Build a long-wheelbase low racer recumbent bicycle

Step 6 Measure the main tube and cut

Sit your hind-end on this thing backed up against the seat tube (after it cools) and stretch out your legs. Clamp a 2x4 (or two) to the seat tube to simulate your seat and padding depth. Stretch your legs out flat-footed and have someone mark the main tube at that point with a sharpie.

Now either measure the distance from where your foot hits the pedal to the back of the bottom bracket (see photo), measure back and then trace the bottom bracket shell on the main tube or fuss the pedal to the line you just marked and then trace the bottom bracket shell this way.

The idea is to locate the bottom bracket in relation to where the pedal needs to be in order to fit your body. I didn't design this with an adjustable seat, so it needs to be right. Once you are sure that you have this measured correctly, cut the main tube and grind/cut it to fit around the bottom bracket shell. This is a pretty critical cut, so take your time, measure it up right and grind it to fit snugly and straight.