They don't make YOU faster, but you'd be kidding yourself if you said a lightweight set of wheels didn't spin up to speed faster. Aero wheels are only beneficial if you are in top shape and can maintain 25mph-30mph for a good amount of time. However, it's impossible to ignore the relatively instantaneous acceleration you get with a 1300g wheelset over a 2000g wheelset, even if you aren't a pro. Like bianchi10 said, it's not just mass off your bike, it's rotational mass off your wheels. Big difference there. That being said, there's no need to spend $2,000 on a fancy set of carbon fiber wheels. You can spend $500-$800 and get something in the 1300-1500g weight range that is still going to be strong enough for a 200lb rider to ride every day.
In the end, it depends on what your idea of "THAT" big of a difference is. To me, the difference in acceleration between a 2000g and 1300g wheelset is huge. And it's not placebo effect.
Last edited by ilovecycling; 09-17-11 at 12:25 PM.