Head Tube and Assembly:
Here is the head tube jigged up for brazing. The gold shims are positioning the sleeve and the chisel is for weight to keep it from moving while I braze.
Once brazed the head tube in it was time to weld the rest of the frame together. I love the way 4130 welds with a torch! And the fumes are somewhat less irritating then brazing too.
After I finished welding I put the fork and rear triangle in place and eyeballed the bike. Yes, definitely too long.
I cut about 4" out of the center section and the bike looks much better.
Once I got to this stage and I realized how complex the relationship between head angle, suspension, seat and pedals were and I changed my strategy. No matter how carefully I built this bike it was probably going to be a test bed, the real bike would be a Mark II.
I mocked up the seat stay with 1" square aluminum so I could play with angles and shock attachment and so I could ride it for the first time to see how it would handle. Low speed handling was very good, very controllable and stable.
Head angle is 72 degrees and the fork offset is about 2 3/4". I am going to try to get the seat a bit further back so the boom will very likely be shortened from what you see here.