IS52 headset standard (integrated, 52 mm)
What a IS52 headset measures under the SHIS standard, and how to tell it apart from lookalikes.
Published dimensions
| SHIS designation | IS52 (integrated (IS)) |
|---|---|
| Cup / bearing outside diameter | 51.8 to 52.0 mm bearing outside diameter |
| Steerer diameter | 38.1 mm (1 1/2 in) |
| Crown race | machined into the fork crown |
Used on: the 1 1/2 in integrated lower on tapered road and MTB head tubes.
IS52 is the integrated 1 1/2 in lower: a 52 mm bearing drops straight into the head tube for a 38.1 mm lower steerer. Paired with an IS42 upper it makes the common IS42/IS52 tapered integrated headset. A 42 mm upper bearing will not fit the 52 mm lower seat.
Frames and related headsets
EC34external cup, 34 mmEC44external cup, 44 mmEC49external cup, 49.6 mmZS44zero stack, 44 mmZS55zero stack, 55 mmBSA bottom bracket shellthe frame's other threaded interface
SOURCES: Park Tool, Standardized Headset Identification System (SHIS) · Cane Creek et al., Standardized Headset Identification System [SHIS] specification