Home mechanics and workshops servicing bikes with cartridge bottom brackets.
The Unior 1671.1/4 is the 20-tooth socket that fits the splined cups of Shimano cartridge (square taper and Octalink) and ISIS bottom brackets. If your bike has an internal cartridge bottom bracket rather than outboard bearings, this is the tool that turns it.
It is made from premium flex plus carbon steel in Slovenia and weighs 112 g. Drive it with a 1/2 inch ratchet or breaker bar for stubborn cups, or a torque wrench when fitting.
It will not fit Hollowtech II or other external 16-notch cups, so count the splines in your cup before you start.
20-tooth spline
Fits Shimano cartridge, Octalink and ISIS cups.
1/2 inch drive
Use a ratchet, breaker bar or torque wrench.
Hardened carbon steel
Built for workshop use and backed by a lifetime warranty.
Made in Slovenia
From Unior's toolmaking home in Zrece.
Tool
Compatibility
Great for
Maybe not for
Fits 20-spline cartridge bottom bracket cups. Needs a 1/2 inch drive ratchet, breaker bar or torque wrench.
Keep it seated
The usual failure is the socket walking out of the splines under load. Hold it pressed in firmly, or use a through bolt or quick release skewer to keep it in place while you break the cup loose.
Left cup first
Start with the non-drive (left) cup, then remove the cartridge from the drive side. On English threaded frames the drive-side cup loosens clockwise.
Hand tools forged in Slovenia since 1919.
Unior has been making hand tools in Zrece, Slovenia since 1919.
Its bike tools line is used in professional workshops around the world and sponsors pro road and mountain bike teams.
