Road Cycling - Newbie upgrade question

As a new owner of a Cannondale Road Bike, I am considering upgrading my handlebars, stem and seat post. I have been primarily looking at products manufactured with carbon fiber technologies. I have noticed that handlebars with a 26mm diameter are a little lighter than those with a 31.8mm diameter. My question is... Aside from the lighter weight of the smaller diameter bar, what are the pros and cons of handle bars with the two diameters? In other words, are the 26mm bars so compromised in strength/ rigidity that the loss of weight is unjustified? If there are other key issues other than strength and rigidity regarding the handlebars, stem or seat post that I have missed, please inform me. Thanks for any help you can give me. Sisco

I don't for sure but I think the 31.8 diameter is just the new Euro fad, supposedly giving more stiffness than the 26.0. Isn't bigger going to cause more weight and isn't bigger going to cause more air drag? It's kind of like the new Shimano 10spd stuff. Why? Was there something wrong with the 9spd? Or is it more ilkely just all marketing hype to sell more stuff?

Careful going with all carbon. Carbon seatposts and bars/stems tend to slip if not torqued enough. However, just a little too much torque and the carbon will crush. Expensive lessons to be learned.

Any particular reason why carbon handlebars, seatpost, etc? They look cool but they aren't any lighter.

I'd talk with your LBS(local bike store) and get an idea of what size bars, stem, etc. you'll need. And once you put that stuff on your bike, it's a good idea to get a professional bike fit if you've not done that already. As for handlebar diameters, I'd get the ones that feel the most comfortable.

Is this a new bike or are you the new owner of a used bike?

Thanks for all the good input so far... My bike is a 2006 Cannondale R5000, New. I was formally the owner of a Bianchi Vigorelli and passed it on to get something lighter and livelier, which it certainly is. However, it came with the widest handlebars I have ever seen on a bike. I feel that 40 cm in width, feels better to me. I was thinking there may be a weight advantage to carbon fiber but now with some input, it sounds as though that may not be true. Are there any suggestions for ultra light aluminum bars, stems and seat posts? Yes, the cats out of the bag, I am indeed a weight weenie. Thanks for all the help so far. Sisco

There is an advantage to SOME carbon fiber parts. The more money you spend, the lighter they get. Some carbon parts are actually heavier than their aluminum counterparts. Some parts, such as a carbon fiber seatpost, or carbon forks, will provide a bit of suppleness to an all aluminum frame and can make a big difference in comfort levels. The seatpost in particular can be a really noticable change. However if you want to really shed grams with items like handlebars, be prepared to spend upwards of 5 to 10 dollars per gram. For me that's just silly. I always seem to buy the parts that fall just short of depreciating gains.