A Simple Bicycle

After years wrenching on bikes fabricated by other people, I decided to learn to weld and put together my own bike from steel tubes. With the help of John Martin, founder of the New Haven Bradley Street Bicycle Co-op, a community-focused bicycle shop in New Haven, I designed a frame (BikeCAD), mitered the tubes (hack saw and metal files). Powder-coating was done at a local industrial shop (Paint and Powder Coating Pros (North Haven, CT) in a subtle shiny brown in attempt to reduce the chance of theft (though perhaps a 60cm fixed gear bicycle is a tough target as is). Fixed gear/single speed frames are the easiest to fabricate given their symmetry and simplicity in terms of braze-ons, but perhaps a more versatile commuter and adventure bike will be coming sometime soon.

Some tips for anyone considering the process:

• Oxy-acetylene braze-welding is forgiving as you are holding up a bright light source to your parts, and the heating is gradual, but make sure you have proper ventilation, proper protective welding goggles with a darkness of 4 or 5 (https://www.osha.gov/sites/default/files/publications/OSHAfactsheet-eyeprotection-during-welding.pdf) not quite as dark as arc welding, but darker than sunglasses!

• Don’t start with the thinnest tubes you can find (0.7/0.5/0.7mm for example) for your first build, as they are most likely to be overheated while you are still developing your technique

• It’s helpful to use a lugged bottom bracket shell and silver-braze the joint (lower temperature than brass), even if the other joints are mitered, as it can be tricky to get the torque in the correct place and manage heat with so many tubes in one location

• I have seen shops use hole-saws on drill presses/mills to miter tubes instead of hand tools. This requires some fabricated fixtures to hold the shaped tubes precisely, but might be quite a bit less time intensive than using hand saws and a file and repeated checking fitment. Either way, watch out for this sharp edges! A deburring tool likely saved me lots of blood during this process

• If you need to refill oxygen or acetylene tanks, Airgas won’t let you transport them in the trunk of a normal sedan or wagon/SUV. While I don’t often advocate for them for efficient daily commuting, you should use a pickup truck with the ability to strap the tanks safety for this.