Re: Roller Wear in Chains?

I just did a quick calculation. Your wear limit of .065 in the length of
the chain amounts to only .0005" per link. That amount of wear on the
outside of the rollers probably would not show to the unaided eye.

Leo Lichtman said:

I just did a quick calculation. Your wear limit of .065 in the
length of the chain amounts to only .0005" per link. That amount of
wear on the outside of the rollers probably would not show to the
unaided eye.

Fore 1% wear, one inch of chain elongates 0.010"
(1/8" per twelve pins)

Actually it's twice that because elongation occurs in every second
roller pair, two rollers in a link always being in pitch while the
link between roller pairs elongates. 0.01" would be readily visible
on a roller but that isn't the point. Roller wear is not additive
over a length of chain. Only the longitudinal position of the
bearings on which the rollers run has an effect on sprocket wear.

[email hidden]

Could you explain what you mean by "in pitch?" Thanks.

[email hidden] asked:

Quoted message said:

Could you explain what you mean by "in pitch?" Thanks.

The "pitch" of a chain is the distance from the center of one roller to
the center of the next one. On all modern bicycle chains, this distance
is supposed to be exactly 1/2 inch.

As the chain elongates, every other roller pair (the pairs connected by
'outside' plates) get slightly farther apart due to wear-induced slop in
the moving parts. This causes a mis-match to the spacing of the
sprocket teeth.

See also: http://sheldonbrown.com/chains

Sheldon "Stretch" Brown
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Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
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http://captainbike.com http://sheldonbrown.com

On Mon, 28 Mar 2005 16:06:34 -0500, Sheldon Brown
<[email hidden]> wrote in message
<[email hidden]>:

Quoted message said:

As the chain elongates, every other roller pair (the pairs connected by
'outside' plates) get slightly farther apart due to wear-induced slop in
the moving parts. This causes a mis-match to the spacing of the
sprocket teeth.

Which leads in turn to an expensive trip to the bike shop, especially
if you're running 61/52/39 TA rings on a 130PCD chainset...

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

85% of helmet statistics are made up, 69% of them at CHS, Puget Sound

"Sheldon Brown" wrote: As the chain elongates, every other roller pair (the
pairs connected by 'outside' plates) get slightly farther apart due to
wear-induced slop in the moving parts. This causes a mis-match to the
spacing of the sprocket teeth.
^^^^^^^^^^^^^^^^
Since approximately half the cogs have an odd number of teeth, does this
result in more rapid wear than on the even numbered ones?

<[email hidden]> wrote: Fore 1% wear, one inch of chain
elongates 0.010" (1/8" per twelve pins) Actually it's twice that because
elongation occurs in every second roller pair, two rollers in a link always
being in pitch while the link between roller pairs elongates. 0.01" would be
readily visible on a roller(clip)
^^^^^^^^^^^^^^^
The only point I was trying to make was that, since pin/hole wear is
cumulative, an amount of chain stretch which is easily visible would be
caused by an amount of wear which, if it occurred on the outside of the
rollers, would not be noticed.

Guy Chapman said:

On Mon, 28 Mar 2005 16:06:34 -0500, Sheldon Brown
<[email hidden]> wrote in message
<[email hidden]>:

Quoted message said:

As the chain elongates, every other roller pair (the pairs connected by
'outside' plates) get slightly farther apart due to wear-induced slop in
the moving parts. This causes a mis-match to the spacing of the
sprocket teeth.

Which leads in turn to an expensive trip to the bike shop, especially
if you're running 61/52/39 TA rings on a 130PCD chainset...

You could always buy a cheap Dotek crank such as the 62/52/39 that came
on my RANS Rocket.

--
Tom Sherman - Earth (Downstate Illinois, North of Forgottonia)

Leo Lichtman said:

Quoted message said:

Fore 1% wear, one inch of chain elongates 0.010" (1/8" per twelve
pins) Actually it's twice that because elongation occurs in every
second roller pair, two rollers in a link always being in pitch
while the link between roller pairs elongates. 0.01" would be
readily visible on a roller.

Quoted message said:

The only point I was trying to make was that, since pin/hole wear is
cumulative, an amount of chain stretch which is easily visible would
be caused by an amount of wear which, if it occurred on the outside
of the rollers, would not be noticed.

On a cylindrical surface such deviations are visible but they make no
difference because they don't change the roller pitch that is given by
inner side plates and between roller pairs by pin and bore wear, the
real dimension of interest.

[email hidden]

Leo Lichtman said:

Quoted message said:

"Sheldon Brown" wrote: As the chain elongates, every other roller
pair (the pairs connected by 'outside' plates) get slightly farther
apart due to wear-induced slop in the moving parts. This causes a
mis-match to the spacing of the sprocket teeth.

Quoted message said:

Since approximately half the cogs have an odd number of teeth, does this
result in more rapid wear than on the even numbered ones?

That might be the case for a fixed gear bicycle but with derailleur
shifting that makes no difference.

[email hidden]

I said:

As the chain elongates, every other roller pair (the
pairs connected by 'outside' plates) get slightly farther apart due to
wear-induced slop in the moving parts. This causes a mis-match to the
spacing of the sprocket teeth.
^^^^^^^^^^^^^^^^

Leo Lichtman asked:

Quoted message said:

Since approximately half the cogs have an odd number of teeth, does this
result in more rapid wear than on the even numbered ones?

It would only make a difference if you have even-numbered sprockets on
both end of the drive train, and were scrupulous about maintaining the
phase relationship between the chain links and sprocket teeth.

I do pay attention to this for tandem synch chains, otherwise, it's not
practical.

This is, however one of the advantages of the old 1" pitch "skip-link"
chains, because the wear is the same for every link. You never see
these worn out. The one on my 1916 Mead Ranger is probably original,
and is still going strong.

Sheldon "The 3/16 Inch Thickness Doesn't Hurt Either" Brown
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Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

Wear is concentrated on the pins too. Rollers have much lower wear rates due to diameter.

Thanks!