On Sunday, May 29, 2016 at 11:40:18 AM UTC-7, wrote:
With all the bikes I have I also have a bike for which I built the wheels on old Campy record hub on the back and DuraAce on the front.

After getting this bike back from a friend who was saving it for me while I was not in the best of health I rebuilt the wheels with new balls and Campy grease.

I have mostly modern wheelsets from Campy or Fulcrum (the people who make the modern Campy hubs etc.) These wheels have sealed bearings. These sort of bothered me when I saw them because of the drag of the seals. You can tell simply spinning the wheels in a stand. But I imagined that with the weight of a person this would be insignificant.

For the last couple of days I have been riding the old Look and in fact you CAN feel the difference between the open bearings and the sealed. It does coast much further and with less noise.

Has anyone else noticed this?

From the discussion it would appear that the lost of 2% of the pedaling energy in the wheel bearings doesn't appear to be noticeable to most people.

I most surely notice it so I assume that most of you ride well within your limits while a large part of my time I am at or near mine. And I am not a very fast rider anymore.