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Chain stretch

Old 01-05-21, 01:40 PM
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alecd
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Chain stretch

Here is my experience with chain stretch and using a chain stretch tool.

I was having problems with adjusting the cable tension on my rear derailleur (RD). It would not shift gears in either direction consistently.

I started firstly by checking chain wear. I checked with the Parktool 3.2 chain wear checker which has 0.5 and 0.75% wear indicators. The tool did not drop down into the chain at 0.5%, indicating that it was less than 0.5% worn (despite it being the original chain since 2018 and over 11K km).

The gear inner cable had been replaced about 9 months ago, but this time I replaced inner and then outers - having to partially unwrap two layers of handlebar tape to get to the handlebar outer! All to no effect.

I then completely overhauled my RD (Shimano 5800 SS). The RD was sluggish to return under main spring pressure once the main pivot bolt was tightened up. Removing the main pivot dust seal solved this problem. Also checked that the bolt rotated freely before re-assembly. Still no joy with gear adjustment.

I then de-greased / re-lubed the STI shifter with WD-40 and then LM-85(?) No change.

I had noticed that the Parktool chain checker did drop in if not up against one of the roller pins so I decided to double check. I realise now that the chain is so worn that the checker fouls the previous roller pin - and doesnít drop into the chain. Checking the chain wear with a steel rule gives a wear of +1/8Ē over 12Ē. IE +1% wear.

So, I left it too late before purchasing the Parktool chain checker, by which time the chain was already 1% worn and the tool was giving a false reading. A new chain is on its way!

Meanwhile, Iíve been thinking about chain wear consequences: A chain +1% (1/8Ē) stretched (worn) over 12Ē will probably be stretched 5/8Ē over its entire length. I have a short cage RD, so chain length is critical if you exceed the maximum cassette cog size (IE 32T): in small / small combination the chain may foul the RD as the chain wears, or in large / large when the chain is new, there may be little bend around the pulleys.

When the new chain arrives, Iíll take the difference in length between a well stretched and a brand new chain into consideration when replacing & checking the length of the chain before cutting.

Iím prepared for the fact that the cassette, jockey wheels and chainrings may be worn, so that the new chain will cause the cassette to skip, or the jockey wheels to be noisy or not guide the gear changes correctly. Not sure what the consequences of a worn chainring could be - bad chainring gear changes or chain drop / suck?

At some point (when no longer out of stock) Iíll probably replace the short cage with the medium cage (GS) version.

