Bottom bracket tools need to match the spline pattern of the lockring or cup you're removing, and the BBT-29 handles one specific interface: Shimano and compatible external bearing bottom brackets with 16 notches. That covers most Shimano Hollowtech II installations, along with FSA MegaExo, Race Face X-Type, and other external systems using the same 16-notch pattern. The tool seats into the notches around the outside of the cup or lockring, letting you apply torque without the slipping that happens when you try to make a close-but-not-quite tool work.

The 44mm diameter matches the standard external cup size, and the 16 notches are precision-cut to engage fully rather than riding up on partial contact. This matters because bottom bracket cups get torqued to spec during installation and can be stubborn during removal, especially if they've been in place for a few seasons. A tool that doesn't seat properly rounds the notches on the cup, turning a simple job into a much more complicated extraction.

Park Tool machines this from CRV steel, which handles the torque loads without deforming. The 3/8" hex center accepts a ratchet, breaker bar, or torque wrench directly, and the through-hole design means you can use a long bolt or quick-release skewer to hold the tool in place against the cup while you turn it. That's the difference between fighting the tool and actually removing the bottom bracket.... Read More