Chain Stretch

On Friday, September 15, 2017 at 5:59:57 AM UTC-7, Dennis Davis wrote:
In article ,
John B. wrote:

...

There seems to be three options. One, to use a ruler and measure from
pin to pin. Two to use a chain tool and measure from roller to roller.
Or three, to use some combination of the two.

Or perhaps there is a fourth - ignore the whole thing as a tempest in
a tea pot :-)

Chains are half an inch pitch. Put the chain under tension and
measure 24 links. At 12 and one eighth inches you're looking at 1%
elongation and you're likely to need to replace both the chain and
sprockets at the same time. At 12 and one sixteenth inches you're
at 0.5% elongation and you're likely to just need to replace the
chain.

Looks like I need to replace both the sprockets and chain on my
hybrid bike :-(

If your chainstays are short, you may need to measure just 20 links
and work with tenths and twentieths for the elongation.

Bear in mind that most riders will mainly use a few sprockets.
Those at the extreme end of the cassette get less use. You may find
the much used sprockets will not run well with a new chain even if
the old chain did not appear to have worn too much.

With chains getting ever more expensive, how do you prevent chain theft when out and about?

Joerg wrote:
On 2017-09-15 05:59, Dennis Davis wrote:
In article ,
John B. wrote:

...

There seems to be three options. One, to use a ruler and measure from
pin to pin. Two to use a chain tool and measure from roller to roller.
Or three, to use some combination of the two.

Or perhaps there is a fourth - ignore the whole thing as a tempest in
a tea pot :-)

Chains are half an inch pitch. Put the chain under tension and
measure 24 links. At 12 and one eighth inches you're looking at 1%
elongation and you're likely to need to replace both the chain and
sprockets at the same time. At 12 and one sixteenth inches you're
at 0.5% elongation and you're likely to just need to replace the
chain.


That's how I monitor it. Why buy a chain gauge when one already has a
sufficiently long ruler? After I clean a chain and before lubing it I
put a little pull on the chain by leaning my hand on a pedal, then hold
the ruler with the 0" mark to a link edge and read the value 12" down
the chain. I let my chains to about 0.8% which IME still allows same
cassette use. One chain accidentally went to 1% on a long hilly and very
dirty MTB ride (with KMC X10.93 it seems the wear accelerates a lot y
towards the end) and that ruined the cassette.


I assume you don't use 11 speed chains. .8 would mean your cassette was
likely shot.
I used to use a ruler pin to pin test but this doesn't really tell you if
the rollers are sloppy. A cheap chain gauge will test that.


Looks like I need to replace both the sprockets and chain on my
hybrid bike :-(

If your chainstays are short, you may need to measure just 20 links
and work with tenths and twentieths for the elongation.

Bear in mind that most riders will mainly use a few sprockets.
Those at the extreme end of the cassette get less use. You may find
the much used sprockets will not run well with a new chain even if
the old chain did not appear to have worn too much.


With many the cogs can be turned around which requires dremeling off
part of the wider spline for HG cassettes. Fast shifting is gone then
but on a road bike that never mattered much to me.

Yeah but you're a unique individual when it comes to what matters to you.
Sloppy shifting is not something I would put up with to save a few bucks.
Certainly not if it means hacking my cogs with a Dremel tool.


--
duane

On 9/15/2017 7:45 PM, Doug Landau wrote:

With chains getting ever more expensive, how do you prevent chain theft when out and about?

With a lock and chain, of course.


--
- Frank Krygowski

On Fri, 15 Sep 2017 07:44:29 -0500, AMuzi wrote:

On 9/15/2017 4:48 AM, John B. wrote:

I've been thinking about chain wear, sometimes called chain stretch,
and have done a bit of research on the subject.

One method is to lay the chain on a flat surface and measure the wear
over, perhaps 12 inches of chain length, from the head of one pin to
another. But modern multi speed chains are a bit more complex then the
old fashioned chains and the rollers on a modern chain are not
supported by the pins but by protrusions on the inner surface of the
inner links thus does the distance from roller to roller relate to
distance from pin to pin?

