I have used a screw driver to spread the stem (and am alive to post about it)--- we are talking about a fraction of a mm here. I fail to see the problem here. I doubt many stems or bars are truly built to exact specs anyway. We aren't talking about bearings here.
Originally Posted by
Mike Mills
I've done similar things. You need a solid wedge, preferably steel, of an appropriate size. You tap the wedge into the bolt pinch gap in the stem (of course, you leave it there, too). This prys open the gap and allows you to insert the bars. Pop out your wedge and you are done.
You do run the risk of cracking (destroying) the stem if you try to wedge open it too far. Open it only enough to accept the bars.
By far, the preferred approach is to get a properly fitting stem.