Is therer I great difference between aluminim bikes with carbon forks, and full carbon bikes? I am trying to see if the price difference is worth it . Thanks.

It depends. Which bikes are you checking out?

It also depends what you want: do you want comfort, super-light weight, stiffness.. looks?

No, exactly the same.

Each bike is different. Ride them and see what you like.

Generally speaking, the knock on aluminum is a harsh ride.

Adding carbon bits is an effort to alleviate this. It works on my Sequoia; it's smooth and comfortable. But these guys are right- there's just way too many variables here for any kind of blanket statements.

Other than this, and this'll probably turn out to be debatable, but here goes... an all-carbon bike is your best shot at BOTH maximum stiffness AND a tolerably comfortable ride.

It depends on what kind of ride you want. I have 1 aluminum road bike with carbon seat stays and a carbon fork, and 1 full carbon bike. The full carbon bike is a much better bike, its lighter and significantly more comfortable, but it costs alot more. The carbon seat stays on the aluminum bike may help a little, but they are not designed to be as compliant as the stays on my carbon bike.

I think other features of the bike other than material contribute to how a bike rides. You can design an aluminum bike to be fairly comfortable, and can design a carbon bike to be stiff and harsh.

I recommend test riding a bunch of different bikes to figure out if a carbon bike is worth the extra money. If you can't afford it, there is nothing wrong with an aluminum bike.