Things to know

So if you take a front road wheel and spin it by hand how long does yours spin before stopping? Today I check my front Ultegra bearings and they were fine the 10000 plus miles shows zero wear. I did pull the bearings and re-greased, cleaned them up but of course when you dump the while lithium grease back they look dirty again. Maybe should have used my marine grease but did not.

In any case I spun the wheel afterward by hand the computer has it getting to 9mph and it spins about 45 seconds. I then went over to the other bike that has pretty much a front wheel with 105 hubs and simply spun that one. It manages to spin for a minute. Both smooth but I wonder if that means a damn thing?
Deacon Mark

On Sunday, December 6, 2020 at 2:17:15 PM UTC-8, wrote:
So if you take a front road wheel and spin it by hand how long does yours spin before stopping? Today I check my front Ultegra bearings and they were fine the 10000 plus miles shows zero wear. I did pull the bearings and re-greased, cleaned them up but of course when you dump the while lithium grease back they look dirty again. Maybe should have used my marine grease but did not.

In any case I spun the wheel afterward by hand the computer has it getting to 9mph and it spins about 45 seconds. I then went over to the other bike that has pretty much a front wheel with 105 hubs and simply spun that one. It manages to spin for a minute. Both smooth but I wonder if that means a damn thing?
Deacon Mark
Most of the drag on wheel bearings are from the seals. So the length of time that the wheel will spin is pretty long and dependent upon the weight of the wheel. Do NOT use heavy marine grease, pro mechanics use light oil in TT wheels. Normally you would use a light grease as Campagnolo markets. It is little more than jellied oil. I don't like lithium grease since it seems to pick up dirt from a distance.

On Sunday, December 6, 2020 at 2:17:15 PM UTC-8, wrote:
So if you take a front road wheel and spin it by hand how long does yours spin before stopping? Today I check my front Ultegra bearings and they were fine the 10000 plus miles shows zero wear. I did pull the bearings and re-greased, cleaned them up but of course when you dump the while lithium grease back they look dirty again. Maybe should have used my marine grease but did not.

In any case I spun the wheel afterward by hand the computer has it getting to 9mph and it spins about 45 seconds. I then went over to the other bike that has pretty much a front wheel with 105 hubs and simply spun that one. It manages to spin for a minute. Both smooth but I wonder if that means a damn thing?

Looking around I don't see the light grease that Campagnolo used to sell but White Lighting and WD40 both sell clear lubricating grease and Park tool sells some sort of black stuff that is made to be completely water repellent. Of course I believe that sort of thing don't I?

On 12/6/2020 2:17 PM, Mark Cleary wrote:
So if you take a front road wheel and spin it by hand how long does yours spin before stopping? Today I check my front Ultegra bearings and they were fine the 10000 plus miles shows zero wear. I did pull the bearings and re-greased, cleaned them up but of course when you dump the while lithium grease back they look dirty again. Maybe should have used my marine grease but did not.

In any case I spun the wheel afterward by hand the computer has it getting to 9mph and it spins about 45 seconds. I then went over to the other bike that has pretty much a front wheel with 105 hubs and simply spun that one. It manages to spin for a minute. Both smooth but I wonder if that means a damn thing?
Deacon Mark

I doubt the 15sec difference means much. Could be a difference in seal
friction (if either of your hubs has the rubber cone-to-dust cover seals
that used to be popular). Could be a minor difference in how tight you
adjusted the cones. Both sound fine to me. Besides, I doubt we're very
consistent with how hard we spin a wheel.

What might be a finer measure of hub friction: Spin the wheel very
slowly so that the wheel quits "turning over" and starts
spinning/swinging back and forth as the heaviest point (usually either
valve, reflector, or rim join, but not always) seeks bottom. Usually
the wheel stops when the heaviest point is *near* bottom but not *at*
bottom - the heavy point swings past bottom then stops, b/c friction
overcomes the tiny bit that the weight is off-bottom.

Spin a few times and compare the distance of the shortest "swing," and
how close to bottom the heavy point is. Less friction will make the
wheel continue to oscillate with shorter swings. Higher friction will
stop the wheel when the swings are still kinda large. Of course a
better-balanced wheel will confound all this.

PS - just so long as you get *some* oscillation before the wheel stops,
you're probably doing just fine.

