This replacement fits perfectly on my 2011 Cervelo RS with OEM IS-2 FSA headset. I guess over time the original was somehow damaged because of friction or bad torque on the headset?
Double check the diameter, in doubt I emailed fsa support and they replied on the same day. I needed the 1" 1/8.
Received the part 2 days later, too bad shipping was 4x the price of the part.
Cheers,