Another method is to ignore the pin to pin distance and simply measure
the roller to roller distance using a chain gauge. But I have also
read that when comparing roller to roller measurement to pin to pin
measurement there is not necessarily a correlation, or in other words
a pin to pin measurement might show one thing while the roller to
roller might show a totally different wear pattern. In addition I read
that in at least one case the roller to roller wear was not constant
and varied from place to place in the length of the chain

Brandt, I believe, wrote a treatise on chain measuring gauges and
argued that nearly all of them gave an incorrect figure for wear, or
perhaps, did it the wrong way.

So the question is what is the best system to use to avoid unnecessary
sprocket wear, assuming that sprockets cost more and are more trouble
to change than chains.

There seems to be three options. One, to use a ruler and measure from
pin to pin. Two to use a chain tool and measure from roller to roller.
Or three, to use some combination of the two.

Or perhaps there is a fourth - ignore the whole thing as a tempest in
a tea pot :-)

Interrupted sideplate chain does indeed wear faster than
full roller chain. However both economy of manufacture and
side flex (for index shifting) are better with interrupted
sideplates.

Generally, chain wear is measured with enough tension to
take up any slack, not merely laid out on a table.

The outer plates are joined by the rivet. The innies float
and exhibit wear. By measuring 24 rivets' worth of slop we
can effectively get an expanded 'vernier scale' of the very
small per-rivet clearance change. Since our functional
aspect for chain-to-sprocket efficiency is pitch, a
rivet-t-rivet measurement seems right to me and all our
gauges here measure that.

See section #8d.2 he
http://www.faqs.org/faqs/bicycles-faq/part3/

Yup, Brandt (in all his glory :-)

I've been using an 18" stainless scale (ruler) which assuming a 1%
wear limit is 3/16". (old eyes need big marks :-)

I recently came across another chain measuring scheme that seemed to
make good sense. Simply pull on the chain at the front of the chain
ring forwards to see how much it moves away from the sprocket teeth.
--
Cheers,

John B.

On Fri, 15 Sep 2017 07:56:27 -0700, Joerg
wrote:

On 2017-09-15 05:59, Dennis Davis wrote:
In article ,
John B. wrote:

...

There seems to be three options. One, to use a ruler and measure from
pin to pin. Two to use a chain tool and measure from roller to roller.
Or three, to use some combination of the two.

Or perhaps there is a fourth - ignore the whole thing as a tempest in
a tea pot :-)

Chains are half an inch pitch. Put the chain under tension and
measure 24 links. At 12 and one eighth inches you're looking at 1%
elongation and you're likely to need to replace both the chain and
sprockets at the same time. At 12 and one sixteenth inches you're
at 0.5% elongation and you're likely to just need to replace the
chain.


That's how I monitor it. Why buy a chain gauge when one already has a
sufficiently long ruler? After I clean a chain and before lubing it I
put a little pull on the chain by leaning my hand on a pedal, then hold
the ruler with the 0" mark to a link edge and read the value 12" down
the chain. I let my chains to about 0.8% which IME still allows same
cassette use. One chain accidentally went to 1% on a long hilly and very
dirty MTB ride (with KMC X10.93 it seems the wear accelerates a lot
towards the end) and that ruined the cassette.


The reason for the chain gauge is that the length of a chain, between
pins has little to do with the distance from roller to roller as the
rollers are not mounted on the pins.

Although to be honest Brandt in one of his essays argued that most
chain gauges don't measure the wear correctly either.
--
Cheers,

John B.

On Fri, 15 Sep 2017 10:30:56 -0500, Tim McNamara
wrote:

On Fri, 15 Sep 2017 16:48:59 +0700, John B wrote:

I've been thinking about chain wear, sometimes called chain stretch,
and have done a bit of research on the subject.

...snip...

So the question is what is the best system to use to avoid unnecessary
sprocket wear, assuming that sprockets cost more and are more trouble
to change than chains.

There seems to be three options. One, to use a ruler and measure from
pin to pin. Two to use a chain tool and measure from roller to roller.
Or three, to use some combination of the two.

Before I check the other answers: I use a chain measuring tool that goes
betweenthe rollers. This is on the assumption that what the cog teeth
see is the rollers, not the pins. I am assuming that the designers of
the tools (I have two, a Park and a Rollhof) took into account that the
tools measure two rollers at once, which may double the wear measurement
as the two rollers are being pushed in opposite directions. IIRC this
was Jobst's complaint about chain checkers.

