Next step was to begin the design process. Up to this point, I have been using good ol’ AutoCad. In my efforts to be a bit more professional, I used two programs (rattleCAD and BG101) to create my design and set up the jig. Maybe I will post more detailed descriptions of these programs later, but safe to say they provide a ton of data and give you the jig setup, not just the bike geo.
As usual, I like to do something different with my builds than the standard bike. What is the point of building custom frames if they are the same as any other? I decided to go with an integrated seatpost (more on that later) and a ever so slight compact geometry.
Since S3 tubes come in some crazy shapes (only the seat tube and head tube are round), the miter templates were not terribly useful. I am crazy about getting miters correct and I was pleased that I could really get a perfect fit. A good bike jig is really helpful for miter fit. You can put the bike together without a single weld and check the miters. I was able to refined the miters through this process and definitely get them spot on. I was also able to check the geometry in this process and make design decisions as I went. For instance, I was able to think about where I wanted my seat stays to connect to my seat tube with the bike put together and not have made any commitments on welds yet.
As you can see, this steel is paper thin. Once I get in to brazing, I’ll talk more about working on such thin tubing.