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Chain Stretch...

Old 10-28-07, 03:01 PM
  #1  
kill.cactus
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Chain Stretch...

The mechanic at my LBS says I have "Quite a bit" of chain stretch.

I know this messes up the cassette, but will it mess up other (more important and expensive) items like the chainrings or derailleur?

Thanks

Edit: I guess the derailleur shouldn't be affected since it is only the replaceable cogs that come into contact with the chain.
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Old 10-28-07, 03:30 PM
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You should probably get a new chain. Check the condition of your rings and cassette, and replace those if needed.
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Old 10-28-07, 05:53 PM
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how long have you had your chain?
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Old 10-28-07, 06:08 PM
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Originally Posted by kill.cactus View Post
I know this messes up the cassette, but will it mess up other (more important and expensive) items like the chainrings or derailleur?
Yes, very easily.
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Old 10-28-07, 06:39 PM
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+1 "Yes, very easily."
I just got to drop some cash on a whole new drive train. After getting a new chain I learned that my cassette was jacked, after replacing my cassette I learned my middle chain-ring was jacked. Since I still had the cheapo crankset that you can't get the middle chainring off of, I bought a new bottom bracket and crankset. Granted, my plan all along was to upgrade things as they broke a 5-10 dollar chain-wear tool would have saved me a lot of trouble and lost riding time. If you don't want to invest in a wear-tool ( a good investment though because it is very quick to use) you can measure 12 full links in your chain, and however much farther over 12" it is, is how much your chain has stretched. Good luck and hopefully you haven't worn too many parts out.
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Old 10-28-07, 07:41 PM
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Man I hate to see what kind of problems I am going to run into when I finialy get my bike to the LBS for a one over. I have removed a few links but my chain has been on my bike since the day I got it about 15 years ago.
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Old 10-28-07, 08:36 PM
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hm thanks for the info. yeah I kind of cross posted across several forums thinking I wouldn't get too many responses :0

I have about 650 miles on the bike. I'm really not buying that my chain is stretched. Maybe my mechanic was just BSing me...

Although this is a MTB and I find myself mashing a lot...

Thanks for all the info!
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Old 10-28-07, 08:58 PM
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Originally Posted by kill.cactus View Post

I have about 650 miles on the bike. I'm really not buying that my chain is stretched. Maybe my mechanic was just BSing me...

Although this is a MTB and I find myself mashing a lot...

It's entirely possible to wear it out in 650 miles, but unusual in my opinion. If you don't trust your bike mechanic, get another. Also, get yourself a chain wear indicator like this:

https://www.parktool.com/products/det...=5&item=CC%2D3
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Old 10-29-07, 06:23 AM
  #9  
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I'm not a big fan of those Rohloff and Park chain gauges. They err early, causing unnecessary chain replacement. I find the ruler method much more accurate.

Here is a cut & paste of something I posted up on MTBR a little while back ( https://forums.mtbr.com/showthread.php?t=215824 ) :

Simple? Yes. Repeatable? Yes. Accurate? No.

Here's what I'm getting at.

This first picture I took from Rohloff's instruction manual and modified.

Ignore the chain gauge, for a moment.

To depict the gap (slop) between each roller and bushing, I drew an off-center circle inside of each roller.

Imagine rollers 2 through 9 each have perfect 1/2" pitch. The teeth of the chainring pull against the rollers in the same direction. The slop is displaced in the same direction.

Therefore, even though we don't know how much slop exists, it can be assumed it is equal at each link of the chain, and the 1/2" chain pitch is maintained.



Now drop the Rohloff Caliber 2 chain gauge in place (or Park's CC-2, a rip-off of the Rohloff that works in a similar fashion), and Roller number 1 is displaced in the opposite direction of all the others.

The guage is measuring slop that is invisible to the chainring and cog!

The result is this: the gauge sits flat against the chain, indicating it is worn. Stick a fork in it! Finito!

The Rohloff gauge, on the 'A' side, is measuring for 0.075mm per link, or about 0.59% chain stretch -- a bit above the .5% mark.



But wait, here comes my 15" ruler for a second opinion.

[A few quick note: The 15" ruler is an easy extension of Mike T.'s 12 1/16 method. I picked 15" because it should be ~25% more accurate (or 25% easier to read) than a 12" rule, due to its longer length.

Additionally, I converted to millimeters, because my brain has an easier time reading them. 368mm = brand new, and 370mm = 0.5% stretch.

Left in inches, the 0.5% wear point would be just past the 14-9/16" mark.

These combination inch/metric 15" rulers are available for about $5 at Office Max and Staples.]

In any case, there is really nothing difficult or imprecise about lining up the 0 mark with the top of one roller...



...and looking for the proper indication at the business end.

I've marked this ruler with a piece of white tape (370mm) to make my "NO GO" point obvious.



This same chain just declared "dead 'n buried" by the chain tool, is in fact only about halfway there, as judged by the ruler.



Just to verify, I removed this same chain and hung it against a yard stick.

In this case, I picked the 39.5" (79 link) mark to measure at. At exactly this length, each 0.1% of "stretch" translates to exactly 1.0mm of added length. Of course, this is an inch ruler, so that is really of no consequence.

However:

- The link we're measuring is indicated by the yellow arrow.
- New = 39.5" (or 1103mm), as indicated by the green arrow.
- 0.5% wear = 39 11/16" (or 1108mm), as indicated by the red arrow.

The yardstick confirms what the 15" ruler already told us: This chain is only halfway to the accepted point of being worn out.



So my point is simple: Chain gauges, whether Park or Rohloff, have to make some assumption about roller slop. At short lengths, the slop can be greater than the "chain stretch" the gauge is testing for.

The good news is the Rohloff Caliber 2 and Park CC-2 will always give a false "fail" early, so you'll never be stuck running a worn chain.

The bad news is that in doing so, the cost of your chains has just doubled.

There is really nothing difficult or imprecise about using a steel ruler. It's quick, it's inexpensive, and it measures exactly what you are trying to measure.


BTW -- if you want a well-designed drop 'n go gauge, check out the Shimano TL-CN40. I personally haven't used one, but it addresses the inherent weakness of Rohloff's chain gauge (and Park's rip-off of it), and if it is manufactured to the standards I expect of Shimano, it ought to be as accurate as a ruler!

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Old 10-29-07, 08:59 AM
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If you ride about once- twice a week you probably need a new chain once a year. They do stretch, if you change your chain out at this interval it will make your cassette and chain rings last longer. if you put a worn out chain on good casette and chainrings you will have shifting problems, if you put a new chain on worn cassette and chainrings it will wear the chain faster and you will have shifting problems. there is a tool you can buy to check for chain stretch, pricepoint.com of jensonusa.com
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Old 10-29-07, 09:09 AM
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Speedub.Nate:

Thanks very much for your detailed study. Fairly concise and right on the money. I do like the ruler as the better/accurate measurement. Do you figure eyeballing the roller center is accurate?
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Old 10-29-07, 09:45 AM
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Originally Posted by kill.cactus View Post
The mechanic at my LBS says I have "Quite a bit" of chain stretch.

I know this messes up the cassette, but will it mess up other (more important and expensive) items like the chainrings or derailleur?

Thanks

Edit: I guess the derailleur shouldn't be affected since it is only the replaceable cogs that come into contact with the chain.
It won't mess up your cassette. Your cassette is already messed up as are your rings. There is no real load placed on the jockey wheels so they should not have worn. Though, if you listen closely enough you'll be able to here them click and clack as the chain rides up the teeth then suddenly drops back down.

Your choices are to keep riding the drivetrain as is or replace the whole thing. In the meantime, buy a chain machine and get used to getting the dirt out of it on a regular basis as the griding of sand inside the rollers is what causes them to wear and this is what causes the chain to ENLONGATE (not stretch).

Originally Posted by Speedhub Nate


Now drop the Rohloff Caliber 2 chain gauge in place (or Park's CC-2, a rip-off of the Rohloff that works in a similar fashion), and Roller number 1 is displaced in the opposite direction of all the others.

The guage is measuring slop that is invisible to the chainring and cog!


It's stretching (and I mean this in the actual sense of the word) the chain to gauge the true distance. The chain feeding into the cassette is being tensioned by the derailleur. Any slop that the derailleur can pull out will absoluetly be relevant. I'll stick by my Park as I've let things get past the OTHER side of the gauge and have had poor results.

Last edited by BearSquirrel; 10-29-07 at 10:00 AM.
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Old 10-29-07, 09:53 AM
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Originally Posted by BearSquirrel View Post
It won't mess up your cassette. Your cassette is already messed up as are your rings. There is no real load placed on the jockey wheels so they should not have worn. Though, if you listen closely enough you'll be able to here them click and clack as the chain rides up the teeth then suddenly drops back down.

Your choices are to keep riding the drivetrain as is or replace the whole thing. In the meantime, buy a chain machine and get used to getting the dirt out of it on a regular basis as the griding of sand inside the rollers is what causes them to wear and this is what causes the chain to ENLONGATE (not stretch).
How can you deduce all this from "quite a bit"?
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Old 10-29-07, 11:36 AM
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Originally Posted by kenhill3 View Post
Speedub.Nate:

Thanks very much for your detailed study. Fairly concise and right on the money. I do like the ruler as the better/accurate measurement. Do you figure eyeballing the roller center is accurate?
I believe so. The follows the age-old "twelve and one-sixteenth" rule, but there is nothing magic about that precise number. So a few hairs off one direction or the other isn't catastrophic.

But like BearSquirrel wrote, it's necessary to ensure the chain is tensioned while making this measurement.

