Lugged bicycle frames, for example, are now manufactured by automated machines.Ĭustom framebuilders still provide fillet-brazed construction, and tandem framesets were often fillet-brazed when lugs to fit their frame angles were not available. (For additional strength Schwinn also brazed steel sleeves into the interior of its frame tubes at the joints.) Fillet-brazed bicycle frames are strong and have a neat and clean appearance, but they are uncommon because of the additional craftsmanship required. The extra thickness of the fillet also provides strength, and its smooth contour distributes stresses evenly. (See illustration below) In this method of bicycle frame construction, 'mitering' or cutting the tube ends so that they fit together precisely is critical so that capillary action will draw the molten filler into gaps for a strong joint. After the prefix is a number, and the first 2 numbers usually represent the last 2.įillet brazing involves building up brass filler metal in a smooth 'fillet' around joints.
Just search for Schwinn serial number database using your favorite search.
This website feature a vast array of photos and restoration services for vintage bicycles. Enzymatic activation of alkanes constraints and prospects fastpitch. We have shown that a chiral self-assembled M 4L 6 supramolecular tetrahedron can encapsulate a variety of cationic guests with varying degrees of stereoselectivity.
Supramolecular chemistry represents a way to mimic enzyme reactivity by using specially designed container molecules. Reactive iridium guests can be encapsulated, and the C−H bond activation of aldehydes occurs with the host cavity controlling the ability of substrates to interact with the metal center based upon size and shape. Brazing is a joining process employing a filler metal, like brass, that melts below the melting temperature of the parent metal workpiece. Fillet-brazing is an alternative method of constructing high-quality lightweight bicycle frames without the use of lugs. Until the recent rise of quality TIG-welded and composite bicycle frames, most high quality lightweight bicycles used lugs (external metal sleeve fittings) to join their frame tubing. They are worth recalling as a unique Schwinn production strategy and a sidebar in the evolution of the bicycle industry. The story of these unique bicycles is a meaningful branch of Schwinn's history. For 41 years, from 1938 to 1978, the offered a unique but little-known line of specially constructed lightweight bicycles: The fillet-brazed models, which were tucked into Schwinn's model lineup between the Paramount and Schwinn's fillet-brazed models were beautiful and sweet handling, but in the 1970's bicycle-boom they lost ground to more popular -frame construction, and never recovered.