Custom Bike Frame Progress

For those of you who don’t know, I have changed my plans for my final project entirely. I have been working on an independent study course where I design, manufacture, and ride my own custom bike frame. Initially, I intended to leave this project separate from this course; however, after beginning the assembly of the frame, I decided that I would like to document my progress on the frame. I was pleasantly surprised by the progress and the outcome of my initial work and I decided that it would be a good opportunity to divert more of my attention to this bike project by also applying it to Aesthetics in Design.

About two weeks ago, I received raw materials for the bike frame and I began to cut, miter, and bend the tubes that would be used for the frame. Furthermore, I ordered stock rear dropouts, a rear brake mount, a bottom bracket, and a head tube to make up the remainder of the frame. All of the materials are 4130 Chromoly steel given the fact that I am most comfortable with TIG welding steel and I have a fair amount of experience in the process. I began with cutting and bending the tubes that would be used to construct the frame. I did this by hand and using bending dies. After bending the tubes, I placed the bottom bracket, head tube, and dropouts in a frame jigging system that was provided for me by James Bleakley at Black Sheep Bicycles. This jigging system allowed me to place the frame components and tubes in the proper position to ensure that I maintained the desired geometry for my frame. This meant that I was then able to miter the tubes to interface with the frame and double-check the fitment of the tubes. Following jigging the frame, I was then able to tack weld the frame while it was still in the jigs to then be removed for finish welding.

Bent Steel Tubes

Tube Mitering

Frame Jig System

The finish welding on the frame was done in the Idea Forge machine shop using the TIG welders. I wanted to use TIG for this frame because it is better for thin wall tubing (some tubes on the frame have .035″ wall thickness) and I prefer the elegant look and finish that TIG welding is able to achieve without splatter from slag, creating an appearance of “stacking dimes.” It took me four to five hours to finish welding the entire frame. Although there were not a lot of joints to be welded on the frame, there were many complex geometries that required some care to weld.

Frame Finish Welds

After the initial welding of the frame, I was able to finish welding the frame gussets to the head tube that I got water-jetted at the in the idea forge. Following this step, all that was left to do was to go back to Black Sheep Bikes to chase and face the bottom bracket and headtube, add the chainstay and seat stay bridges, and weld the brake amounts and cable routing. Following this process the assembly and structural work on my frame was complete.

Fully Manufactured Frame

After completing the welding, I will now need to finish the surface of the frame and prevent it from rusting. To do this, I will coat the frame in boiled linseed oil which will go on clear and prevent rust on the frame in the future. I want to maintain the raw steel color of the frame with the iridescent blue, pink, and purple colors that appear from the stainless steel filler rod that I used for the frame. This will hopefully be done in the next week.