Should I consider Ceramic Wheel Bearings?

At that dealer, the ABEC 5 are all steel bearings, at least that’s how it appears to me. And their ceramics are hybrids with no mention of ABEC 5.

I did not look closely at the wheel bearing page but the ceramic Hybrid kits I am using for our bottom brackets uses ‘Silicone Nitride Ceramic Balls (GRADE 5) and Cryogenically-treated hardended chromium steel races’. My interpretation is the ‘GRADE 5’ refers to ABEC 5 - the same language is used in for the reference to these bearings on the ABI Industries website (US distributor/importer for Enduro bearings).

"so the moral of the story is “maintain your bottom bracket and wheel bearings with good lube”? Splendid. "

Amazing - so the simple, straight-forward, common sense approach wins out again! Funny how that works out.

Fleck

this is going to rock Slowtwitch to its very core!

nope the grade 5 is a classification of the balls. The ABEC rating is for the bearing race. Grade 5 balls are very highly rated (grade 25 being bad grade 2 being the best), but it is the ABEC rating which for the most part determines if the bearing is good or not - E

If you’ve followed my posts, you know I ride around with both a Powertap and an SRM on my bikes just about all the time. So, I have a pretty good sense of the effect of various changes on drivetrain friction. For example, I can see the how the SRM-Powertap difference changes based on gearing, how new the chain is, &etc.

I recently tried the Tacx jockey/pulley wheels with ceramic bearings and actually saw a decrease of 1-2 watts in performance. Strange, because they spin much better than the stock Shimano ones when you turn them with your finger.

– jens

…they spin much better than the stock Shimano ones when you turn them with your finger.

– jens
I had occasion to attend a business meeting with a consulting mechanical engineer last week. He helps companies fine-tune products for final manufacturing. During a little break, I asked about ceramic bearings in bike wheels. He looked at me like I was a retard. After I did the, “Hey, don’t look at me! I don’t use 'em…” routine, he explained that they are suited for low-load bearing situations, like turbines and engine parts – things that spin fast, but don’t bear a heavy weight. You don’t use them in wheels. Wheel bearings have to roll nicely, and they have to bear the weight of the axle while they are rolling nicely. He said hardened steel will do that, and ceramic won’t do it so good. In a sense, the ceramic is too hard to roll against a steel axle and steel bearing race. He was baffled that anybody would put ceramic bearings in bike wheels.

What about in a bottom bracket? Same scenario or different since torque is more directly applied?

http://weightweenies.starbike.com/phpBB2/viewtopic.php?t=22710&highlight=bearings
.

What about in a bottom bracket? Same scenario or different since torque is more directly applied?
Don’t know – I just asked about wheels. I didn’t even know that there were bb’s with ceramic bearings until I read this thread!

…they spin much better than the stock Shimano ones when you turn them with your finger.

– jens
I had occasion to attend a business meeting with a consulting mechanical engineer last week. He helps companies fine-tune products for final manufacturing. During a little break, I asked about ceramic bearings in bike wheels. He looked at me like I was a retard. After I did the, “Hey, don’t look at me! I don’t use 'em…” routine, he explained that they are suited for low-load bearing situations, like turbines and engine parts – things that spin fast, but don’t bear a heavy weight. You don’t use them in wheels. Wheel bearings have to roll nicely, and they have to bear the weight of the axle while they are rolling nicely. He said hardened steel will do that, and ceramic won’t do it so good. In a sense, the ceramic is too hard to roll against a steel axle and steel bearing race. He was baffled that anybody would put ceramic bearings in bike wheels.

It’s interesting that the “improved” spinning performance degrades just from the load that’s put on a derailleur pulley. How much can that be? A lot less than what’s on a wheel bearing, I’ll wager.

-jens

FSA has relatively new ceramic bottom brackets. The owner of my LBS is swearing by them (he’s a good dude who I ride with all the time and not out to just sell you stuff). Here’s a link to the product on FSA’s site: http://www.fullspeedahead.com/fly.aspx?layout=product&taxid=29

Don’t know if this article is propoganda, maybe the experts can weigh in: http://www.fullspeedahead.com/downloads/Ceramic_InsertBook.pdf

…they spin much better than the stock Shimano ones when you turn them with your finger.
– jens

yes thats when they are not under load but when underload then its differant!!

…they spin much better than the stock Shimano ones when you turn them with your finger.
– jens

yes thats when they are not under load but when underload then its differant!!
Um yeah. That was my point, which you would have seen if you had read the whole post.

Um yeah. That was my point, which you would have seen if you had read the whole post. sorry you right did not read good enough my fault

This has been an excellent thread with input (albeit some of it heresay) from mechanical engineers, aerospace engineers and bicycle/multisport retailers.

