Originally Posted by
Ebuzz
Well, maybe I mislabeled my top cap and called it a compression plug. It very well may be a 1" threaded fork, I got it a few years ago and don't remember the specifics. Like I said, it's an older steel bike that came with an quill stem and steel fork. I replaced the steel fork with a carbon one so it might be of the threaded kind. Does that change anything?
The odds of you having a carbon fork with a threaded steerer are really, really small. Having a 1" steerer with a shim for a 1 1/8" stem would be far more likely.
Do you have a vernier caliper? Or failing that, an adjustable wrench and a ruler? Two quick measurements of the steerer and the stem diameter would settle this nicely.