Tension wheel with or without tyre?

Quoted message said:

It's well known that the measured spoke tension in a wheel decreases
when a tyre is inflated on the rim.

"Well known" but not actually true!

Quoted message said:

So this raises the question, should the maximum spoke tension be
reached with or without a tyre on the rim?

It is best to make spoke adjustments with no tire on the rim.

Sheldon "Elderly Female Spouse's Story" Brown
+----------------------------------------------------+
| A little inaccuracy sometimes saves tons of |
| explanation. --H.H.Munro ("Saki"😉(1870-1916) |
+----------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

It's well known that the measured spoke tension in a wheel decreases
when a tyre is inflated on the rim. It's also recognised that for best
strength a wheel should be tensioned to its maximum capacity for
holding that tension.

So this raises the question, should the maximum spoke tension be
reached with or without a tyre on the rim?

Doesn't matter as long as the tire is not inflated.
--------------
Alex

Alex Rodriguez said:

[email hidden] says...

Quoted message said:

So this raises the question, should the maximum spoke tension be
reached with or without a tyre on the rim?

Doesn't matter as long as the tire is not inflated.

Probably doesn't make much difference these days whether the tire is
inflated or not - assuming you have double-wall rims. In the old days,
with rim strip pressed hard into the slot of the spoke nipple,
tightening spokes with an inflated tire could chew up the rim strip.

I don't believe for a minute that the tire inflation affects the spoke
tension.

On the other hand, I like to have the tire and rim strip off, so I can
see how much I'm turning the spoke. I can probably pretty much do it by
feel, but I'm so visually oriented...

Mark Janeba

Mark Janeba said:

I don't believe for a minute that the tire inflation affects the spoke
tension.

Have you measured it?

I did and found measurable tension change with tire pressure and
without. Don't remember how much. Maybe 12 or 25 pounds?

Mark Janeba said:

Alex Rodriguez said:

[email hidden] says...

Quoted message said:

So this raises the question, should the maximum spoke tension be
reached with or without a tyre on the rim?

Doesn't matter as long as the tire is not inflated.

Probably doesn't make much difference these days whether the tire is
inflated or not - assuming you have double-wall rims. In the old days,
with rim strip pressed hard into the slot of the spoke nipple,
tightening spokes with an inflated tire could chew up the rim strip.

I don't believe for a minute that the tire inflation affects the spoke
tension.

On the other hand, I like to have the tire and rim strip off, so I can
see how much I'm turning the spoke. I can probably pretty much do it by
feel, but I'm so visually oriented...

Mark Janeba

Dear Mark and Sheldon,

I haven't noticed my spokes going slack when I pump the tire
up, so you seem to be right, but now I'm wondering why I
can't crush my helpless rim with my mighty telescoping
mini-pump.

Why doesn't applying 100 psi all the way around a roughly 80
x 1 inch rim have much (if any) effect on the rim?

I'm guessing that both the tube and tire foil my cruel
intentions by expanding mostly outward, not inward, because
air pressure offers little resistance compared to a
pre-tensioned metal rim.

If so, I'm also guessing that if I enclosed the rim, tire,
and tube in a tight-fitting metal mold, I could then succeed
in using my air-pump to compress my rim and reduce my
haughty spokes to cowering submission.

Am I close?

Carl Fogel

dianne_1234 said:

Mark Janeba said:

I don't believe for a minute that the tire inflation affects the spoke
tension.

Have you measured it?

I did and found measurable tension change with tire pressure and
without. Don't remember how much. Maybe 12 or 25 pounds?

Dear Dianne,

I kinda-sorta suspect that you'll get much less
spoke-tension reduction than the tire pressure, probably
because most of the swelling goes outward against the
resistance of the air and the tire/tube reluctance to
expand.

I'm thinking of an aneurysm, where the material balloons and
bulges out under pressure--if the tire does this to a much
smaller extent, it's the tire that moves outward much more
than the rim moves inward.

The less elastic the tire, the more pressure it could put on
the rim.

Now I have to go play with my air compressor and tensiometer
and see what happens.

