I have a leftover 2005 Roubaix that I bought last year. It has Shimano 105, Ultegra shifter, Carbon frame, Carbon Crank. It's a VERY nice bike. But the wheels are Alexis ? rims. I had those on my cheap Giant road bike. The bike is very light, but someone told me wheels are the best upgrade to make. it will be lighter and roll better. ??? I don't know if it's worth $500. And I'm doing a Duathlon in June, anything to help.