To the OP.
I took a moment and searched out a photo of a bike like yours. (
here).
It doesn't appear to have a 1-1/8" fork, but photos can be deceiving. So there may be a possibility that the stem has a step, measuring 1" where you measured it, and narrowing to 7/8" inside the fork.
To be sure, loosen and lift the stem as I described in the post immediately above, and check for a step, then measure the part that was inside the fork.