Weight Weenies

^^^ voice of reason

i've actually got a bb30 full ceramic bb, it's a ucb one, they were being sold off for less than sram hybrids, ultra low drag but the only time i fitted it there was severe fretting on the crankset axle within less than an hour, it took almost that long to remove the bearing - maybe the reason it was being sold off!

i'm thinking of trying loctite 609 on it, but i'm wondering how long the loctite will hold up, anyone had experience of it in this application?

Hi,

If by full ceramic you mean ceramic races and balls then I can tell you that these are notoriously hard to fit without shattering the races.
These really should not be fitted on a bike as most of these bearing endure both radial as well as axial loads.

Ciao,

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sungod wrote: ... i've actually got a bb30 full ceramic bb, it's a ucb one, they were being sold off for less than sram hybrids, ultra low drag but the only time i fitted it there was severe fretting on the crankset axle within less than an hour, it took almost that long to remove the bearing - maybe the reason it was being sold off!

fdegrove wrote:Hi,
If by full ceramic you mean ceramic races and balls then I can tell you that these are notoriously hard to fit without shattering the races.
These really should not be fitted on a bike as most of these bearing endure both radial as well as axial loads.
Ciao,

Hi fdegrove and sungod, this is the same issue with using ceramic wheel and headset bearings and why SS (abec5 or 9) are far more durable/reliable and still very high quality ... I believe

Also, you can be a little rough with SS sealed bearings, without damaging them, unlike ceramic sealed bearings ...

thanks KL

yeah, it was a moment of ww madness as the price was relatively low

they fit fine, snug but without a lot of force, no indication that the bearings are distorted (spin *very* freely once fitted), but the fretting on the axle shows something, maybe the shell, maybe the bearings, maybe the axle itself, is not quite an interference fit

they seem to fit the shell just a little more freely that the ss ones, which makes me wonder if the ceramic races aren't to the same tolerance, now as i type this i'm thinking "silly sungod, why haven't you got the calipers out and measured!", so i'll do that when i get home

i can put it down to experience, there're much worse things in life!

Loctite makes a number of products for filling gaps like this- slight interference fits that are looser than they are supposed to be. I have used 641 with success on cranks which were slightly loose on the spindle.

hmm, the ceramic bearings measure 30.02 to 30.03 inside, 41.98 outside

i couldn't find any info on the bb30 site about the required tolerance for bearings or axle, only for the bb shell, 41.96 +0.025/-0

which puts the bearing od just smaller than the largest tolerance for the shell, and a tiny bit larger than the nominal 30mm of the axle

which could explain the fretting

by the way if anyone is interested. I went to my LBS and we opened the hubs to confirm the size of the bearings. It reads....

Front Hub - 609RS . The brand bearing is IJK made in Japan with a Black Seal
Rear Hub - 6902RS / Cassette - 6802RS . The brand is IJK made in Japan with a Blue Seal. (Does the blue seal mean Ceramic ?)

Hi,

Hi fdegrove and sungod, this is the same issue with using ceramic wheel and headset bearings and why SS (abec5 or 9) are far more durable/reliable and still very high quality ... I believe

This is just not true. If you replace SS bearings with ceramic bearings you need to care about how they're put on just the same.
Thinking you won't damage SS bearings by taking less care is not right, they will be damaged just the same. Ceramic balls will make dents into races because they're harder than the steel races making the damage more obvious.
The same impact will spread the damage across the balls and the races of a steel bearing. Nonetheless, the damage is still there.
That's all there's to it really.
All in all SS bearings are nowhere near as durable as a decent ceramic hybrid provided they're mounted properly.
It seems to me you have a somewhat distorted idea about the materials involved and how to handle them properly.

Sorry if I sound harsh, just trying to provide the facts.

Ciao,

Hi,

gchin954 wrote:by the way if anyone is interested. I went to my LBS and we opened the hubs to confirm the size of the bearings. It reads....

Front Hub - 609RS . The brand bearing is IJK made in Japan with a Black Seal
Rear Hub - 6902RS / Cassette - 6802RS . The brand is IJK made in Japan with a Blue Seal. (Does the blue seal mean Ceramic ?)

Japanese bearings have a good reputation. No idea whether or not the blue seal stands for a ceramic hybrid. A look at the IJK company's catalogue could clarify that. I doubt it though.

Or, how about DT helping you out on this?

Ciao,

Hi,

they seem to fit the shell just a little more freely that the ss ones, which makes me wonder if the ceramic races aren't to the same tolerance, now as i type this i'm thinking "silly sungod, why haven't you got the calipers out and measured!", so i'll do that when i get home

They may be of different ABEC ratings which could explain the difference in tolerance. However, in this particular case, assuming the lack of precision is in the inner race, the only thing that will happen is that over time the inner race will effectively cut a groove every time it slips on the axle under load.

Unless the axle is pretty soft compared to the inner race of the bearing, this is going to take some time before it becomes a problem.
In any case it can't impact the performance of the rear hub as the tension of the RD spring and chain will engage the bearing and make it spin. This is in essence no different from how freewheels work anyhow.

If you notice too much slack between an axle and the inner race, my advice would to lube the axle with a high pressure resistant grease. Upon which you'll have something akin to a bushing hybrid and wear on the axle should be minimal.

Either that or get a bearing of the correct tolerance. Either way the impact can and will be minimal. It should not in any way effect the performance of the drivetrain. Just wear, depending on x number of factors....

Ciao,

gchin954 wrote: ... Front Hub - 609RS . The brand bearing is IJK made in Japan with a Black Seal
Rear Hub - 6902RS / Cassette - 6802RS . The brand is IJK made in Japan with a Blue Seal. (Does the blue seal mean Ceramic ?)

Hi gchin954, Black usually means ABEC5 standard and Blue usually means ABEC3 standard

thanks KL

fdegrove wrote: ... If you replace SS bearings with ceramic bearings you need to care about how they're put on just the same.
Thinking you won't damage SS bearings by taking less care is not right, they will be damaged just the same.
Ceramic balls will make dents into races because they're harder than the steel races making the damage more obvious.
The same impact will spread the damage across the balls and the races of a steel bearing.
Nonetheless, the damage is still there. That's all there's to it really.
All in all SS bearings are nowhere near as durable as a decent ceramic hybrid provided they're mounted properly.
Ciao,

Hi fdegrove, no worries and yes ... thanks KL

I've never dealt with a bearing supplier where seal color indicated the ABEC rating.

BTW, here's a nice breakdown of ABEC rating specs:
http://www.engineersedge.com/bearing/ba ... rances.htm