I have a four bolt 26mm stem and 25.4mm bars. I put the bars on without a shim and it didn't appear that there was any sizing issue. But .6mms is pretty significant, so I want to get this right. I cut some shims out of an aluminum soda can. Two, one for each face of the stem that comes in contact with the bar. I don't have a micrometer, so I can't measure the actual thickness of the metal (and I'm far too cheap to pay $10+shipping for a shim). Anyone know what the thickness is? I googled aluminum can wall thickness and got a range of average thickness from .009 inches to .013 inches. If my can falls within that range I should be pretty close to the .6 mms I need. When do I just call it good enough?