringer S1020, I got it from parts-express.com for $100, it weighs about 20 pounds.   American Musical has a lot of speaker choices too.

Go MONO!  Stereo doesn't make a lot of sense when you are riding around on a bike.  Using one larger speaker you get will more sound and less weight than two small ones, and its less work to mount it.

How big a speaker can you fit on a bike rack?  The speaker in my project photos has a 10" woofer, most models with a 10" woofer are about this size.  The Gemini 8" speaker is quite a bit smaller, it fits into a milk crate that you might already have on your rack.

Hacker Tip:  Occasionally I've seen hackers try to use a bare speaker cone with no box to save weight.  Do not do this!  The box of a speaker is critical to its ability to create sounds. When you get rid of the box you lose most of your sound output.

Efficient amplifiers:

For amplifiers there is really only one choice: a Tripath-based amp, sometimes called a T-amp, Class-T amp or Digital amp.  These ultra-efficient wonders are inexpensive but obscure.  T-amps are available in a couple of different sizes.  parts-express.com sells the 10 watt DTA-1 for $45 and it includes a built-in battery holder.  It runs at full power for 4-6 hours on 8 rechargeable AA's - wow!

On Ebay.com there are several vendors with higher power T-amps.  For a 20 watt amp I recommend the TA2020 amp from ebay seller indeed-hi-fi-lab.  It's only $20 and is very good quality with durable construction.  indeed-hi-fi-lab seems to have 2 variations called the "Tripath TA2020 Mini Cute Class T Amp Amplifier Ipod MP3" and the "NEW Class T Amp TA2020 Amplifier Tripath Chip TA 2020".  Rest assured the one I bought is the "mini cute" type, but the other one looks equally well made in their photos.

The larger T-amps don't include a battery holder, you will need to supply an appropriate 12V battery.  12V "SLA" type batteries are very inexpensive, and also easy to find at recycle yards.  For a new one try batterymart.com.  A 7.0 Ah capacity should last you all day and costs $20.  They also have a nice charger for $15.  Amazon has these batteries too.

Much more details about speakers and amps I have tested if you need it.

