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Does chain stretch really exist?



 
 
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  #1  
Old March 4th 05, 05:14 PM
Ken Marcet
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Default Does chain stretch really exist?

I have just measured 2 "old" 3/32 chains using the method described on
Sheldons page he
http://sheldonbrown.com/chains.html
One just came of of the "western flyer" I am rehabing,
and the other came off my ofter beater road bike,
and I could not even measure the "stretch" not even 1/32 of an inch.
Is this a myth created and spread by the makers of chain to get us to buy
more chain?

Ken

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  #2  
Old March 4th 05, 05:29 PM
Neil Brooks
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"Ken Marcet" wrote:

I have just measured 2 "old" 3/32 chains using the method described on
Sheldons page he
http://sheldonbrown.com/chains.html
One just came of of the "western flyer" I am rehabing,
and the other came off my ofter beater road bike,
and I could not even measure the "stretch" not even 1/32 of an inch.
Is this a myth created and spread by the makers of chain to get us to buy
more chain?


Quoting the very page you cited (and letting Sheldon save his voice):

==
"Chain "Stretch"

Cyclists often speak of chain "stretch", as if the side plates of an
old chain were pulled out of shape by the repeated stresses of
pedaling. This is not actually how chains elongate. The major cause of
chain "stretch" is wearing away of the metal where the rivet rotates
inside of the bushing (or the "bushing" part of the inside plate) as
the chain links flex and straighten as the chain goes onto and off of
the sprockets. If you take apart an old, worn out chain, you can
easily see the little notches worn into the sides of the rivets by the
inside edges of the bushings. With bushingless chains, the inside edge
of the side plate hole that rubs against the rivet has a smooth radius
instead of a sharp corner. This probably contributes to the greater
durability of bushingless chains.
==

It happens . . . and if it doesn't happen to you, it could happen to
somebody that you love . . . .
  #3  
Old March 4th 05, 05:47 PM
RonSonic
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On Fri, 4 Mar 2005 11:14:36 -0500, "Ken Marcet" wrote:

I have just measured 2 "old" 3/32 chains using the method described on
Sheldons page he
http://sheldonbrown.com/chains.html
One just came of of the "western flyer" I am rehabing,
and the other came off my ofter beater road bike,
and I could not even measure the "stretch" not even 1/32 of an inch.
Is this a myth created and spread by the makers of chain to get us to buy
more chain?


There is no meaningful stretch, only wear in the bearings that allow the chain
to lengthen.

Just measure them and replace when worn. It is just that simple.

I don't know about any myths spread by the chain makers. I'd imagine they would
be horrified if you accused their products of being so damn cheap and shoddy
that they could be stretched by a cyclist. They are aware that their products
wear.

Ron




  #4  
Old March 4th 05, 05:51 PM
Art Harris
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Ken Marcet wrote:

I could not even measure the "stretch" not even 1/32 of an inch.


Not a myth. But since most bikes are never ridden even 1,000 miles, the
chain on an older bike may not be elongated. Make sure the chain is
under some tension when measuring. It's best to measure while the chain
is on the bike and on the big chainring.

Art Harris

  #5  
Old March 4th 05, 05:59 PM
Calvin Jones
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As described by Sheldon Brown, chains wear at the pivot points.
However, there was one chain I saw that had some interesting wear
features. This was a well used chain that had peened rivets. The
peening was double parallel marks, looking somewhat like (=). This
chain had several rivets with peening marks not parallel, but rather
they were pointing off at an angle, more or less like (//). Normally
the rivet is a tight press fit into the outer plate. However, it may
have been that these holes became deformed and allowed the rivet to
rotate. I wish I still had this chain sample. It had failed during a
ride, and the rivets were easily removed, which may be a further
indication of side plate deformity.

  #6  
Old March 4th 05, 06:18 PM
Neil Brooks
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And here it is, folks . . . in all its photographic glory:

http://www.execulink.com/~dtierney/w...m#Chain%20wear

or http://tinyurl.com/ysep8
  #7  
Old March 4th 05, 06:41 PM
Werehatrack
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On Fri, 4 Mar 2005 11:14:36 -0500, "Ken Marcet"
may have said:

I have just measured 2 "old" 3/32 chains using the method described on
Sheldons page he
http://sheldonbrown.com/chains.html
One just came of of the "western flyer" I am rehabing,
and the other came off my ofter beater road bike,
and I could not even measure the "stretch" not even 1/32 of an inch.
Is this a myth created and spread by the makers of chain to get us to buy
more chain?


Chain components don't stretch, but the pins, plates and rollers wear
in a manner that causes the measured length over a number of links to
increase. It's *very* real, but it's not uncommon for bikes that have
not been ridden much to still have no measurable "stretch" even though
they're many years old. Your WF probably falls into that category.

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  #8  
Old March 4th 05, 06:57 PM
(Pete Cresswell)
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Per Neil Brooks:
http://www.execulink.com/~dtierney/w...m#Chain%20wear


Nice piece of work.

Thanks.
--
PeteCresswell
  #9  
Old March 4th 05, 07:01 PM
A Muzi
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Bicycles which are never ridden can't exhibit wear.

A Western Flyer is the sort of bike which commonly is ridden
for a few day after purchase and then parked in the back of
the garage until one day it lands on the curb.

Which is the point where you came in.

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




Ken Marcet wrote:
I have just measured 2 "old" 3/32 chains using the method described on
Sheldons page he
http://sheldonbrown.com/chains.html
One just came of of the "western flyer" I am rehabing,
and the other came off my ofter beater road bike,
and I could not even measure the "stretch" not even 1/32 of an inch.
Is this a myth created and spread by the makers of chain to get us to buy
more chain?

  #10  
Old March 4th 05, 07:04 PM
Zog The Undeniable
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Default

Art Harris wrote:


Not a myth. But since most bikes are never ridden even 1,000 miles, the
chain on an older bike may not be elongated. Make sure the chain is
under some tension when measuring. It's best to measure while the chain
is on the bike and on the big chainring.


Also best to measure it clean, in case grit and sludge has taken up the
slack between the pins and bushes.
 




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