PARAGON MACHINE WORKS TITANIUM BOTTOM BRACKET
Paragon Machine Works of Greenbrae, California, has an extraordinary reputation for engineering and manufacturing difficult to make, because of high machine tolerances or hard to use materials, parts. Paragon is relied on by several bike part makers as a subcontractor for tricky parts used under other labels. Their bottom bracket is a simple, well built, and serviceable unit. The spindle is made from Titanium Ti 6Al-4V alloy. It is turned from rod reducing the outer dimension to smooth 17mm ends with a 19mm center section, for a light torsionally rigid spindle. This oversized center section helps to eliminate some of the flex traditionally associated with Titanium spindles. This 19mm rise also provides a shoulder for the sealed bearing cartridge to seat against. The spindle is drilled through from end to end to reduce weight and then tapped for the crank bolts. The B/B comes with two precisely made 2024 aluminum alloy adjustable bearing cups. The cup ends are drilled with small holes, but not all the way through, so that any pin spanner tool can be used to accomplish installation. Because this is a "floating" type B/B, which permits the spindle to sidle laterally to perfection, there is a lockring for each cup. The lockring is machined from aluminum plate, with four square cuts on the outer diameter, at each compass point for lockring spanner grip. In each cup rests a sealed bearing cartridge, these are the French made SKF brand model 61903-2RS1. The bearing cups and lockrings are hard anodized in the Grey color. The Paragon B/B is available in 112mm, 118mm, 124mm, and 130mm spindle lengths. The 124mm version of the PMW bottom bracket weighs 170.5 grams. It doesn't come with crank bolts, steel or aluminum ones are recommended. This B/B never became very popular, and we haven't sold any of these since 1993. We don't believe they are made anymore. We sold them for $139.99