Full Ceramics

vio765

Ok, some of you know i am really big into the future of cermic bearings, dimpled goodies, etc. I present to you this question:

full ceramics are entering the market. what is you opinion of this technology? we all know these bearing are super expensive, so keep that factor out of your response.

my opinion: right now they are untested. no concrete data or opinions from anyone. but they seem to offer superlow friction which could prove noticable gains in spped. i fear that if used on the road, a hard hit would shatter them. they would be fine on the track for now.

artemidorus

Good steel hub bearings lose up to 0.37 W at 44 km/h (both wheels). Good ceramic hub bearings improve bearing power loss by ~4%. This is 0.015 W. Hub seal rolling resistance is not altered. Let us be really conservative and say that you can maintain 44 km/h at 350W total power output (I couldn't, probably ~400W). This is a 0.004% total power saving from ceramic bearings, for only ~A$300!!!! Crikey, where's my wallet?
For those that need it: [/irony].

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lohsnest

Full ceramics have been used in other applications and are relatively wear and corrosion resistant. Packed tightly, I don't see how they would necessarily shatter. here is some information that will hopefully shed light on your question:
Full ceramic(All-ceramic) bearing of ZrO2 material
Full ceramic bearing have excellence performance as special electrical and magnetism resistance, wear and corrosion resistance, lubrication and maintenance free when working, especially high and low- temperature application. etc. could be used in awful environment and specially condition. The rings and balls made by full ceramic material:ZrO2, as a standard constructor, the cage made by PTFE, generally we also could make the cage with GFRPA66-25,PEEK,PI,AISI,US304,SUS316,Cu,etc

Full ceramic(All-ceramic) bearing of Si3N4 material
Full ceramic bearing made with Si3N4 have some better performance than ZrO2, the rings and balls made by full ceramic material:Si3N4, as a standard constructor, the cage made by PTFE, generally we also could make the cage with GFRPA66-25, PEEK, PI, Phenolic Textolite Tube ,etc. Compares than the material of ZrO2, The SiN4 ceramics bearings could endure heavier load and could be used in higher temperature environment. Also we could offer precision ceramic bearing which generally used in high-speed and high-rigidity spindle. the manufactured clearance could be P4 TO UP grade.

Full ceramic (All-ceramic) bearing of full complement balls
Full ceramic bearing of full complement balls has an add-ball gap on its side. Because using no frame design, the bearing able to install more ceramic balls than the standard construction, so the heavier load ability increased more. In addition, to avoid the limited of the frame material, this bearing same as the full ceramic bearing of ceramic cage has corrosion resistance and high temperature application. This series of bearing is not for high –speed choice, it should be to install on the unforced side.

Full ceramic(All-ceramic) bearing of ceramic cage
Ceramic cage has excellence performance as wear and corrosion resistance, high strength, lubrication and maintenance free when working. Adopting the ceramic cage, Ceramic bearing can be used in the most inclemency environments as corrosive, low temperature, high vacuum. The normal used ceramic materials are ZrO2, Si3N4 or Sic.

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vio765

where did you get this data? seems awfully low. steel bearings losing .37W @ 44km/h?

garage sale GT

Other applications which use ceramic bearings do not necessarily include the same degree of impact loading so you cannot draw any conclusions about whether they'll shatter from other sources. I've cracked steel balls so we don't have a large margin of safety.

Also, do not assume they would not have been developed if they didn't offer a significant performance advantage. There are other reasons they are needed. Some industrial applications need nonconductive bearings and some bearings are required to run in environments which would corrode metal bearings.

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artemidorus

From this site.

Fella seems to know what he is talking about, but clearly this is not peer-reviewed data at first hand. Note that the total hub rolling resistance is greater, as the seals contribute. Most sources seem to overestimate the size of bearing drag by at least one order of magnitude, perhaps because they are not distinguishing between bearing drag and total hub drag, although I don't think that seal drag is much bigger.

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vio765

no argument here! but what about cycling specific applications? would you aggree that full ceramics can provide a noticable advantage in speed?

vio765

thanks for the link! according to the site, it does not take much to move these things in circles. but something i just thought of: if these numbers were "learned" via testing and under zero load, i would kinda ignor the data. but what if these bearings are installed in some wheels and asked a 70kg rider to ride for a while? you think those small numbers would be amplified like the loses from the chain and tires?

garage sale GT

I don't have any data but I doubt it. Maybe if they could be run without lube, but they can't. Even so, it wouldn't add up to much.

Why not direct your attention putting together the best training program and most cost effective equipment for your bike and budget? For example, you could get a Red Ryder and 2500 bb's for less than $50, and start dimpling your wheels and frame tubes.

Or get skinwalls, maybe experiment if latex tubes help, maybe get tubeless...

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artemidorus

I don't think that anyone would bother testing an unloaded hub, that would be a very elementary error, but I concede that I don't know for sure.
I'm not sure what you mean about amplified power losses.

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garage sale GT

Yup, BTW both types of bearings need seals and lube when used in a bike. Does the data include seals and the appropriate lube?

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artemidorus

As I understand it, the drag data are for lubricated bearings in the absence of seals. Seal drag would be the same with both bearing types, obviously.

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vio765

why a BB gun? SHOTGUN!!!! lol. seriously, this whole thing is out of curiousity. i never said i was actually going to buy full ceramics. and the topic at hand is providing thoughts on full ceramic bearings, not money or fitness programs.

531Aussie

From HED:

"There was a measurable drag difference between ceramic bearings and steel bearings when we tested unloaded wheels, but the difference was small enough that we could not measure it on a loaded wheel ."


There are more details on the link

http://www.hedcycling.com/wheels/ceramicbearings.php