I am an avid cyclist who does the bulk of my commuting to work on two wheels. On most days, my commute is one of the best parts of my day. Unfortunately, on rare occasions, I will have an encounter with someone acting dangerously or aggressively. Since law enforcement rarely acts on hearsay alone, I started riding with cameras pointing forward and backward a while ago. My front camera is a GoPro and my rear camera is a combination camera and rear light called the Cycliq Fly 6.

The Fly 6 is a great piece of engineering. It is waterproof, has a bright light for safety, and works as a continuously recording camera that you can start with the press of a button. It even senses if you've been in a crash and prevents the video from being overwritten. Unfortunately, it has one design flaw: the straps that mount it to your seat post. Out of the box the Fly 6 comes with some black rubber straps that connect to the light to provide a firm and removable connection to your seat post. The problem is that those straps eventually break and replacements are hard to come by. Cycliq sells replacements, however, they don't sell them alone (you have to buy a water bottle with them), and once you pay for shipping they end up being around $36 US. Considering how they keep breaking, that is a very expensive consumable. Subsequent versions use a velcro strap instead, but there is no retrofit for my model.

I thought to myself, there has to be a better solution.

Enter 3D printing. I took one of my existing straps and my trusty digital calipers and started taking measurements from the strap that was already starting to fall apart. Next I used Fusion 360 to model a replacement strap from those measurements. At first I tried to make my model as close to the original design as I could, including the tapered pull tab on the end.

I decided to print my model using TPU (Thermoplastic Urethane) which is a flexible filament that is quite strong. To be able to successfully print it, I had outfitted my printer with a new extruder assembly from Micro Swiss that better supported flexible filaments. The straps printed nicely, and after using about $0.22 US in TPU, I had a functional replacement.

The strap worked really well and I was able to use my Fly 6 without worrying about breaking the straps all while saving $35.78! There was one downside of my design: it was hard to remove. Part of the problem was that the tapered head which I copied from the original did not give a good platform to grip while taking the strap off the bike. Also, the TPU was so strong that it took a fair amount of force to remove it. So I went back to the drawing board and created a second version without the taper and I added some taller ribbing to give a more secure grip. This time I tried another flexible filament, TPE (Thermoplastic Elastomer), which isn't quite as strong as TPU but is a lot more flexible. I printed it out and the problems from before were now solved. It was stretchy and easier to remove.

The new version was a joy to use, and I've been using it for months with no signs of deterioration. During this time also got a Capital Bikeshare membership (a bike sharing system in the Washington, DC area) and I thought it would be great to be able to use the Fly 6 on the bikeshare bikes as well as my own bike. One day I took my Fly 6 with me and tried to get it on the bike and I was faced with a problem: it would not fit! It turns out the seat post on the Capital Bikeshare is significantly larger than a standard seat post, so the strap was just not long enough. Not one to let that kind of thing get in my way, it was back to the drawing board.

After spending a few minutes with Fusion 360 I made an extra long strap that fit Capital Bikeshare with room for even bigger seat posts. After printing it out I took it to a Capital Bikeshare bike and it fit like a charm.

I have been quite pleased with how the designs came out and I enjoy using them every day I commute into my office. I particularly enjoyed extending the previous design so I could do something that was not possible before.