Wheel Truing Tutorial

http://www.amazon.com/s/ref=nb_ss_b/002-5045544-5000040?url=search-alias%3Dstripbooks&field-keywords=CARTOON+COMPUTER+GRAPHICS&x=17&y=18

Tom Sherman said:

Quoted message said:

... I think the concept of pre-stressing has been here often, as
in pre-stressed concrete that has much in common with pre-stressed
spokes, except that concrete cannot support tension and spokes
cannot support compression without being pre-stressed.

Quoted message said:

That is not entirely true. When a compressive load is applied to
the top of a slab over a limited area, does it not result in tensile
stresses in the bottom portion of the slab below the "neutral axis"?

Bridges and other structural beams have tensile preload rods internally
to insure that the entire beam is in compression even though most of
the tensile elements are in the foot of the cross section. The
condition you cite would cause cracking (failure) but structures are
not designed or loaded that way if they follow prudent procedures and
of course the building code.

Quoted message said:

And do concrete pavement slabs generally fail from fracture due to
tension in the bottom of the slab from a single load, or from
fatigue from many load cycles? The answer should be obvious to
anyone who know about pavement engineering.

They fail for insufficient reinforcement (steel) but they are not
pre-stressed in roads I have seen built other than bridges, and they
were pre-stressed.

Quoted message said:

Fiber reinforced concrete is not pre-stressed, and the fibers do
increase tensile strength (as evidenced by the fibers increasing the
rupture modulus for a given mix).

That's a composite and I am not familiar with that use. It seems
highly difficult, considering the elastic modulus of stone and fibers
one might use. I suppose asbestos might be a candidate. I don't know.

Jobst Brandt

BicycleTutor said:

I hope the group finds this week's wheel truing tutorial useful. I
tried to cover all the aspects of truing without running overtime. I'd
love to hear what you think...

http://bicycletutor.com/wheel-truing/

I was aware of your website and threw a link in my blog. Great work,
keep it up.

Ron
http://cozybeehive.blogspot.com

Quoted message said:

Alexander Ramon said:

Quoted message said:

Whow? Pre-stressing? Not stress-relieving?

Quoted message said:

After truing, the spokes will get stressed when you take the first
ride, and you'll have to re-adjust anyways. Therefore, you should
pre-stress them beforehand. Or you can call it 'stress-relieving'
if you wish... I think most people get the meaning.

What causes the stress when you first ride it, stress that wasn't
there before, when it was freshly built? I think you have an
incorrect visualization of stress in wheels. Bicycle wheels are pre
stressed structures, an effect that enables their spokes to withstand
compressive loads.

who cares about the spokes? spokes would be useless without rims, and
rims are the things that keep a wheel together, even with slack spokes.

Quoted message said:

Tensioning spokes is where pre-stressing occurs.

Stress relieving is performed to prevent spokes from fatigue failures
caused by load cycles with every rotation when in use.

wot? no assertion that it reduces metallurgical "residual stress"?

Quoted message said:

Reducing peak
stress in a freshly spoked wheel is an important operation to make
wheels durable.

Quoted message said:

Quoted message said:

Really? Two turns? Not a turn and a half? Or one and

one-quarter?

Quoted message said:

In this regard, each wheel is different, depending on how many
sprockets are on the rear cluster or freewheel. I've given the
average as there was not enough time to be more specific about every
type of wheel.

This can be described in a generic way and is so in "the Bicycle Wheel"
where the process is explained in plain language.

rubbish - that book contains a bunch of b.s. "materials theory" that is
not just "slightly wrong", it's outright misleading. b.s. is not "plain
language".

Quoted message said:

Quoted message said:

Quoted message said:

Hopeless.....

Quoted message said:

You might be missing the point... If this tutorial helps one single
person true their own wheel, then it is far from hopeless.

I think that is generous criterion.

i think you need to correct the errors in your book if you want to keep
on trying to sell it.

Skip said:

Quoted message said:

Because JB is snotty and pedantic.

Yes, but Jobst also knows his stuff cold and is a true expert on the
bicycle wheel.

actually, he's not. he writes /like/ he is, but if you know the facts,
you'll understand why he is in reality, just a bullshitter trying to
sell a book.

Quoted message said:

You won't find a better "expert".

there's any number of qualified engineers that understand pre-stressed
structures better. and there's any number of materials people that
understand the difference between materials that strain age and those
that don't. jobst thinks that pre-stress increases strength - all it
does is borrow from one component to another - and that he can eliminate
fatigue from a material where there is no metallurgical mechanism that
allows it. that ain't no "expert".

