Wednesday, March 14, 2012
Lugs on my Mercian Vincitore Special
I have been asked to show some details of the lugwork on the bike and an overview of the final construction. The frame is constructed from Reynolds 853 tubing because I think it’s the best, Reynolds have an excellent heritage and this combination of high tensile strength enabling thinner tubes and hence light weight seemed the optimum cost effective approach for me.
The actual process of frame building is carried out by a single craftsman.
The individual tubing and components for the frame are then set aside or ordered-in by a frame-builder and boxed ready for the build date. When the frame is ready for building, the frame-builder begins by filing the lugs; with skill and patience the lugs are cut and filed with hand-tools to create the cut-outs and intricate designs which make Mercian frames distinctive and beautiful. The Vincitore lugs are crafted from plain lugs with spearpoints welded to the plain lugs then drilled, cut out and filed by hand for many hours to create the intricate distinctive look that is unique to a Mercian Vincitore Special.
The Reynolds tubes are then carefully mitred and fitted into the lugs and placed against an alignment board where the builder can create the right angles for the frame. The lugs and tubes are fitted together and the frame is pinned to hold securely in position while the frame is brazed in the open hearth. This part of the build process takes years of experience to perfect and has been passed down from frame-builder to frame-builder. The open hearth method of joining the tubes and lugs with a combination of air and natural gas has been used since the 1940’s and reduces the possibility of overheating the tubing, this method is gentler and kinder to the tubes than the quicker frame-jig and oxy-acetylene method often used today, a much higher and direct heat which can be too harsh in the wrong hands.Once heated to correct temperature the brass or silver solder is carefully flowed into the lug/tube joint to secure the tubing in the correct position. Each frame-builder has their own preferred methods of manufacture, but wMercian believe their construction methods are the reasons why their frames have longevity. It also means that if a frame tube is damaged in riding, it is possible to undo the brazing and replace a single tube or tubes without problem, meaning the frame can be repaired rather than buying a new one, giving me many years of pleasure.