KMC Chains, specs, speeds and wear-resistance

[wafter]

Rightly or wrongly I've fallen into the habit of exclusively buying KMC chains. I think this was initially because they offered quick links when Shimano didn't; but they seem well-regarded, are used by many OEMs and my experiences have been good.

In the 8, 9 and 11 speed fitments I require there are a lot of variants and choosing can be difficult. Having gone down this rabbithole again I have a better understanding so thought I'd share as an aid-memoir that hopefully might be of use to others

KMC do two main lines for 8-12sp bikes; "X" and "E"; the number of speeds denoted by an appropriate suffix - for example X8, X9 etc for 8 and 9 speed X-series chains repectively.

The X-series are the core range, the E-series are aimed at E-bikes; I think the big difference being a different pin configuration in the latter to handle more load. They're all offered in various different (aesthetic) finishes which won't be covered here, as well as different models which are broadly summarised below.

Of key importance to those of us looking for longevity is the chain's resistance to wear. KMC communicates this using the term "SP" for "stretch proof" and assigns a rating (single, double, triple or 1, 2, 3) depending on wear-resistance (which I guess is a reflection of component hardness rather than coatings). Higher numbers are more resistant to wear. I'm not sure if KMC's ratings are intended to be taken as a direct reflection of longevity (i.e a 2-rated chain lasts twice as long as a 1) or whether these are just to signify relative superiority of one over another.

Anyway, we have (in ascending order of typical cost for each series):

X8 - X12: Basic model - X8 & X9 are SP1 while X10, X11 & X12 are SP2.
X8 - X12 EPT: Corrosion-resistant coating - X8 & X9 are SP1 while X10, X11, X12 are SP2.
X10 - X11 EL: "Extra light" with cutouts in sideplate - X10 & X11 are SP3 (X8, X9 and X12 have no EL variant).
X9 - X11 SL: "Super light" with cutouts in sideplates and hollow pins - X9 is SP2 while X10 & X11 are SP3 (X8 and X12 have no EL variant).

E8 - E11 Sport: Basic model - E8, E9, E10 & E11 are all SP2 (X12 has no E-Sport variant)
E8 - E11 Sport EPT: Basic model with corrosion resistant coating - E8, E9, E10 & E11 are all SP2 (X12 has no E-Sport EPT variant)
E8 - E12 Turbo: Posh model - E8, E9, E10, E11 & E12 are all SP3 - Seems these aren't available in the UK
E8 - E12 Turbo EPT: Posh model with corrosion resistant coating - E8, E9, E10, E11 & E12 are all SP3 - Seems these aren't available in the UK


Takeaways from the above are that the 8 and 9 speed variants of the X-series chains are all one SP-rating lower than the 10-12 speed variants across the range, while the E-series are all apparently made to the same standard regardless of speed / fitment. 10 and 11 speed chains have the greatest product range, with chains of higher wear resistance offered in the X-series compared to those available for 8, 9 or 12sp.

All other factors notwithstanding if you want the most wear-resistant KMC chain in the UK your options are:

8 speed: E8 Sport (badged simply as "E8" in the UK) @ SP2 (probably an E8 EPT as this is all most suppliers tend to stock)
9 speed: E9 Sport (badged simply as "E9" in the UK) @ SP2 (again, probably the EPT flavour) or X9 SL @ SP2 (more expensive but lighter with different finishes)
10 speed: X10 EL or S10 SL (lighter, more expensive) both SP3
11 speed: X11 EL or S11 SL (lighter, more expensive) both SP3
12 speed: X12 or X12 EPT; both at SP2


Some advocate fitting chains from systems with more speeds (i.e. a 9sp chain on an 8sp drivetrain) for improved quality / wear resistance. In the case of what's currently available from KMC, to get a meaningful improvement in quality on 8 or 9sp drivetrains would require a 10 or 11sp chain which will physically fit but may or may not work correctly due to the chain's narrower outer width. There's apparently nothing to be gained in terms of wear resistance by fitting either a 9sp chain to an 8sp drivetrain, or 11sp chain to a 10sp setup.