Quoted message said:

Sheldon Brown probably was more
diverse, but I'm not sure he was more expert than Jobst in Jobst's
field(s).

see above. sheldon was an artisan of considerable skill and experience.
jobst is just an ego seeking a b.s. outlet with the lowest possible
risk of detection. what better than an audience of non-engineers?

Skip said:

Quoted message said:

Because JB is snotty and pedantic.

Yes, but Jobst also knows his stuff cold and is a true expert on the
bicycle wheel.
You won't find a better "expert". Sheldon Brown probably was more
diverse, but I'm not sure he was more expert than Jobst in Jobst's
field(s).
- Skip

Well, snipping his snotty, needless remark sure bolsters your case. (Hint:
it was not constructive or informative; it was merely a cheap shot*.)

*if he wrote more than the OP quoted, then perhaps I'm wrong. I plonked JB
long ago because he's often dishonest and even more often hypocritical.

JB's style is of teaching methods.

illustration for graphic use a teaching tool.

nipple tighten nipple loosen...

rim shown in hand external circumference, zoom in, see nipple head
inside rim, say nipple tighten turned right , clockwise.

clockwise arrow appears around nipple.

turn rim viewing from hub position to inside rim circumference, zoom
toward nipple/spoke junction,

clockwise other side arrow duplicates self, you're now seeing two
arrows either side rim, second 200 degree arrow around nipple spoke
junction.

view changes to bent rim, of 6 nipple section centered. comment.
arrows appear, arrows turn, rim unbends (as a center turnout in a
later segment). flip rim over and show both sides arrows turning with
rim unbending.....

go on to do the same with Quad retruing, hub centering of the egg
shaped rim...

datakoll said:

JB's style is of teaching methods.

illustration for graphic use a teaching tool.

nipple tighten nipple loosen...

rim shown in hand external circumference, zoom in, see nipple head
inside rim, say nipple tighten turned right , clockwise.

clockwise arrow appears around nipple.

turn rim viewing from hub position to inside rim circumference, zoom
toward nipple/spoke junction,

clockwise other side arrow duplicates self, you're now seeing two
arrows either side rim, second 200 degree arrow around nipple spoke
junction.

view changes to bent rim, of 6 nipple section centered. comment.
arrows appear, arrows turn, rim unbends (as a center turnout in a
later segment). flip rim over and show both sides arrows turning with
rim unbending.....

go on to do the same with Quad retruing, hub centering of the egg
shaped rim...

datakoll said:

datakoll said:

JB's style is of teaching methods.

Quoted message said:

illustration for graphic use a teaching tool.

Quoted message said:

nipple tighten nipple loosen...

Quoted message said:

rim shown in hand external circumference, zoom in, see nipple head
inside rim, say nipple tighten turned right , clockwise.

Quoted message said:

clockwise arrow appears around nipple.

Quoted message said:

turn rim viewing from hub position to inside rim circumference, zoom
toward nipple/spoke junction,

Quoted message said:

clockwise other side arrow duplicates self, you're now seeing two
arrows either side rim, second 200 degree arrow around nipple spoke
junction.

Quoted message said:

view changes to bent rim, of 6 nipple section centered. comment.
arrows appear, arrows turn, rim unbends (as a center turnout in a
later segment). flip rim over and show both sides arrows turning with
rim unbending.....

Quoted message said:

go on to do the same with Quad retruing, hub centering of the egg
shaped rim...- Hide quoted text -

- Show quoted text -

off course, a true line appears outboard bent rim section, and a close
up of rim squeezing over to true line.

if drawn then thought about, more examples and procedures surface,

Skip said:

Quoted message said:

Because JB is snotty and pedantic.

Yes, but Jobst also knows his stuff cold and is a true expert on the bicycle
wheel.
You won't find a better "expert".

The above proves that, indeed, "you can fool some of the people all of
the time".

Ozark Bicycle said:

Skip said:

Quoted message said:

Because JB is snotty and pedantic.

Yes, but Jobst also knows his stuff cold and is a true expert on the bicycle
wheel.
You won't find a better "expert".

The above proves that, indeed, "you can fool some of the people all of
the time".

And looking in the mirror I'd agree with you.

