there are 2 different steerers .. The OD of a 1" fork*, is the ID of a 1,125" steerer tube the wall thickness is 1/16"

you could use a 1" fork in a frame made to use a 9/8 steerer
and use conversion parts to make up the difference ,

but not the other way .. like 9 pints in an 8 pint pitcher doesn't work out.


There is Competing standards Too .. JIS for Japan , ISO for Europe. .. small but significant ..

* 1" forks with threaded headsets use a stem that is 7/8"

threaded 1,125" used a 1" quill stem , but Threadless stems grip the Outside of the Tube.




bene sugg : go where someone can see the task at hand, like your favorite Bike Shop.