Originally Posted by
cc700
aluminum frames will only make your actual hands hurt because your grip has to compensate for chatter, and your lower spine and butt hurt. again, chatter.
beyond that, even the lowest quality aluminum bike won't hurt you if it's fit properly.
also, carbon fiber is NOT the answer to everything, especially carbon seatposts. especially cheap carbon. cheap carbon is likely to be just as stiff as aluminum in the wrong areas and just as compliant in the areas that it shouldn't be. carbon weaves are extremely stiff in one or two directions, and flex a LOT in others. unfortunately, to get those properties where you want them, you have to design the part extremely well and most cheap carbon parts are not designed well. they're just made out of carbon because people will pay a lot for it.
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While I agree that carbon seat posts will do nothing for ride quality, the rest of your post is wrong. Cheap Al frames ride much, much, rougher than a cheap carbon frame. I went from a top of the line Al cannondale road frame to an entry level Fuji carbon frame, and its night and day. The real world stiffness is the same, but the ride quality improvement is night and day.
Large diameter Al tubes will results in a rough ride, period. Even with a proper fit, you will end up more fatigued on an Al frame than a well designed CF frame. There is a reason there isn't anyone riding Al frames in the pro peleton, and it's not that CF frames are lighter.