Carl Fogel

On Wed, 12 Jan 2005 18:10:26 -0700, [email hidden]

Quoted message said:

dianne_1234 said:

Mark Janeba said:

I don't believe for a minute that the tire inflation affects the spoke
tension.

Have you measured it?

I did and found measurable tension change with tire pressure and
without. Don't remember how much. Maybe 12 or 25 pounds?

Dear Dianne,

I kinda-sorta suspect that you'll get much less
spoke-tension reduction than the tire pressure, probably
because most of the swelling goes outward against the
resistance of the air and the tire/tube reluctance to
expand.

I'm thinking of an aneurysm, where the material balloons and
bulges out under pressure--if the tire does this to a much
smaller extent, it's the tire that moves outward much more
than the rim moves inward.

The less elastic the tire, the more pressure it could put on
the rim.

Now I have to go play with my air compressor and tensiometer
and see what happens.

Carl Fogel

Dear Dianne,

Nothing happened, just as Sheldon predicted--whew!

My Park tensiometer needle repeatedly sat on 16 on its scale
on the handiest spoke on the handiest wheel with tire with
the tube deflated.

It sat there again repeatedly at 16 after I pumped the tire
up to 130 psi with my gorgeous new yellow floor pump (whose
dual head needed a brisk rap before it would pay attention
and stop snorkelling out the Schrader orifice).

Carl Fogel

Hi Dianne
I curious what tensiometer did you use to see that much accuracy? Did
you average it for all the spokes? As am matter of fact, I'm curios
what equipment all the various folks that build wheels here @ rbt use.
I'll even start off first:

Park TS 2 mounted in the plastic thingey that allows the angle to be
adjusted. Which in turn is mounted to a thin steel countersunk
plate to
keep it more rigid.
Park WAG 2 or 3 (crummy one that splits in half)
Wheelsmith Tensiometer
I've had little or no success w/ "plucking spokes" (Tone deaf?)
Sylvac digital 6" caliper for measuring the gap btn. 2 spokes for ERD.
Among
other things.
Park spoke wrenches (I have all 5? gages) (usually use which ever color
fits 14ga Sapim, DT nipples)
Ring style spoke wrench, when no other fits. Cheap
Have used "Spokey"'s but neither one fits above nipples.
Park SW 10 (the adjustable one) If necessary.
Phillips head #2? Screwdriver 1/4" socket plug ins, ground to different

depths to attempt to start all spokes @ an even tension.
Deburring (swivel) tool for rim spoke hoses, & valve hole.
30 wt motor oil
or
Wheelsmith Spoke Prep
Two 300 watt halogen construction lights on a stand, bounced off
ceiling & walls.
There are probably other things I've forgotten, John

Quoted message said:

My Park tensiometer needle repeatedly sat on 16 on its scale
on the handiest spoke on the handiest wheel with tire with
the tube deflated.

You have a tensiometer? How about testing my
rim-heating/spoke-tension theory. Remove the tire from the front
wheel, measure the tension of a particular spoke. Now, using a
hot-air gun (a hair dryer should do reasonably well), heat the rim,
turning it slowly to make it uniform. Then remeasure the spoke
tension. Ideally you'd measure the rim temperature. Ideally I'd be
the one doing the experiment, but for the lack of a tensiometer...

Joe

Mark Janeba said:

Quoted message said:

Quoted message said:

So this raises the question, should the maximum spoke tension be
reached with or without a tyre on the rim?

Quoted message said:

Quoted message said:

Doesn't matter as long as the tire is not inflated.

Quoted message said:

Probably doesn't make much difference these days whether the tire is
inflated or not - assuming you have double-wall rims. In the old
days, with rim strip pressed hard into the slot of the spoke nipple,
tightening spokes with an inflated tire could chew up the rim strip.

Quoted message said:

I don't believe for a minute that the tire inflation affects the
spoke tension.

It does, and the equation for tire constriction on inflation is given
in "the Bicycle Wheel".

Quoted message said:

On the other hand, I like to have the tire and rim strip off, so I
can see how much I'm turning the spoke. I can probably pretty much
do it by feel, but I'm so visually oriented...

I don't understand what this has to do with spoke tension on
inflation.