Mark J.

On 12/6/2020 4:17 PM, Mark Cleary wrote:
So if you take a front road wheel and spin it by hand how long does yours spin before stopping? Today I check my front Ultegra bearings and they were fine the 10000 plus miles shows zero wear. I did pull the bearings and re-greased, cleaned them up but of course when you dump the while lithium grease back they look dirty again. Maybe should have used my marine grease but did not.

In any case I spun the wheel afterward by hand the computer has it getting to 9mph and it spins about 45 seconds. I then went over to the other bike that has pretty much a front wheel with 105 hubs and simply spun that one. It manages to spin for a minute. Both smooth but I wonder if that means a damn thing?
Deacon Mark


No idea.Too many variables.

Heavier rim/tire spins longer (you aren't measuring your
energy input)

Properly adjusted bearing will spin longer than a tight one.
A bearing adjusted too slack will spin pretty well with no
load but will wear quickly in normal service.

Before service, your lubricant may be a bit dried and pushed
away from the balls. Fresh lubricant is 'in the way' and
lubricants cover quite a range of viscosities.

I'm curious about "they look dirty again". That may mean
you didn't clean the hubshell or threads on the axle etc.
That sort of problem can lead to really fast wear if the
crud previously pushed to the corners is now running in your
lubricant.

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

On 12/6/2020 6:28 PM, AMuzi wrote:
On 12/6/2020 4:17 PM, Mark Cleary wrote:
So if you take a front road wheel and spin it by hand how long does
yours spin before stopping? Today I check my front Ultegra bearings
and they were fine the 10000 plus miles shows zero wear. I did pull
the bearings and re-greased, cleaned them up but of course when you
dump the while lithium grease back they look dirty again. Maybe should
have used my marine grease but did not.

In any case I spun the wheel afterward by hand the computer has it
getting to 9mph and it spins about 45 seconds. I then went over to the
other bike that has pretty much a front wheel with 105 hubs and simply
spun that one. It manages to spin for a minute. Both smooth but I
wonder if that means a damn thing?
Deacon Mark


No idea.Too many variables.

Heavier rim/tire spins longer (you aren't measuring your energy input)

Properly adjusted bearing will spin longer than a tight one. Â*A bearing
adjusted too slack will spin pretty well with no load but will wear
quickly in normal service.

Before service, your lubricant may be a bit dried and pushed away from
the balls. Fresh lubricant is 'in the way' and lubricants cover quite a
range of viscosities.

I'm curious about "they look dirty again".Â* That may mean you didn't
clean the hubshell or threads on the axle etc. That sort of problem can
lead to really fast wear if the crud previously pushed to the corners is
now running in your lubricant.

I agree with all of what Andrew said, including cleaning things
thoroughly. When comparing two wheels, the weight of the rim, tube and
tire make a difference, since heavier flywheels spin longer, other
things being equal. I suppose even different spokes could affect things
- although ...

I remember years ago when I was playing with aerodynamics, I did your
test with my bike's stock wheel. Then I replaced the spokes with bladed
spokes and tested again. I'd changed nothing else in the wheel. I knew
that the lesser air resistance of the spokes would allow it to coast
longer, but I wanted to see how much longer.

Except it didn't. The wheel stopped sooner with the bladed spokes. Not
much sooner, but multiple trials gave consistent results. I can't say why.

The important thing to remember is, bearing friction is practically
negligible, unless things are really terrible in there. It's a minuscule
portion of the forces holding you back when you ride. It's kind of like
clipping your fingernails to save weight.

--
- Frank Krygowski

On 12/6/2020 5:45 PM, Frank Krygowski wrote:
On 12/6/2020 6:28 PM, AMuzi wrote:
On 12/6/2020 4:17 PM, Mark Cleary wrote:
So if you take a front road wheel and spin it by hand how
long does yours spin before stopping? Today I check my
front Ultegra bearings and they were fine the 10000 plus
miles shows zero wear. I did pull the bearings and
re-greased, cleaned them up but of course when you dump
the while lithium grease back they look dirty again.
Maybe should have used my marine grease but did not.

In any case I spun the wheel afterward by hand the
computer has it getting to 9mph and it spins about 45
seconds. I then went over to the other bike that has
pretty much a front wheel with 105 hubs and simply spun
that one. It manages to spin for a minute. Both smooth
but I wonder if that means a damn thing?
Deacon Mark


No idea.Too many variables.

