DIY Rearview Bike Camera for ~$40

In this post I’ll not only tell you WHY I wanted a rearview camera for my tri-bike (oh, the horrors!), but also show you HOW to make one — for less than $50 to boot!

The Three Essential Parts:


A Waterproof Camera — $9.99 from Amazon Prime


A 4.3” Monitor — $13.40 from Amazon Prime


A 12V Rechargeable Battery — $14.30 from DealXtreme

And Some Optional Fun Bits:


Blinking Red LEDs — $0.48 each from LighthouseLEDs

Part 1: Why Would Anyone Want a Rearview Camera for Their Bike?

The Short Version: Runners >> Cyclists. Pie >> Cake. Ergo, a rearview camera.

The Long Version: By in large, runners are an easy-going and friendly bunch of people. They'll listen intently with genuine interest as someone describes their losing battle with blackened toenails, joyously accept a glob of vaseline on a popsicle stick from a perfect stranger at a race, and paw through their race-day swag with the same enthusiasm as a 3-year-old on Christmas morning. 

Cyclists, not so much.

In my opinion, cyclists take themselves way too seriously. Perhaps it's because they're condemned to wear lycra cycling shorts with a built-in diaper in public. Perhaps it's because they'll never be allowed to race with their heroes — whereas I've raced with Meb. Twice.* Perhaps it's because they feel guilty for spending more money on their bicycles than they did on their kid’s college education… 

It's not 100% clear what the reason is. But what is clear, is that cyclists live by a rigid set of Rules that make obsessive-compulsive people seem like free-wheeling Woodstock hippies by comparison. If you’re unfamiliar with The Rules you can find a complete copy on The Velominati website, the self-proclaimed “Keepers of the Cog”.

If you think I'm exaggerating about the cyclist OCD tendencies, check out Rule #7.

Rule #7

Tan lines should be cultivated and kept razor sharp.

Under no circumstances should one be rolling up their sleeves or shorts in an effort to somehow diminish one’s tan lines.  Sleeveless jerseys are under no circumstances to be employed.

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This tan line, while acceptably razor-sharp, was acquired on my tri-bike (The shame! The shame!) so it doesn’t count…

True story: When I showed up with my fancy road bike to ride with my cycling “friends” the first thing they told me was to get rid of the factory spoke reflectors. They said the reflectors made me look like a newbie because real cyclists don't use them. Having been face-planted into the tarmac by a pickup truck a couple of years ago, I'm firmly in the “more is better” mode when it comes to being visible. My cycling buddies just wouldn't let it drop though and hounded me for weeks.

I ride a tri-bike now which puts my teeth (which I’m quite fond of, I hasten to add) about 2” above the stem when I’m in the aero position. Tri-bikes are twitchier than road bikes. (Ever see a cyclist sit up and pedal with their hands off the handlebars? Yeah, I guarantee they weren’t riding a tri-bike.) To add to the problem, when you’re in the aero bars you don’t have quick access to your brakes. And finally to top it all off, I’m paranoid about what’s behind me when I ride on roads. (See the face-plant reference above.)

(Actually, is it paranoia? Two of the guys I ride with regularly have been hit by cars. A car passed JP and turned in front of him, cutting him off. JP ended up t-boning into the side of the car while he was going a good clip. Jimmie was riding on the shoulder in broad daylight when a pickup truck veered out of his lane and hit Jimmie from behind, knocking him unconscious and breaking ribs and fracturing bones in his spine. These incidents happened on roads that I ride on in Dallas… Come to think of it, of the 5-6 guys that ride in our group regularly, three of us have been hit by cars. A word to the wise: don’t join our cycling group. Apparently we’re cursed.)

Back to our regularly scheduled blog: 

So my two options to see what’s behind me on the road are to swivel my head and glance backwards every 15 seconds — and risk losing control of the bike which someday is going to result in me french-kissing the stem violently — or get a mirror so I can see what’s coming up on my six.

It seems like an obvious choice, right? 

Except that mirrors are even lower than reflectors on the totem pole of what’s unacceptable on a real cyclist’s bike. For the curious, the pecking order seems to be something like this:


Carbon Fiber “Fill-In-The-Blank” 

Rear Disc Wheel

Power Meter

Glue-On Tires

Raw Sewage

The Black Plague



Wheel Reflectors

Handlebar Streamers

Rearview Mirrors



Even those discrete helmet-mounted dental mirrors are openly scorned by real cyclists.

