Sealed bearings question....

[Tickdoc]

Something that has been bothering me for like...ever.

Sealed bearings....how sealed are they?

Just wondering what happens on a microscopic level when I say, douse my sealed bearing bits in a solvent based cleaner like simple green, then wash the heck out it.

So none of the sealed stuff gets out and none of my stuff gets in?

And if I oil a sealed bearing nothing gets in?

Inquiring minds want to know.

[oldpotatoe]

Something that has been bothering me for like...ever.

Sealed bearings....how sealed are they?

Just wondering what happens on a microscopic level when I say, douse my sealed bearing bits in a solvent based cleaner like simple green, then wash the heck out it.

So none of the sealed stuff gets out and none of my stuff gets in?

And if I oil a sealed bearing nothing gets in?

Inquiring minds want to know.

He's a good article about 'sealed' bearings..yes, they have a 'seal' but aren't 'sealed', otherwise they wouldn't turn.

https://www.sheldonbrown.com/brandt/sealed-bearings.html

[bigbill]

My experience with sealed bearings in industrial applications, conveyors that are moving 1100 feet a minute using small diameter rollers and larger diameter drive rolls, is to just leave them alone until they get rough or fail.

In cycling, I've used PW bottom brackets, PW hubs, and Campy UT cranksets. Campy steel and USB UT bearings are sealed on one side and another seal is installed by the user. I commuted on Oahu using a stainless PW bottom bracket and with the almost daily rain and red dirt mud, I'd get about a year between rebuilds. I tried being proactive and popping out the seal to add PW grease but it didn't make a difference. PW eventually came out with a heavy duty sealed bearing and the rebuild that used those bearings and it's been 15 years, still smooth.

I've replaced a handful of UT bearings. Since it's a 20 minute repair and the steel bearings are around $30, I replace them at the first sign of roughness. My gravel bike has an Ultegra crankset and bearings. I've had to replace them but again, 20 minutes and $15. Not worth attempting any kind of maintenance.

[Hindmost]

They are not super-sealed and yes, fluids will penetrate. In many applications they are not serviced and are simply replaced. It's possible and sometimes desirable to clean and lubricate a sealed bearing. With a sharp instrument (dental pic) carefully pry up the edge of the rubber seal and it will pop loose. Wash out the bearing with cleaner and blow it out to dry. Re-lubricate and pop the seal back in.

[Tickdoc]

He's a good article about 'sealed' bearings..yes, they have a 'seal' but aren't 'sealed', otherwise they wouldn't turn.

https://www.sheldonbrown.com/brandt/sealed-bearings.html

Great article and thank you peter. Now on to sealed ceramic, which I didn’t see mentioned in the article ( I’m guessing due to age).

So they can and should be serviced or replaced from time to time.

Pretend I just did a major mild solvent based wash on my bike. What bearings now need to be serviced?
Disassemble hub and inspect for water and reseal?
Bb Cups?
Headset is almost a never for me, unless I feel something untoward.
Pedals?
Jockey wheels?

Just hit it all with a little oil on the little ones like the jockey wheels?

[NHAero]

I think there are different levels of seal available within the cartridge bearing world as well. I've had a couple of sets of White Industries hubs apart and the bearings as far as I can tell have what I'd call shielded bearings - non-contact for lower drag. When I rebuilt them I opted for bearings with rubber seals.

[ultraman6970]

IMO it depends a lot of luck and how good are you with equipment, i barely ride and i do not go out in the rain, and a pair of UT bearings can last me 10 years easy, actually i have swapped bearings in one crankset that i got used, from the ones I got I have not swapped a single one yet.

OP you will notice when the bearings are going bad... dont sweat it. Maybe get a couple of bearings sets just in case but you will notice, because besides getting gritte some bearings tend to develop play aswell... so you will notice when to swap them.

[weaponsgrade]

My rear wheel was running a little rough. Bearings aren't that expensive but before I went that route I decided to try repacking them. The extension tube on my shop vac happened to be the perfect diameter for a hub support for knocking the axle out and tapping it back in. I used a utility knife to pry the rubber seals off the bearings, squirted in some brake cleaner, followed by a WD40 flush, and then packed them with Philwood grease. The hub is now silky smooth.

[dustyrider]

Sealed is just another term like standard. It sort of exists!

[dddd]

Any liquid like water having a surfactant ("soap") in it, or any kind of liquid hydrocarbon, will tend to aggressively creep into the smallest of spaces. In fact, the smaller the gap the stronger that the liquid draws into it.

Cartridge bearings rely on a super-clean environment at the rolling surfaces to achieve a full "rated" service life, and even the smallest amount of abrasive dust/grit can reduce their lifespan to almost nothing compared to having it kept clean.

Dousing cartridge bearings in solvent might make no difference in a bearing already contaminated, but is the death of an internally-clean bearing (in terms of whether it is then even worth installing since it's lifespan is so severely shortened by contamination).