Heavier rim/tire spins longer (you aren't measuring your
energy input)

Properly adjusted bearing will spin longer than a tight
one. Â A bearing adjusted too slack will spin pretty well
with no load but will wear quickly in normal service.

Before service, your lubricant may be a bit dried and
pushed away from the balls. Fresh lubricant is 'in the
way' and lubricants cover quite a range of viscosities.

I'm curious about "they look dirty again". That may mean
you didn't clean the hubshell or threads on the axle etc.
That sort of problem can lead to really fast wear if the
crud previously pushed to the corners is now running in
your lubricant.

I agree with all of what Andrew said, including cleaning
things thoroughly. When comparing two wheels, the weight of
the rim, tube and tire make a difference, since heavier
flywheels spin longer, other things being equal. I suppose
even different spokes could affect things - although ...

I remember years ago when I was playing with aerodynamics, I
did your test with my bike's stock wheel. Then I replaced
the spokes with bladed spokes and tested again. I'd changed
nothing else in the wheel. I knew that the lesser air
resistance of the spokes would allow it to coast longer, but
I wanted to see how much longer.

Except it didn't. The wheel stopped sooner with the bladed
spokes. Not much sooner, but multiple trials gave consistent
results. I can't say why.

The important thing to remember is, bearing friction is
practically negligible, unless things are really terrible in
there. It's a minuscule portion of the forces holding you
back when you ride. It's kind of like clipping your
fingernails to save weight.


Yes, I'm with you mostly.

As with so may things, sometimes we don't know what it is we
don't know. In my small understanding of aerodynamics for
low speeds (sub-mach = bicycles, autos) the effects change
dramatically sometimes. Aero spokes may well give an
advantage at 30~35mph (race speeds) imperceptible in your
test. I don't know but it's very possible.

Fashionable rear spoilers on autos are mostly geegaws but
can be very useful at 100, 120mph and up. My own Corsa drops
noticeably at just over 85mph when using the front air dam.
A guy driving it below 65mph would never know that.

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

On Sun, 6 Dec 2020 18:45:23 -0500, Frank Krygowski
wrote:

On 12/6/2020 6:28 PM, AMuzi wrote:
On 12/6/2020 4:17 PM, Mark Cleary wrote:
So if you take a front road wheel and spin it by hand how long does
yours spin before stopping? Today I check my front Ultegra bearings
and they were fine the 10000 plus miles shows zero wear. I did pull
the bearings and re-greased, cleaned them up but of course when you
dump the while lithium grease back they look dirty again. Maybe should
have used my marine grease but did not.

In any case I spun the wheel afterward by hand the computer has it
getting to 9mph and it spins about 45 seconds. I then went over to the
other bike that has pretty much a front wheel with 105 hubs and simply
spun that one. It manages to spin for a minute. Both smooth but I
wonder if that means a damn thing?
Deacon Mark


No idea.Too many variables.

Heavier rim/tire spins longer (you aren't measuring your energy input)

Properly adjusted bearing will spin longer than a tight one. *A bearing
adjusted too slack will spin pretty well with no load but will wear
quickly in normal service.

Before service, your lubricant may be a bit dried and pushed away from
the balls. Fresh lubricant is 'in the way' and lubricants cover quite a
range of viscosities.

I'm curious about "they look dirty again".* That may mean you didn't
clean the hubshell or threads on the axle etc. That sort of problem can
lead to really fast wear if the crud previously pushed to the corners is
now running in your lubricant.

I agree with all of what Andrew said, including cleaning things
thoroughly. When comparing two wheels, the weight of the rim, tube and
tire make a difference, since heavier flywheels spin longer, other
things being equal. I suppose even different spokes could affect things
- although ...

I remember years ago when I was playing with aerodynamics, I did your
test with my bike's stock wheel. Then I replaced the spokes with bladed
spokes and tested again. I'd changed nothing else in the wheel. I knew
that the lesser air resistance of the spokes would allow it to coast
longer, but I wanted to see how much longer.

Except it didn't. The wheel stopped sooner with the bladed spokes. Not
much sooner, but multiple trials gave consistent results. I can't say why.