Tosspot said:

Ozark Bicycle said:

Skip said:

> Because JB is snotty and pedantic.
Yes, but Jobst also knows his stuff cold and is a true expert on the bicycle
wheel.
You won't find a better "expert".

Quoted message said:

The above proves that, indeed, "you can fool some of the people all of
the time".

And looking in the mirror I'd agree with you.

Your mirror, your eyes, your visage. :-)

datakoll aka gene daniels said:

no seriously, what Jay wants to do is teach wheel trueing and he's
succeeding.
I try it here. I could just as well walk in front of a bus.

Perfectly harmless as long as the bus is stationary.

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful

aka Jobst Brandt said:

Tom Sherman said:

Quoted message said:

... I think the concept of pre-stressing has been here often, as
in pre-stressed concrete that has much in common with pre-stressed
spokes, except that concrete cannot support tension and spokes
cannot support compression without being pre-stressed.

Quoted message said:

That is not entirely true. When a compressive load is applied to
the top of a slab over a limited area, does it not result in tensile
stresses in the bottom portion of the slab below the "neutral axis"?

Bridges and other structural beams have tensile preload rods internally
to insure that the entire beam is in compression even though most of
the tensile elements are in the foot of the cross section.

Actually, post-tensioning is more common on larger structures, since
pre-stressing outside of items that can be made in a plant is not very
practical.

Quoted message said:

The
condition you cite would cause cracking (failure) but structures are
not designed or loaded that way if they follow prudent procedures and
of course the building code.

Specifically, ACI 318 "Building Code and Commentary".

Quoted message said:

Quoted message said:

And do concrete pavement slabs generally fail from fracture due to
tension in the bottom of the slab from a single load, or from
fatigue from many load cycles? The answer should be obvious to
anyone who know about pavement engineering.

They fail for insufficient reinforcement (steel) but they are not
pre-stressed in roads I have seen built other than bridges, and they
were pre-stressed.

All plain reinforcement does for slabs is to hold the pieces together
AFTER the slab cracks. Portland cement concrete will fracture at a
strain where the reinforcing steel is far below yield, and the
reinforcement does little to reduce fatigue stress.

There are some post-tensioned on-grade pavements, but they are rare.
Post-tensioned bridge decks (and floor slabs in mid-rise and high-rise
buildings are common).

Quoted message said:

Quoted message said:

Fiber reinforced concrete is not pre-stressed, and the fibers do
increase tensile strength (as evidenced by the fibers increasing the
rupture modulus for a given mix).

That's a composite and I am not familiar with that use. It seems
highly difficult, considering the elastic modulus of stone and fibers
one might use. I suppose asbestos might be a candidate. I don't know.

Fiber reinforced concrete floor slabs (in industrial applications) and
pavements are quite common. The fibers can be polymers or deformed
steel. The fibers make quite a difference in rupture modulus, which is
typically determined by breaking beam specimens in either third-point or
half-point loading.

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful

Ozark Bicycle said:

Tosspot said:

Ozark Bicycle said:

On Feb 28, 8:13 pm, "Skip" <[email hidden]> wrote:
>> Because JB is snotty and pedantic.
> Yes, but Jobst also knows his stuff cold and is a true expert on the bicycle
> wheel.
> You won't find a better "expert".
The above proves that, indeed, "you can fool some of the people all of
the time".

And looking in the mirror I'd agree with you.

Your mirror, your eyes, your visage. :-)

'Twas my point, fooling some of the people all of the time seems to be
trotted out by people trying to fool all of the people some of time,
which leads to suspect very little is believable in this world. Apart
from the fact that GWB was piloting the WTC planes by remote control
with Elvis acting as copilot. This is fact.

On a related note, I've had two driveside spokes fail in around 6,000
miles commuting. One failed at the knee, which I took to be an
undertensioned wheel (I built it), the second went a few millimetre
further up, shearing across the spoke around 3,000 miles after the
first. No signs of rubbing, or other defect, it looks like it just
broke. I'm sure these are up to full tension, but I don't have a
calibrated tensiometer to check.

Any ideas that could be checked without too much complexity? Wish I'd
kept it and photographed it now 🙁

Quoted message said:

I think that is generous criterion.

Jobst Brandt

Jobst,

add an essentail visual action scene for a hypothetical spoke graphic
tutorial?

g.daniels

sure. after insertion then after tensioning, lube and fill spoke holes
and cover 4 flange sides with Finish Line dry lube