I have a Cinelli 1R stem and Criterium bar. Both I believe are 26.4. I'm having a heck of a time getting the bar through the stem. Should I keep trying to work it?

Measure closely, never assume.

Measure two times and cut once. That was my Dad's motto. And I totally agree with wkr101 - never assume anything - measure accurately.

[MENTION=456989]mackgoo[/MENTION] - which part of the bar are you having difficulty with?

Before you scratch it up, loosen the clamp as much as possible. I also have a small wedge I put in those to hold things open a bit when I install the bar, then tap out to finish up.

1R stem is full-wrap, so can't pry it open. They normally slip freely over a 26.4mm bar and I've not known of any 1R stems made to a different size than 26.4mm.

The wedging mechanism seems to not be retracting inside of the stem-clamping area. Pull out the wedge and inspect the mechanism. These wedges are known to have cracks so there may be some distortion.

By the time Cinelli went to 26.0, at least all of their handlebars were being clearly labeled or stamped to indicate the new-era diameter, they did not take this lightly.

Perhaps there is such 26mm marking on the quill that might be revealed by carefully buffing with steel wool or fine sandpaper?

There were also some French-sized 1R's which had a mere shallow cylindrical divot on the quill to denote their 22.0mm quill diameter.

I did finally get it on. It was very tight. Just getting it around the bends was a process. Once I got to the middle section of the bar it was a bear. Needless to say, this bar and stem combo will never be separated.