This press-in bottom bracket is specifically designed for original aluminum Pivot Cycles. These frames had protrusions inside the BB shell (see product pictures for details). In addition, the original press fits were unusually tight, sometimes over-compressing the bearings. Our aluminum cups are machined to the perfect tolerance to fit the Pivot BB shells. The bearing-to-cup clearance has also been custom engineered to prevent ovalized BB shell tubes from distorting the bearings--leading to much longer bearing life than the OE bottom brackets provide. The machined aluminum center sleeve is a special narrow design that won't interfere with the extruded supports that protrude inside the Pivot aluminum BB shells.

Angular contact bearings are a step forward in outboard bottom bracket design. Why? Deep groove radial ball bearing cartridges are not designed to be "adjusted." Any inward or outward pressure on the inner races put them out of alignment with the outer races, forcing the balls to ride up the side of the groove and exerting greater pressure on the races. This results in increased friction and premature wear. Since almost all outboad crank sets exert some inward pressure on the bearings when installed, it only makes sense to use a bearing designed specifically for such loads. Angular contact bearings also result in 100% ball engagement when pre-loaded, making them stronger and longer-wearing.

ENDURO ANGULAR CONTACT CERAMIC HYBRID "CH SERIES" GRADE 5 BALLS / ABEC 5 CARTRIDGE RATING

THE BALLS are made from pure Silicon Nitride material with extreme high density from uniform compaction (3.25 g/cm3). The micro-structural development of this material during manufacture is second to none. These high precision Grade 5, SI3N4 pure ceramic balls are 5/1,000,000” from exactly round in sphericity. They are 60% lighter in weight, and 7 times harder than steel. Friction is reduced to near zero.

THE RACES ARE A PATENT-PENDING ANGULAR CONTACT DESIGN with vacuum de-gassed alloy hardened to Rockwell C-64. These high precision races