EC49 headset standard (external cup vs IS42 headset standard (integrated: specs compared
Updated 05 September 2026.
4
specs differ
EC49 headset standard (external cup and IS42 headset standard (integrated differ on 4 specs: shis designation, cup / bearing outside diameter, steerer diameter, crown race.
| Spec | EC49 headset standard (external cup | IS42 headset standard (integrated |
|---|---|---|
| SHIS designation | EC49 (external cup (EC)) | IS42 (integrated (IS)) |
| Cup / bearing outside diameter | 49.6 to 49.7 mm cup outside diameter | 41.8 to 42.0 mm bearing outside diameter |
| Steerer diameter | 38.1 mm (1 1/2 in) | 28.6 mm (1 1/8 in) |
| Crown race | 40.0 mm crown race seat | 30.0 mm crown race, or machined into the fork |
Questions and answers
How do EC49 headset standard (external cup and IS42 headset standard (integrated compare?
EC49 headset standard (external cup and IS42 headset standard (integrated differ on 4 specs: shis designation, cup / bearing outside diameter, steerer diameter, crown race.