Why I needed it
GoPro videos get terribly boring when shot from one perspective only. When I decided to tackle my first two day mountain bike race, over what promised to be interesting terrain, I knew that I wanted to try and document it. Unfortunately, none of the official GoPro mounts are suitable for adjusting during a race. Without multiple cameras you are stuck with one boring shot for the whole race.
Why the world needs it
Because YouTube really doesn't need any more 15-minutes-of-my-handle-bars GoPro clips. Please!
My Design Goals
Must be easy to change perspective
Must be stable
Must be cheap
Step 1: Parts and Tools
Hardware Store Spring Clamp (I chose 100mm)
M5 Bolt and nut (smaller is ok, so long as it is long enough to go through the width of the clamp)
Straight GoPro Mount arm (If you ever bought a spare mount you should have 2 of these)
Measuring Device (Ruler/Vernier)
Maker of 3mm Holes (I used a Dremel with a 3mm bit, but Electric Drill/Hand Drill/Laser Vision will work just as well)
Spanner (to fit the nut you chose)
Something sharp (pin or blade) to make marks in the plastic
Step 2: Choose Mount Position
Position the Arm
If you are using a small clamp, make sure to choose a position where the bottom of the mounting arm won't protrude into the jaws of the clamp.
Step 3: Measure the Slots
Positioning the Slots
Here are the critical measurements of the GoPro's mount as I measured them.
Gap Between Legs: 3.5mm (a bit variable at the tips due to to their flex)
Width of Legs: 3mm
Diameter of Hole: 5mm
Slot Positioning Method 1: "High Tech"
Most clamps have a useful line down the centre from the moulding process. In order to place the slots accurately, measure from the centre line to the centre of the slots. This means, the centre of your slots needs to be (Gap Between Legs)/2 + (Width of Legs)/2 = 3.25mm away from the centre line.
Measure 3.25mm from the centre line in a few points with a vernier and make marks in the plastic with the tip of your blade or a pin. You should end up with two parallel rows of marks, 6.5mm apart.
Slot Positioning Method 2: "Low Tech"
Draw all over the edges of the GoPro arm's legs with a felt-tip pen or highlighter, then roll the legs on some paper to get a trace.
Cut this paper out and stick it to the clamp with a bit of clear tape, then poke through the paper along the edges of your traces with a pin or blade to make marks.
Step 4: Cut the Slots
Pilot Holes for Accurate Drilling
I find it helpful to start the hole by making a pilot-hole with the tip of a knife or a pin, this stops the drill from skipping around one the plastic. You should already have these notches from the measuring step, but it helps to make them a bit deeper.
Drill them Holes
Use a drill to make a series of holes that you will later join to make a slot. Make sure you use a bit that is a little smaller than you need (3mm), not bigger.
Join them Holes
Once you have all your holes, join them to form a continuous slot. The plastic tends to be quite soft, so use whatever you have, I used a drill for most of it and a scalpel for the touch up. Keep testing with the GoPro mount to see how it fits. The goal is a tight fit, so don't take too much away at once.
Step 5: Drill the Bolt Hole
Position the Bolt Hole
Measure the distance between the centres of the two holes on the GoPro mount (On this short one it is 20mm), then insert the mount and measure that distance down from the first hole and make a mark for drilling.
Drill the Hole
First remove the GoPro arm and then drill where you made the mark. I used a 3mm bit and wiggled it around a bit to make the hole almost as big as the M5 bolt. Leaving the hole slightly smaller means that the bolt will bite into the plastic when you screw it in.
Bolt it Up
When tightening the bolt through the plastic, you will feel some resistance, but make sure that your bolt is going cleanly through the hole in the mounting arm. If you are unwittingly tightening the bolt against the side of the arm you could bend and break it.
If your bolt is too long, trim it down with a Dremel cutting disc or a hacksaw, you really don't want a sharp protrusion on your handle bars.
If your slots are tight enough there should be no movement, but if there is any vibration it can easily be solved by filling the gaps with epoxy. Of course once you have done this you won't be getting that arm out again.
Step 6: Usage and Conclusion
I was extremely happy with my results. The mounting is probably not suited for something like downhill mountain biking, since it can vibrate a bit with big hits, but one doesn't have much time to move the mount around in downhill anyway.
For marathon or cross country type events, the mount works very well and is surprisingly stable. The ability to move the camera position in seconds during a ride makes for far more interesting videos.
I have attached pictures of some of the mounting positions that I found worked well as well as some screengrabs from the race footage.
The video below is the one that I took on my race, although it is a bit long I think it is infinitely more watchable than if it was the same length taken from one static mount.