How "sealed" are sealed bearings?

I believe that sealed bearings should remain sealed. My primary experience is with incredibly
expensive open-bearings in strategic mission-critical applications.

The seal keeps only big dirt chunks out. As the bearing heats its internals expand and the fluid
(technical word - not just liquid) component extruded out through the seal. When the bearing then
cools whatever fluid may be present outside is sucked into the interior to equalize pressure. This
might be clean lubricant or it might be dirty water or mud or saltwater or whatever. The sealed
bearing is now contaminated.

Phil Wood bearings cost IIRC $15. Common sealed bearings of the same size and type cost about $5.
They're changed in a few minutes and last a long time.

"res09c5t" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Hi, I've got a Phil bottom bracket with about 10,000 miles over three years that I noticed was
turning rough and almost sounded dry. Figuring that I didn't have much to lose, I pulled it,
popped off the seals on the

bearings,

Quoted message said:

cleaned and re-greased them. It now seems a lot better- not perfect but much improved. It's on a
road bike that I generally don't ride under

dirty

Quoted message said:

conditions and is very rarely in rain or wet- only when I get really surprised. I have weighed in
the 270-290 lb range most of the time I've owned this BB.

My questions: I've always kind of assumed that sealed bearings could just be ignored- nothing
needed to be done and the Phil's would last almost forever but I'm beginning to question this.
Should I have some kind of schedule to open, clean and grease these guys? Also, as I look at the
seals, they would keep most of the grease in, but I'm not so sure they can keep dirt out?

Thanks in advance. Lyle

"Doug Huffman" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

I believe that sealed bearings should remain sealed. My primary

experience

Quoted message said:

is with incredibly expensive open-bearings in strategic mission-critical applications.

Perhaps but the Phil bb isn't an incredibly expensive open-bearing in a strategic mission-critical
application. Opening them is a no-brainer.

Quoted message said:

The seal keeps only big dirt chunks out. As the bearing heats its

internals

Quoted message said:

expand and the fluid (technical word - not just liquid) component extruded out through the seal.
When the bearing then cools whatever fluid may be present outside is sucked into the interior to
equalize pressure. This might be clean lubricant or it might be dirty water or mud or saltwater or
whatever. The sealed bearing is now contaminated.

None of this applies to bicycle bearings.

Quoted message said:

Phil Wood bearings cost IIRC $15. Common sealed bearings of the same size and type cost about $5.
They're changed in a few minutes and last a long time.

"res09c5t" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Hi, I've got a Phil bottom bracket with about 10,000 miles over three years that I noticed was
turning rough and almost sounded dry. Figuring that

I

Quoted message said:

Quoted message said:

didn't have much to lose, I pulled it, popped off the seals on the

bearings,

Quoted message said:

cleaned and re-greased them. It now seems a lot better- not perfect but much improved. It's on a
road bike that I generally don't ride under

dirty

Quoted message said:

conditions and is very rarely in rain or wet- only when I get really surprised. I have weighed
in the 270-290 lb range most of the time I've owned this BB.

My questions: I've always kind of assumed that sealed bearings could

just

Quoted message said:

Quoted message said:

be ignored- nothing needed to be done and the Phil's would last almost forever but I'm beginning
to question this. Should I have some kind of schedule to open, clean and grease these guys?
Also, as I look at the seals, they would keep most of the grease in, but I'm not so sure they

can

Quoted message said:

Quoted message said:

keep dirt out?

Thanks in advance. Lyle

--
Robin Hubert <[email hidden]

"res09c5t" <[email hidden]> wrote in message
news:<[email hidden]>...

Quoted message said:

Quoted message said:

My questions: I've always kind of assumed that sealed bearings could just be ignored- nothing
needed to be done and the Phil's would last almost forever but I'm beginning to question this.
Should I have some kind of schedule to open, clean and grease these guys? Also, as I look at the
seals, they would keep most of the grease in, but I'm not so sure they can keep dirt out?

Thanks in advance. Lyle

From my experience, "sealed bearings" = bearings with a rubber seal on them.

These rubber seals do HELP keep water out and grease in, but are not foolproof. Not that I'm all
that smart, but I've yet to see a "sealed bearing" that did not get stiff after a few years of use
without servicing (Shimano cartridge bottom brackets excluded!).

I say, do the periodic service. Even King headsets (which are one of the best in the business)
require maintainace.

Ed

I've used Phil bottom brackets for the last 20 years and have never had to service them. They still
run smooth. I ride under mostly dry conditions, but on occasion get caught in the rain.

