Finely Crafted Custom Framesets Since 1987
Custom frames, mechanical and frame repairs, parts and our complete bikes. We specialize in road racing, touring, and tandem bicycles, and the unique S and S Bicycle Torque Coupling travel system. If you travel often, one of the best things you can do for yourself is to have S & S Couplings installed on your bike.
Steve and Peggy Rex at the finish of the 750mile Paris-Brest-Paris bicycle ride done on their S and S Coupled Rex tandem.
Steel Construction and Finish
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.
High quality seamless bicycle tubing comes in many brands, models, and configurations, but essentially can be broken into two categories; standard duty and high strength.
Standard duty cromoly variations (could be called "old school tubing") are similar in strength and composition to the venerable Columbus SL. Examples of standard cromoly are Reynolds 525 and Columbus Brain. They are generally tough, and can be made into a frame of reasonable, but not super light weight. They are a good choice for touring bikes, and economical track bikes, where stiffness is important and toughness is a plus. I like to build touring bikes stout, using tubing with larger diameters and thicker walls to avoid unwanted flex that loaded packs can cause. The extra mass that is added to the frame beefs up the strength and makes for a super stable bike. some of the higher strength steels aren't available in appropriate thickness and diameters. Extra wall thickness resists dings and affords more strength of structure. Extra diameter increases stiffness.
High strength (by our definition) steels have tensile strength above 150,000 Ksi. The greater strength is achieved either by heat-treatment, or by varying te elements of composition, or both.
Because of the higher strength of these tubes, for any given rider we can build a lighter bike that is as strong as a standard cromoly bike by using thinner-walled tubes. The desired stiffness is maintained by using the appropriate diameters.
The first high-strength bicycle tube was Reynolds 753, a heat-treated variation of their 531 tubeset. the current version is 725, a heat-treated version of 525, which will replace 531. 853 is a specially alloyed heat-treated tube that has a super-high tensile strength of around 200,000 Ksi!
After 753 came the beautiful Tange Prestige to the high strength steel ranks. this versatile tubing is no longer being produced, but is still available in limited quantities. The superlight 0.6mm thick chainstays will be particularly missed. I especially like to use these for small to medium sized bikes or for anyone who wants a springy comfortable ride. Fortunately, for now I have a good stock of these stays. This is great tubing.
Next came Columbus Nivacrom. Nivacrom gets its strength not from heat-treatment, but from special composition. Niobium and vanadium are alloyed with the other elements to produce a high strength and dependable steel. The high end Columbus tubesets are all made of this same material, with different shapes and butting profiles. Examples are EL/OS, Genius, Neuron, Nemo, and Max.
Dedacciai Zero Uno has similar characteristics to Nivacrom. Zero is the heat-treated version, and has tensile strength of around 200,000.
After the position of the person on the bike, the most important design consideration is the tube selection. Light people need light, smaller diameter tubes so that the bike has enough flex for a nice, supple, lively ride. Bigger people need larger diameter tubes so that the bike isn't too flexy. Balancing the needs for light weight, comfortable flex, and stiffness for stability is the key.
We often mix tube models and brands to get the best mix for our customers.
Phone: (916) 446-5706