The important thing to remember is, bearing friction is practically
negligible, unless things are really terrible in there. It's a minuscule
portion of the forces holding you back when you ride. It's kind of like
clipping your fingernails to save weight.

I believe that drag force, increase as a square of the speed (assuming
turbulent flow), in a constant medium, so idly spinning a wheel isn't
going to prove a thing. You would need to spin the wheel at a constant
speed equal to some specific speed over the ground and measure
resistant force which would give you the wind resistance at that
speed.

Note: Laminar flow causes increases in proportion to the velocity.

And, of course wind drag is also dependent on the density of the fluid
in which the part is tested so "air drag" varies with both altitude
and temperature.

Or, as you say, roughly similar to cutting your fingernails at bicycle
speeds :-)
--
Cheers,

John B.

On 12/6/2020 8:04 PM, John B. wrote:
On Sun, 6 Dec 2020 18:45:23 -0500, Frank Krygowski
wrote:

On 12/6/2020 6:28 PM, AMuzi wrote:
On 12/6/2020 4:17 PM, Mark Cleary wrote:
So if you take a front road wheel and spin it by hand how long does
yours spin before stopping? Today I check my front Ultegra bearings
and they were fine the 10000 plus miles shows zero wear. I did pull
the bearings and re-greased, cleaned them up but of course when you
dump the while lithium grease back they look dirty again. Maybe should
have used my marine grease but did not.

In any case I spun the wheel afterward by hand the computer has it
getting to 9mph and it spins about 45 seconds. I then went over to the
other bike that has pretty much a front wheel with 105 hubs and simply
spun that one. It manages to spin for a minute. Both smooth but I
wonder if that means a damn thing?
Deacon Mark


No idea.Too many variables.

Heavier rim/tire spins longer (you aren't measuring your energy input)

Properly adjusted bearing will spin longer than a tight one. Â*A bearing
adjusted too slack will spin pretty well with no load but will wear
quickly in normal service.

Before service, your lubricant may be a bit dried and pushed away from
the balls. Fresh lubricant is 'in the way' and lubricants cover quite a
range of viscosities.

I'm curious about "they look dirty again".Â* That may mean you didn't
clean the hubshell or threads on the axle etc. That sort of problem can
lead to really fast wear if the crud previously pushed to the corners is
now running in your lubricant.

I agree with all of what Andrew said, including cleaning things
thoroughly. When comparing two wheels, the weight of the rim, tube and
tire make a difference, since heavier flywheels spin longer, other
things being equal. I suppose even different spokes could affect things
- although ...

I remember years ago when I was playing with aerodynamics, I did your
test with my bike's stock wheel. Then I replaced the spokes with bladed
spokes and tested again. I'd changed nothing else in the wheel. I knew
that the lesser air resistance of the spokes would allow it to coast
longer, but I wanted to see how much longer.

Except it didn't. The wheel stopped sooner with the bladed spokes. Not
much sooner, but multiple trials gave consistent results. I can't say why.

The important thing to remember is, bearing friction is practically
negligible, unless things are really terrible in there. It's a minuscule
portion of the forces holding you back when you ride. It's kind of like
clipping your fingernails to save weight.

I believe that drag force, increase as a square of the speed (assuming
turbulent flow), in a constant medium, so idly spinning a wheel isn't
going to prove a thing. You would need to spin the wheel at a constant
speed equal to some specific speed over the ground and measure
resistant force which would give you the wind resistance at that
speed.

Note: Laminar flow causes increases in proportion to the velocity.

I think the rates of increase can be more complicated. If the drag
coefficient were constant, you may be correct; but Cd can vary quite a
bit. See
https://www.researchgate.net/figure/...fig1_221913856

Also, note the scatter in the results by various experimenters.
Aerodynamics can be very sensitive, very tricky.

And, of course wind drag is also dependent on the density of the fluid
in which the part is tested so "air drag" varies with both altitude
and temperature.

Right. Ideally, that's covered in the experimental data by using the
Reynolds Number instead of just velocity, which accounts for fluid
properties. In the real world, those properties do change.

Or, as you say, roughly similar to cutting your fingernails at bicycle
speeds :-)

Indeed. That's what I eventually decided, after fussing with bladed
spokes, "aero" water bottles, disc wheel covers, etc. The big aero gains
are in tight vs. floppy clothes, and drop bars or even aero bars when
you can use them.

