Some marketing BS from roadie world...

In a well-known St Kilda cafe the other day someone in gaily-coloured lycra was banging on about the wonder of ceramic bearings. Being naturally curious and in a work-avoidance frame of mind this arvo I found this:


?Last but not least, ceramic bearings can generally be made more round than steel ones. The ceramic balls we use are Class 5 or better. The class of a ball bearing refers to its sphericity in millionths of an inch. Thus, our bearings are round to 5 millionths of an inch and better in many cases. In comparison, the best bearings that come stock in Campagnolo Record or Shimano Dura-Ace is Class 25. That means our ceramic bearings are at least 5 times more round which results in less rolling resistance?

This got me thinkin’ (instead of workin’). 5 times as round? Who taught these guys arithmetic? Hold that thought and work with me for a minute or two?

Consider a 1? ball bearing for the moment, because the arithmetic is easier. A 1? class 25 ball will be no more than 25 millionths of an inch, or 0.0025% out of round. Put another way, that?s 99.9975% spherical or better. A 1? class 5 ball will be no more than 5 millionths of an inch out of round. Put another way, that?s 99.9995% spherical or better.

Unless my arithmetic has gone horribly wrong, 99.9995% round is NOT ?5 times more round? than 99.9975% round. It?s more like 1.00002 times more round, but hey, what do I know? I never studied marketing maths…

(If you scale it down from our 1? ball to a ?? or 3/16? inch ball, the ratios stay the same)

Now all this extra roundness translates to about three hundred bucks for a chinese-made bottom bracket.

Fuck that, I’m round enough. :expressionless:

hahaha that’s brilliant!

Marketing brainstorm session at “Superfly Cycles”:

“Class 5” [long pause] “Class 25” [very long pause] - those two things, [pause again] “numbers”! - hey that reminds me of something we memorised in school… um… wait… five times three equals fifteen, no that’s not it, five times four equals twenty… nope, WAIT ! five times five is twenty-five. Shit Karl! These bearings are five times better. Print it! Let’s get chinese takeout.

10,000 rpm! they must be good for cycling.

Guess he’d been reading from RBR newsletter last week …they had even more crazy stats to play with…???

  1. UNCLE AL: Ceramic Bearings

When an RBR roadie asked about the merits of ceramic ball bearings, I said to myself, “Self, how hard can the answer be?”

After nearly three weeks of research, I may as well have been trying to get the lowdown on the latest super-secret weapon the military is working on.

There is not much hard information, just claims made by manufacturers. They say ceramic bearings (silicon nitride or Si3N4) are superior to typical steel bearings for a number of reasons, such as:

—They’re harder. But to be honest, I’ve never really wondered if steel balls are hard enough.

—They’re 60% lighter. A 1/4-inch (6.35-mm) steel bearing weighs about 1 gram. A Dura-Ace rear hub uses 18 bearings that size. 18g x 60% = 10.8g, a savings of 7.2g. Not bad.

—They withstand higher temperatures. Ceramic bearings can handle heat up to 2,552F degrees (1,302C). That’s important if your sprint is so hot it can melt steel.

—They’re rounder. Grade 3-5 ceramic balls mean accurate roundness to 0.00003-0.00005 inches. The standard Grade 25 chrome steel bearings used by Shimano and Campagnolo in their best equipment are accurate only to 0.00025 inch. Check this with your tape measure and you’ll see.

—They withstand high loads as well as high speeds. One manufacturer actually compared this feature to the ceramic tiles of the Space Shuttle upon reentry. I think it means you may need a fireproof suit for that next big descent.

—They reduce friction by at least 40%. That’s a pretty impressive figure, but I could not find proof of it anywhere.

—They last 3-5 times longer. If you overhaul your hubs every year, this means you need to replace the bearings 3-5 times less often. Sounds good to me.

Interested? Oh, I forgot one other thing – ceramic bearings cost 48 times more than Grade 25 chromium steel balls.

A Grade 25, 1/4-inch steel bearing sells for 15 cents in my shop. The same size Si3N4 ball would cost you $7.20 if I had them, which I don’t. If you want 18 steel bearings for a Dura-Ace hub rebuild, you’d pay $2.70. To get the advantages of ceramic bearings, you’d pay $129.60. Whew!

Ceramic parts kits are available. A set of derailleur pulleys costs $150. A bottom bracket bearing/cup assembly costs $190-$230. A hub kit for wheel systems using sealed cartridge bearings, like Mavic and Zipp, costs $400-$500 for both wheels. For Campy and Shimano wheels, you’re looking at spending $200 for ceramic balls.

Are they worth it? Maybe. Do you need them? Only if you can afford them.

Imagine going so fast in the next city limit sprint that you burst into flames, your ceramic bearings being the only thing that survives. It’d be like going Back to the Future, wherever that is.

if someone would like to sponsor me with two sets of identical track wheelsets, I could perform some double-blind time trialling - see if the ceramic balls make any dfifference :wink:

39 x 16 down Balcombe Hill?

Yep, that extra fraction of a percent will make you heaps faster on the road, just like shaving your legs…

:? :? :? :? :? :? :? :? :? :? :? :? :? :?

1+1 still equals 2, right!?!?!

:? :? :? :? :? :? :? :? :? :? :? :? :? :?

fuck’n nerds.

Hmm. CraigC, time for you to read up on Invalid Proofs.



after reading that and not understanding a bloody word of it, I think you math types just make up shit to confuse the knuckle-dragging part of the community, of which I’m one.

yep, it’s the reason they won’t let me wear rings during bushfire season.

Incorrect, it is in-fact five times more round.

The methodology behind this assumption has alot more to do with interger’s, rather than your ‘times by five method’. It is manufacturing speak based on six sigma, and the % of defects per 1,000,000 opportunites.



Where do the ceramic bearings fall into Maslow’s Hierarchy of Needs?

How empowered is the cyclist by the additional roundness and lack of friction efficacy?


What demographic is the ceramic bearings user compared to his less round alternative good?

What is the elasticity of demand for the ceramic bearing?

Please, answer these so I can sleep at night…