How "sealed" are sealed bearings?

Discussion in 'Cycling Equipment' started by Res09c5t, Apr 17, 2003.

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  1. Res09c5t

    Res09c5t Guest

    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
     
    Tags:


  2. Doug Huffman

    Doug Huffman Guest

    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 protected]> wrote in message news:[email protected]...
    > 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
     
  3. Robin Hubert

    Robin Hubert Guest

    "Doug Huffman" <[email protected]> wrote in message news:[email protected]...
    > I believe that sealed bearings should remain sealed. My primary
    experience
    > 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.

    > 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.

    >
    > 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 protected]> wrote in message
    > news:duvna[email protected]...
    > > 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
    > >

    --
    Robin Hubert <[email protected]
     
  4. Ed Ness

    Ed Ness Guest

    "res09c5t" <[email protected]> wrote in message
    news:<[email protected]>...
    > >
    > 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
     
  5. Ted

    Ted Guest

    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 protected]> wrote in message
    news:<[email protected]>...
    > 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
     
  6. Doug Huffman

    Doug Huffman Guest

    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 protected]> wrote in message
    news:p[email protected]...
    >
    > "Doug Huffman" <[email protected]> wrote in message news:[email protected]...
    > > I believe that sealed bearings should remain sealed. My primary
    > experience
    > > 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.
    >
    > > 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.
    >
    > >
    > > 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 protected]> wrote in message
    > > news:[email protected]...
    > > > 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
    > > >
    >
    >
    > --
    > Robin Hubert <[email protected]>
     
  7. Muffa

    Muffa Guest

    "res09c5t" <[email protected]> wrote in message
    news:<[email protected]>...
    > 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
     
  8. Muffa

    Muffa Guest

    "res09c5t" <[email protected]> wrote in message
    news:<[email protected]>...
    > 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
     
  9. Bluto

    Bluto Guest

    "res09c5t" <[email protected]> wrote:

    > 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.

    > 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.

    > 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 smut 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
     
  10. Doug Taylor

    Doug Taylor Guest

    [email protected] (muffa) wrote:

    >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
     
  11. Matt O'Toole

    Matt O'Toole Guest

  12. Tim McNamara

    Tim McNamara Guest

    In article <[email protected]>, "Doug Huffman" <[email protected]> wrote:

    > 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.

    > 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.

    > 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?

    > 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."
     
  13. Jay Beattie

    Jay Beattie Guest

    "Doug Huffman" <[email protected]> wrote in message news:[email protected]...
    > 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 protected]> wrote in message
    > news:p[email protected]...
    > >
    > > "Doug Huffman" <[email protected]> wrote in message
    > > news:[email protected]...
    > > > I believe that sealed bearings should remain sealed. My primary
    > > experience
    > > > 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.
    > >
    > > > 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.
    > >
    > > >
    > > > 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 protected]> wrote in message
    > > > news:[email protected]...
    > > > > 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.

    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.
     
  14. B. Sanders

    B. Sanders Guest

    "Doug Huffman" <[email protected]> wrote in message news:[email protected]...
    > I believe that sealed bearings should remain sealed. My primary
    experience
    > 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?

    > 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?

    > 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
     
  15. Jobst Brandt

    Jobst Brandt Guest

    Matt O'Toole writes:

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

    > This is probably the link you were looking for:

    http://www.bontrager.com/keith/rants.asp?id=26

    > 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:

    http://draco.acs.uci.edu/rbfaq/FAQ/8f.6.html

    Jobst Brandt [email protected] Palo Alto CA
     
  16. Jobst Brandt

    Jobst Brandt Guest

    Matt O'Toole writes:

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

    > This is probably the link you were looking for:

    http://www.bontrager.com/keith/rants.asp?id=26

    > 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:

    http://draco.acs.uci.edu/rbfaq/FAQ/8f.6.html

    Jobst Brandt [email protected] Palo Alto CA
     
  17. Matt O'Toole

    Matt O'Toole Guest

    <[email protected]> wrote in message news:[email protected]...

    > 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.

    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.

    > The essence of the "sealed bearing" issue has been
    discussed here
    > often, often enough that the FAQ has an entry:
    >
    > http://draco.acs.uci.edu/rbfaq/FAQ/8f.6.html

    '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.
     
  18. Bluto

    Bluto Guest

    "Doug Huffman" <[email protected]> wrote

    > "Robin Hubert" <[email protected]> wrote:
    > >
    > > "Doug Huffman" <[email protected]> wrote:
    > >
    > > > 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"
     
  19. 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": http://www.geocities.com/czcorner
     
  20. Jobst Brandt

    Jobst Brandt Guest

    Matt O'Toole writes:

    > 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.

    > 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.

    > "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 protected] Palo Alto CA
     
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