I was at a loss until I found a weakness in the cyclist armor-of-scorn that I could exploit: Cyclists are nearly as obsessive over gadgets as triathletes. Thus large, complex cycling computers are revered. It occurred to me that I could mount a rearview display on my handlebars and as long I didn’t turn it on until I was in motion everyone would assume is was just a very large cycling computer. 

So I started searching for rearview cameras for bikes. It turns out that rearview monitors are available for cyclists but the ones I found were well north of $100 and thus too expensive for me. Some of high end ones automatically loop and record the last 10 minutes of the video stream (to use as evidence presumably if you’re in a crash, as in: “Your honor, if you’ll allow this video recording into evidence you’ll clearly see the defendant’s car veering onto the shoulder and hitting my client. Or I could just ask my client to moon the bench; the imprint of the pickup truck’s license plate is permanently embossed on his left cheek…”)

I don’t really care about that recording feature. In a car-versus-bike incident it’s a moot point who had the right of way. Either way, the cyclist is going to the hospital. I just wanted a simple system that will enable me to glance down and see what’s coming behind me so I can take evasive action if needed or at least swear loudly before the impact.

I did a little research and realized that the pieces to assembly a home-made rearview monitor are easy to come by and pretty cheap… So I built one. :-) The instructions are below so you can build one, too. But remember, if anyone asks, it’s a cycling computer, okay?

(And by the way, pie is better than cake. QED.)

*Of course, the last time he finished right about the time I cross the mile 2 marker. But, for the briefest moments, we were on the same race course together!

Part 2: How to Build Your Own Rearview Bike Monitor for Less Than $50

Add-on rearview cameras and monitors for cars are available for dirt-cheap at discount websites like DealXtreme, GearBest, and even Amazon. I’ve had pretty good experience with DealExtreme in the past (the one time my order got lost, they promptly sent another when I contacted them by email) but I’m going to assume that you’d prefer to order from Amazon. The prices are within spitting distance anyway.

The camera and monitor that I used came from Amazon. You can order the exact same things as shown below here and here. (There are cheaper versions of these items available if you forego the Amazon Prime option. If the pictures and descriptions look similar they’ll undoubtably work, too.)

Now you’ll just need a 12V battery to power them. (They’re car accessories so they are made for a 12V supply.) Don’t worry, you don’t need to mount a car battery to your bike frame; there are small, lightweight rechargeable lithium ion battery packs configured for 12V. I got a 4000 mHh (milli-amp-hour) battery from DealXtreme here. It powers my rearview camera for about 4 1/2 hours on a single charge. It comes with a charger meant for European plugs — you’ll need a European to USA adapter (no need for a transformer) like this one for $1.09:

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European to USA plug adapter from DealXtreme

Wiring the devices together is pretty simple:

The yellow plugs are for the video signal. The red plugs are for the power. The white plug on the monitor is for audio and isn’t used. There are two black plugs on the battery — male and female — and either one can be connected the camera and monitor. If you don’t care about appearances, you could go to Radio Shack and buy the cables to connect everything up without any further work. Throw in a little duct tape to mount everything on your bike and you’re done.

I was opting for something more discrete though. (I suspect that yellow tipped video cables wrapped around my top tube would be a bit of a tip off to my cycling group.) Also, I decided to have some fun and mount some blinking red LEDs to the camera. My thought process was something like this: “Heck, I’m gonna have a massive 4000 mAh battery mounted on my bike. I might as well use it to power some blinky lights.” 

So… I needed to bring power to the camera and LEDS, power to the monitor, and the video signal from the camera to the monitor. I got some black telephone extension wire at Home Depot to wire everything together. It’s not quite as cutting the cables, stripping back the wires, and soldering everything together.

As it turns out, the Y-branches on the cables from the camera and the monitor have some electronics embedded inside. (Don’t ask me how I found out.) For example, the Y-branch for the camera reduces the voltage from 12V down to 3.3V. If it isn’t in the loop somewhere, the camera won’t work. 


But the Y-branches are bulky and I wanted to move them closer to the battery (which I placed under my seat). So I modified the wiring diagram to this:

This new diagram has has the exact same functionality as the previous one. I merely cut the Y-branches out from in-line and moved them to the battery and added some LEDs. 

Note that the LEDs I used require 12V — so there are actually two different voltages running from the battery to the tail camera: the modified 3.3V from the Y-branch to power the camera and the ‘raw’ 12V directly from the battery to power the LEDs. The ground (or black wire) can be shared by the camera and the LEDs; there’s no need to run two ground wires. 

