ceramic bearings

On Sat, 12 Apr 2008 05:46:50 GMT, Ryan Cousineau
may have said:

In article ,
Werehatrack wrote:

You've never taken one apart, then? It would be educational. The
contaminated grease will be everywhere that wasn't an active loaded
surface, and the clean grease will have flowed right past it.

Hm... Okay, I have a lot to learn here, but does this apply to Bearing
Buddy designs, too?

Those hub covers that are peddled to boat trailer owners? The serious
fisherman of my acquaintance all started off swearing by them...and
ended up swearing *at* them. First off, trailer hubs either have
seals which are entirely ineffective at excluding water when the hub
is submerged (this is why the manufacturers uniformly warn NOT to
submerge the hubs) or you dare not install a Bearing Buddy. If the
hub uses a spring-loaded-lip seal, using the Bearing Buddy will
cheerfully cause the seal to be pumped right out of the hub. If the
seal is unloaded or felt, water will come in as easily as grease comes
out. Bottom line: Boat trailer owners learn to repack their bearings
every time they let the hubs get into the water. (Fresh water boaters
might get off easier on this, but most fishermen around here are going
out from a salt water ramp, and one maintenance lapse will put them by
the side of the road waiting for a spare hub and stub axle assembly on
the next trip.)

My sense is that at least in the local (rain-dominated) environment,
loss of grease is the fundamental killer of bearings. Lots of grease
prevents water from getting in.

Only to an extent, and usually not for long. Grease in motion with
water present will turn into a (usually corrosive) emulsion of water,
oil and soap. A bearing with just enough grease that the balls are
pretty much running free (which you noted will be the case for any
bearing that's been run for a short period in a hub that's not
completely air-excluded) is going to allow the water to come in direct
contact with the balls; the lube on the active bearing surfaces will
emulsify, and if the metals are easily corroded, that's what's going
to happen.

You don't have to believe me. Grease-ported hubs are cheap: pump and see.

I used to work on them. I'm glad that modern hubs don't have grease
fittings.


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Camilo wrote:
On Apr 9, 9:04 pm, Rick Roof wrote:
Just installed ceramic bearings in my front wheel. The original
bearings seem much smoother. Is this just because the ceramics are
not broke in? They just don't seem as smooth as the bearings I took
out. I ended up putting the originals back in for now. Any info
would be appreciated. Thanks.

Rick


I'm wondering if anyone is going to even remotely answer your question
instead of highjacking it for a totally irrelevant discussion. Often
the argument starts with at least a disagreement on actual advice.
Didn't even get that far! I'm curious about your question so I will
stand by (but not hold my breath).


Wow, and how does this help?
Let me try, if the OP replaced only the bearing balls the races have to
brake in. The ceramics balls are harder en more spherical and have a
smoother surface than steel balls. The ceramics balls will hone the
races after a while.
If the OP installed a complete ball bearing the ceramic bearing should
be smooth from the beginning.


Lou

"Lou Holtman" wrote in message
...


That is the second stupiest way to maintain a hub. The first is not to
maintain the hub at all. You have to inject a ton of grease to push out
the
old dirty grease through the seal. Not very healthy for the seal. Choose a
hub that is easy (take apart and adjust afterwards) to maintain. Then you
maintain it more often. I vote for Campy hubs.

Lou

Lou: you run a bike shop that actively discourages your clients from doing
any maintenance on their bikes - right?

Anyway: I ran a set of inexpensive Campagnolo Tipo hubs for more than 30
years by injecting a little grease every few months. I overhauled them once
to see what was going on inside, and the races and balls were A-OK. I would
still be running them, but in a weak moment I sold the wheels to get a
70s-vintage set with Record hubs.

Unsealed Campy Record freewheel hubs is what I run on my rain commuter bike.
I ride these wheels 12 months a year, even in pouring rain. The hubs have
no seals. Seals are as good as keeping contaminants and water in contact
with the bearings as keeping them out.

After a downpour I spend a few minutes squeezing grease into the hub shells
and wiping up the excess.

So back to the initial purpose of this thread: using ceramic bearings in
bicycles is pointless, with no tangible benefits, designed only to extract
big $$ from the gullible.

Dave Mayer wrote:
"Lou Holtman" wrote in message
...

That is the second stupiest way to maintain a hub. The first is not to
maintain the hub at all. You have to inject a ton of grease to push out
the
old dirty grease through the seal. Not very healthy for the seal. Choose a
hub that is easy (take apart and adjust afterwards) to maintain. Then you
maintain it more often. I vote for Campy hubs.

Lou

Lou: you run a bike shop that actively discourages your clients from doing
any maintenance on their bikes - right?

No. I'm a mechanical engineer who rides a lot for a long time and did my
share of experimenting maintenance wise. My opinion is based on this. I
run Record hubs now ( 2002 and later) on all my road wheels. Injecting
grease leaves a mess (in freewheel mechanism ie) and, like Wherehatrack
mentioned, leaves a lot of contaminated grease where it is. I prefer to
take these apart, clean them and repack. It takes me half an hour per
wheelset. I do it once or twice a year. It is so easy, especially
adjusting the hubs afterwards, everyone learn that so there is no
reason/excuse not to so.


Anyway: I ran a set of inexpensive Campagnolo Tipo hubs for more than 30
years by injecting a little grease every few months. I overhauled them once
to see what was going on inside, and the races and balls were A-OK. I would
still be running them, but in a weak moment I sold the wheels to get a
70s-vintage set with Record hubs.

Good for you.
I run DT Swiss 240 hubs on all my ATB's and singlespeed which I use in
the winter on the road. As someone mentioned these are almost
maintenance free. Very good seals. For someone who rides a lot, hates
maintenance or is technical challenged I advise these hubs.


Unsealed Campy Record freewheel hubs is what I run on my rain commuter bike.
I ride these wheels 12 months a year, even in pouring rain. The hubs have
no seals. Seals are as good as keeping contaminants and water in contact
with the bearings as keeping them out.

Modern Record hubs have seals.


After a downpour I spend a few minutes squeezing grease into the hub shells
and wiping up the excess.

After a downpour, and we have our share of it in the Netherlands, I just
dry my bike. Repack once or twice a year is enough to keep my Record
hubs in A-OK condition.


So back to the initial purpose of this thread: using ceramic bearings in
bicycles is pointless, with no tangible benefits, designed only to extract
big $$ from the gullible.

Agreed.

Lou