This is Unior’s 8-tooth cartridge bottom bracket tool for installing and removing traditional internal cartridge bottom brackets. Designed for square taper, Octalink, ISIS, and similar splined cartridge systems, it pairs with a 1/2" ratchet or adjustable wrench for proper leverage. Key Functional Details 8-tooth splined bottom bracket tool Compatible with common cartridge bottom brackets Works with 1/2" drive ratchet or adjustable wrench Hardened tool steel construction Precision-machined splines for tight engagement Model: 1671.2/4 Compatibility & Technical Notes Compatible with square taper cartridge bottom brackets Compatible with Shimano Octalink and ISIS cartridge systems Fits most 8-spline internal cartridge bottom brackets NOT compatible with external threaded bottom brackets (Hollowtech II, GXP, DUB, etc.) NOT compatible with press-fit bottom brackets Use with proper leverage to prevent slipping Service / Ownership Context This is a workshop tool for servicing older threaded cartridge bottom brackets. Proper spline engagement prevents rounding and protects aluminum BB cups during removal. Fit & Use Signals Good Fit: Bikes with square taper, Octalink, or ISIS cartridge bottom brackets. Not A Fit: Modern external bearing systems or press-fit frames. This is for old-school internal cartridge BBs. Square taper, Octalink, ISIS. If it has external cups, this is the wrong tool. Biggest mistake: customers buy this thinking it works on Hollowtech II or DUB. It doesn’t. Always fully seat the splines before applying torque. If you’re loose on engagement, you’ll round the aluminum BB. Some older BBs are seized badly. Penetrating oil first. Don’t just reef on it and slip. Use a long 1/2" ratchet for leverage. Adjustable wrenches work but can slip. Failure point is usually user error — not seating tool fully or trying to remove with crank bolt still installed. Who this is really for: home mechanics working on older road, MTB, or hybrid bikes. Who should avoid: anyone on modern external or press-fit systems. Mechanic advice: remember English-threaded BBs are reverse thread on drive side. Double check direction before applying torque.
