OK I have just received an explanation...can anyone back this up? "For some chemical reason, carbon fiber likes aluminum. Aluminum seat posts can run the risk of seizing to a carbon frame, and vice versa. When left in contact for a long period of time, carbon and aluminum will bond together making seat post adjustment difficult if not impossible.<?: prefix = o ns = "urn:schemas-microsoft-com:office:office" /> Carbon bonding with aluminum isn't necessarily common, but it happens. If you're carbon bike has been sitting for a couple of years and you can't adjust your seatpost, hope is not lost. You're probably going to have to pull that bottom bracket out and see if you have a hollow seat-tube (Bianchi is a popular brand which often doesn't). If so, make sure the top end of you seatpost is fully sealed (if not, plug up the hole), get a can of Coke and pour it down the seat-tube and let it sit overnight. Seriously. I don't know much about chemistry, but there is something in carbonated sodas that loosens up seized parts. Just be careful once you get the seatpost to budge that you don't get coke all over the place, and flush it out thoroughly with some sudsy water so you aren't wondering where all those ants are coming from next summer. For the scientific blah blah ... Idealy, you would have a carbon seat post, to prevent galvanic corrosion. The aluminum will corrode because it is the anode with a potential of -1.67, and the carbon the cathode with a potential of +0.81. A difference in potential of 2.48 volts. Where as titanium and carbon both have + potential, and the resulting difference is only 0.755 volts, which is negligible. (Remember kids, that even though both carbon and titanium are both + charges, its the difference in potential that creates a charge. So, something about + and ? charges causing anodizing process. Don?t know if their Coke technique works but hey ? there it is. "