Assemblies having cartridge bearings vary wildly in terms of their resistance to creeping liquids and contaminants, and some employ labyrinth air spaces to positively prevent capillary action from pulling dirt in. This is why some brands of bottom bracket and hub bearings often last much longer than others.
Secondary sealing rings as found on axle and freehub assemblies often rely on grease in order to work to their potential in protecting the cartridge bearings behind them, so periodic removal of the axle and freehub body to clean and renew grease can prevent the meager seals on bearing cartridges from ever getting fouled with contamination.

I often wonder who came up with the advice to use soapy water on a bicycle drivetrain, either it was originally advice given to teams who were firstly charged with accelerated durability testing of prototypes, or it was someone who wanted to make more money selling replacements for moving parts damaged by surfactant/ionic water mixtures.
I can't tell you how many bb30 bearings I have replaced on bikes where the owner kept their bike super-clean, where I inquired as to their washing methods and so learned about how quickly that exposed "sealed bearings" can be destroyed.
The same goes for applying liquid lubricants to installed bearings, where a shot of Triflow or WD40 can instantly seal a bearing's fate.

[cmg]

bought a wheelset from a guy who decided to remove the inner seal on the bearing on the freehub side. i guess he thought it would be friction free. all was good until the ball retainer burst and scattered the bearings thru the rest of the hub. so don't do that.............. how sealed is sealed starts the experiment.

[oldpotatoe]

TicDoc
Great article and thank you peter. Now on to sealed ceramic, which I didn’t see mentioned in the article ( I’m guessing due to age).

So they can and should be serviced or replaced from time to time.

Pretend I just did a major mild solvent based wash on my bike. What bearings now need to be serviced?
Disassemble hub and inspect for water and reseal?
Bb Cups?
Headset is almost a never for me, unless I feel something untoward.
Pedals?
Jockey wheels?

Just hit it all with a little oil on the little ones like the jockey wheels?

'Problem' with ceramic are the VERY hard ceramic bearing balls and steel cones and races..many times NOT a hardened steel like Campag's CULT so, get a wee bit of dirt/crud in there and the bearing balls hardness damages the steel parts so yes, grease into ceramic to act as an additional seal to keep crud out.

Hubs-Spin the hubs in your hand, if they feel gritty or full of sand, disassemble and service/replace.
BB-take chain off, spin crank with your hand on the seat tube..it you feel grit/crappy-ness-same..take apart and service/replace.

Same for pedals, pulleys, depends on type. Older Campag and lower end like Chorus, brass bushing, no bearing balls so a little oil is fine.

Once a month I take drive train off, pulleys out of rear der, chainrings off..clean all, check BB and hubs(see above), OVH pulleys. Ders stay on bike as does crankset.

Once a year, I take all apart, open all up and replace/service as necessary.

BUT clean bike? Sure..Clean drivetrain?...chain, cogs, pulleys, chainrings..NOTHING inside...I recommend against any kind of power wash type thing..bucket of water with dish soap, sponge, hose at end w/o a nozzle on it..

[Tickdoc]

Sounds great and sage advice, as always. I will quit obsessing over it and turn my attention to more important matters like why don't we have iron-on lycra repair kits for our kits like my mom used to use on my jeans when I was a kid?

[Mark McM]

Cartridge bearings rely on a super-clean environment at the rolling surfaces to achieve a full "rated" service life, and even the smallest amount of abrasive dust/grit can reduce their lifespan to almost nothing compared to having it kept clean.

.......



I just wanted to point out that, as implied by the above post, the term "sealed bearing" is really just a marketing term to imply some type of superiority to what should more correctly be called "cartridge bearings". Yes, cartridge bearings often (but not always) have a seal of some type, but has been pointed out, the seals that come on these bearings aren't really intended to perfectly seal out the environmental conditions often found on bicycles (particularly, water).

[dddd]

I just wanted to point out that, as implied by the above post, the term "sealed bearing" is really just a marketing term to imply some type of superiority to what should more correctly be called "cartridge bearings". Yes, cartridge bearings often (but not always) have a seal of some type, but has been pointed out, the seals that come on these bearings aren't really intended to perfectly seal out the environmental conditions often found on bicycles (particularly, water).

I think of them as being sealed up in terms of handling them, where the mechanic doesn't have to deal with, or even see, the lubricant inside.
Of course one still gets their hands or gloves greasy doing the service, but the bearing is a modular, "sealed" assembly.
And then some ball bearing cartridges are more heavily sealed, but their friction can be so high that they might never find their way onto a bicycle.

I'm somewhat amazed how well that the exposed cartridges in Phil hubs and bottom brackets can last, but my perspective is likely tainted by my West-coast environment. And I have got years of hard use out of the larger exposed cartridge bearings on Viscount and Klein bikes that used these at the bottom bracket.