Fifteen horsepower. That’s the rule in motorsport; fifteen horsepower is the minimum difference in power modification that you will be able to feel in a car. Anything less and, broadly speaking, it’s pretty much impossible to tell the difference. Now we’re going to go out on a limb here and ask you to imagine applying this same concept to a bike. With that said, five percent power delta should be the minimum difference you can feel between component swaps.

As we reflect on our past reviews and their associated wind tunnel tests, this seems to be about right. Five percent of a steady 250 watts is 12.5 – about half of what one sees from tunnel data for modern aero wheelsets versus the standard box rim. If Friction Facts is to be believed, it is also about what gains in efficiency can be harvested from optimizing your drivetrain between the chain, pedals, derailleur pulleys, and lube to make it all spin smooth. And that’s where Ceramic Speed comes in.

We’re going to be up front with you – we cannot tell the difference between the Ceramic Speed derailleur pulleys and the Dura Ace set it replaced. There is lab data that shows the difference is around 0.12W or about 0.05 % – a full two significant digits from our detection threshold. The case against Ultegra is about four-times better at about half a watt, and one-quarter of a percentage point. Better still for 105, which is nearly a watt. But let’s put this into context. The Ceramic Speed derailleur pulleys are the same price as a Dura Ace 7900 derailleur itself, and nearly three times the cost of the 105 part one would drop them into! At that point, the cost effective option is the 7900 derailleur—especially given that it is lighter weight and smoother shifting. Simply put, this is not a product that can be recommended for anyone who doesn’t have competitive times at Kona in their sights.

With that said, Ceramic Speed’s offering is incredibly pretty and does have the lowest drag figure out there. If you’re in search of that last half a watt and you’ve already spent a mint in the tunnel, routed and re-routed every cable, and perhaps even gone through a series of aero helmets to find the one that compliments your form the best, then you just might be the ideal Ceramic Speed customer. We are talking about being on the bleeding edge of performance, where seconds count—not minutes. And in that, these derailleur pulleys become the separation between first place and first loser, which as far as we’re concerned, is all that matters.