When I moved to London I started cycling to work to avoid the costs of public transport and owning a vehicle. I picked up a used single-speed and invested in some gear to keep me warm and dry throughout the colder winter months. For the hazy days and cycling at night, I also needed to invest in one of the most crucial pieces of equipment: a good commuting light. I felt that the light I chose was lacking in certain areas, so I decided to try my hand at 3D printing a better bike light mount for myself.
Being on a budget (moving is expensive), I opted for a more inexpensive option, the Knog Plugger. It is a decent light, with more than enough brightness and battery life for my 20–25 minute commute. Where it doesn’t quite meet the mark is in its mounting system. Like many other budget bike lights, it mounts to the handlebars or frame using a simple rubber band, basically an O-ring. For the past few months I have been using this light as it came from the box, and found 2 major problems with this O-ring mounting setup:
- The light was difficult to quickly remove and replace for charging
- The light moved whenever I hit bumps in the road
To tackle these 2 minor annoyances, I decided to design and 3D print a new bike light mount specifically for my Knog Plugger and my bicycle.
Choosing a Mounting System
There are two parts to the mounting system: a permanent mount affixed to the handlebars, and a quick-release mechanism to easily removed the light from this mounting point. Looking at more expensive handlebar-mounted bicycle accessories, they usually have some sort of rigid clamping mechanism to fully fix it in place. This was the easy part of the design, and I mocked up a quick 2-part fixture to be mounted using two standard M3 bolts and nuts. My bicycle handlebars measure at 26mm in diameter, so I designed it to fit that. I made sure to leave a small 2mm gap between the clamping sections to ensure a tight fit and avoid rotations/slippage.
The tricky part was the mechanism to attach and quick-release the bike light from this mount. I researched some other bike accessories and fount a couple of common designs for quickly removing components from their fixtures:
My favorite of these is definitely the Quad Lock system, so I wanted to model my design after this in some fashion. I love the quick twisting action and elegant design of it. I actually found a great 3D printable model of a Quad Lock style system, which can be found here. This design is cool because it even includes a 3D printed spring! I considered adapting it to fit my bike light, but after some test prints I decided I needed a simpler design for my humble Ender 3 to handle, still based on a twist-release model but without any springs.
I decided to go with a twisting mechanism of my own design, using 4 extruded pins to slide into curved slotted tracks. There is a drop-out at the end of each track to keep the light from twisting backward while riding. It is necessary to physically lift the light straight up before twisting it counterclockwise to release it.
With a twisting mechanism to keep the light in the right position while allowing me to quickly release it when needed, I just needed to attach this base with pins to the bike light itself. I designed another clamping system to attach to the light, with the locking pins on the bottom section. I made some rough measurements to model the Knog Plugger, especially with the cut-out on the underside of the light.
My 3D prints turned out pretty nice. The approximations I made in modeling the Knog Plugger worked out fine, and the parts mounted nicely to the light as expected. It took me a couple of iterations to get the tolerances right, but the light twists in and out of the mount with ease now. The light is a little bit shaky while riding, but has not popped out of its locked position during my commutes. My setup is now very easy to remove when I need to leave my bike locked outside or bring my light in to charge!
I used Fusion 360 for the design and an Ender 3 Pro for the print. If you want to print this for yourself or modify it to your specific bike light or handlebars, you can find the STL files here.