Ted

"res09c5t" <[email hidden]> wrote in message
news:<[email hidden]>...

Quoted message said:

Hi, I've got a Phil bottom bracket with about 10,000 miles over three years that I noticed was
turning rough and almost sounded dry. Figuring that I didn't have much to lose, I pulled it,
popped off the seals on the bearings, cleaned and re-greased them. It now seems a lot better- not
perfect but much improved. It's on a road bike that I generally don't ride under dirty conditions
and is very rarely in rain or wet- only when I get really surprised. I have weighed in the 270-290
lb range most of the time I've owned this BB.

My questions: I've always kind of assumed that sealed bearings could just be ignored- nothing
needed to be done and the Phil's would last almost forever but I'm beginning to question this.
Should I have some kind of schedule to open, clean and grease these guys? Also, as I look at the
seals, they would keep most of the grease in, but I'm not so sure they can keep dirt out?

Thanks in advance. Lyle

Damn! No wonder JB has such a hard time here. I hadn't realized that physics was cancelled for
bicycles. Truly, the conspiracy of ignorance masquerades as common sense.

"Robin Hubert" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

"Doug Huffman" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

I believe that sealed bearings should remain sealed. My primary

experience

Quoted message said:

is with incredibly expensive open-bearings in strategic mission-critical applications.

Perhaps but the Phil bb isn't an incredibly expensive open-bearing in a strategic mission-critical
application. Opening them is a no-brainer.

Quoted message said:

The seal keeps only big dirt chunks out. As the bearing heats its

internals

Quoted message said:

expand and the fluid (technical word - not just liquid) component

extruded

Quoted message said:

Quoted message said:

out through the seal. When the bearing then cools whatever fluid may be present outside is
sucked into the interior to equalize pressure. This might be clean lubricant or it might be
dirty water or mud or saltwater

or

Quoted message said:

Quoted message said:

whatever. The sealed bearing is now contaminated.

None of this applies to bicycle bearings.

Quoted message said:

Phil Wood bearings cost IIRC $15. Common sealed bearings of the same

size

Quoted message said:

Quoted message said:

and type cost about $5. They're changed in a few minutes and last a

long

Quoted message said:

Quoted message said:

time.

"res09c5t" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Hi, I've got a Phil bottom bracket with about 10,000 miles over three

years

Quoted message said:

Quoted message said:

Quoted message said:

that I noticed was turning rough and almost sounded dry. Figuring

that

Quoted message said:

I

Quoted message said:

Quoted message said:

didn't have much to lose, I pulled it, popped off the seals on the

bearings,

Quoted message said:

cleaned and re-greased them. It now seems a lot better- not perfect

but

Quoted message said:

Quoted message said:

Quoted message said:

much improved. It's on a road bike that I generally don't ride under

dirty

Quoted message said:

conditions and is very rarely in rain or wet- only when I get really surprised. I have weighed
in the 270-290 lb range most of the time

I've

Quoted message said:

Quoted message said:

Quoted message said:

owned this BB.

My questions: I've always kind of assumed that sealed bearings could

just

Quoted message said:

Quoted message said:

be ignored- nothing needed to be done and the Phil's would last almost forever but I'm
beginning to question this. Should I have some kind

of

Quoted message said:

Quoted message said:

Quoted message said:

schedule to open, clean and grease these guys? Also, as I look at the seals, they would keep
most of the grease in, but I'm not so sure they

can

Quoted message said:

Quoted message said:

keep dirt out?

Thanks in advance. Lyle

--
Robin Hubert <[email hidden]>

"res09c5t" <[email hidden]> wrote in message
news:<[email hidden]>...

Quoted message said:

Hi, I've got a Phil bottom bracket with about 10,000 miles over three years that I noticed was
turning rough and almost sounded dry. Figuring that I didn't have much to lose, I pulled it,
popped off the seals on the bearings, cleaned and re-greased them. It now seems a lot better- not
perfect but much improved. It's on a road bike that I generally don't ride under dirty conditions
and is very rarely in rain or wet- only when I get really surprised. I have weighed in the 270-290
lb range most of the time I've owned this BB.

My questions: I've always kind of assumed that sealed bearings could just be ignored- nothing
needed to be done and the Phil's would last almost forever but I'm beginning to question this.
Should I have some kind of schedule to open, clean and grease these guys? Also, as I look at the
seals, they would keep most of the grease in, but I'm not so sure they can keep dirt out?

