Old Centurion: Found on Street

Cups come out of the frame with one of these.

what a simple but effective tool.

what does one do in lieu of one of those through?

and how do you get the bit off the top of the fork?

You can get a metal tube less then 22.2" inetrnal diameter and cut two slices through it to make your own.

The locknut and the top of the cup should just unscrew off the fork steerer with a spanner. Then the fork drops out of the frame. If the bearings aren’t caged you spend the next half hour looking for the bearings that fell out when the fork came out. Then use the above tool to knock the cups out of the frame.

That’s about it. If you’re changing the crown race as well you can usually tap that off the fork crown from below with a big screwdriver and a hammer. Although, quite often the crown race just slides off pretty easily.

Threadless headsets are pretty similar except there’s nothing to unscrew.

Park Tools have some great articles explaining various maintenance stuff. Here’s their page on headset servicing.