Pitted cones and shells--just how bad is it?

Folks,

I know that you should check your hubs and overhaul them on a regular basis, but if you fail to
do so and discover, when you do get around to it, that the cones and / or hub shell have
developed pits, what would the consequences be, if any, of overhauling them as they are and
continuing to use them?

Trent, who doesn't have any trashed hubs, but is curious about such things

Checking for hub play is part of my daily pre- and post-ride inspection. I keep the cones adjusted
and overhaul all my hubs at least once a year, using new balls. Since I started doing this in '95 or
thereabouts I have never had to replace a cone and I have one set of wheels with close to 20k miles
on 'em. Paying attention to your hubs is a good long-term economy -- end of lecture.

Should you ride those damaged hubs? One consideration is the level of damage you can do. Often the
cones get pitted before the cup does. So by replacing your cones you can prevent damage to the cup.
But you are already past that point...

My hunch is you can probably continue to use them, expecting the cones, cups and balls to wear at
an accelerating rate. Eventually they will be shot. If this happens a mile from home on your beater
bike, it will be insignificant. If it happens 200 miles from home on a loaded tour it can be a
major problem.

I once bought a beater bike whose bottom bracket axle was badly pitted on both sides. I just cleaned
it, put in new balls, greased and adjusted it and rode it for a year (~1000 miles, mostly in the
rain) before finally replacing it. It always had a wee little bit of play, but worked OK.


Mike Yankee

(Address is munged to thwart spammers. To reply, delete everything after "com".)

Trent Gregory Hill writes:

> I know that you should check your hubs and overhaul them on a regular basis, but if you fail to do
> so and discover, when you do get around to it, that the cones and/or hub shell have developed
> pits, what would the consequences be, if any, of overhauling them as they are and continuing to
> use them?

I think you are talking about cones and outer race and in these mainly the cone gets pitted from use
but mainly from overload. The FAQ item on this has been waiting a while to appear but here it is:

Subject: 8c.6 Wheel Bearing adjustment From: Jobst Brandt <jobst.brandt@stanfordalumni.org> Date:
Tue, 26 Nov 2002

Bicycle wheel bearings, as most, require a slight preload so that under load, more than the one ball
under the cone (inner race) is not carrying the entire load. With proper preload, slight drag should
be perceptible. This drag is small compared to the drag when the bearing is loaded, drag that we
cannot feel. Adjusting ball bearings to spin freely unloaded does not reduce operating friction. A
bearing with clearance has higher drag when loaded than one with proper preload. For high quality
bearings, preload should be just enough to cause light drag when rotating the axle between thumb and
forefinger. Low grade bearings will feel slightly lumpy with proper preload.

Wheels with quick release (QR) axles present an additional problem of altering bearing clearance as
the QR is closed. Closing the lever requires increasing force with a slight over-center feel near
the end of the stroke. This lever force arises from compressing the hollow axle and stretching the
skewer. The ratio of elastic length change between axle and skewer is that of their cross sectional
area and effective lengths.

Although small, axle shortening on QR hubs is large enough to affect bearing clearance and should be
considered when adjusting bearings. They should be adjusted just loose enough so that closing the QR
leaves no bearing clearance but rather a slight preload. Excessive preload from QR closure is the
cause of most wheel bearing failures not caused by water intrusion. Clearance, in contrast can be
felt as disconcerting rattle when encountering road roughness.

To test for proper adjustment, install the wheel and wiggle the rim side-to-side to determine that
there is no clearance (rattle), then let the wheel rotate freely to a stop, noting whether it halts
with a short (indexed) oscillation. If the wheel stops with an oscillating "shudder" at the end of
motion, bearing preload is too high.

Adjusting QR force is more than a safety matter. It is also one of bearing life and should be kept
at a known constant level once the desired closure force has been determined. Rear vertical
dropouts require a lower and more predictable closure force than was formerly required with axles
that could move forward from chain tension. Because vertical dropouts do not rely on friction to
resist chain load, many hubs now have smooth faced jam nuts that do not damage dropout faces as
older knurl faced ones did.
------------------------------

Jobst Brandt jobst.brandt@stanfordalumni.org Palo Alto CA

jobst.brandt@stanfordalumni.org wrote:

> Subject: 8c.6 Wheel Bearing adjustment From: Jobst Brandt <jobst.brandt@stanfordalumni.org> Date:
> Tue, 26 Nov 2002
>
> Bicycle wheel bearings, as most, require a slight preload so that under load, more than the one
> ball under the cone (inner race) is not carrying the entire load. [...]

Is that worded correctly?

Tom Ace

jobst brandt wrote:

> Tom Ace writes:
>
>>> Bicycle wheel bearings, as most, require a slight preload so that under load, more than the one
>>> ball under the cone (inner race) is not carrying the entire load. [...]
>
>> Is that worded correctly?
>
> What part of that is unclear?

I think it should read something like "... so that under load, more than the one ball ... is
carrying the load".

