My calipers are plastic and suck so measuring .4 of a mm is not withing the margin of error. Besides it's hard enough to get the bars in the clamp in the first place.
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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