Originally Posted by
Kopsis
This test is not meaningful. To prove it, I just did the same test on a frame that had a seriously corroded alloy seatpost and got the same result. At a macroscopic level, carbon has a high electrical impedance ... that's why it's used to make electrical resistors. Galvanic corrosion happens on the microscopic, not macroscopic scale.
Respectfully, that sounds like poor measurement technique. To determine the conductivity (or the reciprocal, resistance) of a material, you don't measure its oxidized surface. You penetrate to bare material and measure. As for macroscopic vs microscopic---it's all microscopic AND macroscopic. It's simply a matter of how closely you view the phenomenon.
Originally Posted by Kopsis
I have. Multiple times. In high end, undamaged frames. One of the "joys" of riding in a place where temperature and humidity race each other to reach the 90s and you can smell the salt spray in the air.
And it never occurred to you that the oxidation was due to these environmental factors (moisture, temperature, salts)? Why do you conclude it was an interaction between the alloy and the carbon fibers sealed inside an epoxy resin? It seems like you're avoiding the simple answer in favor of a more complicated one. I've seen aluminum alloys oxidize very rapidly due to the environmental factors you described and carbon composites where not present at all.