I really can't specify anything. In my opinion (and it's only mine), it really doesn't matter if it's carbon or aluminum. Just look to get a solid bike with quality components (Shimano or Sram, typically.) Unless your riding hills a lot, I'd stay away from 3x's (meaning three front chain rings.) Get something that has 2. Anything with 9, 10, or 11 gears at the back is fine. be sure to look at the rear derailleur closely to see if it is really banged up. Rim brakes are fine. Disc brakes are overkill for you. Make sure the wheels are quality. Aluminum wheels are fine. Good quality wheels at the cheaper end will say Shimano, Mavic, Easton, DT Swiss (and others.) If you're getting a first road bike to bang around and do a sprint, stay under $600 for the complete package. You can always modify it. My BD bike was a $450 when I bought it. It now has $1,500 in mods and kills.