Thanks in advance. Lyle

You can have a look at www.keithbontrager.com In one of his "rants" he discusses this subject
extensivley. cheers

"res09c5t" <[email hidden]> wrote in message
news:<[email hidden]>...

Quoted message said:

Hi, I've got a Phil bottom bracket with about 10,000 miles over three years that I noticed was
turning rough and almost sounded dry. Figuring that I didn't have much to lose, I pulled it,
popped off the seals on the bearings, cleaned and re-greased them. It now seems a lot better- not
perfect but much improved. It's on a road bike that I generally don't ride under dirty conditions
and is very rarely in rain or wet- only when I get really surprised. I have weighed in the 270-290
lb range most of the time I've owned this BB.

My questions: I've always kind of assumed that sealed bearings could just be ignored- nothing
needed to be done and the Phil's would last almost forever but I'm beginning to question this.
Should I have some kind of schedule to open, clean and grease these guys? Also, as I look at the
seals, they would keep most of the grease in, but I'm not so sure they can keep dirt out?

Thanks in advance. Lyle

Have a look at www.keithbontrager.com in one of his "rants" he discusses this topic
extensivley. cheers

res09c5t said:

My questions: I've always kind of assumed that sealed bearings could just be ignored- nothing
needed to be done and the Phil's would last almost forever but I'm beginning to question this.

Sealed bearing cartridges are somewhat unfortunately named to give the superficial impression that
the sealing is their unique and defining feature. In fact they are no better sealed than any other
mechanism using a single rubber contact seal, meaning that they can be infiltrated by water and
contaminants under some conditions.

The chief merit of sealed bearing cartridges is that they are easily and cheaply replaceable in
their entirety once they have become damaged or contaminated. A secondary benefit is that they are
routinely held to much tighter tolerances and higher finishes than the cup & cone bearings otherwise
used on bicycles.

Your bearings should be replaced. Whether you choose to use a Phil Wood-certified bearing, a heavily
greased bike-specific replacement, or a generic industrially standard version is up to you.

Quoted message said:

Should I have some kind of schedule to open, clean and grease these guys?

No, just inspect them periodically and replace as necessary. Don't be too exuberant about cleaning
them (e.g. don't spray them clean) as this is likely to breach the seals and contaminate the
bearings. If you have ever used a high-pressure hose or even a garden spray nozzle to clean your
bike, this could be the reason that your bearings went bad.

Quoted message said:

Also, as I look at the seals, they would keep most of the grease in, but I'm not so sure they can
keep dirt out?

The seals ooze a grease "lip" which attracts all kinds of crud, and in principle it is possible that
some [censored] could be drawn back inside the bearing from this area. In practice it seems that the flow
is all from inside to outside and does not suck this junk back in. The stuff must be pushed if it is
to re-enter the bearing, as in the case of spray washing or clumsy wiping. If the vicinity is so
caked with filth as to cause abrasion of the seal and a resultant gap, this too could promote the
introduction of contaminants into the grease.

Chalo Colina

(muffa) said:

Have a look at www.keithbontrager.com in one of his "rants" he discusses this topic
extensivley. cheers

That would be www.bontrager.com and specifically www.bontrager.com/keith/rants.asp?id=26 --dt

"muffa" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

You can have a look at www.keithbontrager.com In one of his "rants" he discusses this subject

extensivley.

Quoted message said:

cheers

This is probably the link you were looking for:

bontrager.comrants.aspOpen ↗

There's lots of other good stuff there too.

Matt O.

In article said:

I believe that sealed bearings should remain sealed. My primary experience is with incredibly
expensive open-bearings in strategic mission-critical applications.

Sealed bearings shuld remain sealed. Phil and Co do not use sealed bearings; they use cartridge
bearings that look sealed, but the "seals" are simple contact seals and do little more than keep the
grease from globbing out.

Quoted message said:

The seal keeps only big dirt chunks out.

And they do this, too. But not water or other liquids, and not contaminants suspended in liquid.

Quoted message said:

As the bearing heats its internals expand and the fluid (technical word - not just liquid)
component extruded out through the seal. When the bearing then cools whatever fluid may be present
outside is sucked into the interior to equalize pressure. This might be clean lubricant or it
might be dirty water or mud or saltwater or whatever. The sealed bearing is now contaminated.

And how fast does a bicyclist have to pedal to heat up the bearings to the point where the bearing
metals expand, the lubricant becomes significantly less viscous, etc? A cadence of about 10,000
rpm or more?