Jobst Brandt
[email hidden]

Joe Riel said:

Quoted message said:

My Park tensiometer needle repeatedly sat on 16 on its scale
on the handiest spoke on the handiest wheel with tire with
the tube deflated.

You have a tensiometer? How about testing my
rim-heating/spoke-tension theory. Remove the tire from the front
wheel, measure the tension of a particular spoke. Now, using a
hot-air gun (a hair dryer should do reasonably well), heat the rim,
turning it slowly to make it uniform. Then remeasure the spoke
tension. Ideally you'd measure the rim temperature. Ideally I'd be
the one doing the experiment, but for the lack of a tensiometer...

Why not use a strain gauge or extensometer?

--
Tom Sherman - Near Rock Island

Carl Fogel said:

Quoted message said:

Quoted message said:

I don't believe for a minute that the tire inflation affects the
spoke tension.

Quoted message said:

Quoted message said:

Have you measured it?

Quoted message said:

Quoted message said:

I did and found measurable tension change with tire pressure and
without. Don't remember how much. Maybe 12 or 25 pounds?

Quoted message said:

I kinda-sorta suspect that you'll get much less spoke-tension
reduction than the tire pressure, probably because most of the
swelling goes outward against the resistance of the air and the
tire/tube reluctance to expand.

Quoted message said:

I'm thinking of an aneurysm, where the material balloons and bulges
out under pressure--if the tire does this to a much smaller extent,
it's the tire that moves outward much more than the rim moves
inward.

Quoted message said:

The less elastic the tire, the more pressure it could put on the
rim.

Quoted message said:

Now I have to go play with my air compressor and tensiometer and see
what happens.

Carl, with your search abilities you could find the thread where this
was beat to death and explained a while ago. I think this may be
another subject for the FAQ but I am loath to rewrite it if you can
possibly find it.

Jobst Brandt
[email hidden]

Tom Sherman said:

Joe Riel said:

Quoted message said:

My Park tensiometer needle repeatedly sat on 16 on its scale
on the handiest spoke on the handiest wheel with tire with
the tube deflated.

You have a tensiometer? How about testing my
rim-heating/spoke-tension theory. Remove the tire from the front
wheel, measure the tension of a particular spoke. Now, using a
hot-air gun (a hair dryer should do reasonably well), heat the rim,
turning it slowly to make it uniform. Then remeasure the spoke
tension. Ideally you'd measure the rim temperature. Ideally I'd be
the one doing the experiment, but for the lack of a tensiometer...

Why not use a strain gauge or extensometer?

I don't have those, either. For the moment I was thinking of just
listening to the change in spoke tone, however, I'm somewhat tone
deaf---I can tell the difference between two pitches played one
after the other, but probably not if the interval between them is
several minutes, or more. Heating the rim might take a while.

Joe

Joe Riel said:

Quoted message said:

My Park tensiometer needle repeatedly sat on 16 on its scale
on the handiest spoke on the handiest wheel with tire with
the tube deflated.

You have a tensiometer? How about testing my
rim-heating/spoke-tension theory. Remove the tire from the front
wheel, measure the tension of a particular spoke. Now, using a
hot-air gun (a hair dryer should do reasonably well), heat the rim,
turning it slowly to make it uniform. Then remeasure the spoke
tension. Ideally you'd measure the rim temperature. Ideally I'd be
the one doing the experiment, but for the lack of a tensiometer...

Joe

Dear Joe,

Regrettably, Fogel Labs is equipped only with a
state-of-the-Walmart Park tensiometer, available for $54.99
at Performance Bike:

http://www.performancebike.com/shop/profile.cfm?sku=16496

A hair drier powerful enough to heat a bare bicycle rim to
over 200 degrees F is not part of the arsenal against
ignorance, the flowing locks of the chief technician being
more a fond memory, rather than any protection against
sunburn.

(Frankly, that's an impressive hair drier that you have in
mind--do you breed woolly mammoths?)

Both the gas oven and the microwave appear to be too small
for the next obvious solution.

The tame approach of heating the rim by simply rolling down
a steep hill under heavy braking is denied to me because of
the lack of convenient steep hills of sufficient length.

And it's snowing.