If you order the exact camera linked above, you’ll also get a power cord that fits the battery plug perfectly. (One less thing to buy.)

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Telephone wire (the stuff I used to make the long runs to the camera and the display) has four leads: black, red, green, and yellow. I used black for ground, red for power coming from the Y-branch, and yellow for the video signal. There is no need for a 4th wire to the display so green isn’t used from the battery to the display. I broke all wiring color conventions and used the green wire as the 12V power supply from the battery to the LEDs.

I designed the camera and display mounting units in a free, online CAD program called OnShape and then 3D printed them. (I made the files public here so if you have a 3D printer feel free to use them.)

The CAD drawing of the camera mount from OnShape

The CAD drawing of the display shell (the GoPro mount is underneath)

The camera unit has locations for 3 LEDs. Strictly speaking, it’s bigger than it needs to be. I left extra space as a place to stuff the wires from the LEDs. The display mount has a Go-Pro attachment mount on the backside.

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Camera/LED housing

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The display shell before sanding and painting

To start, I unscrewed the end off the camera, peeled off the blue protective film, and removed the metal spring clip. Then I screwed it back together.

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Then I hooked the camera to the display and battery using ordinary cables (to make sure everything worked). While checking the system, I made sure to note the camera orientation so I could mount it in the camera housing right-side-up.

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A partially assembled system

I cut and stripped the LED wires to length and glued the LEDs in place with a little silicone. I used a thin amount of silicone sealant to ‘glue’ the camera into the mounting unit and placed it so that the camera was oriented ‘up’.  

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I ran the free end of a piece of telephone wire into the camera mount, stripped the wires, and hooked up all the black wires together (camera, LEDs, and telephone), connected the white camera wire to the yellow telephone wire, connected the red camera wire to the red telephone wire, and connected the red LED wires to the green telephone wire. Then I stuffed the wires into the camera mount and glued on the back cap.

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Next up, I disassembled the display from it’s original plastic housing and reassembled it into my 3D printed housing. 

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Disassembling the LED display from it’s original housing

(This was only for aesthetic reasons: my housing looks more aerodynamic than the original housing.) I used a little more silicone glue to hold the screen in the shell. 

The beige rectangle with the red and black wires coming from it are actually the contrast, brightness, and menu buttons which are used to control the display. It’s attached to the bottom half of the display shell shown below.

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I ran another piece of telephone wire into the housing and connected black to black, red to red, and yellow to yellow. The white wire (from the display cable) is not used. The green wire (from the telephone wire) is not used.

Then I glued the two shells together.

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Display shell fully assembled and ready to mount to the bike

(In hindsight, I could have added a power switch on the display unit. As it works today, I need to turn the power on/off at the battery.)

The display housing has a standard GoPro mount flange. I ended up making a mounting bracket for my aerobars shown below. I zip-tied the bracket to my aerobars and then attached the display to it. The GoPro mount lets me adjust the viewing angle easily.

GoPro aerobar mount … or Klingon Bird of Prey?

I salvaged a piece of elastic from a Lace Lock shoestring off an old pair of running shoes and ran it through the hole in the camera mount body.

The camera is attached to a CO2 cartridge mounted behind my seat. The ‘gears’ in the base of the camera mount allow me to adjust the camera so that it’s horizontal even though the CO2 cartridge sticks out at an angle.

I stuck some velcro tabs to the battery and used some velcro straps to secure it under my repair kit under my seat. 

Finally, I zip-tied the telephone wires to my frame. Heres a video of it assembled and working:

The blinking lights aren’t terribly bright — although they are a great decoy. My cycling friends just thought I had a crappy light; no one suspected it was really a camera.

I tested my new system out on the Hotter’N Hell 100 a couple of weeks ago. I got about 4 1/2 hours of use from a fully charged battery. In full sunlight the display can be difficult to see but overall I was pretty happy with it. 

One note about charging the battery: Make sure the switch is in the ‘on’ position when charging — which seems counter-intuitive. As you can see below, if you put the switch in the off position, the charger shows a green light. In this case, it means that the battery isn’t accepting any charge — not because it’s fully charged already but because it’s switched off. When the switch is turned on in the right picture, the charger light changes to red — meaning it’s charging the battery. Eventually, it will turn green when the battery is fully charged.


 © Phil Miller 2014, 2015, 2016