It seems that currently the best value chain within the whole range in terms of wear-resistance is the vanilla X11, which can typically be had in the basic grey finish for £17-20 depending on where you're looking.. perhaps offering an argument for trying on drivetrains of lesser speeds as a cost-effective alternative to more expensive "proper" options.

It's also worth noting that the market's evidently flooded with fake KMC chains - so it pays to buy from a legit, established bike shop and not one of the shifty online market places.

I hope this might help some get their heads around what's available / best for their application - as it took me long enough

 

[Ajax Bay]

Great post. I used to favour KMC chains but after three separate link side plate fails (all caught by reasonably frequent chain @mickle ing - fractured plates catch on the paper towel I use) I moved to SRAM with no further failure issues.
Maybe these KMC ones were fakes but all bought through large retailers on and off line.

 

[presta]

My Horizon came with a KMC Z51, but all the ones I've bought have been SRAM for no other reason than an LBS where I bought the first one had SRAM, and I wanted to stick with them to compare like with like. They've all been PC58 on 8 speed, and PC971 after I switched to 9 speed, each were the middle one of three models ascending in price.

This is the wear data I've collected over about 45,000 miles, plotted alongside data from wear tests published by Wippermann, and some figures quoted on here by 'Reiver':

When comparing chain wear rate with small samples though, it's worth bearing in mind that:

"there is an extremely large natural variation in roller chain wear rates. Many engineers are surprised to see so much variation"
John L Wright, Standard Handbook of Chains.

 

[Ming the Merciless]

I bought a 50m reel of KMC X9 grey chain. The price worked out at approx £5 per normal length chain.

My last chain off the reel, lasted 9,543km of riding in all weathers. That’s on my recumbent where the chain is equivalent to 2 1/4 standard length chains. Thus assuming wear scales with chain length, we get 4,200km per normal length KMC X9 chain. I use ISO 64 chainsaw oil mixed with a lighter mineral oil around ISO 25.

I tend to replace the chain in winter and before my main Audax of each year. Given the relative price it works out at, I don’t try and squeeze out every last km before replacing.

 

[Bristolian]

Rightly or wrongly I've fallen into the habit of exclusively buying KMC chains. I think this was initially because they offered quick links when Shimano didn't; but they seem well-regarded, are used by many OEMs and my experiences have been good.

In the 8, 9 and 11 speed fitments I require there are a lot of variants and choosing can be difficult. Having gone down this rabbithole again I have a better understanding so thought I'd share as an aid-memoir that hopefully might be of use to others

KMC do two main lines for 8-12sp bikes; "X" and "E"; the number of speeds denoted by an appropriate suffix - for example X8, X9 etc for 8 and 9 speed X-series chains repectively.

The X-series are the core range, the E-series are aimed at E-bikes; I think the big difference being a different pin configuration in the latter to handle more load. They're all offered in various different (aesthetic) finishes which won't be covered here, as well as different models which are broadly summarised below.

Of key importance to those of us looking for longevity is the chain's resistance to wear. KMC communicates this using the term "SP" for "stretch proof" and assigns a rating (single, double, triple or 1, 2, 3) depending on wear-resistance (which I guess is a reflection of component hardness rather than coatings). Higher numbers are more resistant to wear. I'm not sure if KMC's ratings are intended to be taken as a direct reflection of longevity (i.e a 2-rated chain lasts twice as long as a 1) or whether these are just to signify relative superiority of one over another.

Anyway, we have (in ascending order of typical cost for each series):

X8 - X12: Basic model - X8 & X9 are SP1 while X10, X11 & X12 are SP2.
X8 - X12 EPT: Corrosion-resistant coating - X8 & X9 are SP1 while X10, X11, X12 are SP2.
X10 - X11 EL: "Extra light" with cutouts in sideplate - X10 & X11 are SP3 (X8, X9 and X12 have no EL variant).
X9 - X11 SL: "Super light" with cutouts in sideplates and hollow pins - X9 is SP2 while X10 & X11 are SP3 (X8 and X12 have no EL variant).

E8 - E11 Sport: Basic model - E8, E9, E10 & E11 are all SP2 (X12 has no E-Sport variant)
E8 - E11 Sport EPT: Basic model with corrosion resistant coating - E8, E9, E10 & E11 are all SP2 (X12 has no E-Sport EPT variant)
E8 - E12 Turbo: Posh model - E8, E9, E10, E11 & E12 are all SP3 - Seems these aren't available in the UK
E8 - E12 Turbo EPT: Posh model with corrosion resistant coating - E8, E9, E10, E11 & E12 are all SP3 - Seems these aren't available in the UK


Takeaways from the above are that the 8 and 9 speed variants of the X-series chains are all one SP-rating lower than the 10-12 speed variants across the range, while the E-series are all apparently made to the same standard regardless of speed / fitment. 10 and 11 speed chains have the greatest product range, with chains of higher wear resistance offered in the X-series compared to those available for 8, 9 or 12sp.

All other factors notwithstanding if you want the most wear-resistant KMC chain in the UK your options are:

8 speed: E8 Sport (badged simply as "E8" in the UK) @ SP2 (probably an E8 EPT as this is all most suppliers tend to stock)
9 speed: E9 Sport (badged simply as "E9" in the UK) @ SP2 (again, probably the EPT flavour) or X9 SL @ SP2 (more expensive but lighter with different finishes)
10 speed: X10 EL or S10 SL (lighter, more expensive) both SP3
11 speed: X11 EL or S11 SL (lighter, more expensive) both SP3
12 speed: X12 or X12 EPT; both at SP2


Some advocate fitting chains from systems with more speeds (i.e. a 9sp chain on an 8sp drivetrain) for improved quality / wear resistance. In the case of what's currently available from KMC, to get a meaningful improvement in quality on 8 or 9sp drivetrains would require a 10 or 11sp chain which will physically fit but may or may not work correctly due to the chain's narrower outer width. There's apparently nothing to be gained in terms of wear resistance by fitting either a 9sp chain to an 8sp drivetrain, or 11sp chain to a 10sp setup.

It seems that currently the best value chain within the whole range in terms of wear-resistance is the vanilla X11, which can typically be had in the basic grey finish for £17-20 depending on where you're looking.. perhaps offering an argument for trying on drivetrains of lesser speeds as a cost-effective alternative to more expensive "proper" options.

It's also worth noting that the market's evidently flooded with fake KMC chains - so it pays to buy from a legit, established bike shop and not one of the shifty online market places.

I hope this might help some get their heads around what's available / best for their application - as it took me long enough

Thank you for taking the time to research and post this information

 

[Pat "5mph"]

Useful info @wafter, thank you.
I'll pin this thread for easy reference.

 

[Big John]

Very useful, thank you. I've used KMC whenever they've been available and found them to be reliable chains. I've used SRAM, Shimano and other odd ones over the years but only because I was desperate and the shop didn't have KMC. I now tend to buy online and keep a stock of them in my shed.

 

[Gunk]

I moved to SRAM

Me too.

 

[HLaB]

Great post. I used to favour KMC chains but after three separate link side plate fails (all caught by reasonably frequent chain @mickle ing - fractured plates catch on the paper towel I use) I moved to SRAM with no further failure issues.
Maybe these KMC ones were fakes but all bought through large retailers on and off line.

I've had one KMC chain fail prematurely (warped at a few hundred miles) but all my others have been great. I put it down to a fake even though it was through a large on line retailer.

 

[Fastpedaller]

Another 'thank you wafter' very useful and informative. That X10 I recently bought for the Brompton is identified as a good purchase
The E chains may well be the best value for money - I know when I had Sedisport chains years ago they never seemed to wear, even though I did mega-miles compared to todays.