Stem shaft diameters?

[Evolution]

How many different stem shaft diameters are there? I have a Streetbeat F&F, as my first build, along with a stem with a 22.2mm shaft that does not fit into the forks. What other  sizes are there or which stem do I need.

Thanks in advance for any help.

David.

[fouronethreeoh!]

Generally i think most old school stems are 21 mm diameter.

Yep, just measured an old suntour stem, 21 mm shaft. 

[OrgasmDonor]

as above, but, some early midschool stems seemed to be that bit wider, dyno stems for one can be 21mm or 22.2