However, when I've built handlebar bags I have given them a streamlined
shape. It just bothers me to be pushing a big rectangular box right out
there in the frontal air flow.

--
- Frank Krygowski

On Sun, 6 Dec 2020 21:12:36 -0500, Frank Krygowski
wrote:

On 12/6/2020 8:04 PM, John B. wrote:
On Sun, 6 Dec 2020 18:45:23 -0500, Frank Krygowski
wrote:

On 12/6/2020 6:28 PM, AMuzi wrote:
On 12/6/2020 4:17 PM, Mark Cleary wrote:
So if you take a front road wheel and spin it by hand how long does
yours spin before stopping? Today I check my front Ultegra bearings
and they were fine the 10000 plus miles shows zero wear. I did pull
the bearings and re-greased, cleaned them up but of course when you
dump the while lithium grease back they look dirty again. Maybe should
have used my marine grease but did not.

In any case I spun the wheel afterward by hand the computer has it
getting to 9mph and it spins about 45 seconds. I then went over to the
other bike that has pretty much a front wheel with 105 hubs and simply
spun that one. It manages to spin for a minute. Both smooth but I
wonder if that means a damn thing?
Deacon Mark


No idea.Too many variables.

Heavier rim/tire spins longer (you aren't measuring your energy input)

Properly adjusted bearing will spin longer than a tight one. *A bearing
adjusted too slack will spin pretty well with no load but will wear
quickly in normal service.

Before service, your lubricant may be a bit dried and pushed away from
the balls. Fresh lubricant is 'in the way' and lubricants cover quite a
range of viscosities.

I'm curious about "they look dirty again".* That may mean you didn't
clean the hubshell or threads on the axle etc. That sort of problem can
lead to really fast wear if the crud previously pushed to the corners is
now running in your lubricant.

I agree with all of what Andrew said, including cleaning things
thoroughly. When comparing two wheels, the weight of the rim, tube and
tire make a difference, since heavier flywheels spin longer, other
things being equal. I suppose even different spokes could affect things
- although ...

I remember years ago when I was playing with aerodynamics, I did your
test with my bike's stock wheel. Then I replaced the spokes with bladed
spokes and tested again. I'd changed nothing else in the wheel. I knew
that the lesser air resistance of the spokes would allow it to coast
longer, but I wanted to see how much longer.

Except it didn't. The wheel stopped sooner with the bladed spokes. Not
much sooner, but multiple trials gave consistent results. I can't say why.

The important thing to remember is, bearing friction is practically
negligible, unless things are really terrible in there. It's a minuscule
portion of the forces holding you back when you ride. It's kind of like
clipping your fingernails to save weight.

I believe that drag force, increase as a square of the speed (assuming
turbulent flow), in a constant medium, so idly spinning a wheel isn't
going to prove a thing. You would need to spin the wheel at a constant
speed equal to some specific speed over the ground and measure
resistant force which would give you the wind resistance at that
speed.

Note: Laminar flow causes increases in proportion to the velocity.

I think the rates of increase can be more complicated. If the drag
coefficient were constant, you may be correct; but Cd can vary quite a
bit. See
https://www.researchgate.net/figure/...fig1_221913856

Also, note the scatter in the results by various experimenters.
Aerodynamics can be very sensitive, very tricky.

And, of course wind drag is also dependent on the density of the fluid
in which the part is tested so "air drag" varies with both altitude
and temperature.

Right. Ideally, that's covered in the experimental data by using the
Reynolds Number instead of just velocity, which accounts for fluid
properties. In the real world, those properties do change.

Or, as you say, roughly similar to cutting your fingernails at bicycle
speeds :-)

Indeed. That's what I eventually decided, after fussing with bladed
spokes, "aero" water bottles, disc wheel covers, etc. The big aero gains
are in tight vs. floppy clothes, and drop bars or even aero bars when
you can use them.

However, when I've built handlebar bags I have given them a streamlined
shape. It just bothers me to be pushing a big rectangular box right out
there in the frontal air flow.

I think, without making any measurements, that if you'll just get off
the bike it's aerodynamics will be pretty good :-)
--
Cheers,

John B.