The Bike Mike

This project came out of a couple other ones - and the fact that I am an avid cyclist. The Bike Mike is a stereo microphone that can be mounted on a bicycle and connected to an action camera. It is a combination of a few things all coming together:

1. Action Cameras that can directly use USB audio interfaces
2. A compact interface that provides PIP power to the mic capsules
3. A pair of really good Omni mic capsules
4. Wind Protection with shock mounting
5. Me figuring out how to mount all of it on a bike

My bike is a Specialized gravel/road bike and I use a Wahoo bike computer. My mount lets me put an action camera under the bike computer out front. Don't worry about the brands. My bike mount works with either a Wahoo or a Garmin. A quick search on Amazon for “bicycle computer mount” shows many styles of these that work with different bikes, different computers and include a gopro style mount. The included gopro mount is the important part. I personally use DJI action Cameras and have an Action 6. These all let me directly connect a USB Audio interface. Yes, even a full on studio one! They are USB Audio compliant.

I rode Ragbrai this summer, my 7th time. If you have never heard of this it is a ride across the state of Iowa every summer and this was the 53rd year. In the past I have had a Sony pocket recorder in my bike bag and a pair of mics on the handle bar ends. That meant having to sync things later. I did have little furry wind screens on the mics, they still picked up vibrations etc. They worked, just not the best option.

Previously I designed an ORTF mount with a pair of Cardioid capsules that sounds great and works well hand held and on a stand. Would it work for this?... Um no. It worked great when the bike wasn't moving! The capsules were in direct contact with the frame which was in direct contact with the bike. So as soon as I had road vibration it picked that up. Back to the drawing board.

There were two things I needed here. Wind protection and vibration protection. I know from film and TV audio that there are things called “foamies” That are small pieces of foam rubber with holes in them that you can slip over a lavalier mic to help keep the mic AND the mic cable from rubbing against the actors' clothing. So what if we used a couple of those to keep the wires from touching the 3D printed frame? And what if we used a foam windscreen on the mic capsule and then lightly glued it to the frame? Finally, what if we then put that in a dead cat for the final wind protection? Well, then you have the Bike Mike! And it works amazingly well. I built one before Ragbrai and rode with it during the Peach Pedal ride in Texas. Then I took it to Ragbrai. Amazing to me I was stopped at a rest stop and someone came up to me and asked if I was Sound Sleuth! He had seen the Peach Pedal video and asked where the build video was. I dedicate this Instructable to him.

Parts:

Quick Release Plate: https://www.amazon.com/dp/B09HBW4QCS?

Extension piece/cold shoe adapter: https://www.amazon.com/dp/B0DQXS3Q1R?

Screw https://www.amazon.com/Release-Adapter-Thumbscrew-Mounting-Frgyee/dp/B096FG59D2/

Mike Adaptor https://www.amazon.com/dp/B08DTP7R8M

USB splitter https://www.amazon.com/MOGOOD-Splitter-Adapter-Monitor-Charging/dp/B0CQY65B3H/?th=1

Wahoo Mount https://www.amazon.com/dp/B0BFJCN8PS?

Bike Light (USB Battery) https://www.amazon.com/dp/B0DGL64R2C?th=1

Action 6 Mag Mount https://www.amazon.com/ULANZI-OA24-Expansion-Connector-Dual-Claw/dp/B0GS9KZ6VF/

½ inch Foam Rubber… I got this at Hobby Lobby but Michels and even Walmart should have it.

Wind Protection:

https://www.amazon.com/Windscreen-Audio-Technica-Microphones-Filtering-Plosives/dp/B0BL1C5XT9/?th=1

Omni foam screen https://www.amazon.com/dp/B0C85GV7S8?th=1

Foamies https://www.amazon.com/dp/B093SG56ZW?th=1

Mics: Pick a pair of these. The instructable is written around the EM273 but the other two will work fine

EM273 https://www.digikey.com/en/products/detail/primo-company-limited/EM273/25870405

EM272 https://www.digikey.com/en/products/detail/primo-company-limited/EM272J/25870265

PUI5024 https://www.digikey.com/en/products/detail/pui-audio-inc/aom-5024l-hd-r/7898328

Wire https://www.redco.com/Mogami-W2368.html

3.5mm Connector https://www.redco.com/Rean-Neutrik-NYS231BG.html

This one is pretty straight forward. The wiring is super simple. It is wiring the capsules to a 3.5mm connector that will plug into our little USB interface. I have a diagram for the Capsule I used, my new Favorite Omni capsule, the Primo EM273. It sounds amazing. It is a 3 wire but has a 2 wire sibling, the EM272. Either one works and so will the PUI5024. I highly recommend the EM273. All the audio you will hear in the video is from that.

