The 16-notch external bottom bracket is the dominant cup pattern on current bikes. Shimano Hollowtech II (the BBR60, BB9000, and the BB-MT/BBR series), SRAM GXP and DUB, FSA MegaExo, Race Face Cinch, Chris King, Campagnolo road external; all of these share the 16-notch outer engagement. The generic 16-notch socket is the everyday tool for the most common cup profile a workshop sees. The 1671 Aluminum BB Socket for 16-notch cups is cut to the generic 16-notch envelope. It fits the Shimano-pattern BBs that share the outer notch geometry without specializing to any one brand's specific cup OD. On a bench that sees a mix of Shimano, SRAM, FSA, and Chris King cups, this is the socket that handles most jobs; the brand-specific cuts (BBR60, BB9000, T47, BSA30, FSA MegaEvo, e13, Hope) handle the cups where dimensional precision matters more than category breadth. Why aluminum, not steel Bikerumor's 2019 coverage of the 1671 line documented the rationale plainly: “These new tools mark a fairly big shift in the company's 100 year history – because they're made from aluminum. Previously, all of Unior's tools have been manufactured from forged steel.” And: “For a tool like a bottom bracket socket where steel could damage pricey aluminum cups, the company has opted for a more task-specific approach.” The right material for the cup face on premium current-generation BBs is the same hardness order as the cup. Forged steel is the right material for chain tools, pliers, and most of the rest of Unior's catalog; aluminum is the right material for sockets that touch anodized cups under torque, where the cup's finish is part of the product. Compatibility Shimano Hollowtech II generic (most BBR / BB-MT / BBR60-class cups) SRAM GXP and DUB external BBs FSA Mega Exo, Race Face Cinch, Chris King external Most other current 16-notch external cups in the workshop palette Not for cups with brand-specific notch profiles (BB9000, T47, BSA30, FSA MegaEvo, e13, Hope); use the corresponding socket in the 1671 family Specs Drive: 1/2" square drive (use with a torque wrench, ratchet, or fixed handle such as the Pro Socket Handle) Material: CNC-machined aluminum, red-anodized Notch fit: generic 16-notch outer engagement, knurled grip for hand setting Includes: the socket itself; pair with the Bottom Bracket Socket Retaining Tool when servicing cups with low-profile engagement Built in Zreče Unior has been forging hand tools in Zreče since 1919, and sponsors professional road and mountain-bike race teams. The 16-notch generic socket is the foundational SKU of the aluminum BB socket line: the cup pattern that most current bikes use, served by the material choice that doesn't mar them. Pro tip from our mechanics When in doubt about which socket in the 1671 family to reach for, start with the generic 16-notch. If it seats fully without play and the splines mesh across all sixteen notches, use it. If it rocks on the cup or sits proud on the outer face, the cup has a brand-specific profile and one of the dedicated sockets in the line (BBR60, BB9000, T47, BSA30, FSA MegaEvo, e13, Hope) is the right call. Five seconds of test-fit before applying install torque saves a rounded cup. For the BB install / remove procedure and torque references: Replace or clean your bottom bracket →.