And finally, Iíll check chain wear often in future!
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Old 01-05-21, 01:59 PM
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At such wear ratio, it's a 99% certainty the cassette is toast and the new chain will skip (you have been riding with a worn chain for at least half of those 11K). Chainrings may or may not still be allright. I haven't noticed significant deterioration in front shifts due to chainring wear, but chainsuck is possible, although not certain. Jockey wheel wear is easy to detect visually, but no big deal in itself, at worst the gear changes won't be as crisp as they could possibly be, as long as there are still any teeth left on them jockey wheels.
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Old 01-05-21, 01:59 PM
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Throw that checker into the recycle bin. If you want to use a checker instead of a ruler buy the Pedros' or the new Park that is a copy of the Pedros. Amazon.com : Chain Checker Plus II, Black : Sports & Outdoors
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Old 01-05-21, 02:40 PM
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5/8" chain length difference is irrelevant to shifting efficiency, regardless of cage length. Unless you install a "half-link", you're adjusting your chain length in 1" increments in any case. Chain wear, on the other hand, can mess up shifting. As others have said, your cassette, and possibly your chainrings, are likely toast, so I would suggest just ordering a cassette now - you're going to need it. When I install a new cassette, I start with three new chains, and rotate them every few hundred miles, so there's always a well-cleaned and waxed chain to go back on when I take the old one off. I run this setup for ~12k-14k miles. I gave up on chain checkers, and use a decent steel ruler instead, but in general I don't bother with monitoring chain wear - I just keep rotating chains until the shifting starts to get squirrelly, then replace the lot. I replace one or both chainrings if they start making noise with a new cassette/chain set, so I never get to the point where they're negatively affecting shifting or causing chain suck - life's too short. This generally works out at new ring(s) every ~2 cassette/chain set replacements.
Once your drivetrain is back together, back to your shifting problem - has the shifting always been bad, or did it deteriorate gradually? How good are you at setting up and diagnosing the shifting (this isn't a dig - lots of people are content to let an LBS take care of this stuff. I know that I fecked around for years, adjusting stuff without any real understanding until some "aha" moment somewhere back in the mists of time). Did you crash or otherwise whack your RD, possibly resulting in a bent RD hanger? You recently replaced the cables and housing, but how many miles are on the shifters and the RD? A decent RD with routine care should last easily 50k miles, maybe even 100k (jockey wheels will likely need replacing at some point), but shifters will likely wear out before that, in which case cleaning/lubing won't do it. If your shifter and RD hanger are good, then "in-shifting" (small to large sprocket) problems are likely due to inadequate cable tension. Can you increase the tension by whatever adjusters are available to you, to at least get the in-shifting to behave? If out-shifting is an issue, either too much cable tension or cable friction (inadequate lube, corrosion, too sharp cable bends, cable fraying in the shifter) is usually the culprit.
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Old 01-05-21, 02:49 PM
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The recommended wear limit of 0.5% is only a little more than 1/4 inch over the full length. There is no need to consider it when cutting the chain to length, since only 1 inch changes can be made. Just use the big/big plus 1 inch method. If the ends that come together can't be joined, then another link or 1/2 inch is needed. Nothing bad will happen if the chain is a little loose in the little/little. That combo really shouldn't be used anyway.

Parktool.com has a lots of info on the subject.
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Old 01-05-21, 04:11 PM
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Originally Posted by Litespud View Post
....As others have said, your cassette, and possibly your chainrings, are likely toast, so I would suggest just ordering a cassette now - you're going to need it..........
Might as well ride the old parts into the ground and then replace w/new when absolutely needed.
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Old 01-05-21, 04:25 PM
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Originally Posted by Bill Kapaun View Post
Might as well ride the old parts into the ground and then replace w/new when absolutely needed.
Sounds like O.P. is already to the "absolutely needed" point.

I'm not as dogmatic as some about chain checkers. As long as I check regularly (gee, is it the beginning of the month already?) using the 0.5% side of the Park tool, I'll get enough advance warning to get down on my hands and knees, crook my neck, and look through my bifocals at the ruler to get a good measure of chain wear before it wears the cassette excessively.
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Old 01-05-21, 04:53 PM
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Originally Posted by alecd View Post
...I realise now that the chain is so worn that the checker fouls the previous roller pin - and doesnít drop into the chain. ..
This is part of the learning curve with the tool. Whenever I run into this at the non-profit shop, once a month or so, I bring the less experienced folks over to learn something. I always check a positive reading with a ruler before throwing away a chain.

Speaking of throwing away chains, don't throw away your old one until you have the parts you need to rebuild the drive train. You can limp along on the old one much easier than a new chain on a worn cassette.
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Old 01-05-21, 06:20 PM
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Originally Posted by Bill Kapaun View Post
Might as well ride the old parts into the ground and then replace w/new when absolutely needed.
Ordinarily I would agree, but the OP still has issues with his shifting that may or may not be related to drivetrain wear, and diagnosing these issues wonít be made any easier if his new chain is rattling about on a worn cassette. At least if he knows that these components are kosher, he can look elsewhere for the underlying cause
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Old 01-05-21, 08:55 PM
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Please stop saying 'chain stretch' and use the proper terminology that describes what happens in the best way: chain wear.
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Old 01-05-21, 08:58 PM
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More importantly did you have the derailleur hanger aligned?
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Old 01-06-21, 10:24 AM
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Originally Posted by pdlamb View Post
I'm not as dogmatic as some about chain checkers. As long as I check regularly (gee, is it the beginning of the month already?) using the 0.5% side of the Park tool, I'll get enough advance warning to get down on my hands and knees, crook my neck, and look through my bifocals at the ruler to get a good measure of chain wear before it wears the cassette excessively.
For the same reasons as you I have been doing this since the Pedro's Chain Checker Plus II came out as an early warning on the kids and my bikes 10 or more of which I keep in a loose rotation. Monthly check don't work for me, what has is a habit of checking every time a bike hits one of my three stands and this has never let me down.
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Old 01-06-21, 11:09 AM
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Originally Posted by cxwrench View Post
Please stop saying 'chain stretch' and use the proper terminology that describes what happens in the best way: chain wear.
Yeah, but ... the entire cycling world knows exactly what is meant by chain stretch. It is not remotely ambiguous.

