Does chain stretch really exist?

[Ken Marcet]

I have just measured 2 "old" 3/32 chains using the method described on
Sheldons page here:
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

--
More of my mind dribblings: http://mind-dribble.blogspot.com/
And my homepage: http://kcm-home.tripod.com/

 

[Neil Brooks]

"Ken Marcet" <[email protected]> wrote:

>I have just measured 2 "old" 3/32 chains using the method described on
>Sheldons page here:
>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 . . . .

 

[RonSonic]

On Fri, 4 Mar 2005 11:14:36 -0500, "Ken Marcet" <[email protected]> wrote:

>I have just measured 2 "old" 3/32 chains using the method described on
>Sheldons page here:
>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

 

[Art Harris]

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

 

[Calvin Jones]

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.

 

[Neil Brooks]

And here it is, folks . . . in all its photographic glory:

http://www.execulink.com/~dtierney/wmc/SRAM/chains2.htm#Chain wear

or http://tinyurl.com/ysep8

 

[Werehatrack]

On Fri, 4 Mar 2005 11:14:36 -0500, "Ken Marcet" <[email protected]>
may have said:

>I have just measured 2 "old" 3/32 chains using the method described on
>Sheldons page here:
>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.

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.

 

[A Muzi]

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 here:
> 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?

 

[Zog The Undeniable]

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.

 

[Tim McNamara]

"Ken Marcet" <[email protected]> writes:

> I have just measured 2 "old" 3/32 chains using the method described
> on Sheldons page here: 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?

No.

 

[Ted]

In article <[email protected]>,
"Calvin Jones" <[email protected]> wrote:

> 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.

Here's a quote from http://www.diamondchain.com/support/techfaqs.php

11. Roller Chain failure - Broken, Bent, or Turned Pins

Chain failed in service. Inspection of failure revealed a bent or broken
pin, or pins that appear to be turned within the outer (pin) link
plates.

ANSWER: Shock loads that are greater than the components yield
strength, approximately 55-60% of the chains tensile, are the cause of
this problem. Changing to High Strength series chain, increasing the
chain size (i.e. #80 up to #100), or working to eliminate the shock load
on the drive system are some of the ways the chain's performance may be
improved. 

--
Ted Bennett
Portland, OR

 

[Tom Sherman]

Tim McNamara wrote:

> No.

Please try to be more concise!

--
Tom Sherman - Earth

 

[Bruce Graham]

In article <4228a307.0@entanet>, [email protected] says...
> > 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.
>
and rust if an old bike

 

[[email protected]]

Bruce Graham writes:

>>> 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.

> and rust if an old bike

Of course neither of these cleanings will have an effect on what is
measured, rust being superficial and grit greater than a few microns
being sidplaced from the places where wear occurs.

Measuring on the bicycle, center an inch mark on a pin (its easier
than guessing where the edge of a pin is) and see how far it is off
the inch mark at 12 inches. This gives a good indication of chain
wear to the accuracy this operation demands.

http://www.sheldonbrown.com/brandt/chain-care.html

Jobst Brandt
[email protected]

 

[[email protected]]

Bruce Graham writes:

>>> 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.

> and rust if an old bike

Of course neither of these cleanings will have an effect on what is
measured, rust being superficial and grit greater than a few microns
being displaced from the places where wear occurs.

Measuring on the bicycle, center an inch mark on a pin (its easier
than guessing where the edge of a pin is) and see how far it is off
the inch mark at 12 inches. This gives a good indication of chain
wear to the accuracy this operation demands.

http://www.sheldonbrown.com/brandt/chain-care.html

Jobst Brandt
[email protected]