IS52 headset standard (integrated vs ZS55 headset standard (zero stack: specs compared
Updated 05 September 2026.
3
specs differ
IS52 headset standard (integrated and ZS55 headset standard (zero stack differ on 3 specs: shis designation, cup / bearing outside diameter, crown race.
| Spec | IS52 headset standard (integrated | ZS55 headset standard (zero stack |
|---|---|---|
| SHIS designation | IS52 (integrated (IS)) | ZS55 (zero stack (ZS)) |
| Cup / bearing outside diameter | 51.8 to 52.0 mm bearing outside diameter | 55.0 mm cup outside diameter, 54.9 to 54.95 mm head-tube bore |
| Steerer diameter | 38.1 mm (1 1/2 in) | 38.1 mm (1 1/2 in) |
| Crown race | machined into the fork crown | 40.0 mm crown race seat |
Questions and answers
How do IS52 headset standard (integrated and ZS55 headset standard (zero stack compare?
IS52 headset standard (integrated and ZS55 headset standard (zero stack differ on 3 specs: shis designation, cup / bearing outside diameter, crown race.