Originally Posted by Brian Ratliff

When the industry went to external bearings, they started using industry standard, sealed, cartridge bearings. Because of the bigger diameter, the seal drag is proportionally increased, which makes it look like the bearings don't rotate as smoothly as the old cartridge BBs. But it's just seal drag. When you are turning the crank slowly, the seals create, say, 'x' N-m of torque. Because you are rotating the cranks with your hand on a workstand, 'x' N-m is a relatively large proportion of the total torque on the crank. But when you are stomping on the pedals, the seals still only exert 'x' amount of torque, but the total amount of torque on the crank is now 100 times larger, so the percentage of the total torque that 'x' exerts on the crank is now 100 times smaller.

Say seal drag was 10% of the torque on the crank when you spin the crankarms on the workstand. When you are pedaling, that same seal drag is now only 0.1% of the total torque because the actual number stayed the same while the total torque on the crank increased 100 fold. Spinning the cranks on the workstand is a poor measure of bearing drag.

So, all this talk about lower friction in ceramic bearings is just because of better seals which drag less so the cranks rotate more freely on the workstand. The only benefit ceramic bearings have is in increased wear life, because the ceramic balls are harder than any contaminants that might get into the bearings, and they will not pit and become egg shaped over time like steel bearings will. If that's worth going from a $20 bearing set to a $200 bearing set, then more power to you.

Originally Posted by Brian Ratliff

First off, this is seal drag I am talking about; has nothing to do with bearings. I have an old, worn out cartridge bearing (from a formula hub; destroyed by setting my chain tension too high on my fixed gear) sitting on my desk at work with rough, pitted bearings (but no seal) that will easily cause something as massive as a crankset to spin forever on the work stand. Pay a bit more for better sealed steel ball bearings, and you'll get the same benefits. Ceramic bearings come with good seals because the market is the type of people who will pay the premium for all this stuff, and part of the marketing appeal of ceramic bearings is that they roll forever on the work stand. The bearings that come standard in bottom brackets are the same bearings you can get out of the McMaster Carr catalogue.

Second, if 'x' is 0.1% of the torque on the crank, it matters not a bit. It is probably less of an effect than the increase in fluid drag from the grease in the bearings that you encounter when it's cold out vs. riding in 90 degree weather. Pros ride them because they have these products thrown at them by sponsers, though maybe the younger ones are spurred on by the placebeo effect benefits. Hey, if you think you should climb faster because of your equipment, you have a vested interest in proving your thinking right, and if this psycological factor makes you faster, then so much the better.

Originally Posted by Psimet2001

This has been my position from the beginning in my debates on here about ceramic BB's. The OEMs have done a poor job selecting the cartridge bearings they used. They picked the ones they did for a few reasons I am sure:

1. Cheap.
2. Well sealed - will help keep water out.
3. Seal drag is arguably small.

The magnitude of the seal drag and it's overall "power loss" under load is very small. I have read the article where Zinn did testing and basically verified we're talking a very small loss of watts. fractional IIRC.

My other contention though was that even a small loss of power due to poor seal selection/application should be something that could be overcome easily and inexpensively with the correct bearing selection.

Ceramic is not necessary. Feeling faster is in your mind. Can improvements be made? Yes.

Would we even be discussing this or debating it if the difference in price was $10-$15?

...well most of us wouldn't but the poor scientists would be.

Originally Posted by Brian Ratliff

Given the issues with resolving losses that are a two or three of orders of magnitude smaller than the input power (the issue is with subtracting two large numbers, each with independent uncertainties, to assertain a very small number - uncertainty might be well more than 100% of the small number), it is doubtful that Zinn could even repeatably resolve fractional watt losses unless he did the measurement very carefully, or with some clever, robust, indirect method of measurement.

Needless to say, the losses due to seal drag are extremely small. I mean, it is the reason why we now use grease filled, industrial cartridge bearings instead of oil lubricated free bearings for all four bearing locations on a bike. And it's why many pedal bearing systems simply use a journal bearing instead of going through with the expense of using roller or pin bearings.

And, if the price difference were $10-15, then you know that we'd all be rushing out to get this newest latest and greatest thing.

Originally Posted by Psimet2001

Indeed.

I can't remember if Zinn actually did the test himself or if someone else set it up and he observed/reported on the results. The had a pretty decent testing setup from what I recall, but I would be guessing if I tried to recall any of the specific numbers or their repeatability.

The takeaway from that one was that a well worn in Campy voloce or mirage level square taper sealed BB had the lowest drag of all of them. Shouldn't really surprise anyone who understands what's going on, but it seemed to throw a lot of people.

Originally Posted by Brian Ratliff

I've got one of those. After 8 years of service, it was a really free spinning BB. I took that to mean that the seals were worn and the grease was nearly non-existant. When I built up my new cross frame from the old components, I replaced it.

Maybe I should put it back in. Maybe I'll go faster with the lessened drag.

Originally Posted by Brian Ratliff

I've got one of those. After 8 years of service, it was a really free spinning BB. I took that to mean that the seals were worn and the grease was nearly non-existant. When I built up my new cross frame from the old components, I replaced it.

Maybe I should put it back in. Maybe I'll go faster with the lessened drag.

Originally Posted by Brian Ratliff

I am pretty sure that speedplays have journal bearings (bushings) instead of roller bearings because of the small diameter axle. But yea, it might be a similar (though not quite the same) thing. A journal bearing with no lub might spin well under no load, but under load have a lot of drag. Roller bearings without lub will spin freely under any circumstance, loaded or unloaded, but without a layer of lubricant between the ball and race, it'll tear itself apart pretty quickly.

If they have roller bearings, then yes, it's the same phenomena as with the worn BB.

EDIT: Psimet probably knows what kind of bearings are in there. I use Look, Ultegra, and Eggbeater pedals. Never taken a speedplay pedal apart.

Originally Posted by MIN

you will be faster if you shave your mustache.

Originally Posted by kring

So last week I found a great deal on a new FSA Mega EXO ceramic BB for $120 and gave it a shot.

Anyone else have similar experince?

Originally Posted by Pizza Man

I've ordered the same BB. I'll report back in a month.

Originally Posted by kring

FSA I think claims 3-4 seconds improvement on a 100K race... I'd say it's far more then that.