ERW tubing starts as flat bar and is rolled to make a tube. The tube is then welded. A cutter is passed over the weld on the outside of the tube to leave a relatively smooth surface. An 1 inch diameter tubing with an 11 gauge to 10 gauge (0.125 inch) wall thickness has been used for custom bikes. An 1 1/4 inch tubing with 11 gauge to 10 gauge (0.125 inch) wall thickness is common in heavy custom bikes.
While 11 gauge to 10 gauge (0.125 inches) thick tubing is adequate for most of the motorcycle frame, the steering neck tube should be thicker. The recommended thickness is 0.250 inch, which is greater than most gauge scales measure.
Gas metal arc welding is recommended for welding tubes. Lower wire feed and temperatures can result in a better-looking welds when working with round materials. However, the penetration may not be deep enough for a good weld. Welding wire from 0.030 inch to 0.035 inch diameter is recommended for tube with 0.125 inch wall thickness.