Or alternatively, "so that under load, not only one ball ... is carrying the entire load".

--
Benjamin Lewis

"Love is a snowmobile racing across the tundra and then suddenly it flips over, pinning you
underneath. At night, the ice weasels come." --Matt Groening

Tom Ace writes:

>> Bicycle wheel bearings, as most, require a slight preload so that under load, more than the one
>> ball under the cone (inner race) is not carrying the entire load. [...]

> Is that worded correctly?

What part of that is unclear? Maybe when taken to the extreme, the effect would be more apparent.
With substantial clearance (assume the bearing balls remain stuck to the outer race), it should be
evident that the cone will contact only one ball when loaded radially. When rotated, it will then
drop between two balls before it rides up over the next. This displacement is known as "ball drop"
and it causes the entire load to be carried by one ball.

With axial preload, a cup and cone (angular contact) bearing elastically loads all balls of the
compliment so that a radial load will be distributed among several balls that are already in
contact. As the FAQ item explains, this can be overdone to the point that the preload is a large
part of the permissible load and will exceed that limit when its intended load is carried.

Such overloads occur often because correctly adjusted wheel bearings will be overloaded by tight
quick release (QR) closure. That is why most wheel bearings should be adjusted on the verge of
looseness, a looseness that will be taken up when the QR is closed.

Jobst Brandt jobst.brandt@stanfordalumni.org Palo Alto CA

Benjamin Lewis writes:

>>>> Bicycle wheel bearings, as most, require a slight preload so that under load, more than the one
>>>> ball under the cone (inner race) is not carrying the entire load. [...]

>>> Is that worded correctly?

>> What part of that is unclear?

> I think it should read something like "... so that under load, more than the one ball ... is
> carrying the load".

> Or alternatively, "so that under load, not only one ball ... is carrying the entire load".

I see. It is a double negative or tries to be and can be ambiguous. I'll reword that if I can.

Jobst Brandt jobst.brandt@stanfordalumni.org Palo Alto CA

<jobst.brandt@stanfordalumni.org> wrote in message news:Uunfa.435$JX2.40412@typhoon.sonic.net...
> Tom Ace writes:
>
> >> Bicycle wheel bearings, as most, require a slight preload so that under load, more than the one
> >> ball under the cone (inner race) is not carrying the entire load. [...]
>
> > Is that worded correctly?
>
> What part of that is unclear? Maybe when taken to the extreme, the

I though he was querying if the cone was indeed the inner race.

jtaylor@spamkiller.hfx.andara.com wrote:

>
> <jobst.brandt@stanfordalumni.org> wrote in message news:Uunfa.435$JX2.40412@typhoon.sonic.net...
>> Tom Ace writes:
>>
>>>> Bicycle wheel bearings, as most, require a slight preload so that under load, more than the one
>>>> ball under the cone (inner race) is not carrying the entire load. [...]
>>
>>> Is that worded correctly?
>>
>> What part of that is unclear? Maybe when taken to the extreme, the
>
> I though he was querying if the cone was indeed the inner race.

Inner meaning smaller radius. That's the only meaning of "inner" that is relevant in this context.

--
Benjamin Lewis

"Love is a snowmobile racing across the tundra and then suddenly it flips over, pinning you
underneath. At night, the ice weasels come." --Matt Groening

"trent gregory hill" <tghill62@u.washington.edu> wrote in message
news:Pine.A41.4.44.0303221841280.102...washington.edu...
> Folks,
>
> I know that you should check your hubs and overhaul them on a regular basis, but if you fail to do
> so and discover, when you do get around to it, that the cones and / or hub shell have developed
> pits, what would the consequences be, if any, of overhauling them as they are and continuing to
> use them?
>
> Trent, who doesn't have any trashed hubs, but is curious about such things

Depends.

When changing a tire on an XMart bike, typically badly rusted and as devoid of grease as the day
it left the store, I commonly open the hub, shoot in some grease and adjust as well as possible.
Takes under one minute. I do this mostly because it is easier to check the tire's seating if the
axle will spin in the hub so you can spin the wheel in midair. I completely ignore any pits in the
cone. The white grease oozes out red from the powdered metal rust inside. But is it at least
better after that.

If it were my own nice vintage Campagnolo hubs ( horror!) I would replace the damaged cone (and
the cup too if it were gouged out) and rebuild with new balls and fresh grease in a thoroughly
clean hubshell.

Somewhere inbetween, you'll need to decide how much expense and suffering you prefer.

--
Andrew Muzi http://www.yellowjersey.org Open every day since 1 April 1971

jobst.brandt@stanfordalumni.org wrote:

> Subject: 8c.6 Wheel Bearing adjustment
/snip
> To test for proper adjustment, install the wheel and wiggle the rim side-to-side to determine that
> there is no clearance (rattle), then let the wheel rotate freely to a stop, noting whether it
> halts with a short (indexed) oscillation. If the wheel stops with an oscillating "shudder" at the
> end of motion, bearing preload is too high.

