I like to take the lever right off the clamp as it can be annoying trying to get it off still on there and usually results in more scratches to the bars. The cinelli bars should fit nicely through the stem without any forcing whatsoever.
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1 Super Record bike, 1 Nuovo Record bike, 1 Pista, 1 Road, 1 Cyclocross/Allrounder, 1 MTB, 1 Touring, 1 Fixed gear