Quoted message said:

Phil Wood bearings cost IIRC $15. Common sealed bearings of the same size and type cost about $5.
They're changed in a few minutes and last a long time.

Not the bearings in a Phil BB. Those are a factory job to replace, unlik ethe FSA hubs. But as the
OP found out, it's a trivial matter to pry loose the "seal" and regrease. Of course, standard bottom
brackets are also trivial to rebuild and it takes less time than farting around with the Phil's
cartidge "seals."

"Doug Huffman" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Damn! No wonder JB has such a hard time here. I hadn't realized that physics was cancelled for
bicycles. Truly, the conspiracy of

ignorance

Quoted message said:

masquerades as common sense.

"Robin Hubert" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

"Doug Huffman" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

I believe that sealed bearings should remain sealed. My primary

experience

Quoted message said:

is with incredibly expensive open-bearings in strategic

mission-critical

Quoted message said:

Quoted message said:

Quoted message said:

applications.

Perhaps but the Phil bb isn't an incredibly expensive open-bearing

in a

Quoted message said:

Quoted message said:

strategic mission-critical application. Opening them is a

no-brainer.

Quoted message said:

Quoted message said:

Quoted message said:

The seal keeps only big dirt chunks out. As the bearing heats its

internals

Quoted message said:

expand and the fluid (technical word - not just liquid) component

extruded

Quoted message said:

Quoted message said:

out through the seal. When the bearing then cools whatever fluid

may be

Quoted message said:

Quoted message said:

Quoted message said:

present outside is sucked into the interior to equalize pressure.

This

Quoted message said:

Quoted message said:

Quoted message said:

might be clean lubricant or it might be dirty water or mud or

saltwater

Quoted message said:

or

Quoted message said:

Quoted message said:

whatever. The sealed bearing is now contaminated.

None of this applies to bicycle bearings.

Quoted message said:

Phil Wood bearings cost IIRC $15. Common sealed bearings of the

same

Quoted message said:

size

Quoted message said:

Quoted message said:

and type cost about $5. They're changed in a few minutes and last

a

Quoted message said:

long

Quoted message said:

Quoted message said:

time.

"res09c5t" <[email hidden]> wrote in message
"]news:[email hidden]...
> Hi, I've got a Phil bottom bracket with about 10,000 miles over

three

Quoted message said:

years

Quoted message said:

Quoted message said:

> that I noticed was turning rough and almost sounded dry.

Figuring

Quoted message said:

that

Quoted message said:

I

Quoted message said:

> didn't have much to lose, I pulled it, popped off the seals on

the

Quoted message said:

Quoted message said:

Quoted message said:

bearings,
> cleaned and re-greased them. It now seems a lot better- not

perfect

Quoted message said:

but

Quoted message said:

Quoted message said:

> much improved. It's on a road bike that I generally don't ride

under

Quoted message said:

Quoted message said:

Quoted message said:

dirty
> conditions and is very rarely in rain or wet- only when I get

really

Quoted message said:

Quoted message said:

Quoted message said:

> surprised. I have weighed in the 270-290 lb range most of the

time

Quoted message said:

I've

Quoted message said:

Quoted message said:

> owned this BB.
>
> My questions: I've always kind of assumed that sealed bearings

could

Quoted message said:

Quoted message said:

just

Quoted message said:

> be ignored- nothing needed to be done and the Phil's would last

almost

Quoted message said:

Quoted message said:

Quoted message said:

> forever but I'm beginning to question this. Should I have some

kind

Quoted message said:

of

Quoted message said:

Quoted message said:

> schedule to open, clean and grease these guys? Also, as I look

at the

Quoted message said:

Quoted message said:

Quoted message said:

> seals, they would keep most of the grease in, but I'm not so

sure they

Quoted message said:

Quoted message said:

can

Quoted message said:

> keep dirt out?
>
> Thanks in advance.

As a co-conspiring idiot, let me say this: you have to peel back the wipers on Phil hubs and grease
the bearings on a regular (but infrequent) basis. They dry out quickly when ridden in rain. They are
not maintenance free unless you use them as a pencil holder. They are, however, easier to maintain
because there is no bearing adjustment. -- Jay Beattie.

"Doug Huffman" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

I believe that sealed bearings should remain sealed. My primary

experience

Quoted message said:

is with incredibly expensive open-bearings in strategic mission-critical applications.

Then why are you presuming that you know about bicycle bearing applications, which are completely
different?

