Description

Rotation Engineering’s internal T47 version bottom brackets are made right here in Connecticut out of U.S.-sourced 7075-T6 aluminum. Small but necessary refinements set our products apart from our competition. First we optimized the bearing bore press fit tolerance to minimize bearing compression for lower friction. Then we perfected the cups’ thread geometry (major, minor, pitch, crest, flank and root) to ensure accurate frame fitment. Even the installation tool splines have been uniquely machined to keep the BB installation socket from scoring your frameset during installation. We offer two pre-assembled bearing options STANDARD and ULTIMATE (description below). Our bearing ID reducers are machined from high-density Delrin, not injection-molded plastic, to guarantee perfect fitment and protect the crank spindle from wear and fretting. For frame and crank fitment, we support three crank spindle diameters (29mm-24mm/30mm) and two frame width options (86mm-85.5mm). Since we control all aspects of our BB production through design, testing, manufacturing, quality control checks, and assembly, it gives us the ability to refine our product and ensure consistency much better than our mass-produced competition. We also never rest on our laurels! We continuously test other specialty bearing options so please feel free to inquire or check out our recommended options in our “spare parts “ section.

The STANDARD bearing option features hardened 52100 high chromium races, cage, and ball bearings, two low friction rubber seals, and a specially formulated anti-corrosion low friction bearing grease. This option is for the more budget-oriented customer that still wants a premium, USA-made bottom bracket.
The ULTIMATE bearing option features one low friction rubber seal facing out, one non contact PEEK shield on the inside, a PEEK bearing cage, a specially formulated ceramic-bearing-optimized, low-friction grease, grade 3 silicon nitride balls, a d hardened 52100 high chromium bearing races that have been isotropicly polished and coated with WS2 & TDC for the ultimate blend of durability and performance. This option is for the consumer that wants the ULTIMATE, period!