We kept the rear triangle of this prototype intact and used two sections of 1-3/4" "furniture pipe" to extend the Worldbike frame. Adding only two pieces of steel pipe kept  the material cost low and increased our precision. Keeping the original rear triangles intact simplified fabrication and reduced the chances of misalignment.

The cargo rack relied on bends made by taking the standard steel furniture grade tubing and bending it around a section of 4" pipe. No annealing was necessary.  Reducing the number of welds brings the manufacturing time and cost down.