Hi everyone! I am a student at Cal Poly San Luis Obispo in California, and I am studying mechanical engineering. I love Cal Poly because it is a very hands on school. I am in a senior level bike design class, and for my project I am restoring and converting a 1940s bike into a E-Bike to commute to work on when I graduate! Follow along as I document my build.
For the first post I will show the frame I found and my plans for the build.
I would like to design a bike that is stable at higher speed than general road riding. The rider should be comfortable, meaning that he or she can see the road ahead in a comfortable position and that there is some sort of suspension to smooth out the ride at high speeds. Safety will be considered for the rider and from electric hazards. I would like to add disk brakes front and rear for adequate stopping power. Finally, I would like to keep as much of the original styling aspects of these bicycles as possible.
To accomplish this, I will start with a 1940’s Columbia bicycle frame with springer fork and fenders that I found on Craigslist. From here I will modify the geometry of the headtube angle, chainstay, and bottom bracket height for stability at high speed. The desired top speed is 20-30 mph compared to my average road riding pace, 16-17 mph. I will also need to add disk brake mounting tabs to both the front and rear of the bike. The current rear hub spacing is 4 ½ inches, and to accommodate modern hubs at 135mm, I will need to modify the rear end. I expect to make the majority of my geometry changes to the rear of the bike to preserve the aesthetics of the current frame. Since a lot of the required structural changes to the frame are in the rear triangle, this works out well.
I'll add more to this as I continue!
For the first post I will show the frame I found and my plans for the build.
I would like to design a bike that is stable at higher speed than general road riding. The rider should be comfortable, meaning that he or she can see the road ahead in a comfortable position and that there is some sort of suspension to smooth out the ride at high speeds. Safety will be considered for the rider and from electric hazards. I would like to add disk brakes front and rear for adequate stopping power. Finally, I would like to keep as much of the original styling aspects of these bicycles as possible.
To accomplish this, I will start with a 1940’s Columbia bicycle frame with springer fork and fenders that I found on Craigslist. From here I will modify the geometry of the headtube angle, chainstay, and bottom bracket height for stability at high speed. The desired top speed is 20-30 mph compared to my average road riding pace, 16-17 mph. I will also need to add disk brake mounting tabs to both the front and rear of the bike. The current rear hub spacing is 4 ½ inches, and to accommodate modern hubs at 135mm, I will need to modify the rear end. I expect to make the majority of my geometry changes to the rear of the bike to preserve the aesthetics of the current frame. Since a lot of the required structural changes to the frame are in the rear triangle, this works out well.
I'll add more to this as I continue!
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