Aluminum Bottom Bracket Socket E13

e*thirteen's cranksets ("e13" on most shop benches) ship with bottom bracket cups cut to e13's own outer-notch geometry. The dedicated 1671 Aluminum BB Socket for e13 sizes specifically to that engagement profile, so its six-notch profile seats fully on the cup's 49.5 mm notch circle under install torque, and the anodized aluminum body is cut so it will not damage aluminum external cups.

Where this socket fits in the workshop

A shop that services modern MTB builds with e*thirteen cranks; often paired with SRAM Eagle drivetrains, often on enduro and downhill bikes; benefits from an e13-specific socket on the bench rather than a generic 16-notch wrench. The dedicated cut keeps both the socket and the cup engagement clean across multiple service cycles.

Compatibility

• e*thirteen threaded bottom bracket cups, the E13 column on Unior's 1671 compatibility chart: six notches on a 49.5 mm notch diameter
• Also listed by Unior as the e*thirteen chainring/spider lockring and cassette lockring tool; verify the part's marking before applying torque
• Not for generic Shimano-pattern 16-notch cups; use the BBR60, BB9000, or 16-notch generic socket instead

Specs

• Drive: 36 mm hex flats (SW 36) on the back of the socket, not a 1/2-inch square; turn it with a 36 mm wrench, or put a 1/2-inch drive torque wrench on the 36 mm Crowfoot Open-End Wrench 1725/2CF, the pairing Unior's catalogue names for this socket
• Material: CNC-machined aluminum, red-anodized
• Notch fit: six notches on a 49.5 mm notch diameter; socket diameter 54.5 mm, width 30 mm, weight 77 g (Unior datasheet; dimensions may vary in tolerance)
• Includes: the socket itself. The Bottom Bracket Socket Retaining Tool is listed by Unior for aluminum 1/2-inch drive sockets only; this hex-drive socket has no drive square for it

Built in Zreče

Unior has been forging hand tools in Zreče since 1919, and sponsors professional road and mountain-bike race teams. The e13 socket completes the 1671 family's coverage of the BB cups that show up in modern MTB workshops; the aluminum body keeps the cup face mark-free across the install and removal cycles a high-use bike sees over a season.

Pro tip from our mechanics

Verify the cup's outer engagement profile visually before reaching for either the e13 socket or a generic 16-notch one. An e*thirteen threaded cup carries six notches on a 49.5 mm circle, so a 16-notch socket cannot seat on it at all; if this socket rocks or fits with play, the cup is cut to a different profile. Five seconds of test-fit before applying torque is what keeps the cup serviceable for the next install.

For the removal, cleaning, and refit sequence on an external threaded bottom bracket: Replace or clean your bottom bracket →.

FAQ

Which bottom brackets does the 1671.E13 socket fit? Unior's 1671 compatibility chart gives this socket one row: e*thirteen threaded bottom bracket cups. The spec table puts it at six notches, a 49.5 mm notch diameter, and a 54.5 mm socket diameter, with no guide or adapter. Unior's product page adds that the same socket drives e*thirteen chainring/spider lockrings and cassette lockrings. It is not for 16-notch Shimano-pattern cups; those take the 16-notch, BBR60, or BB9000 socket.

Does it take a 1/2-inch ratchet like the other 1671 sockets? No. This socket has no square drive. Its back is a 36 mm hex (SW 36 on Unior's datasheet), so you turn it with a 36 mm wrench, or with the 36 mm Crowfoot Open-End Wrench 1725/2CF on a 1/2-inch drive torque wrench; Unior's catalogue names that crowfoot as the way to reach the torque spec on this socket. Width is 30 mm and weight 77 g.

Can I use the Bottom Bracket Socket Retaining Tool 1671.RET with it? No. Unior lists the 1671.RET as compatible with all aluminum 1/2-inch bottom bracket sockets, and its adapter seats in the socket's drive square. The E13 socket is hex-drive with a plain through-bore, so the retaining tool has nothing to engage. Unior's 1/2-inch drive sockets in the 1671 family are the ones it pairs with.

How does the E13 socket differ from the BSA30, T47, and 16-notch sockets? Notch count, notch diameter, and the drive. Unior's spec table: 16-notch = 16 notches on 42.7 mm; BSA30 = 12 on 44.2 mm; T47 = 16 on 49 mm and 12 on 46.6 mm with a guide adapter; Hope = 16 on 47.6 mm; E13 = 6 on 49.5 mm with no guide or adapter. All are CNC-machined aluminum billet anodized red; the E13 is driven by 36 mm hex flats rather than the 1/2-inch square the family copy describes.