Originally Posted by BearSquirrel
It's stretching (and I mean this in the actual sense of the word) the chain to gauge the true distance. The chain feeding into the cassette is being tensioned by the derailleur.
I don't disagree, but with your Park gauge, you're measuring chain pitch (.5" per pin spacing) PLUS diverging roller slop (2x the actual value the cogs and rings see). This is where the false positive indication comes from.

On the other hand, the ruler (or the Shimano gauge I linked to) measure chain pitch only.

If you want to disagree with me, that's fine, I didn't make this stuff up. But you'll have to disagree with the Shimano page I linked to, as well. They managed to do a much more effective job of illustrating my point. https://cycle.shimano-eu.com/publish/...eck_if_my.html
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Old 10-29-07, 01:44 PM
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Originally Posted by born2bahick View Post
How can you deduce all this from "quite a bit"?
It's an educated guess. No one ever checks their chain until they wear their drivetrain and this whole thing is explained to them.
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Old 10-29-07, 05:52 PM
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Originally Posted by BearSquirrel View Post
It's an educated guess. No one ever checks their chain until they wear their drivetrain and this whole thing is explained to them.
650 miles is about right for a new chain with my XC riding. I've never had to replace the entire driveline in that amount of time though! What type riding are you doing that tears up drivetrains so bad?
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Old 10-29-07, 06:12 PM
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I'm not exactly tearing it up. Most of my miles (about 3/5) are just commuting (I sometimes prefer the MTB to the roadie). When I ride XC, I'm pretty hard on my chain, though. I often can't shift quickly enough and find myself unable to continue pedalling due to inclines and such. So that puts approximately 160lbs plus how much extra I'm pulling down on the frame (I'm guessing no more than 30 pounds) downwards force on the crankset and thus through the chain.

Hm... I'll keep this chain and when I'm really screwed with the stuff I'll replace the cassette and chain together. I'll probably replace my crankset as well sooner or later, as the stock one I have is some no-name Shimano model (I'm gonna replace it with Deore LX).

Thanks for all the information! I'll be sure and check out the chain before I start using it with a metric ruler.
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Old 10-30-07, 01:20 PM
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Get a cheap sette chain tool and be done wit it.
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Old 10-31-07, 05:59 AM
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Originally Posted by RIC0 View Post
Get a cheap sette chain tool and be done wit it.
That Sette is no different than the Rohloff and Park... other than it costs $6, causing me to suspect its quality.

If anybody just wants a reliable go/no-go gauge, pick up the Shimano for $40 at Universal Cycles and "be done wit it."
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Old 10-31-07, 06:03 AM
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Originally Posted by Speedub.Nate View Post
That Sette is no different than the Rohloff and Park... other than it costs $6, causing me to suspect its quality.

If anybody just wants a reliable go/no-go gauge, pick up the Shimano for $40 at Universal Cycles and "be done wit it."
The main difference between the two is the $30 shimano logo other than that they are the same I'm sure...

But as someone mentioned earlier. If you ride your bike 2 - 3 times a week a full drive train replacement should happen once a year no matter what. Good insurance when your 15 miles back into the woods.
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Old 10-31-07, 08:43 AM
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Originally Posted by RIC0 View Post
But as someone mentioned earlier. If you ride your bike 2 - 3 times a week a full drive train replacement should happen once a year no matter what. Good insurance when your 15 miles back into the woods.
I didn't read that anywhere in the thread.
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Old 11-01-07, 07:20 AM
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Originally Posted by godzsun1980 View Post
If you ride about once- twice a week you probably need a new chain once a year. They do stretch, if you change your chain out at this interval it will make your cassette and chain rings last longer. if you put a worn out chain on good casette and chainrings you will have shifting problems, if you put a new chain on worn cassette and chainrings it will wear the chain faster and you will have shifting problems. there is a tool you can buy to check for chain stretch, pricepoint.com of jensonusa.com
right cheer is where it was mentioned.....
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Old 11-01-07, 09:06 AM
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Rico, he said "change your chain" once a year, not your "entire drive train". A blanket
statement that says that you need to change your entire driveline every year,
if you ride several times a week is wrong.
There are to many individual factors involved to make that statement.

Last edited by born2bahick; 11-01-07 at 09:11 AM.
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Old 11-02-07, 03:07 PM
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Originally Posted by RIC0 View Post
The main difference between the two is the $30 shimano logo other than that they are the same I'm sure...
Rico, if you believe that, then I believe that you haven't read this thread. But thanks for your input!
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Old 11-05-07, 05:26 AM
  #25  
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Originally Posted by born2bahick View Post
650 miles is about right for a new chain with my XC riding. I've never had to replace the entire driveline in that amount of time though! What type riding are you doing that tears up drivetrains so bad?
When sanding, you can either increase the friction of the sand paper or increase the pressure you're using to remove more material.

Mile counts are a ridiculous way to decide when to change the chain. When to change will depend on the amount of grit that gets into the chain and the amount of load that is placed on it.

I'm pretty good about washing my chain every 2-3 rides now.
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