Ceramic Wheel Bearings

bcmf

So following on form the 'Bargains...' Thread ....

Got a set of these http://www.swimcyclerun.com/weekly-special-offers/campagnolo-scirocco-h35-wheelset-shimano-hub-.html

The original plan was to get these and pop a set of ceramic wheel bearings in them http://www.ebay.ie/itm/331122152878?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 race on them early season then as the weather improved get a set of dry weather race wheels. This plan has changed but thats another conversation.

I had a set of Khmansins last year and when the front bearings seized after a short while (when I popped out the seized bearings it only has 1 seal*) and when I replaced teh bearings with SKF steel ones it made a huge difference even form when the original campy ones bedded in.
Rode a set of Williams System 30 which had ceramic (hybrid ceramic?!?!) and they just rolled beautifully and forever for what I believe is the entry level wheel in the Williams range.

Considering the SKF one's are €10 and the ones in the ebay link are circa €30 for a set is the ,small extra, cost worth it or will the apparently short life of the ceramics just not be worth the hassle!

Discuss......

*I believe the difference in the cx version of Scirrocco and Fulcrum's range to their standard road versiion is that the cx has bearings sealed on both sides wheras the road version only has a seal on the outer side to , I presume, reduce drag on the bearings.

Seweryn

bcmf wrote: »

Considering the SKF one's are €10 and the ones in the ebay link are circa €30 for a set is the ,small extra, cost worth it or will the apparently short life of the ceramics just not be worth the hassle!

Not worth the hassle. The SKF bearings are of high quality and there are not many bearings on the market that would be equaly as good as SKF, and definitely not within the €10 price bracket.

doozerie

With bearings you pay more the more consistent the roundness of the ball bearings in a batch. That certainly applies to steel bearings and I believe it applies to ceramic bearings too since more consistent roundness = more machining = greater manufacturing cost. Given the significantly greater cost of ceramic over steel, below a certain price point in particular, ceramic ball bearings might actually be of inferior quality/roundness to similarly priced steel ball bearings.

There is also the fact that, while the ball bearings themselves might be ceramic, the races are often steel, so the effective life of the overall bearing will be dictated by the steel race as the "weakest" (relatively speaking) link. So you might pay more for a bearing with ceramic balls and get no better performance, and perhaps a shorter lifespan, than one with the same races and good quality steel balls.

I've never used ceramic bearings personally, but my entirely subjective opinion is that the middle ground of cheaper ceramic balls, or good ceramic balls with steel races, is likely to be a false economy. I'm also not convinced that ceramic bearings offer any advantages for a bike anyway but that's another conversation entirely. I certainly do think though that good quality steel bearings are worth paying for.

The good quality (steel) bearing brands that I am aware of off-hand are SKF, FAG, INA, and Enduro, but they all sell bearings of different grades. Grade 25 seems to be a grade commonly considered adequate for industrial applications so probably more than adequate for the comparatively modest demands of bike parts too. I've read dubious online claims (anecdotes!) that Campag use (higher) grade 10 bearings in their parts. From little bits that I've read though, I believe that the cost as you go up the grades increases logarithmically, so grade 10 bearings in any bike parts seems unlikely.

[As a vaguely related aside, even with good quality ball bearings, the roundness can vary between batches so the advice is to never mix loose ball bearings from different batches, even if they are all labelled as the same grade, or you'll shorten the life of all of the bearings and perhaps the races too. ...yes, I've been spending far too much time reading up on bearings in recent months!]

bcmf

Thanks Doozerie. Great post.
I was/am of the opinion that ceramic bearings only really make a difference at high rpm's. Therefore wasted in say a BB.But maybe in a wheel or would the rpm that a wheel goes through still not be high enough.

doozerie

From my reading, I gather that ceramic bearings are designed to address high load and high temperatures primarily, some of the other benefits being that they are not prone to corrosive substances and they are lighter. Those are by no mean the only selling points of them, just the ones that seem to me of most immediate relevance for use in bike parts.

Of those the one that I reckon is of greatest benefit to cycling is the lighter weight. Bike parts don't get subjected to the kind of (industrial) loads for which ceramic bearings are designed, the rotational speeds of any bikes parts don't generate the kind of temperatures where ceramics shine (up to 1,800F apparently), and well maintained steel bearings on a bike shouldn't rust either so corrosion resistance is arguably not *necessary* for bike bearings even if it is nice to have. I think that ceramic can offer benefits, such as the lighter weight, but is their high cost (assuming good quality ceramic bearings) worth it? Not for me, but as with many things, if I had the cash to spare then the potentially marginal benefits of ceramic might seem more appealing.

In short, I don't think the rotational speed of a bike wheel would really trouble steel bearings so ceramic bearings wouldn't add any notable benefit in my view. It's the seals that are generally considered the source of much of the drag with (good quality) bearings, so good quality ball bearings are not enough in themselves, you also need well designed and made seals to maximise performance. I've read manufacturer claims that ceramic bearings by their nature allow lighter seals to be used (and some claim ceramic allows the use of less, or no, grease too, thereby reducing or eliminating another source of drag) so there may be an argument to say the ceramic bearings spin more freely, but I'm not entirely convinced by the claims I've read and again I'd wonder whether the difference would be detectable anyway even if the claims are true.

