Originally Posted by
redlude97
They make a <0.05mm shim? Thinner than tin foil?
Steel shim is generally available down to 0.001", which is about 0.025mm. Aluminum foil is (according to
this site, which is a manufacture) between 0.0004 and 0.001 inch thick. That's about 0.01 to 0.2mm. Apparently "heavy duty" Al foil is about 0.001", or 0.025mm. If you have a feeler gauge with lots of different gauge leafs, one will probably be 0.0015". Even if you used a steel shim, 0.001 would be pretty delicate. 0.002 has a little more substance but you'd have to be careful with it.
Originally Posted by
JohnDThompson
You have the frame; measure it. You can get a vernier caliper from e.g. Harbor Freight for only a couple bucks. Or bring it to a bike shop and have them measure it.
I'm skeptical that an HF caliper would be of much use for several reasons. First, ID measurements are pretty difficult when you are getting into the area differentiating sliding and transition fit. You can't get measurements anywhere but the lip with a caliper and so the measurements might not be useful. The post hole may not be round, and so you have to take multiple measurements and average them, and this average may not be useful. In machine work, you'd use a telescopic bore gauge and a micrometer, a dial or vernier hole gauge, or a pin gauge (just a precision pin).
If it were my bike I'd use a telescoping gauge to ensure that the hole is the same size (that is, to ensure that previous tightening did not constrict the mouth of the hole). If everything were the same diameter, great. If the mouth is significantly smaller than the tube further in, I'd bend the mouth open (assuming a steel frame) to get a uniform bore size, and use a shim.
I'd probably buy a couple of sheets of shim stock of 0.001, 0.0015, 0.002 and 0.003 inch thickness, cut four strips off each, and see which size allows a "transition fit". That is, loose enough to put the post in easily, but with enough friction to hold it in place without tightening. Presumably, this would allow the tightened post to hold the tube securely when you are riding.
A telescoping bore gage set is shown below. You stick it in the hole, tighten the handle, and it captures the ID. Then you measure it with a micrometer. This setup allows you to measure deeper in the hole than you can with a caliber or a pin gauge.
