Originally Posted by
CACycling
My guess is that the high priced wheelset will have better hubs and a more aero profile which will effect performance. Probably more than weight alone. I will say that dropping 1/3 lb. from each of the wheels on my commuter (dumped the thorn-resistant tubes in favor of standard tubes) made a big impact on average speeds on my commute.
That's also a case where it's much more than the weight alone. Thorn resistant tubes add a substantial amount of rolling resistance which I found to be far more significant than the increase in weight. As your wheel turns the tube is flexing in the region of the contact patch and flexing the thick rubber of a thorn resistant tube requires energy that ultimately has to come from the rider.