OP, the cheap, simple, reliable tool for measuring chain wear (to keep cxwrench placated) is the good ol' steel tape measure. Measure from front of pin to front of the pin just over 12" away. 12" new. 12-1/16" - good time for a new chain. 12-3/32" - tired, a new chain may not work on that cassette. 12-1/8" - certified dead along with cogs and probably rings. (Now carefully using all your cogs and rings, it is possible to run everything to 12-1/8" and beyond, but shifting may be very compromised and no part of the system can be replaced with new. Everything will have to go when the time comes.
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Old 01-06-21, 02:58 PM
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Shifting only recently got to the point where it was shifting two cassette cogs. Since attempting to adjust the cable tension its impossible to adjust so that it shifts consistently in both up / down directions. I checked the derailleur hanger (thanks RJ!). I'll get a new chain, try adjusting again, test ride and probably order a new cassette. I hope the in-ability to adjust cable tension successfully is down to warn chain / and or cassette.
I'll probably go for a Pedro's chainchecker (that measures the rollers from the same side at each end!). My steel rule runs out of markings at 12" - which makes manual measurement even trickier.
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Old 01-06-21, 03:09 PM
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.. eg the chain is reluctant to shift to a lower gear (bigger cog). I increase the cable tension (RD cable adjuster anticlockwise) until the chain just shifts. It will then be reluctant to shift back to a higher gear. Releasing the cable tension (adjuster clockwise) effects the shift, but back to square one.
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Old 01-06-21, 04:23 PM
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Originally Posted by 79pmooney View Post
Yeah, but ... the entire cycling world knows exactly what is meant by chain stretch. It is not remotely ambiguous.

OP, the cheap, simple, reliable tool for measuring chain wear (to keep cxwrench placated) is the good ol' steel tape measure. Measure from front of pin to front of the pin just over 12" away. 12" new. 12-1/16" - good time for a new chain. 12-3/32" - tired, a new chain may not work on that cassette. 12-1/8" - certified dead along with cogs and probably rings. (Now carefully using all your cogs and rings, it is possible to run everything to 12-1/8" and beyond, but shifting may be very compromised and no part of the system can be replaced with new. Everything will have to go when the time comes.
The last time I was tuning my sister-in-laws bike (~2008 era) with Sora. I tried the chain checker and the 0.75% mark on the Park checker dropped through with daylight to spare. I looked at, and ultimately advised them to just keep going, but that it was going to need a full drivetrain at some point in the future. Also, the shifter cables were fraying and almost gone. Basically, it needed new everything....
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Old 01-06-21, 04:47 PM
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Originally Posted by alecd View Post
.. eg the chain is reluctant to shift to a lower gear (bigger cog). I increase the cable tension (RD cable adjuster anticlockwise) until the chain just shifts. It will then be reluctant to shift back to a higher gear. Releasing the cable tension (adjuster clockwise) effects the shift, but back to square one.
What you've got happening sounds an awful lot like cable drag in the housing. You might want to make sure your cable isn't dirty/rusty, or otherwise compromised. I've had worn out chains like yours still shift properly, but never when my cables got cruddy. Good luck,
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Old 01-07-21, 10:20 AM
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Originally Posted by Bigbus View Post
What you've got happening sounds an awful lot like cable drag in the housing. You might want to make sure your cable isn't dirty/rusty, or otherwise compromised. I've had worn out chains like yours still shift properly, but never when my cables got cruddy. Good luck,
I replaced cable inner & outer, so that should not be causing the problem. I thought perhaps the two layers of bar tape could cause the inner to drag in the outer? I re-used the original 105 shifter cable ferrule, as it has a special inner cable extension. At the other end, the cable exits from the RD towards the cable clamp at an acute angle when in high gear - perhaps fouling the RD body. But I donít think any of the above would cause the problem.

