Assuming no damaged parts, if a regular 22.2 diameter Cinelli stem doesn't fit in 22.0 sized steerer then it's a pretty sure bet you need a French headset.
Steerer would be 25mm so you can measure to be sure.
BTW: stem can be made to fit with proper application of emery cloth.
see: http://www.sheldonbrown.com/
Pete Geurds (who just went through "joy" of trying to decide if those Cyclo freewheels were really French thread)
Pete Geurds
Douglassville, PA