I had an giant ocr 1 that had a squeak problem that I thought was coming from the seat post. The LBS greased the seat post and it still did not solve the problem. After they did some research, he suggested the problem was not the seat post, but the headset and stem. He greased the headset and we replaced the two piece adjustable stem with a solid Richey stem and ... no more squeak! Apparently sound travels so it is hard to tell exactly were the problem is coming from. If you have the two piece adjustable stem, I would try replacing that and see if that solves your problem. Hope this helps.