Build a long-wheelbase low racer recumbent bicycle

Step 4 Make main tube bracket and weld

Cut a 1/8" thick piece of mild steel to weld to the chain stays in place of the bottom bracket. It should be wide enough to reach the outer edge of the cut chain stays and at least as tall as the square main tube (1 1/2"). The metal I had was a little taller than the square tubing and I didn't bother to cut it down. Weld it up centered on the end of the 1 1/2" square main tube at a 90 degree angle.

Clamp this assembly upright about 6" parallel from the floor. Weld to the chain stays with the wheel installed and touching the ground. Try not to get sparks from the welder on the tire (or use and old tire you don't care about). Some damp drop cloth material would work.

The 6" measurement is pretty flexible, so do what seems to look right to you. Make sure that you grind the cut ends of the chain stays so they are flat on the bracket you fabricated and that this is a good strong weld. Also sight down the frame and main tube assembly to make sure the frame is straight. It is long enough that you should be able to eyeball it. If not, center up your 1" conduit along the main tube assembly and through the rear triangle (after measuring and clamping up the proper height and removing the rear wheel) and measure the rear dropouts to be equidistant from the conduit ... or just eyeball it.