The Standardized Headset Identification System (S.H.I.S.) creates a common language for describing modern bicycle headsets. The system provides comprehensive and scalable headset fitment information in a standardized format; making it easy to communicate headset requirements based on frame and fork interfaces.
The system addresses the critical interface dimensions required to fit a fork to a frame, as well as bearing location/cup type. To determine fit, four dimensions are needed: (1) stem-clamp diameter of fork, (2) crown-race seat diameter of fork, (3) head-tube top inside diameter, and (4) head-tube bottom inside diameter. Bearing location and cup-type are identified as (a) external cup (EC), (b) semi-integrated or ZeroStack (ZS), or (c) integrated (IS).
Bearing Location / Cup Types
EC (External Cup)
Bearings contained within cups that are located outside of the frame.
Bearings contained within pressed-in cups where the cup and bearings rest inside the frame.
Bearings that fit directly into a bonded or machined interface that is integrated into the frame.