<p>Could anyone tell me whether a battery (not too heavy) could run this little speaker for a long time? http://www.marshallheadphones.com/speakers/stanmore/stanmore-brown/</p>
How did you hook up the amp to a power source? All the amps I found only has the plug to work with wall plugs in homes.... I trying to fix up a portable system to take hunting to play hunting calls off of my iphone and having a hard time...
Thanks Dan, quick question. <br> <br>Have you seen a Stellar Labs 50-10145 Compact 30W Class T Tripath Digital Amplifier and what is your opinion of it as an alternative to the DTA-1? <br> <br>http://www.mcmelectronics.com/product/STELLAR-LABS-50-10145-/50-10145
I've made a simple and LOUD audio system for my bike + you can mount it - unmount it whenever you want! <br> <br>Here is how it sounds like: youtube.com/watch?v=lrgaHQrWwLQ <br>Instructions on how i built it are in the description!
hey dan, <br> <br>Did you ever manage to mount the Behnringer 212XL to a rear rack? Did the suggested plywood method work out? <br> <br>thanks! <br>Ewen
wow, so glad i stumbled on this. i'd like to ask a question about the speaker efficiency... if you happen to know, what sensitivity do PA/DJ speakers run at? I was trying to find the specs but was too successful. i'm no expert, but i kidda remember that sensitivity of a speaker was related to it's efficiency and the higher number the better (please, someone let me know if i'm wrong). i was thinking to build something i could bring on hustle rides, so i was thinking to use a 6x9 or ... when i lived in LA, i remember one of the guys had used large diameter PVC pipe, which seemed like a creative way to do things too. <br> <br>in regards to the mono, some songs play different things on one side than other and if one speaker goes out the song sounds different. if i just use one (i think u'd said to use the right) side on the amp, would i be able to hear all the sounds of the song or would i have to do something like in your monoXover instructables? <br> <br>thx for the help. i suppose i'll ask more at the next bike partyyyyy :)
Thanks for this how-to.It helped alot and i created this. <br>
It's an instant mobile party where ever you go! Thanks for the Build!! <br>In the video it's not even turned up full blast! All the mount details are in the video description... <br> <br>www.youtube.com/watch?v=JApv_hFocTU
I bought the Gemini 308 loudspeaker. It takes a speakon connector. So to get this to work I now need a speak on to raw wire cable which was a little difficult to find but I found it online.
I use active PA speaker, which has the amp built into the speaker, therefore one less component to carry around.<br> Wharfedale EVP-X Rated at 300 watts rms nice and loud and not too heavy.<br> i also have the speaker mounted on rear rack but facing forward, this has the advantage that u get the full benefit of the sound, and can monitor and EQ your output as u ride. You also get the benefit of seeing peoples shocked faces as u approach.<br> http://www.youtube.com/watch?v=4DRW3JwETc8
This is perfect for the Bike Parties here in San Jose, CA! I always see people lugging trailers with 2 PA speakers and a woofer, but the rig is pretty 'nasty' looking, with the battery (car battery) exposed and wires amok.<br><br>I'm very inexperienced with sound systems and amps, so bear with me, but how are the speakers powered? Do they even need power? The use of the amplifier I get, amplifies the sound and such, but does one need the specific model you suggested? Type T? <br><br>The next party is a month away, but I think I can get this going... I shall use this as my Go-To Bible!
This build is awesome.&nbsp; This is EXACTLY what I&nbsp;want out of my party bike.&nbsp; <br /> <br /> I&nbsp;bought the Dayton DTA-1 Amplifier and have been using it with a nice set of book shelf speakers but it is just not loud enough.&nbsp; :)&nbsp; The setup is perfect for my personal use but it has yet to turn heads.<br /> <br /> Now I&nbsp;am a bit of a realist in what I&nbsp;can expect from this amp, but I&nbsp;would love to hear from you what kind of overall volume you get from this exact setup using the Dayton amp. &nbsp;<br /> <br /> How loud does this setup really get?&nbsp; Can you hear it from a half block away?&nbsp; We have a group ride coming up in June and I want to be ready this year.&nbsp; Your feedback would be most appreciated.<br /> <br /> <br />
switching to a PA type speaker will get you a lot more volume from the same amp. bookshelf speakers are not so efficient. to fit on a rear rack you can use a peavey PR10N or a Gemini RS308 (the smallest PA i can find)
I tried it: This system can really knock (aka be really loud). I've got a PR15 and the Dayton T amp handles it wonderfully. Now I just need to figure out how to strap that onto my bike...
Did it. Great idea. http://www.flickr.com/photos/newlow/4740064835/in/set-72157624247589379/
Hey, what batteries are you using?
Double a's my friend.
Surely you're not generating anything like enough power to run that speaker at it's RMS ? So how loud can it go? What's the battery life?
Also, how are you running one speaker off a stereo amp? Are you only using one channel or did you modify it so that one channel was for the tweater and one for the woofer? Thanks for all the help!
Dan...I'm curious-how do we wire things up with a Tripath to go mono??
the easy way: just use the right channel only.<br>the hard way: follow the instructions in my other sound system projects.<br>
I'll take the 'hard' way...any word on 'exploding' 2020 chips? read of an incident where a hacker had this prob, but he was informed to get off the 33v level he was using....
i have not had any trouble with white noise or exploding. perhaps some of the amps out there are not designed right. that's why i have listed several that i tried myself in my projects.<br>
Thx,Dan-I'll take your experience as gospel in this matter !
...also,Dan..I've also heard of persons buying the complete amp and having 'white noise' issues,and that they changed some components to get silent output-(no white noise') Any leads on schematics or components to repair this?
wow! and i thought my 1st bike system was top heavy. that looks like a bike you have to be very careful getting on and off. i'm sure you get much better volume and bass than i could though.<br><br>i'd like to do an on bike system in fiberglass next time to cut weight &amp; be able to use larger &amp; more efficient speakers than my little mission 5 1/4&quot; 2 ways. ideally, i'd like to go with 8&quot; woofers if i built a no holds barred bike system.<br><br>if you're really looking to get loud, parts express just started carrying sure electronics' class D amps including a 24-30v one that puts out a solid 70wpc with very low distortion into 8 ohms. that would make a big speaker like you have shake the bike for certain.<br><br>i like how clean your install looks. everything is integrated &amp; uncluttered. you should post a video of your rig in action on youtube.

About This Instructable


39 favorites


Bio: Dan Goldwater is a co-founder of Instructables. Currently he operates MonkeyLectric where he develops revolutionary bike lighting products. He also writes a DIY column for ... More »
More by dan: Light-Up LED Lollipops How To Fix a Bike Chain How To Ghostride a Bike
Add instructable to: