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Chain Stretch



 
 
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  #1  
Old September 15th 17, 10:48 AM posted to rec.bicycles.tech
John B.[_3_]
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Posts: 3,652
Default Chain Stretch


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 :-)
--
Cheers,

John B.

Ads
  #2  
Old September 15th 17, 01:44 PM posted to rec.bicycles.tech
AMuzi
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Posts: 9,075
Default Chain Stretch

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/

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


  #3  
Old September 15th 17, 01:59 PM posted to rec.bicycles.tech
Dennis Davis[_2_]
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Posts: 25
Default Chain Stretch

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.
--
Dennis Davis
  #4  
Old September 15th 17, 02:16 PM posted to rec.bicycles.tech
[email protected]
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Posts: 6,269
Default Chain Stretch

cure or find dry seasoned 1x4 or 6 ...poss in thick 1.25 hardwood longer than your chain

mark a new chain's length.

measure stretch cleaning, and removing, chain, lubricate n let vertically hang into a container catching drips for 24-36 hours.

measure total chain stretch divide into whatever , 2 feet, of average stretch or ...including the new chain measure.

  #6  
Old September 15th 17, 03:55 PM posted to rec.bicycles.tech
Frank Krygowski[_4_]
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Posts: 5,472
Default Chain Stretch

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.

--
- Frank Krygowski
  #7  
Old September 15th 17, 03:56 PM posted to rec.bicycles.tech
Joerg[_2_]
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Posts: 4,699
Default Chain Stretch

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.


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.

--
Regards, Joerg

http://www.analogconsultants.com/
  #8  
Old September 15th 17, 04:30 PM posted to rec.bicycles.tech
Tim McNamara
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Posts: 6,723
Default Chain Stretch

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.
  #9  
Old September 15th 17, 08:43 PM posted to rec.bicycles.tech
[email protected]
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Posts: 6,269
Default Chain Stretch

On Friday, September 15, 2017 at 8:55:27 AM UTC-6, 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.

--
- Frank Krygowski


I use a steel rule from Nbar with a spoke oblongness looking a lot lie the new tick puller.

the 1x6 is marked at foot or mm intervals whereon chain is laid aside.

calling your attention the the unfortunate fact the new chain has 4 ruined links

in chain's midsection.

reach for the pins you stocked last year n a moderately worn best section of stocked used chain....also found with the board.
  #10  
Old September 16th 17, 12:37 AM posted to rec.bicycles.tech
[email protected]
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Posts: 3,346
Default Chain Stretch

On Friday, September 15, 2017 at 6:25:31 AM UTC-7, duane wrote:

https://www.amazon.ca/s/?ie=UTF8&key...l_9msfsi9pxm_b


Are you insinuating that the people that build chains might have a good idea of how to test them? For shame! That's for people like Frank to do.

 




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