Exactly what it says.
I'm thinking of going for one of these and I'm deciding whether or not the Carbon is worth the jump in price.

How much lighter will the carbon six be?
geometry differences?
spec differences?
handing differences?
comfort over long distances (i want to ride a couple centuries a year)?

I tested the CAAD9 in the LBS and liked it very much. But they don't have a Six to test out.

I thank you in advance for any light you can shed on this situation.

bump. c'mon. someone?

I have not been on the Six, but the mechanic at my LBS just built one up. His response is "meh." He says it's OK, but it doesn't do anything to stand out from the crowd--it's not super light, it's not extraordinarily stiff, it's not particularly exciting in any way.

That's all I've got. I'd go for the CAAD unless you can't live without carbon.

The caad9 is a great bike, but it will beat up a little bit after long rides. If you are looking just to go on longer rides, and not race at all, you might wanna go with carbon.

i think it was velo news where i read a test of the '09 six. don't recall the overall weight. but the fork alone weighed 700gms! more than a colnago cro-mo one. the bike's gotta weigh more than the 9.from what iread they've addressed this for the '10 model tho.

The review from cyclingnews for the "six carbon three" was titled "A Sheep in Wolf's Clothing".
find it here, some of the parts vary- but you are looking at the same bike more or less.

They're both great bikes. I have ridden both and would be happy with both. With that being said I'd probably go with the CAAD9-5. You're getting an amazing aluminum frame vs a decent carbon frame. I ride a Cannondale fixed gear where the frame is very similar to the CAAD9 and I've done some 40-50 mile rides on it without any comfort issues. Just make sure your fit is right and if you feel like being a little more upright, flip that stem up. Obviously the carbon frame will absorb a little more road buzz, but they're both plenty stiff, agile bikes. If you're thinking that the Six Carbon will be some featherweight ride, think again, it is almost identical in weight to the CAAD9. Both equipped with 105 which will perform just great. I was leaning towards the Six Carbon 3 just because I knew I would eventually want a carbon frame, but found a deal on a Trek Madone that I couldn't pass up. Also, Cannondale is rolling out the 2010 SuperSix so you could probably find some sweet deals on last years models. The SuperSix is my favorite of the Cannondale lineup. If you're not trying to race (I'm not) and the the price difference is small, you might find a bit more comfort through the absorption of carbon, but the six carbon is a bit more sluggish feeling than the CAAD9. Sleep on it and give it one last test ride.

Wow. This info has been incredibly helpful. Thank you all so much. I truly appreciate it.

So one last question... how about the Six -5?

Seems to be a blend of aluminum front triangle with carbon stays. the aluminum seems to be Cannondale's strong suit in this price range, and with carbon in the stays for a bit more "road buzz" dampening. It would also mean getting an ultegra RD (not that an amateur like myself is going to notice).

Based on everything I've read, I'd lean away from the Six carbon bikes. but would the six-5 be the best of both worlds? or perhaps the worst of both worlds, and I should just stick with the CAAD9-5?

Edit to add:
It seems that a common complaint about the Six is that the fork is too heavy. According to C-dale's website, the Six has the same fork ("six ultra carbon") as the CAAD9. Why don't I hear people complaining about the CAAD9's fork?

The six carbon is a great bike, I wouldn't take it out of your lineup completely. I would probably stay away from the six 5 though. The CAAD9 is most definitely the better bike vs the Six 5. If its the matter of a smooth ride, a nice set of tires with lower psi on the CAAD9 can make all the difference you'd need. If its the matter of liking the longer headtube of the six, just don't cut your fork down on the CAAD and ride the stem flipped up and the position will feel pretty damn close. If you tested and really liked the CAAD9, I'd say go for it. Check to see if you have other Cannondale dealers in your area though. It's always good to test your options. Good luck in the search.

You don't hear people complaining about the CAAD9 fork because the frame itself is a winner--and a bargain. Is the Six lighter than the CAAD9? If so, it's not by much. It's pretty heavy for a carbon frame.

I'd probably look at other manufacturers (Giant esp.) in the $2000-ish carbon frame game.

Ok. it just so happens that my dealer is both a Cannondale and Giant dealer. I can't afford to spend more than the approx $1700 range at ABSOLUTE maximum.
That means that I can't go FULL carbon in a Giant, but it does break me into the range of the TCRAlliance1.

It's definitely food for thought. How would we say a CAAD9 would compare to a TCR A1 in weight, comfort over a century, and performance overall for a solidly good rider who is nowhere near "pro" nor does he ever intend to race. However I am going to be leader of group rides from the bike shop so i need a light fast bike to help me do my best to stay ahead of the pack.

Edit to add:
I just read a biek review online (by an amateur, not a bike rag or anything) that said the stock TCR-A1 weighs in around 20lbs. Seriously? I feel like that just can't be accurate.

Cannondale had a sale on the Super Six frames for $1600. Not sure if there are any left.