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chainwheel, spokes, and rust

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Emanuel Berg

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Jul 11, 2015, 6:52:56 PM7/11/15
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1) Should you put something on the previously rusty
area after removing the rust, say with a steel
broomstick or steel wool? For example, lube spray
or a drop of oil?

2) Because you apply force to the pedals when the
crank arm is horizontally aligned, does that mean
that the chainwheel will be exposed to irregular
wear? Should you compensate for this by positioning
it in a new way whenever you replace the chain?
And, should you position the crank arm in a certain
way when you range the chain/position the
rear wheel?

3) Is it recommended to get the spokes straight, for
example with a pair of pliers and/or a vise? Or is
it enough to have them straighten out once in
the wheel?

--
underground experts united
http://user.it.uu.se/~embe8573

avag...@gmail.com

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Jul 11, 2015, 7:21:16 PM7/11/15
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Bergoid,


Spokes: read http://sheldonbrown.com/brandt/
Spokes can bend over another spoke yet tighten to spec torque
At the correct 'ping' tension for your building wheels.spokes are straight. Enough. For what you're doing.
Chain and chain rings are of different lengths so the contact you're looking at shifts down the chain and around the Chain ring. Worn chain rings may fall into a groove where one area will wear more than the others but maybe this is a function of other wobbly factors. This is an opinion not a mathematical certainty.

Rust. Oil and gas float on water, are permeable. Wax eg is less permeable to water

Tap the following image:
https://www.google.com/search?site=imghp&tbm=isch&source=hp&biw=1524&bih=692&q=specific+gravity+table&oq=specific+gravity&gs_l=img.1.6.0l10.2597.5526.0.11801.16.10.0.6.6.0.51.319.8.8.0....0...1ac.1.64.img..2.14.485.CkX6zXza6xw#tbm=isch&q=specific+gravity+table+water+equals+1&imgrc=aQzI9NFnUewgcM%3A
boiled* linseed oil thinned with odorless paint thinner applied with small brush then allowed to dry in hot sunny conditions...with metal also HOT before application that is where no humidity rest o surface then coated with the Rustoleum thinner and topcoat will ast for a long time in dry conditions less so in wet. In wet an additional coat of latex paint atop the Rusto topcoat.
Pn cycle bolts and chromes the thinned linseed with or without a Rusot paint should prevent further rusting...if not abraded...linseed hardens but not enough for self protection.
Linseed accumulated dirt, removes with acetone ect not thinner
For example, if your car is rusty then the above method will save it for another day.

If your bike is relatively new then a thinned coat will keep it that way.

If you can treat the linseed with the heat dry method, not live near Portland OR, the linseed hardening to a plastic substance straves rust deposits of O2 and H20. The deposits harden then when the area is examined or redone for more paint the deposits may pry out of the metal surface having shrunk, losing their grip. Small hard rocks of rust dirt.


John B. Slocomb

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Jul 11, 2015, 8:26:28 PM7/11/15
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On Sun, 12 Jul 2015 00:51:31 +0200, Emanuel Berg
<embe...@student.uu.se> wrote:

>1) Should you put something on the previously rusty
> area after removing the rust, say with a steel
> broomstick or steel wool? For example, lube spray
> or a drop of oil?
>
If the metal rusted than simply removing the rust is purely cosmetic
and the metal will rust again if not protected in some manner - paint,
oil, plating, other.

>2) Because you apply force to the pedals when the
> crank arm is horizontally aligned, does that mean
> that the chainwheel will be exposed to irregular
> wear? Should you compensate for this by positioning
> it in a new way whenever you replace the chain?
> And, should you position the crank arm in a certain
> way when you range the chain/position the
> rear wheel?

In theory no. The chain wraps around the chain wheel and, again
theoretically, the pressure on all the teeth engaged by the chain
exert the same pressure on the chain. You actually apply pressure to
the crank throughout about 1/4th to 1/3rd of the revolution.


