I didn't mean to neglect the "machined out of a single block of tool steel" cassettes. They're every bit as expensive, several grams lighter, and just as absurd as ceramic BBs. My apologies to and and all stupidly overpriced cassettes I unintentionally left out.

I have a Record BB from 2001, with around 40K on it.

Still smooth as silk and spins forever... sometimes I wonder if it has any friction at all in there.

Pretty amazing since I am a Clyde. One tough BB.

If you want a cassette to be lightweight, you make it out of aluminum. It's a thing.

Still heavier than the wallet-emptying OMNI Racer cassettes. The Recon 11-28 aluminum is 124g, while the OMNI 11-28 is 112g. It's $10 a gram to get that weight off of there, but we're talking to folks who buy $150 BBs. A PITTANCE!

S-Works Tarmac came with $300.00 ceramic bottom bracket. SL4 Tarmac came with standard. Spin them both with chain off and feel the same. Guess which one I will go with when the $300.00 one needs replacing?

Ceramic bearings is like expensive "high end" hifi cables. No one can prove any actual benefit, but lots of ppl will testify to all sorts of perceived benefits and will ignore both science and engineering and any and all rational arguments. Many will buy for sheer FOMO.

You cannot judge friction by spinning it in an unloaded state.

I believe there is some truth to that.

Gotta get those ceramic bottom brackets and titanium derailleur pulleys for maximum efficiency gainz.

ftfy

I have about 10 of those. All I buy.

Spinning without load is not what steel vs ceramic is about anymore than rolling a 20PSI tire vs a 100PSI tire would tell you on an empty bike.
Smoothness - that is just lack of grit and round bearings - and viscosity of the lube. All are something, but it is the compression/deformation under load which is why ceramic bearings even exist.

Steel compresses more under the same load. So it is like a lower pressure tire and has a larger contact area.
At high speed - like 1000X what you would see on a bike that flexi - matters. It may matter on a bike too, but while I'm not making claims that are scientific, if not tested under real load, it is hard to say anything.

I was replying specifically to #30.

Its super hyperbole comparing steel bearings to a 20 psi tyre. As mentioned many times already, the friction is from the lubricant and the seal. You might as well get a steel bearing with non-contact seals and lubricate with NLGI 0 grease. Thats how friction is reduced in ceramic bearings as well. Ceramics are no more resistant to grit from lack of sealing than steel bearings. It not hard to say anything unless you ignore already established facts.

I've never looked in to them much but Ceramic Speed sells 3D printed titanium pulleys for $1,000. So I figured those were the best.

It was, but the principle is the same. One has a higher modulus than the other.
You only would see that under load.
My point was only load testing matters for this. Seals, grease, grit, roundness are all factors, but do not answer "why ceramic".

I can sell you some laser cut carbons with ceramic bearings for $1,200. So that would make them better?
BTW - you can't 3D print carbon fibre that I know (composite - yes, carbon fibre - no). And why would you 3D print those?

True story.

But some ceramic 13T pulley's on. Shifting went down. So put Shimano back on top, other on bottom. All is good.

Actual load testing shows that there is no difference between ceramic and steel. Its simply not ceramic or not ceramic that accounts for the differences in BB friction. Its all the other factors. Of those other factors lubricants and seals are the most significant, as long as proper installation is assumed.

You mean as I posted on Page 1 https://www.bikeforums.net/19671341-post23.html

You seem to argue more than one position. Why bother advocate expensive ceramic BBs if you agree they are no better?

I don't think I posted they are better. They are harder.
But the reason is you can't get light lube, non contact steel bearings on standard bike parts. But you can in ceramic.

So, stock ceramic sets... Are lighter and lower friction (because of the other start in part).
Ceramic Speed is just a pricey brand having little to do with the material.

I get cheap ceramic for performance bikes and replace when needed. For BB, hubs, not headset, not pedals yet, but I plan to. The headset just for weight weenie reasons. The trick is knowing the size/fit. Then they are similar to steel, you have to get them put in. They don't compress much, neither do steel, but most metal receptacles expand to take the press fit.

I replaced one wheel bearing this year that got messed up in the rain, or hose. ~$30. Last year replaced bb bearings ~$70

Wrote a bit about bicycle bearing(s construction). Generally, the "special" ones are not worth it unless a sponsor is paying for them. Here's the link:
Types and construction of bicycle bearings - Cycle Gremlin
[MENTION=364302]Doge[/MENTION]: did you measure any reduction in watts from lower friction, or a difference in riding time with ceramic bearings?

No numbers. I don't measure power much. I expect the difference is within the tolerance of a PM anyway. I don't know if it is the bearing material, or the seals, or the grease, but the full ceramic from the same manufacturer spins better than the steel bearings. Again, as I posted, this may be just seals, but also as posted, that is how the ceramics come and not how the steel ones come. So my argument is much less scientific (never said it was) and more logistic/what you can get.
I have had 3 Ceramic brand BBs and they are all are pretty lose compared to the steel ones.

I also do things to the freewheel too(used to be more important having a junior). So the system is lose and the ceramic BB is just part of it. So BB bearings, chain, freewheel, pedals - spin freely and can be easily felt by hand. It is somewhat of a stress reliever/popular thing for the kids on the team to just spin it backwards and see how many revs they can get.

It could end up with very little actual watts of friction saved in practice. Even when it feels like a lot easier when turning by hand.

It all adds up. I tend to think my drive train is about 5-10W less drag at 300W than other race bikes I come across.
All guessing based on the number of bearing cartridges, the force on the bearings, and just feel and experience.

My guess is the BB is good for 2W, the chain 4W (PTFE or waxed, vs std lubed), the freewheel 2W, pulleys <1W, pedal bearings 3W... Any number could be challenged. But when I put it all together, I get an <12# bike reported to feel faster under power.
So happens it will be doing a Pikes Peak test ride in about 2 hours. If it is raining - ride is off, can't take the risk of getting those bearings wet. By no means am I'm saying they are "better" just that I do think the friction is a bit lower. RPM for cycling is so low, I think the precision part is less a deal than most say.