Miles2go

I recently replaced an older carbon race bike and suspect the much older wheels are faster...and/or more efficient.
Funny thing is, I've pulled these 2007 Campy Neutron wheels forward to a total of 3 bikes because it they've always been fast and reliable, but now switched from Campy to Shimano. Spin down tests or coast down tests is how I compared.

The new wheelset is a Dura-Ace 9100 C24 and after over 1,000 miles, If I lift the front the front wheel and spin it, it will stop spinning at a consistent average of 1:15 seconds,
and I'm now being passed on big hill coast downs, when on rides with buddies.
The old Campy wheelset using ball bearings consistently spins for 3:45 or longer,
and even though I'm a lightweight, I'm rarely out coasted on descents.

I never would have guessed that in this day, I could buy a well-regarded wheelset and have them turn up slower than my 2007 wheels with a serious amount of miles into them.
So how do I ensure my next wheels are as efficient as the old Campy wheels? Of course you should be able to see the implications of the difference as applied to a long race. One wheelset is taking more of your power to maintain the same speeds.