Yes that was Brandt's objection to chain gauges, and see
http://www.fagan.co.za/Bikes/Csuck/STRETCH-MEASURE.htm

I also repeated my investigation into "stretch" of brand new chains on
the same chains indicated in "Norms when new", using a borrowed Park
Tool. This showed "stretch" of +0.20% to +0.40% (using a method to
interpret the Park reading). So the Park Tool is conservative, but
unneccesarily and wastefully so if the +0.5% criterion is used for
discarding chains. Park's own criterion of +1.0% gets around this to
some degree but leaves a wrong understanding of the issue. There are
fundamental geometric reasons why this device (and other generics
based on the same idea) will over-measure, and the degree of
over-measurement gets worse as the chain wears. I don't know if any
generics have some way of mitigating the problem and providing more
accurate measurements, but it would appear not.
--
Cheers,

John B.

On Fri, 15 Sep 2017 10:55:21 -0400, Frank Krygowski
wrote:

On 9/15/2017 5:48 AM, John B. wrote:

I've been thinking about chain wear, sometimes called chain stretch,
and have done a bit of research on the subject.

One method is to lay the chain on a flat surface and measure the wear
over, perhaps 12 inches of chain length, from the head of one pin to
another. But modern multi speed chains are a bit more complex then the
old fashioned chains and the rollers on a modern chain are not
supported by the pins but by protrusions on the inner surface of the
inner links thus does the distance from roller to roller relate to
distance from pin to pin?

Another method is to ignore the pin to pin distance and simply measure
the roller to roller distance using a chain gauge. But I have also
read that when comparing roller to roller measurement to pin to pin
measurement there is not necessarily a correlation, or in other words
a pin to pin measurement might show one thing while the roller to
roller might show a totally different wear pattern. In addition I read
that in at least one case the roller to roller wear was not constant
and varied from place to place in the length of the chain

Brandt, I believe, wrote a treatise on chain measuring gauges and
argued that nearly all of them gave an incorrect figure for wear, or
perhaps, did it the wrong way.

So the question is what is the best system to use to avoid unnecessary
sprocket wear, assuming that sprockets cost more and are more trouble
to change than chains.

There seems to be three options. One, to use a ruler and measure from
pin to pin. Two to use a chain tool and measure from roller to roller.
Or three, to use some combination of the two.

Or perhaps there is a fourth - ignore the whole thing as a tempest in
a tea pot :-)

I vote for "tempest in a tea pot."

I understand that measuring pin to pin might give slightly different
results than measuring using a chain gauge. But ISTM the difference
must be minimal. If (say) your standard for chain replacement is 1/2%,
and pin-to-pin gives 0.6% while chain gauge gave just under 0.5%,
wouldn't it usually be sensible to replace the chain anyway?

BTW, as Andrew said, I think it's worth while to put tension on the
chain, not lay it out on a table. If the chain's off, perhaps hanging it
from a nail would do. I measure mine on the bike and apply tension by
blocking the rear wheel while applying a little force to the cranks.

I am inclined toward the tea pot solution but something that got me
more interested in the question was an article, somewhere, that
suggested pulling forward on the chain on the centerline of the chain
ring with the chain on the smallest rear cog.

I tried it on two different bikes both of which had essentially the
same length chains (measured with a ruler) and got different results.
--
Cheers,

John B.

In article ,
Doug Landau wrote:

....

With chains getting ever more expensive, how do you prevent chain
theft when out and about?

The chains are the least of my worries. It's the high-end
road cassettes that keep me awake at night. Their price seems
justifiable only if they're hand-crafted out of titanium and mithril
by Tour de France winners. Yes Campagnolo, I mean your Super
Record road cassettes. Although I'm sure there are other exclusive
cassettes I could be using.

On a ride I have my butler follow me in a specially modified
Centurion tank[1]. If I stop for any reason, the priceless bicycle
is loaded into the tank and all battle armament is switched on and
set to "scan and destroy". The "scan and destroy" is a recent
feature installed by my weapons technicians.

It's an arms race out there. Gotta keep up. Times have changed
since the days of my granddad[2]. We Road Warriors need to maintain
a state of high alertness at all times.

[1] https://en.wikipedia.org/wiki/Centurion_(tank)

[2[ https://en.wikipedia.org/wiki/Bicycle_Thieves
--
Dennis Davis

On Sat, 16 Sep 2017 06:52:11 +0000 (UTC), Dennis Davis
wrote:

In article ,
Doug Landau wrote:

...