>3) Is it recommended to get the spokes straight, for
> example with a pair of pliers and/or a vise? Or is
> it enough to have them straighten out once in
> the wheel?

Again your description is wanting, but if the spoke had a very gentle
bend it probably isn't necessary to straighten it but if it is a sharp
kink it is better to straighten it, or maybe not use it if it is very
badly bent.
--
cheers,

John B.

Emanuel Berg

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Jul 11, 2015, 9:30:29 PM7/11/15
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John B. Slocomb <johnbs...@geemail.com> writes:

> If the metal rusted than simply removing the rust is
> purely cosmetic and the metal will rust again if not
> protected in some manner - paint, oil,
> plating, other.

Oil I do have and I've noticed that one drop is often
enough for a small mechanism, so I'll do that in the
future when I remove rust.

Removing rust might be cosmetic (which isn't anything
to frown upon) but isn't it also functional as if
mechanical components get rusty they get more
difficult to interact with (e.g., screw heads, spoke
nipples, and so on)?

It is also more difficult to spot if something is
damaged if it is all rusty.

> In theory no. The chain wraps around the chain wheel
> and, again theoretically, the pressure on all the
> teeth engaged by the chain exert the same pressure
> on the chain. You actually apply pressure to the
> crank throughout about 1/4th to 1/3rd of
> the revolution.

Yeah, that's what I meant (?). But even so, the chain
distributes this evenly, you say. If so,
that's brilliant!

By the way, I don't know how I thought because you
can't do anything about this just because the chain is
gone, because the crank is attached to the
chain wheel. So if you are to do this, you are to do
this not every time you replace the chain, but every
time you open the crank! And tho there are many holes
around the chain wheel, the arm that holds the crank
seems to but locked by wielding (?) so there is no nut
or anything that can be easily removed so the crank
can be changed into another hole!

> if the spoke had a very gentle bend it probably
> isn't necessary to straighten it but if it is
> a sharp kink it is better to straighten it, or maybe
> not use it if it is very badly bent.

When it is badly bent I discard the spoke, for sure.
But by now I have many dislocated spokes and they are
all perhaps not sharply bent but they are far from
straight. It looks like a bouquet of
mechanical flowers!

I tried to group them together tightly with 3-4
strings in the hope of this getting the spokes in the
middle of the group straight if they were like that
for some time. But honestly I don't think that will
happen as I have to apply considerable force to get
even a single one straight. Perhaps a construction
with two parallel poles would do it? But then you
might as well put them into rims and be done with it.

The reason I ask is because I get the impression that
because they retain their "bentness" so stubbornly,
stretching them to fit in a rim is perhaps an illusion
and when you start using the bike they will somehow
twist their way back to an improper constitution?

Sir Ridesalot

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Jul 11, 2015, 11:33:20 PM7/11/15
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On Saturday, July 11, 2015 at 9:30:29 PM UTC-4, Emanuel Berg wrote:
>
> When it is badly bent I discard the spoke, for sure.
> But by now I have many dislocated spokes and they are
> all perhaps not sharply bent but they are far from
> straight. It looks like a bouquet of
> mechanical flowers!
>
> I tried to group them together tightly with 3-4
> strings in the hope of this getting the spokes in the
> middle of the group straight if they were like that
> for some time. But honestly I don't think that will
> happen as I have to apply considerable force to get
> even a single one straight. Perhaps a construction
> with two parallel poles would do it? But then you
> might as well put them into rims and be done with it.
>
> The reason I ask is because I get the impression that
> because they retain their "bentness" so stubbornly,
> stretching them to fit in a rim is perhaps an illusion
> and when you start using the bike they will somehow
> twist their way back to an improper constitution?
>
> --
> underground experts united
> http://user.it.uu.se/~embe8573

An image or two would be so very helpful to those who'd like to try and help you. We'd be able to see exactly what the situation is and whether or not it's something to be worried about.

