Designing a Dynamo Holder For My Bike

My workplace is some distance from the nearest bus station, so I travel there by bus and cycle the rest of the way. For this reason, I keep my bike parked near the bus station. Since it is a very public area, some of my bike accessories have been stolen. However, I noticed that components that are securely integrated into the bike using screws and cables are less likely to be taken. I therefore decided to replace my battery-powered LED light with a dynamo-powered one.

I obtained all the necessary components: a dynamo and a compatible LED light. However, I soon realized that my bike did not have a suitable mounting point for the dynamo. My first idea was to drill a hole in the frame, but every online resource I found strongly advised against doing so.

Instead, I decided to design a custom dynamo holder for my bike. After looking at existing designs for inspiration and taking measurements from my Decathlon Riverside bike, I modeled the part in SolidWorks. The STEP files for the front part and the rear part available for download, and the image below shows how the finished part looks when mounted on the bike.

Since the part is small and has thin sections, I printed it with 100% infill. I used PLA because it was the strongest material I had available at home. After a discussion with my boss, he has pointed out to me that PLA is not UV resistant and would break apart over time. He suggested that I can print it with ASA. So as soon as my filament arrives, I will print it and switch it. The mounting holes were designed for M6 bolts. I also added strips of rubber at the contact points to prevent the holder from sliding and to protect the bike frame. In the finished assembly, however, the clamping screw already held the part firmly against the frame and prevented most of the movement. 

Initially, I had difficulty connecting the LED wires to the dynamo terminals. The LED had exposed wires without connectors, while the dynamo used blade terminals. Wrapping the wires around the terminals and securing them with electrical tape did not seem reliable, particularly because the bike is constantly subjected to movement and vibration.

I also tried soldering the wires to the terminals, but since I am not very experienced with soldering, the connections did not hold securely. I therefore asked my boss, who has considerable experience with electrical connections, about the correct approach. He recommended crimping blade receptacles onto the wires and then sliding the receptacles onto the dynamo terminals. I followed his advice, and the resulting connection worked properly and felt mechanically secure. Since it rains quite often here, i wrapped electrical tape around the connection. A picture of the finished connection is shown below.