gtturbo
Senior Retro Guru
There was no such thing from my recollection of a 1" aheadset for mountain bike application, it was always 1 1/8" or 1 1/4"; road yes, 1" for sure for a while. So as the ad states, this looks to be steerer for threading. The seller doesn't mention anything about aheadset.
1" ahead was definately an mtb thing.