This is the first year that I have fielded an aluminum MTB, a second hand Gary Fisher Advance. It, for lack of a better word, creaks. The seat post area and the head set area are whee the ominous sounds seem to be coming from. I'm a Big Fella, 230 or so. Is this normal? Is this safe? I jumped it yesterday (my first MTB jump in I-don't-know-how-long) and it didn't snap or any thing. My old, old, old steel framed MTB didn't make these noises and my alu framed Tricross doesn't make them (on the road/dirt roads) but I know where they have been their whole lives, the Fisher: not so much.