EC34 headset standard (external cup vs EC49 headset standard (external cup: specs compared
Updated 05 September 2026.
4
specs differ
EC34 headset standard (external cup and EC49 headset standard (external cup differ on 4 specs: shis designation, cup / bearing outside diameter, steerer diameter, crown race.
| Spec | EC34 headset standard (external cup | EC49 headset standard (external cup |
|---|---|---|
| SHIS designation | EC34 (external cup (EC)) | EC49 (external cup (EC)) |
| Cup / bearing outside diameter | 34.0 mm cup outside diameter, 33.8 to 33.95 mm head-tube bore | 49.6 to 49.7 mm cup outside diameter |
| Steerer diameter | 28.6 mm (1 1/8 in) | 38.1 mm (1 1/2 in) |
| Crown race | 30.0 mm crown race seat | 40.0 mm crown race seat |
Questions and answers
How do EC34 headset standard (external cup and EC49 headset standard (external cup compare?
EC34 headset standard (external cup and EC49 headset standard (external cup differ on 4 specs: shis designation, cup / bearing outside diameter, steerer diameter, crown race.