The frame is 3D printed. You need to use PETG as this can be in the sun and PLA softens and bends... Ask how I know. There are two arrows that point forward along with a smooth ridge to identify the front. Yes we are using Omni capsules so they can face any direction. We need to keep track of it so the stereo image remains correct. The rest is assembly.

Step One: Prep the 3D printed parts

1. Insert the ¼-20 brass insert into the base with a soldering iron.
2. Clean up the support material from the outer wind protection frames
3. Glue those to the base with some E6000 glue see the photos. You want the edge of the frame to be next to the cutout of the base.
4. Glue two foamies on each side as shown these will carry the mic cable.
5. Set aside to dry.

Step Two: Prep the wire and solder on the capsules. We only need a short amount of wire before we get to the connector. See the photos for all of this.

1. Cut two pieces of the wire equal length - about 16-20 inches.
2. On one end strip off about ½” of insulation
3. Twist the shield back and together and bend over to one side.
4. Strip back a small amount of the center conductor's insulation.
5. Tin about half of the bare shield from the end.
6. Tin the center conductor.
7. Place the capsule in a hobby Vice.
8. Tin the leads for the G, S, and D.
9. Trim and bend the shield lead so it can connect the G and S lead together.
10. Solder the shield to the G and S lead to connect them both to the shield.
11. Solder the center conductor to the D lead.
12. If you are using a two wire capsule (PUI5024 or the EM272) connect the center conductor to the “+” and the shield to ground.

Step Three: Mount the mics.

1. Insert the microphone into the Foam windscreen. Carefully push it to the end
2. Feed the wire end through the two foamie’s
3. Using some E6000 glue, glue the mics to the cutout on either side of the base. You may need some tape or something else to hold them in place while the glue dries.
4. Let this dry.

We have now isolated the wire and the mic itself from direct contact with the base. I have found that the first few inches of the cable are critical for this. After a few inches, the coupling falls off dramatically. We also have two layers of wind protection. The foam ball around the mic capsule and the final dead cat we will install after testing.

Step Four: Solder on the connector.

1. Identify the mic that is on the right side of the mic while it is facing forward. As in you are behind it looking over it. Facing the front it will be on the left…
2. Slide that wire through the connector shell and inner insulator. Prepare the end of the wire by stripping back ½” of the outer insulation.
3. Pull the shield back and lightly twist it together.
4. Strip a small amount of the center wire insulation.
5. Tin the center conductor.
6. Solder the Right wire to the Ring connection.
7. Slide the other wire through the connector shell and inner insulator.
8. Strip and prepare as before.
9. Solder the Left wire to the Tip connection.
10. Twist the two shields together and wrap them around the ground/shield part of the connector. See the photos.
11. Solder the shield to the connector.
12. Cut back any extra shield sticking out.
13. Bend the cable clamp part inward on the wires but don't crush anything.
14. Slide the inner insulator and the connector shell over the wires and screw it on.

Yeah! You have done the hard part. Test it by plugging the mic into the USB adaptor. The adaptor can be connected to an iPhone, Android, or laptop that has a USB C connector. These things are amazing. It is a 24 bit USB interface with PIP power and designed for electret condenser mics. Once you have verified it works we have one final step.

Wind Protection

1. Slide the furry “Dead Cat” over each of the two frames
2. Cut two small circles of foam rubber and slice it to the center so we can slide it over the base.
3. Slide this on and carefully “Stuff” it into the open space at the base. These fur wind screens are meant for an Audio Technica AT2020 microphone. So we will have a gap that needs to be filled.

If you don't have foam. you can use any kind of filler that will prevent wind directly entering such as pillow stuffing etc.

This is where we turn it into a bike mountable usable tool.

The parts list shows what I used centered around a cold shoe extension and assorted hardware. The key for me is the Quick Release Plate. That lets me take it one and off the bike to film things with great audio while I ride. During Ragbrai I used this a couple times in the video - a high school drum team, Mr Porkchop and Beekmans Ice Cream.

See the pictures and assemble as shown. Feel free to vary some of the parts depending on your specific setup. My parts selection for this part isn't locked in but a starting point. It also depends on your bike. This mic can also be used for Vlogging and other uses. The audio quality is fantastic.

OK the first thing to be aware of - And it kicked my butt at first. The Action 6 is mounted upside down on my bike. It automatically flips the image. It doesn't change left and right in the audio… If you notice that yours is reversed. Just switch it in post. All audio programs let you do that as does Final Cut Pro.

When I rode Ragbrai I used a USB splitter cable and had a bike light on my bike. The bike light acts as a battery for this setup. I didn't film continuously, but this setup will let an Action-6 run for 10-12 hours.

Please see the video for how it all came out. The final downhill as we came into town and the Mississippi river exceeded 40MPH. You can hear how well this works. There are no effects on the audio other than me adjusting levels on the individual clips. This mic can of course be used for many other things than mounting on a bike. Let me know what you come up with and your thoughts.