Can there be much doubt after reading this thread that ceramic bearings really DON’T belong in cycling applications?

Yea I agree its been useful. I always appreciate the input from other knowledgeable & experienced folks to validate or correct my thoughts before I plunking down any $$.

Thanks,

Barb

There has been a lot of good input on this thread, but I think a lot of it is heresay and misses one critical point about bearings. Bearings are incredibly complicated to design and spec in a wheel and I would guarantee that the ceramic bearing problems people are experiencing is using bearings in assemblies they were not designed for. In general, the ceramic ball is harder and lighter than steel. It isn’t necessarily rounder or better unless you specifically spec it that way, and the standard grade 10 zipp ball is rounder than 90% of the ceramic balls people are selling for bicycle wheels.

One huge market for ceramics is industry, where many of the uses are specifically for hot environments, or environments where lubricants aren’t allowed or possibly the parts are subject to chemical exposure, so you have relatively low grade ceramic bearings that have no need for high precision (applications like furnace carts) and also don’t need high speed, but need very high load capacity it is common to see grade 40 and 50 balls for these applications. On the other end of the spectrum you have applications that are extremely high speed and sometimes also high temp, if you buy any car with a turbocharger chances are they are using ceramic bearings as speeds in a turbo can be well over 120,000rpm and get so hot that they glow, a perfect ceramic application. But you also see them in F1 and CART car wheel assemblies due to their light weight, low friction, and extremely high load capacity, or even in wind turbines where you have very high loads and relatively low speeds of only a few hundred rpms. Clearly every one of these instances needs a very different bearing and the same is true with the bicycle application. Choosing an industrial grade bearing designed for high temp, or a marine grade bearing with tight seals and washout resistant grease designed for corrosion resistance are not going to get you any performance gain in your wheels or BB or whatever. Also to consider are internal clearance of the bearing, type of cage, grade of ball, ABEC or ISO rating of the races, race material, race surface finish and grind quality, and finally (and possibly most importantly) the fit of the hubshell into which the bearing is pressed.

I think the hubshell fit is a huge issue as manufacturers cut their bearing bores to specs that work best with their bearings. Since even high ABEC rated bearings have a relatively large tolerance for outer diameter, and since hubs from Asia can have very large variance, you can just have the wrong bearing in the wrong bore. I have seen bearing bore variance of as much as 0.002" between hubs and even high end hubs generally use a +0.0005/-0.0005" tolerance, combined with the ABEC3 outer diameter variance of 0.0003" you can have an interference fit of nearly 0.001 in high end hubs and over 0.001 in other hubs, in machining terms that is huge, you can fix that by using a bearing iwth large internal clearance, but then that bearing will be very loose in a well cut bore, which in some hubs may the the bore on the otherside of the hubshell. Combine all this with variance in seal friction, grease drag, difference in ball cage design and materials, and you can easily end up with a ceramic bearing that it higher friction than steel. Granted, it will still last longer and have a higher load rating, but if it is higher friction, that really doesn’t matter.

We have tested bearings 4 times now in 5 years with an independant lab in california the difference between our ceramic and steel bearing, as well as other grades of steel bearing, trying to find optimal grease type and quantity, optimal internal clearance of the bearing, etc, and when it is all designed to operate together (in this case our bearing bore tolerance of +/-0.0002, the ABEC7 tolerance of +0.000/-0.0002 and our spec for internal clearance and grease, cryogenically tempered races polished to near optical standards, teflon cage, and high hardness bearing steel races (non-stainless)…) the savings under load equate to 0.8 watt for 150lb rider compared to our standard grade 10/ABEC5 steel bearing. Our standard bearing also shows between 0.5 and 1 watt compared to a grade 25/ABEC1 with brass cage and std seal, with that 0.5-1 watt savings being the result of about a 6 factors, mainly reduced seal drag, lower viscosity grease, teflon cage instead of brass, higher ball precision, higher race precision, and use of ultra hard bearing steel instead of stainless.

Anyway, no matter what wheels you have, you are almost always best replacing the stock bearings with bearings from the hub manufacturer as they will know what works and what doesn’t, and there are so many small factors in bearing specification that it can be pretty easy to end up with a very expensive bearing that is slower than what you started out with.

Josh, as usual, great post on info!!

Are you selling/shipping the clincher Zedtech 99’s yet?

Dave

i thought we had a deal dave, you give me the 4k and I give you some “zedteks” (SIC on purpose)!

Typical Joshatzipp post. Trying to confuse us with facts.

Thanks Josh