Quoted message said:

As the bearing heats its internals expand and the fluid (technical word - not just liquid)
component extruded out through the seal. When the bearing then cools whatever fluid may be present
outside is sucked into the interior to equalize pressure. This might be clean lubricant or it
might be dirty water or mud or saltwater or whatever. The sealed bearing is now contaminated.

Mmmmkay... How much heat is generated by a cadence of, say 100rpm under average bicycle crank loads?
I'm going to hazard a guess that the bearings stay very near ambient temperature, and that the
grease does not change viscosity in any measurable way. Do you have evidence to the contrary?

Quoted message said:

Phil Wood bearings cost IIRC $15. Common sealed bearings of the same size and type cost about $5.
They're changed in a few minutes and last a long time.

Phil is probably just marking up the $5 bearings and reselling them. Just a guess. Either way,
replacement seems to be an obvious solution. At that price, I'd be hard pressed to bother with
grease replacement, popping seals, etc. Replacement is easy, and cheap. Heck I bought a whole stack
of silky-smooth ABEC-7 sealed bearings for about $1 each recently at Target. They were sold as
replacements for rollerblade bearings, not for Phil BB's; but you get the idea.

-Barry

Matt O'Toole said:

Quoted message said:

You can have a look at www.keithbontrager.com In one of his "rants" he discusses this subject
extensivley.

Quoted message said:

This is probably the link you were looking for:

bontrager.comrants.aspOpen ↗

Quoted message said:

There's lots of other good stuff there too.

I disagree. Not only does this lengthy diatribe not give any information on bearings and seals, it
offers common anti academic slurs we hear often enough here on wreck.bike. The essence of the
"sealed bearing" issue has been discussed here often, often enough that the FAQ has an entry:

draco.acs.uci.edu8f.6.htmlOpen ↗

Jobst Brandt [email hidden] Palo Alto CA

Matt O'Toole said:

Quoted message said:

You can have a look at www.keithbontrager.com In one of his "rants" he discusses this subject
extensivley.

Quoted message said:

This is probably the link you were looking for:

bontrager.comrants.aspOpen ↗

Quoted message said:

There's lots of other good stuff there too.

I disagree. Not only does this lengthy diatribe not give any information on bearings and seals, it
offers common anti academic slurs we hear often enough here on wreck.bike. The title of these web
pages as "Rants" is odd, although they are rants with little technical content. I find the whole
collection an embarrassing disclosure.

The essence of the "sealed bearing" issue has been discussed here often, often enough that the FAQ
has an entry:

draco.acs.uci.edu8f.6.htmlOpen ↗

Jobst Brandt [email hidden] Palo Alto CA

<[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

I disagree. Not only does this lengthy diatribe not give

any

Quoted message said:

information on bearings and seals, it offers common anti

academic

Quoted message said:

slurs we hear often enough here on wreck.bike. The title

of these web

Quoted message said:

pages as "Rants" is odd, although they are rants with

little technical

Quoted message said:

content. I find the whole collection an embarrassing

disclosure.

I thought the V-brake article was pretty good.

I do think he was correct about the appeal of "sealed bearing" hubs in bike shops. They seem "higher
quality" to people who don't know any better.

Quoted message said:

The essence of the "sealed bearing" issue has been

discussed here

Quoted message said:

often, often enough that the FAQ has an entry:

draco.acs.uci.edu8f.6.htmlOpen ↗

'Struth, as they say in Oz.

Have you ever seen a bicycle hub with a good labrynth seal? The only ones I've seen are on gear hubs
like Sturmey Archer. I had an early 80s Suntour bike a couple of years ago. It had great labrynth
seals on the freewheel. I don't know why they don't use such seals on hubs -- it's such an obviously
perfect design. Probably cheap, too.

Not as good but the best I've seen so far are Shimano MTB hubs from the last 6-7 years, with the
rubber cups in addition to the usual seals. I rarely need to service hubs anymore, while it used to
be a regular ritual. I have a cheap Trek front hub with "sealed" bearings. I've had to replace its
bearings several times -- a real PITA compared to servicing a regular hub, not to mention having to
pay for new bearings every time. It came with the bike, and as soon as the rim wears out that wheel
is going into the trash. Trek probably stuck it on there because it has that kustom hi kwality phat
look, and is cheaper than a real Shimano one.

"Sealed" bearings are used by companies who don't have the ability to manufacture their own
bearings, like Shimano and Campy do. They just turn a hub on a lathe, and press in an off the shelf
bearing that was not really designed for bicycle use.

