To work on a Shimano Hyperglide (HG) system, it is critical to identify whether your bicycle uses:
A modern slide-on HG Cassette, or
A vintage thread-on HG Freewheel.
These two configurations utilize entirely different tool architectures.
Key Details to Consider:
Identical Tool Interface: Both configurations feature a 12-spline, ~23.4mm diameter tool interface.
Compatibility Issue: A standard cassette lockring tool has splines that are too shallow to reach past the protruding axle hardware of a threaded freewheel.
