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12" rule for chain wear?
#1
Being new to this hobby I ran across the 12" rule for chain wear. You pull the chain tight, right on the bike, measure 12 links, the distance between 25 pins, and if it measures 12" the chain is like new. If it measures 12 1/8" you throw the chain away and replace it.
 Something new to check out now. i imagine a worn chain causes shifting problems as well as drive train inefficiency. Do others here you use this method for determining chain wear??
"Where ever we go, there we are"
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#2
Yes , that is a known method for measuring chain wear pin to pin. No need to count links just use the ruler and check what you get at 12''. The pin center should be right at 12". If over 1/8" stretch chain is worn. Typically if chain is worn so are the sprockets...unless steel. Than if all still works well you may be able to keep going, if chain skips and shifting is poor , fix.
Never Give Up!!!
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#3
Everyone has a slightly different rule.  Mine is, more than 1/16" over 12": replace chain; more than 1/8" over 12" replace chain and rear cogs (cassette or freewheel); more that 1/4" over replace chain rings too.
Nigel
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#4
My approach is slightly different, on my personal bikes, if it ain't broke don't fix it. I check the rings for wear and the cogs for wear. Not a big problem for me as I have many bikes to choose from to ride and do not wear them out too soon. On most any refurb for resale bike, I put a new chain and rear cluster on as standard procedure. It takes a long time to wear out chain rings, alloy Mtb granny inner rings can go in a season or two depending on the rider. Chain suck would be indicative of this happening along with "mushrooming" the edges of the chainring. To much side to side play in a chain can cause bothersome chain throw when dropping to the smaller ring by the quick slap of the front derailleur on Sti type shifers. This whip type action may not always be noticed or measured by standard means spoken above. From a repair perspective and to try to save money for most on a budget' If they know the chain has never been replaced, test run the after doing the chain only to see how it goes. 2 chains per cluster in most cases for city use, one chain, one cluster for off-road use is the norm. I would mostly insist changing both at the same time and be done with it. I also check every bike's derailleur hanger alignment when ever dealing with the drivetrain before tuning the derailleurs. A decent cluster and chain to suit the average person can be had for $60 or under in most cases
There are two kinds of people in the world, "Those who help themselves to people, and those who help people!"
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#5
(03-13-2015, 05:47 PM)painkiller Wrote:  My approach is slightly different, on my personal bikes, if it ain't broke don't fix it. I check the rings for wear and the cogs for wear. Not a big problem for me as I have many bikes to choose from to ride and do not wear them out too soon. On most any refurb for resale bike, I put a new chain and rear cluster on as standard procedure. It takes a long time to wear out chain rings, alloy Mtb granny inner rings can go in a season or two depending on the rider. Chain suck would be indicative of this happening along with "mushrooming" the edges of the chainring. To much side to side play in a chain can cause bothersome chain throw when dropping to the smaller ring by the quick slap of the front derailleur on Sti type shifers. This whip type action may not always be noticed or measured by standard means spoken above. From a repair perspective and to try to save money for most on a budget' If they know the chain has never been replaced, test run the after doing the chain only to see how it goes. 2 chains per cluster in most cases for city use, one chain, one cluster for off-road use is the norm. I would mostly insist changing both at the same time and be done with it. I also check every bike's derailleur hanger alignment when ever dealing with the drivetrain before tuning the derailleurs. A decent cluster and chain to suit the average person can be had for $60 or under in most cases

I think there is a tool to check the rear derailer to see if it is bent, maybe the front one too? I think derailers can bend at the hanger and below as well? What is this tool called and  is it  inexpensive and easy to use?
"Where ever we go, there we are"
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#6
http://www.amazon.com/Park-Tool-Derailleur-Hanger-Alignment/dp/B0028YWHPW

I have a Sunlite version that I found on ebay for about $40-
Nigel
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#7
(03-13-2015, 06:12 PM)elmore leonard Wrote:  painkiller

I think there is a tool to check the rear derailer to see if it is bent, maybe the front one too? I think derailers can bend at the hanger and below as well? What is this tool called and  is it  inexpensive and easy to use?

I use a metal ruler, cheap, easy to read
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#8
(03-14-2015, 04:12 PM)1FJEF Wrote:  I use a metal ruler, cheap, easy to read

Please explain your process and what you do to correct the alignment.
Nigel
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#9
(03-14-2015, 06:09 PM)nfmisso Wrote:  
(03-14-2015, 04:12 PM)1FJEF Wrote:  I use a metal ruler, cheap, easy to read

Please explain your process and what you do to correct the alignment.

I'm an idiot, I was responding to checking chain wear! My point was that I don't use a wear gauge.
I use a Park Tool RD Aligner. It's weak spot is soft materials, I'm very careful to avoid bending the (IMO) soft stud that threads into the frame. Many find the stud bent upon inspection after only a couple of uses, the arm looks so massive & robust that people "go at it" too hard.

Sorry for the dumb post
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#10
no problem.  I was hoping to learn a new technique.  The Sunlite one I have has a hardened steel threaded post to thread into the hanger, and the "bending" rod, which threads into the post that threads into the hanger is also hardened steel - appear to be equivalent to a ASTM class 10.9 bolt.
Nigel
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#11
(03-15-2015, 01:25 AM)nfmisso Wrote:  The Sunlite one I have has a hardened steel threaded post to thread into the hanger, and the "bending" rod, which threads into the post that threads into the hanger is also hardened steel - appear to be equivalent to a ASTM class 10.9 bolt
I think Park Claims the threaded post is hardened but it is weak (soft, malleable, whatever) IMO. I have seen others note this also. The "bending rod" is excellent.
  Reply


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