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Discussion Starter · #1 ·
Is. 80 chain wear when I should replace a 10speed chain?

I bought a KMC chain checker with .80mm wear checker

If .80mm wear is too much how can I measure .75mm wear using the chain checker
 

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Is. 80 chain wear when I should replace a 10speed chain?

I bought a KMC chain checker with .80mm wear checker

If .80mm wear is too much how can I measure .75mm wear using the chain checker
This will soon turn into an argument about what you shold have already done, and what one persons experience is vs. another and why it's better.

At this point, purchase a chain and install. If it doesn't skip, continue riding with new chain. If it does skip. Put new chain back in the packaging (making sure it's still greased/oiled). Install old chain and ride till drivetrain is shot then replace.

No need to replace drivetrain (yet) if your chain is somewhat over-worn but otherwise works well.

10 speeds (they say) is a bit more forgiving than higher geared bikes.

Is your bike a 1x? Maybe that has increased some wear with potentially more side loading.

I'd still say just get a new chain and see if it works. If not, ride the old stuff until it's junk.
 

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Uhh so basically wear out the chain till the tool says it needs replacing, replace the chain, if there's any skipping use the old chain and grind it down to junk?
I'd recommend installing a new chain now and see how it goes. If it's smooth don't worry and if it skips or grinds replace the cassette and/or chainring.
 

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Discussion Starter · #9 ·
Sorry if the message wasn't clear, the chain is still pretty fresh and doesn't indicate more than .80mm of stretch, what I meant to ask is that if .80mm is a good time to replace a 10speed chain
 

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Is. 80 chain wear when I should replace a 10speed chain?

I bought a KMC chain checker with .80mm wear checker

If .80mm wear is too much how can I measure .75mm wear using the chain checker
Sorry if the message wasn't clear, the chain is still pretty fresh and doesn't indicate more than .80mm of stretch, what I meant to ask is that if .80mm is a good time to replace a 10speed chain
I'm not sure of the units on the KMC checker... are they really in mm?

The units I know are:

0.5% (or 12-1/16" on a 12" ruler) for 11/12 speed
0.75% (or 12-3/32" on a 12" ruler) for 9/10 speed
 

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I change my 9/10/11 speed chains at .75 (measured with a Park CC-2 chain checker) and all of the drive trains have lasted for thousands of miles.

I just retired an 11 year old Stylo 3x9 crank and rings that had >10 chains swapped in over its lifetime. I left the last one on for quite a while (knowing it was getting swapped out) and turned the middle ring into shark teeth lol
 

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Discussion Starter · #14 ·
Umm the tool measures 0.8mm over 8 links, should I head down to the LBS and pick up one that does 0.75mm?

Also the tool doesn't drop into the chain even with a ton of force, I'm just wondering if theres that much of a difference between 0.75mm wear and 0.80mm wear that calls for a new chain tool
 

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Umm the tool measures 0.8mm over 8 links, should I head down to the LBS and pick up one that does 0.75mm?

Also the tool doesn't drop into the chain even with a ton of force, I'm just wondering if theres that much of a difference between 0.75mm wear and 0.80mm wear that calls for a new chain tool
Where is 0.75mm coming from in your question? Are you confusing it with 0.75%

Sorry, I don't know how your KMC checker works. The measurement could be "normalized" to 24 links even though it measures 8 links... no idea.

But regardless, you can let a 10 speed chain wear/stretch to 12-3/32" over 24 links which is usually stated as 0.75% stretch (even though it's mathematically 0.78%)
 

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0.80 is a little more worn than 0.75. Most people recommend replacing a chain @ 0.75 but I like to change them a bit sooner. I think you should replace it now.

I don't think you need a new chain tool but I'd calibrate it by checking it's measurement against a ruler.
 

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Where is 0.75mm coming from in your question? Are you confusing it with 0.75%

Sorry, I don't know how your KMC checker works. The measurement could be "normalized" to 24 links even though it measures 8 links... no idea.

But regardless, you can let a 10 speed chain wear/stretch to 12-3/32" over 24 links which is usually stated as 0.75% stretch (even though it's mathematically 0.78%)
OK... this was bugging me, so I did some math.

In the end, KMC's metric measurement over 8 links (or 4 inches) is about the same as old-school "percent" measurements.

(0.8 mm / 25.4 mm/in) / 4 in)*100% = 0.79%

Long story short, 0.8mm on a KMC checker is more-or-less the same as 0.75%.

If you're there, it's time to replace the chain.
 

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If your end goal is to determine if now is too early to change the chain, the answer is NO. It is NOT too early to change.

As mentioned previously, replace the chain and if you have issues with the drivetrain with the new chain, reinstall old chain until drivetrain wears out.

A new chain on a worn sprocket will skip. A new chain on a spocket that isn't too worn will work fine.



Additional information:
A chain changed early will give you the most possible use from the cassette and chainring. Usually two or 3 chains over the live of the gears (depending on maintenance). If you wail till a chain is worn out -you stand the chance of prematurely wearing the cassette and chainring. Unsure if you knew that was the purpose of changing a chain early.

Also, given the wear of your current chain, it is near enough to end of life (in chain speak) that if you choose not to replace now, you are still probably only a couple hundred miles from replacing......and how many rides does it takes to get 200 miles.
For reference, I had about 1100 miles on the chain I replaced. Previously I replaced the whole drive train, then got 1100 before changing the chain. I wanted to change it sooner -my Park tool gauge was barely .5%, but for $30 it isn't worth wearing out a cassette. Everybody has varied results with miles on a chain.
Depending on how hard they ride (masher vs. spinner). How often is chain clean and lubed. What conditions do they drive in.
 

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Discussion Starter · #19 ·
OK... this was bugging me, so I did some math.

In the end, KMC's metric measurement over 8 links (or 4 inches) is about the same as old-school "percent" measurements.

(0.8 mm / 25.4 mm/in) / 4 in)*100% = 0.79%

Long story short, 0.8mm on a KMC checker is more-or-less the same as 0.75%.

If you're there, it's time to replace the chain.
That's nice to hear, I'll probably replace when the tool drops halfway down the links, thanks for everyone's contributions.

So basically if i replace my chain earlier, aka before the tool can fully drop down into the links (0.75% wear), I'll get more life out of my cogs?
 

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That's nice to hear, I'll probably replace when the tool drops halfway down the links, thanks for everyone's contributions.

So basically if i replace my chain earlier, aka before the tool can fully drop down into the links (0.75% wear), I'll get more life out of my cogs?
These kind of checkers don't really go half-way -- they are more "go / no-go", but you can play with it. Use a ruler to check when 24 links are 12-1/16" for 0.5%.

But yes, your cogs will last slightly longer. Cost benefit wise, it depends on the price of the cassettes and chains you use. There are a million posts on this topic.
 
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