Custom frames are joined either by using fillet brazing, by using lugs or by tig welding. Simply put with a lugged frame, the tubes are joined by being brazed in a sleeve (the lug), while with a fillet brazed frame, the tubes are joined by the brazing alone.

The big advantage of fillet brazing is versatility. Any tube size or angle, is possible. Lugs confine the maker to the exact diameter and angles of the lugs. The fillet also allows to raised (extended) headtube that enables the rider to get a higher hand position. Strengthwise the fillets produce the smallest stress riser because they taper out to nothing.

Stress risers are a problem with some lugged frames, and these are more likely to develop cracks near the joint, usually next to the lug. To avoid this problem, we use silver solder with lugged frames, which has a lower temperature liquidus state (1200 degrees F) and puts less stress on the tube. We also taper the lugs.

TIG joints also create more of a stress riser because of the short transition from the highly heated joint to the tube. Fillet brazing is done with brass, but at a lower temperature than when brass is used with lugged brazing, where the brass has to hit an 1800 degress F to capilate through the lug. Fillet brazing is done closer to the melting point, 150 degrees cooler.