BB30 Bearing; SKF or Ceramic?

bernithebiker

I need to replace the non-drive side bearing on my Sworks SL4 - it's feeling a bit rough.

I ordered 2 bearings on the internet - one is SKF standard, the other is a cheap(ish) ceramic hybrid from China.

They cost 20 Euros each.

They look pretty similar at first glance, but the SKF does feel a little stiff to rotate in your fingers - the ceramic one is a lot smoother.

Any opinions on which I should use? The not used one will of course just hang around as a spare.

(The originals are ceramic, but Spesh would want 120 quid or so for those).

sungod

ceramic may feel smoother if it has non-contact seals and no lube, if you took the seals off the steel ones and removed the lube you should find they spin very freely

as far as steel vs. ceramic goes, for bearings of equal quality the ceramic will be a tiny smidge more efficient under load, and ceramic don't care about water etc. you really can run them dry (if they're pure ceramic, not hybrids)

what's important for bb30 is the bearings and shell being within tolerance, if things are a bit too tight the ceramics may get trashed fast, steel is more flexible, but with either if things are loose you could face creaking or wear of bearing seats/spindle

for a bike bb, i think quality is more important than material, i'd fit the skf ones

btw if the current bearings feel rough, i'd clean and regrease, that may be all that's needed, my original sram ones are well over 20,000km, i obey sram's instructions and clean/grease every few months, still spinning smooooooooth

bernithebiker

Externally, the bearings look very similar - they are both sealed.

Good tip re. tolerances - I'll present them both to the cup and see which one is the best fit.

How do you clean and regrease the current bearing? I can't get into it, it's sealed!

sungod

use a fine pick to remove the seals, degrease, dry, regrease

there's an fsa video on youtube that shows the process

take care not to damage the edges of the seals, taking them out may bend them a bit, but you can put them between a couple of bits of kitchen towel and then use something round to roll them flat (same action as rolling pastry)

how much grease to use depends on riding conditions, i ride all weather so i pack them full and also smear some on the outside of the seals and also under the shields (the bits between crank and outside face of bearing, it adds a bit more drag but this way it takes a lot of wet rides before redoing

i've seen two types of seals on bb30 bearings, there're the full ones that contact both inner and outer races, these add a smidge of drag, the others are non-contact, they seal onto the outer race but do not quite touch the inner race

bernithebiker

Here's a pic of the bearings. The one on the right is the SKF; it came very slightly corroded on the outside face, which is a bit annoying, but it's only cosmetic.

The one on the left is the cheap hybrid ceramic from China. Both their seals look identical.



I'll have a go at cleaning the current bearing.

ugo.santalucia

SKF are stiff because they use some tight seals, which means longevity... ceramic bearings use no seals or cheap ones and very low lubricant. In my experience SKF last at least three times longer, on an extrnal BB probably more

proto

bernithebiker wrote:

Good tip re. tolerances - I'll present them both to the cup and see which one is the best fit.

Bearings are made to incredibly tight tolerances, if you can detect any difference between them without some very serious measuring equipment then there's a job for you at the National Physical Laboratory.

To mere mortals like us, the bearings will be dimensionally identical, made to within less than a micron. If you want quality, use the SKF ones, you can't buy better.

sungod

not all bearings are, i got some 'bargain' bb30 bearings, the were trouble within minutes, took them out, measured them at 41.98mm, which is smaller than the upper bound on bb30 shell size, now they're novelty paperweights

which is why skf got my vote too