Chainring bolt replacement PROTOTYPE for single chainring

cults3d

Disclaimer: This project is still in its early stages and serves as a prototype for testing its feasibility. I will be conducting personal experiments using my own bike mounted on a trainer, so if it fails, I am unlikely to suffer serious injury. If you decide to try this out, keep in mind that it's an untested concept and may pose significant risks. In the event of failure while riding, the consequences could be severe. *Updates:* 25 Jan 2018 - I recently broke two v1 designs during a maximum watt sprint session when I accidentally threw the chain due to mishandling the shift mechanism. This incident occurred after the initial breakage of one v1 design where the edge under the bolt head sheared off. Since then, I have redesigned and created a v2 that appears stronger, but it's essential to emphasize again that this project is highly experimental and may not be safe for use. I'm currently testing these parts on my indoor trainer bike, which reduces the risk of injury in case they fail during usage. However, if you decide to try this out, please understand that the odds of a catastrophic failure are still present. Here's a concept for replacing traditional single chainring mounting nuts with standard M5x0.8mm screws: I've opted to use disk brake mounting screws since I have them readily available, but any normal M5x0.8 screw should work as long as it measures at least 8mm in length. The design consists of two main parts: the chainring nut and the washer. The chainring nut is threaded for the M5x0.8 screw, while the washer fits on the other side of the chainring under the head of the M5 screw. To assemble the parts, simply thread the nut from the backside of the crank and secure it with the screw and washer on the opposite side. Provided your threads are clean, the assembly should go smoothly without requiring excessive force. I was able to hold the nut in place using just hand pressure, eliminating the need for a screwdriver slot in the back. I plan to build my bike up soon and test its strength using a trainer. As an avid cyclist, I can generate over 1300W for short sprints, making me well-equipped to thoroughly test this design's durability. To create accurate models of standard threads, I utilized FreeCAD's BOLTS library. However, it appears to be offline at the moment, and based on the GitHub issue discussion, it seems that there isn't much momentum behind its revival. To circumvent this limitation, I downloaded a STEP file from McMaster-Carr featuring an M5 high nut, which has proven incredibly useful for my project.