Cheers

John B. Slocomb

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Jul 12, 2015, 8:12:19 AM7/12/15
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On Sun, 12 Jul 2015 03:29:03 +0200, Emanuel Berg
<embe...@student.uu.se> wrote:

>John B. Slocomb <johnbs...@geemail.com> writes:
>
>> If the metal rusted than simply removing the rust is
>> purely cosmetic and the metal will rust again if not
>> protected in some manner - paint, oil,
>> plating, other.
>
>Oil I do have and I've noticed that one drop is often
>enough for a small mechanism, so I'll do that in the
>future when I remove rust.
>
>Removing rust might be cosmetic (which isn't anything
>to frown upon) but isn't it also functional as if
>mechanical components get rusty they get more
>difficult to interact with (e.g., screw heads, spoke
>nipples, and so on)?
>
Certainly, but your initial comment about removing rust seemed to be
concerned with the looks of things.
I probably wouldn't reuse a spoke that had a sharp bend - you might
say kink - but if a wheels is laced "cross three" there will be a
rather noticeable bend there the spokes cross and I've reused those
spokes with no problems. But, I don't try for maximum tension on my
wheels either.

>I tried to group them together tightly with 3-4
>strings in the hope of this getting the spokes in the
>middle of the group straight if they were like that
>for some time. But honestly I don't think that will
>happen as I have to apply considerable force to get
>even a single one straight. Perhaps a construction
>with two parallel poles would do it? But then you
>might as well put them into rims and be done with it.
>
>The reason I ask is because I get the impression that
>because they retain their "bentness" so stubbornly,
>stretching them to fit in a rim is perhaps an illusion
>and when you start using the bike they will somehow
>twist their way back to an improper constitution?

I'm not sure what you are doing here. If the spoke has a sharp bend,
what might be called in English a "kink", I wouldn't use it but an
even gentle bend I wouldn't worry about and have never had a problem
with the spoke pulling straight. But really, spokes are probably the
cheapest part of a wheel, and probably the most important variable you
have in building a wheel. I would go for spokes that I felt
comfortable using.
--
cheers,

John B.

Emanuel Berg

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Jul 12, 2015, 12:52:57 PM7/12/15
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John B. Slocomb <johnbs...@geemail.com> writes:

> I probably wouldn't reuse a spoke that had a sharp
> bend - you might say kink - but if a wheels is laced
> "cross three" there will be a rather noticeable bend
> there the spokes cross and I've reused those spokes
> with no problems.

Aha! I didn't reflect why the spokes are like that.
Some of the wheels are laced but far from all, but on
the other hand I don't know from what rims all the
spokes came from.

Sir Ridesalot

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Jul 12, 2015, 3:40:15 PM7/12/15
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All bicycle wheels have the spokes "laced" except for radial spoked wheels. Radial lacing is very easily recognized by the fact that no spoke crosses another spoke. A radial spoke bicycle wheel looks like an old wooden wagon wheel.

Cheers

(null)

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Jul 14, 2015, 5:35:05 AM7/14/15
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In article <uob3qatttqf16jq7a...@4ax.com>,
John B. Slocomb <johnbs...@geemail.com> wrote:
>In theory no. The chain wraps around the chain wheel and, again
>theoretically, the pressure on all the teeth engaged by the chain
>exert the same pressure on the chain.

It's not the same. The pressure between roller and tooth
decays exponentially for a few teeth starting from the chain entry
(or exit). This is commonly referred to as GPLD (geometric progression
load distribution) in the literature. The rate of the exponential decay
depends on the slope of the tooth face the chain rollers are pressing.

The pressure decays exponentially at the same time as the
rollers engage teeth further and further away from the pitch circle of
the chainwheel. This only goes on up to the point where the rollers hit
the base circle (the bottoms between teeth) instead of the sides of
teeth. Rollers at this point rest on the chainwheel as though the
chainwheel had no teeth, and carry none of the load.

I'd worked out the numbers years ago, and if I remember
them correctly, the first three teeth of engagement carry most of the
load, with practically none being supported 6 teeth in.

-Luns
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