I have a question regarding modifying motorcycle frames. Generally the material is mild steel about an inch tubing. I want to extend the downtubes and stretch out the front...traditionally the tubing is extended by inserting a solid slug or smaller piece of tubing at the place of the weld...I believe it's just a butt type weld. However I ran into this fellow who says inserting a smaller piece of tubing in the junction is in effect creating a spot where the diameter of the tubing is different, and because of expansion and contraction eventually the weld will crack. His background is in pipe welding and he claims when they used back up rings they ran into this problem. His method is to cut the tubing into kind of a straight "S" shape so the two ends fit together and there is more area to weld. My question is do you all think the expansion and contracting is that much of an issue on such small diameter material? I believe the pipes he's talking about are huge. What is the general consensus on the best way to extend the downtubes and other parts of a motorcycle frame? Obviously it would be subjected to a lot of jolts and strength is imperative as a frame coming apart in a high lean turn at 90 mph + does not sound like fun! Thanks.