Some gaskets and weather boots can cause the wheel to stop suddenly with a shudder even when the
bearings are loose.

~PB

jobst.brandt@stanfordalumni.org wrote in message news:<5kbfa.371$JX2.31145@typhoon.sonic.net>...
> Trent Gregory Hill writes:
>
> > I know that you should check your hubs and overhaul them on a regular basis, but if you fail to
> > do so and discover, when you do get around to it, that the cones and/or hub shell have developed
> > pits, what would the consequences be, if any, of overhauling them as they are and continuing to
> > use them?
>
> I think you are talking about cones and outer race and in these mainly the cone gets pitted
> from use but mainly from overload. The FAQ item on this has been waiting a while to appear but
> here it is:
>
> Subject: 8c.6 Wheel Bearing adjustment From: Jobst Brandt <jobst.brandt@stanfordalumni.org> Date:
> Tue, 26 Nov 2002
>

I do not know whether the damage he refers to is from overload, but I would like to request that you
answer assuming water damage, since this is something I have been wondering.

I have damage to one side of a hub only, so clearly not a load problem. The grease was rust-colored,
which made me suspect water.

I would like to avoid replacing the hub for as long as possible, so how should I take care of it at
this point? I have heard you say that nothing can be done to fix races, but can you continue to
preserve them? Will there be a sudden or catastrophic failure at some point? I have also heard you
say you carry extra balls to use in case of water damage. Can I gather that replacing the balls is
good even if they go in a damaged hub?

Thank you, Karl.

Pete Biggs <pLime{remove_fruit}@biggs.tc> writes:

>> Subject: 8c.6 Wheel Bearing adjustment ... To test for proper adjustment, install the wheel and
>> wiggle the rim side-to-side to determine that there is no clearance (rattle), then let the wheel
>> rotate freely to a stop, noting whether it halts with a short (indexed) oscillation. If the wheel
>> stops with an oscillating "shudder" at the end of motion, bearing preload is too high.

> Some gaskets and weather boots can cause the wheel to stop suddenly with a shudder even when the
> bearings are loose.

I don't believe so. Boots and gaskets slide with viscous friction that has no detents as do ball
bearings that are excessively preloaded. I don't think you could demonstrate such behavior with any
reasonable hub on the market today. Maybe you could name such a product.

Jobst Brandt jobst.brandt@stanfordalumni.org Palo Alto CA

Karl Nelson writes:

>>> I know that you should check your hubs and overhaul them on a regular basis, but if you fail to
>>> do so and discover, when you do get around to it, that the cones and/or hub shell have developed
>>> pits, what would the consequences be, if any, of overhauling them as they are and continuing to
>>> use them?

>> I think you are talking about cones and outer race and in these mainly the cone gets pitted
>> from use but mainly from overload. The FAQ item on this has been waiting a while to appear but
>> here it is:

>> Subject: 8c.6 Wheel Bearing adjustment From: Jobst Brandt <jobst.brandt@stanfordalumni.org> Date:
>> Tue, 26 Nov 2002 ...

> I do not know whether the damage he refers to is from overload, but I would like to request that
> you answer assuming water damage, since this is something I have been wondering.

As Andrew Muzi mentioned, if it isn't an expensive hub, one for which replacement parts are
available, just squirt some heavy oil in there and ride it. It will never be much good and with rust
pits (that form around each ball contact when parked) they will only grow. Get new outer race, cone
ands a set of bearing balls.

> I have damage to one side of a hub only, so clearly not a load problem. The grease was
> rust-colored, which made me suspect water.

I don't know what is available for your hub. Mine (ancient Campagnolo) have spare bearing cups and
cones. Bearing balls are available in most bicycle shops.

> I have heard you say that nothing can be done to fix races, but can you continue to preserve them?

There's not much you can do beyond what Andrew Muzi suggested unless you can get parts.

> Will there be a sudden or catastrophic failure at some point? I have also heard you say you carry
> extra balls to use in case of water damage. Can I gather that replacing the balls is good even if
> they go in a damaged hub?

It just gets harder to adjust as it wears and will have tight and loose areas. Nothing sudden. Even
a cracked bearing ball will make a lot of noise and you put on the brakes and stop.

Jobst Brandt jobst.brandt@stanfordalumni.org Palo Alto CA

trent! i change cones/bearings twice a year at about 5-6000miles or more year commuters mileage
often with a 50+ lb. load on the back for 15+ miles at 20mph(downwind). I installed quality cones
from wheels mfg as the standard generic replacements, 'standard tiwanese'?, go out of adjustment
within a few-say 100 miles- and show pits and gouged bearing paths when open to see what's
**))!^&&%%^&^ going on in there. still, the cones do wear quickly even with continuos maintenance to
hold the lateral play down and JB's more bearings to contact/load support motion in. floated a few
questions on more expensive hubs than shimano deore or ST using cartridge bearings as for touring
across-Peru?-Staten Island?-or hauling the goods from superduper but no comments from long term
users rather than boulevardiers.