And let me guess the salesman was like 140lbs. In reality it's a fact same as any material have you ever heard of an aluminum frame failing while leaning against a wall duhhhhh, all material breaks while under load. Another thing a carbon frame is likely easier to have repaired than aluminum unless you know of a real good aluminum welder. Buy the carbon if that's the bike you want and it feels good to you. I ride carbon and at 225lbs have had no issues with almost 4000k on mine since May. Any carbon bike in a giving price range is no better or worse IMHO I would however steer clear of a used carbon frame unless you can be sure it has no issues or crash history.