IMO the best hubs are the cheapest Shimano ones that have the rubber cups -- LX or Deore or
whatever that is these days. Anything "more" is just a waste of money, unless a nicer finish is
important to you.

Matt O.

"Doug Huffman" <[email hidden]> wrote

Quoted message said:

Robin Hubert said:

Doug Huffman said:

The seal keeps only big dirt chunks out. As the bearing heats its internals expand and the
fluid (technical word - not just liquid) component extruded out through the seal. When the
bearing then cools whatever fluid may be present outside is sucked into the interior to
equalize pressure. This might be clean lubricant or it might be dirty water or mud or
saltwater or whatever. The sealed bearing is now contaminated.

None of this applies to bicycle bearings.

Damn! No wonder JB has such a hard time here. I hadn't realized that physics was cancelled for
bicycles. Truly, the conspiracy of ignorance masquerades as common sense.

Typical unhelpful, oblivious, blinkered jackassery from Doug Huffman. Funny how this guy, who
believes he knows better than everyone, never has anything useful to offer.

How much bearing temperature rise to you expect to see from a maximum perhaps 130rpm shaft speed at
the bottom bracket? It ain't an electric motor, you know. Anybody with even a flirting level of
experience and observation of sealed bearings on bicycles knows that grease oozes out from shaft
rotation alone (only if there's enough fill grease in the bearing to ooze out at all) and does not
appear to suck back in any significant quantity. As I noted in my previous post, contaminated grease
must be pushed, squished, squirted, or blown back into the bearing if it is to get in.

Chalo Colina

"The conspiracy of fatuousness masquerades as Doug Huffman"

Good move! The seals on a "sealed bearing" are not completely sealed. If they were, the thing
wouldn't be able to turn.

So water (and microfine grit) can get inside. Also, the metal itself does wear some, and that grit
is no better that what makes it's way in from outside.

Also lubricants, even grease, do evaporate after time. If you've ridden in wet conditions, water can
wash some out as well, depending on what type you use. Which is why I pack all my bearings with
waterproof boat trailer wheel bearing grease, which is designed to be used in situations where the
entire bearing may be submerged (I still clean and repack them at least once a year).

I bought a PW hub for my MTB in 1986. I still have it, it's still on the original bearings. that's
the original five year warranty met 3 1/2 times over. nearly 50,000 miles, mostly commuting (rain or
shine) and some off road miles, and yes, a few hub-deep stream crossings.

May you have the wind at your back. And a really low gear for the hills! Chris

Chris'Z Corner "The Website for the Common Bicyclist": geocities.comczcornerOpen ↗

Matt O'Toole said:

Have you ever seen a bicycle hub with a good labyrinth seal? The only ones I've seen are on gear
hubs like Sturmey Archer. I had an early 80s SunTour bike a couple of years ago. It had great
labyrinth seals on the freewheel. I don't know why they don't use such seals on hubs -- it's such
an obviously perfect design. Probably cheap, too.

I still ride those FW's (New Winner Pro) but they aren't as good as they might be, because a
labyrinth must have an air gap proportional to the film strength of the fluid (water). The gap in
this case is so small it is reasonably close to a capillary. They are far more immune to water than
old freewheels that did not have such a seal.

Quoted message said:

Not as good but the best I've seen so far are Shimano MTB hubs from the last 6-7 years, with the
rubber cups in addition to the usual seals. I rarely need to service hubs anymore, while it used
to be a regular ritual. I have a cheap Trek front hub with "sealed" bearings. I've had to replace
its bearings several times -- a real PITA compared to servicing a regular hub, not to mention
having to pay for new bearings every time. It came with the bike, and as soon as the rim wears out
that wheel is going into the trash. Trek probably stuck it on there because it has that kustom hi
kwality phat look, and is cheaper than a real Shimano one.

There are many ways to make a good seal, especially ones that reject splash water, the principal
problem for most bicycle equipment. Under water sealing is another problem entirely and should not
affect the equipment that 99% of bicyclists use. As with most bicycle design problems, the People
solving them are not skilled engineers, but rather bicycle repair shop mechanics who learned their
skills through apprenticeship, mostly unskilled in theory and test methods.

Quoted message said:

"Sealed" bearings are used by companies who don't have the ability to manufacture their own
bearings, like Shimano and Campy do. They just turn a hub on a lathe, and press in an off the
shelf bearing that was not really designed for bicycle use.

Ah yes, but they believe in them unwittingly.

Jobst Brandt [email hidden] Palo Alto CA