TJClay

Maybe it's the color of the nipples......

RT

When it comes to nipple color, red is faster.

surgeonstone

Wheels slow? Nope, maybe i am slow but any wheel I use goes as fast as the bike.

big chainring 

+1
Equipment really doesn't matter. Some of my fastest rides this year were on a 30 yr old Peugeot UO-8. Steel cottered crank, Simplex derailleurs, and a generator light to boot. A bike is a bike. Changing wheels won't make the bike "faster". Come on guys, get real.

EDIT: yikes, its a 40 yr old UO-8.

surgeonstone

I used to have a Peugeot PX-10, i sold it in college- big mistake, loved that bike.

rruff

The A23 is a very non-aero rim. The Shimano wheels always tested well in the tunnel, so there is a slight aero benefit there. Not enough to account for what you are seeing though.

If you've controlled for the tires and tubes, then the likely source is some other friction. See how the wheels spin when clamped in the bike. For the rear you will need to get the chain out of the way. Also check the resistance of the freehub.

And... if you are doing coast-downs, do it when wind is minimal and no traffic. Traffic can make a pretty huge difference. Or just do at least a dozen runs with each and swap after each run. A tuck with your butt on the saddle and your chin just above the bar should be fairly consistent to reproduce.

waterrockets 

For the coast down, what's the difference in maximum speed? That's about the only measure that has a hope of giving you a real answer. If there is any wind at all, the test is completely invalid.

ericm979

You should use aerolab (the Chung method) for this. See https://robbellracing.blogspot.com/20...h-aerolab.html

Gluteus

^ good stuff.