I'm just a layman though, someone with a background in engineering or material design would have a far better understanding of some of this stuff and could probably dismiss or support some of the claims out of hand. I can't help focusing on the high cost of ("good") ceramic bearings though and I can't imagine that they'd outperform good quality steel enough to justify their premium price.

Quigs Snr

I have ceramic bearings in a set of Easton EC90 SLX and also the Ceramic editions of some Zipp 808's. Noticed no difference in performance, feel or durability to be perfectly honest. Have/had ceramic SRAM bottom brackets too.. have removed them, only 4g lighter than the regular ones, 4 times the price and last about a quarter of the time from what I have experienced.

cdaly_

bcmf wrote: »

Thanks Doozerie. Great post.
I was/am of the opinion that ceramic bearings only really make a difference at high rpm's. Therefore wasted in say a BB.But maybe in a wheel or would the rpm that a wheel goes through still not be high enough.

Circumference of a wheel = 2 m
1 m/s = 3.6 kph
50 kph = 13.9 m/s
13.9 m/s / 2 m = 7 Hz
7 Hz * 60 s = 420 rpm
50 kph = 420 rpm
70 kph = 588 rpm

I suspect that's nowhere near the 'high rpms' of a ceramic bearing...

Harrybelafonte

I spent a fair whack of time researching this last year as I was trying to pick parts for the new track bike. Sugino make a BB with ceramic bearings and I wanted to see if it was worth it. So, my mind is not that of an engineer and I can't work in hypotheticals, only other's empirical knowledge. My conclusions were basically as mentioned before:

1. Cheaper ceramic bearings are of less functional value than good steel bearings, partially due to the steel elements they contain, but also because of what Doozerie explains.

2. Ceramic bearings involve a greater upkeep than steel bearings.

3. Ceramic bearings will never be used at speeds on a bike where their superiority over steel would be evident.

4. On the basis of using the best value ceramic over best value steel, their weight saving vs cost argument Is not tenable.

Basically, general agreement is that high-end steel bearings are the most sensible choice and ceramic bearings on a bike are fundamentally a top end of the bike market "desperate and liberal with the truth to make money" ploy.

I have to replace bearings in my Corima four spoke and disk and I do think I'll get the best steel I can (once I work out how to actually do it). I also need to replace the bearings in my son's BMX BB so I might be researching it all over again.

kumate_champ07

doozerie wrote: »

From my reading, I gather that ceramic bearings are designed to address high load and high temperatures primarily, some of the other benefits being that they are not prone to corrosive substances and they are lighter. Those are by no mean the only selling points of them, just the ones that seem to me of most immediate relevance for use in bike parts.

Of those the one that I reckon is of greatest benefit to cycling is the lighter weight. Bike parts don't get subjected to the kind of (industrial) loads for which ceramic bearings are designed, the rotational speeds of any bikes parts don't generate the kind of temperatures where ceramics shine (up to 1,800F apparently), and well maintained steel bearings on a bike shouldn't rust either so corrosion resistance is arguably not *necessary* for bike bearings even if it is nice to have. I think that ceramic can offer benefits, such as the lighter weight, but is their high cost (assuming good quality ceramic bearings) worth it? Not for me, but as with many things, if I had the cash to spare then the potentially marginal benefits of ceramic might seem more appealing.

In short, I don't think the rotational speed of a bike wheel would really trouble steel bearings so ceramic bearings wouldn't add any notable benefit in my view. It's the seals that are generally considered the source of much of the drag with (good quality) bearings, so good quality ball bearings are not enough in themselves, you also need well designed and made seals to maximise performance. I've read manufacturer claims that ceramic bearings by their nature allow lighter seals to be used (and some claim ceramic allows the use of less, or no, grease too, thereby reducing or eliminating another source of drag) so there may be an argument to say the ceramic bearings spin more freely, but I'm not entirely convinced by the claims I've read and again I'd wonder whether the difference would be detectable anyway even if the claims are true.

I'm just a layman though, someone with a background in engineering or material design would have a far better understanding of some of this stuff and could probably dismiss or support some of the claims out of hand. I can't help focusing on the high cost of ("good") ceramic bearings though and I can't imagine that they'd outperform good quality steel enough to justify their premium price.

needed for motorsport, not needed for cycling


weight loss at the center point of rotation has no benefit

the good(expensive) ceramic bearings need special tools for installation, if they dont go in 100% straight they will wear out very quickly. even cheap ceramic bearings need to be installed with better care than needed for steel.

sealing type(less contact, less friction), space between bearings, bearing load, grease type and quantity all effect performance. for the heavier rider there is enduro max, the shields can be swapped out and lighter grease can be added, the bearings in those are loose with no retainers. other than that they are exactly the same as standard

Lumen

CeramicSpeed coated give you ceramic balls and ceramic-coated steel races.

They're a very economical upgrade.

e.g.

http://ceramicspeed.com/sport/products/WheelKits/product/CSWK0202010/Mavic-2-Coated

You even get a sticker sheet included!

bcmf

Lumen wrote: »

CeramicSpeed coated give you ceramic balls and ceramic-coated steel races.

They're a very economical upgrade.

e.g.

http://ceramicspeed.com/sport/products/WheelKits/product/CSWK0202010/Mavic-2-Coated

You even get a sticker sheet included!

Ohhhhh....Stickers.


and yes a very economical upgrade indeed.