With chains getting ever more expensive, how do you prevent chain
theft when out and about?

The chains are the least of my worries. It's the high-end
road cassettes that keep me awake at night. Their price seems
justifiable only if they're hand-crafted out of titanium and mithril
by Tour de France winners. Yes Campagnolo, I mean your Super
Record road cassettes. Although I'm sure there are other exclusive
cassettes I could be using.

On a ride I have my butler follow me in a specially modified
Centurion tank[1]. If I stop for any reason, the priceless bicycle
is loaded into the tank and all battle armament is switched on and
set to "scan and destroy". The "scan and destroy" is a recent
feature installed by my weapons technicians.


The Butler? How improper. Most gentlemen would have the Coachman in
the tank while the Butler to hold the fort in the "Big House" while
the Master is abroad.

After all, if the Butler were to leave who would there be to defend
the wine cellar? And the Cheval Blanc 1947 is $33,781 a bottle.



It's an arms race out there. Gotta keep up. Times have changed
since the days of my granddad[2]. We Road Warriors need to maintain
a state of high alertness at all times.

[1] https://en.wikipedia.org/wiki/Centurion_(tank)

[2[ https://en.wikipedia.org/wiki/Bicycle_Thieves
--
Cheers,

John B.

On 9/15/2017 10:20 PM, John B. wrote:
On Fri, 15 Sep 2017 07:44:29 -0500, AMuzi wrote:

On 9/15/2017 4:48 AM, John B. wrote:

I've been thinking about chain wear, sometimes called chain stretch,
and have done a bit of research on the subject.

One method is to lay the chain on a flat surface and measure the wear
over, perhaps 12 inches of chain length, from the head of one pin to
another. But modern multi speed chains are a bit more complex then the
old fashioned chains and the rollers on a modern chain are not
supported by the pins but by protrusions on the inner surface of the
inner links thus does the distance from roller to roller relate to
distance from pin to pin?

Another method is to ignore the pin to pin distance and simply measure
the roller to roller distance using a chain gauge. But I have also
read that when comparing roller to roller measurement to pin to pin
measurement there is not necessarily a correlation, or in other words
a pin to pin measurement might show one thing while the roller to
roller might show a totally different wear pattern. In addition I read
that in at least one case the roller to roller wear was not constant
and varied from place to place in the length of the chain

Brandt, I believe, wrote a treatise on chain measuring gauges and
argued that nearly all of them gave an incorrect figure for wear, or
perhaps, did it the wrong way.

So the question is what is the best system to use to avoid unnecessary
sprocket wear, assuming that sprockets cost more and are more trouble
to change than chains.

There seems to be three options. One, to use a ruler and measure from
pin to pin. Two to use a chain tool and measure from roller to roller.
Or three, to use some combination of the two.

Or perhaps there is a fourth - ignore the whole thing as a tempest in
a tea pot :-)

Interrupted sideplate chain does indeed wear faster than
full roller chain. However both economy of manufacture and
side flex (for index shifting) are better with interrupted
sideplates.

Generally, chain wear is measured with enough tension to
take up any slack, not merely laid out on a table.

The outer plates are joined by the rivet. The innies float
and exhibit wear. By measuring 24 rivets' worth of slop we
can effectively get an expanded 'vernier scale' of the very
small per-rivet clearance change. Since our functional
aspect for chain-to-sprocket efficiency is pitch, a
rivet-t-rivet measurement seems right to me and all our
gauges here measure that.

See section #8d.2 he
http://www.faqs.org/faqs/bicycles-faq/part3/

Yup, Brandt (in all his glory :-)

I've been using an 18" stainless scale (ruler) which assuming a 1%
wear limit is 3/16". (old eyes need big marks :-)

I recently came across another chain measuring scheme that seemed to
make good sense. Simply pull on the chain at the front of the chain
ring forwards to see how much it moves away from the sprocket teeth.


The ancient rule of thumb for that is replace chain when a
4mm key will slip under the chain. Index shifting will be
poor when a 5mm key fits. You cannot stand on the pedals
when a 6mm key slides under the links. That's a very rough
gradient and not always accurate, but a starting point anyway.

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