Roller Wear in Chains?

Guy Chapman wrote:

On Mon, 28 Mar 2005 16:06:34 -0500, Sheldon Brown
wrote in message
:


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 writes:

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.

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.

Leo Lichtman writes:

"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?

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

I 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.
^^^^^^^^^^^^^^^^

Leo Lichtman asked:

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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Thanks!