Otherwise, 4 chains arrived today - one for the 11speed in question and for 3 other bikes that are seemingly over 0.5% worn. Also ordered a new cassette! Iíll wait and replace the chain and cassette at the same time.
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Old 01-12-21, 03:42 PM
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Update

The new chain and cassette arrived recently. I removed old cassette and started to degrease the freehub before fitting the new cassette, at which point the freehub became loose! A 10mm hex went straight through the hub while the 12mm didnít locate. So it must be an 11mm hex to remove, which I have ordered. However, the actual freehub bolt is NOT loose. It seems the two halves of the hub body itself have come undone. Once the 11mm hex arrives, Iíll take it off to see whats going on, and what type of freehub it is!. Meanwhile I have fitted the new cassette on my summer wheels (Cero AR30ís). The hubs of the Bontrager wheels in question were already damaged after less than 1 years riding - both cones pitted and non drive side cup also pitted. I replaced both cones on previous service. Iíve yet to have a good look at them since recent disassembly, but these hubs were probably mal-adjusted from new - causing the pitting. I have disassembled and re-assembled a freehub body and a freewheel before, so I might have another go with this one, or order a new freehub - if I can confirm which one to order (perhaps a Bontrager Race Lite). Either way the summer wheels are going to get a winter bashing. Iíll fit the 11speed chain and test the new drivetrain tomorrow. Perhaps the original shifting problem was due to this disintegrating freehub!

Otherwise two other chains replaced ok, but 7 speed freewheel wobbling and hub noisy / clicky while peddling. Noticed that the solid axle was bent. So a freewheel remover tool and replacement axle on its way. By the way, this bike is 10 years old with possibly 22k km on it and less than 0.75% chain wear nor any service before I changed the chain. At least it will get both hubs serviced now.

Pedros chainchecker also ordered! Iíve also had a look at Hambiniís chainwear check method with steel rule. Seems easier to check 10Ē (20 links) in mm. 254mm = no wear. 256mm = 0.75% wear. Still need good light / good glasses / steady hand!
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Old 01-13-21, 07:59 AM
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Originally Posted by cxwrench View Post
Please stop saying 'chain stretch' and use the proper terminology that describes what happens in the best way: chain wear.
'Stretch' has a wider meaning than you are allowing, try out: Cambridge dictionary.

I have a good memory, but a restricted recall that is easily overloaded, and I will use alternatives when the darn 'proper' word refuses to download from my memory...
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Old 01-14-21, 02:26 PM
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Update 2.
I can report that barring a road test, the new chain, cassette, and change of wheels (freehub) has solved the problem. Thanks for all your comments.
Meanwhile still waiting for freewheel remover tool to service the 7-speed Ridgeback. Front wheel serviced ok. About time after 10 years!
4th and last chain to fit will be my British Eagle / Harry Quinn mid 80's steel bike. Again cassette may be toast, but this time I'll just change the chain and road test first.
Pedro's chain checker arrived. Not sure how the 3-point checker works, but I presume that if the tool does NOT drop into the chain then it is not worn.
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Old 01-24-21, 03:59 PM
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Update 3.
All road tested ok. I'm now going to refit the winter wheels with the old cassette - to see if it was worn.
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Old 01-30-21, 02:37 PM
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I've refitted the winter wheels, and the old cassette seems to be OK despite 1% wear on the chain.
So the root of the problem was a loose freehub mounting bolt, and luckily descovered 1% worn chain.

Parktool freewheel remover tool has arrived, but it might be a while before I try it out!

Thanks again.
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