What is the Park Tool TAP-10 Frame Tap used for?

The Park Tool TAP-10 is a 10mm x 1mm high-carbon steel frame tap for chasing and cleaning derailleur hanger threads on bicycle frames. Precision ground and hardened to stay sharp, it cuts cleanly into the standard 10mm x 1mm thread used on the vast majority of derailleur hangers across road, gravel, and mountain bike frames. It fits conventional tap handles, making it compatible with any standard shop tap handle you already own.

Derailleur hanger threads get damaged from crashes, cross-threaded derailleur installations, and corrosion over time. Chasing the threads with the correct tap restores clean thread engagement, which is essential for accurate derailleur alignment and reliable shifting. The TAP-10 is a specialty tool, but when you need it there is no substitute for the correct size.