Carl Fogel

Joe Riel said:

I don't have those, either. For the moment I was thinking of just
listening to the change in spoke tone, however, I'm somewhat tone
deaf---I can tell the difference between two pitches played one
after the other, but probably not if the interval between them is
several minutes, or more. Heating the rim might take a while.

You could use a musical instrument (or a computer program that can play
tones) for reference. If someone with a tensiometer wants to do the
experiment that will probably be easier and more accurate, however.

--
Benjamin Lewis

Luke, I'm yer father, eh. Come over to the dark side, you hoser.
-- Dave Thomas, "Strange Brew"

Quoted message said:

Dear Joe,

Regrettably, Fogel Labs is equipped only with a
state-of-the-Walmart Park tensiometer, available for $54.99
at Performance Bike:

http://www.performancebike.com/shop/profile.cfm?sku=16496

A hair drier powerful enough to heat a bare bicycle rim to
over 200 degrees F is not part of the arsenal against
ignorance, the flowing locks of the chief technician being
more a fond memory, rather than any protection against
sunburn.

(Frankly, that's an impressive hair drier that you have in
mind--do you breed woolly mammoths?)

Both the gas oven and the microwave appear to be too small
for the next obvious solution.

I would think a gas stove-top would be perfect; just hold the wheel over
the flame and spin. Oh, and you might want to remove the tire first.

--
Benjamin Lewis

Luke, I'm yer father, eh. Come over to the dark side, you hoser.
-- Dave Thomas, "Strange Brew"

Quoted message said:

Carl Fogel said:

Quoted message said:

> I don't believe for a minute that the tire inflation affects the
> spoke tension.

Quoted message said:

Quoted message said:

Have you measured it?

Quoted message said:

Quoted message said:

I did and found measurable tension change with tire pressure and
without. Don't remember how much. Maybe 12 or 25 pounds?

Quoted message said:

I kinda-sorta suspect that you'll get much less spoke-tension
reduction than the tire pressure, probably because most of the
swelling goes outward against the resistance of the air and the
tire/tube reluctance to expand.

Quoted message said:

I'm thinking of an aneurysm, where the material balloons and bulges
out under pressure--if the tire does this to a much smaller extent,
it's the tire that moves outward much more than the rim moves
inward.

Quoted message said:

The less elastic the tire, the more pressure it could put on the
rim.

Quoted message said:

Now I have to go play with my air compressor and tensiometer and see
what happens.

Carl, with your search abilities you could find the thread where this
was beat to death and explained a while ago. I think this may be
another subject for the FAQ but I am loath to rewrite it if you can
possibly find it.

Jobst Brandt
[email hidden]

Dear Jobst,

I doubt that it would have taken you as long to explain it
as you just spent not doing so. It is amazing how many posts
on a technical newsgroup prefer declaration to explanation.

Carl Fogel

Quoted message said:

A hair drier powerful enough to heat a bare bicycle rim to
over 200 degrees F is not part of the arsenal against
ignorance, the flowing locks of the chief technician being
more a fond memory, rather than any protection against
sunburn.

(Frankly, that's an impressive hair drier that you have in
mind--do you breed woolly mammoths?)

Mammoths, woolly or otherwise, aren't terribly fond of San Diego.

I haven't worked out the heat-transfer coefficients, maybe
it's worse that I imagined. My other idea is to use a
camp stove to heat a wok filled with water to boiling,
the wheel would be turned through that. It has the advantage
of controlling the temperature, but might be a bit messy.

Quoted message said:

And it's snowing.

Well, you could plunge a wheel into a snowbank and see
if the tension decreases. Just be sure to thermally
isolate the spokes, so they stay at room temperature.

Joe

Joe Riel said:

Quoted message said:

A hair drier powerful enough to heat a bare bicycle rim to
over 200 degrees F is not part of the arsenal against
ignorance, the flowing locks of the chief technician being
more a fond memory, rather than any protection against
sunburn.

(Frankly, that's an impressive hair drier that you have in
mind--do you breed woolly mammoths?)

Mammoths, woolly or otherwise, aren't terribly fond of San Diego.

Dear Joe,

Nonsense! Myth and lore!

The La Brea Tar Pits are within easy driving distance and
bulging with woolly mammoths.

Carl Fogel