Ceramic Bearings

There's a glaring misstatement in this video, namely that "ceramic bearings last longer."  This myth is precisely the sort of marketing hype that now pervades the cycling industry (along with other goodies like the "power transfer" of a bike frame).  The reality is that ceramic bearings—let's be specific, we're talking about Si3N4 (silicon nitride) rolling elements on hardened steel races, aka ceramic hybrid bearings—have drastically less load bearing capacity than conventional all-steel bearings.  The advantages of these hybrid bearings are higher speed (at a level irrelevant for cycling), more stiffness (at a level irrelevant for cycling), and less rolling friction.  In a high-load, super-low-speed application like a bottom bracket bearing, they will last LESS long than an all steel bearing.

Another pervasive myth in the cycling that just won't die is that components like the rear derailleur pulleys rob you of significant power, on the order of 4-10 watts that can be saved with a $$$$ ceramic pulley system.  NO, not even close!  Not even 0.2 watts vs a Dura-ace jockey wheel set.  Consider that fact that a bottom bracket with what most would call unacceptable tightness being spun (on a bike stand) by your finger on a crank only amount to, at most, 0.4 watts.  Somehow, company after company is able to cash in massively on the technical illiteracy of cyclists dying to hand over wads of cash for the latest technical fad.

Power (hp) = applied_force (lbs) x lever_arm (inches) * RPM / 63025.  To convert to watts, multiply hp by 745.7.  You can use this simple equation to convince yourself just how silly it is to worry about how freely a crank arm spins (or any component) producing finger pressure levels of drag.

And here's another related myth, that the friction from bicycle wheel bearings amounts to something significant.  Using the same equation, let's consider a 175 pound rider, with a wheel hub bearing race radius of 0.375 inches, traveling at 25 mph with 700c x 25mm tires.  A properly loaded conventional steel ball bearing with seals and grease has a rolling coefficient of friction of, to be generous, 0.003.  So how many watts are your steel wheel hub bearings robbing you of—maybe 5, 10, maybe even higher?  The answer is 0.74 watts max (total, both wheels).  And how much could you save by paying mega $$$$ for shiny new ceramic-hybrid wheel bearings?  Drum roll...a stunning 0.30 watts max (total, both wheels).

Just step back and look at the big picture of how far this marketing silliness has gone.  The highest-end road bikes now sell for upwards of $15,000, all to handle a 1/3 hp external 'motor' to be supplied by the customer (i.e., your legs).  Now put one of those next to a high-end Ducati Panigale V4 motorcycle, including a 200 hp engine with combustion temperatures in thousands of degrees at a thousand psi and timing to almost 500 firings per second, 200 mph top speed, 300+ lbs of advanced aerospace-grade materials (incl gobs of carbon fiber, titanium alloys, etc), and a comparatively insane number of (actually) advanced technical components...all for $21,000.  If the Ducati were priced like our bicycles, it would cost closer to $21 million.

Bottom line, these bicycle manufacturers should be laughing their asses off at our technical ignorance and eagerness to part with cash.  China, please save us from this overpriced lunacy.