Bicycle Mechanics - KMC Missing Link - too loose??

So I decided to install KMC "Missing Links" on two mountain bikes - thinking it will make it much easier to keep the drivetrain clean. Both bikes have KMC chains - both marked "narrow". I brought the chains to LBS in order to make sure I got the right part (7.1 mm pin - the shortest of the 6/7/8-speed chain options). Anyway, after installing, I noticed there is A LOT of play in the missing link. Way more than my SRAM powerlink on my road bike. In fact, there is so much play, that when I was relubing the chain in a ziplock, it came undone in the bag. I know the riding tension is required for proper function, but it doesn't give me a "warm fuzzy feeling" to see it just fall apart that easily.

Anyone have any experience here?

First time post, long-time follower! :thumb:

I have not noticed play in any of the links that came with the KMC Z chains that I have used. Current chain is a 9-spd 'Super Narrow Z' with the supplied Z master link.
Looks like there are three varieties to choose from:
http://www.jensonusa.com/store/product/CH409Z19-Kmc+Missinglink.aspx?sc=FRGL

So I decided to install KMC "Missing Links" on two mountain bikes - thinking it will make it much easier to keep the drivetrain clean. Both bikes have KMC chains - both marked "narrow". I brought the chains to LBS in order to make sure I got the right part (7.1 mm pin - the shortest of the 6/7/8-speed chain options). Anyway, after installing, I noticed there is A LOT of play in the missing link. Way more than my SRAM powerlink on my road bike. In fact, there is so much play, that when I was relubing the chain in a ziplock, it came undone in the bag. I know the riding tension is required for proper function, but it doesn't give me a "warm fuzzy feeling" to see it just fall apart that easily.

Anyone have any experience here?

First time post, long-time follower! :thumb:
Is the missing link black or silver? If it's black, it's a 7.3mm, silver is 7.1.

I have not noticed played in any of the links that came with the KMC Z chains

Hmmmm.

I don't know the exact model of chains. All I can get from the marking is a big "Z" in the middle of each link - is this the same series of "Z" chains to which you refer? If I recall, I think it had something like Z-XL on some links. The other chain had the same "Z" - no additional markings that I could find.

Do you use the 7.1mm missing links? If so, do you have the markings on that link. Mine have the part # CL571R - which according to KMC docs, is in fact the 7.1mm.

Is the missing link black or silver? If it's black, it's a 7.3mm, silver is 7.1.

Silver.

Hmmmm.

I don't know the exact model of chains. All I can get from the marking is a big "Z" in the middle of each link - is this the same series of "Z" chains to which you refer? If I recall, I think it had something like Z-XL on some links. The other chain had the same "Z" - no additional markings that I could find.

Do you use the 7.1mm missing links? If so, do you have the markings on that link. Mine have the part # CL571R - which according to KMC docs, is in fact the 7.1mm.

Most likely a Z 51. That is a 7.1mm chain, although they market it as a 6/7 speed.

Most likely a Z 51. That is a 7.1mm chain, although they market it as a 6/7 speed.

If I had noticed how loose it was at the LBS, I would have questioned it. But the mechanic seemed OK with it. Why do I think I'm going to regret this in a few days? I outfitted my GF's bike too ... can only imagine when her link fails. "You broke a perfectly good chain for what? :rolleyes:"

The link on my 9spd chain is a CL566R, which would be 6.6mm.
My experience with KMC/Nashbar master links is that, once they have been 'pressured' into place, which normally involves riding in a higher gear for a moment, they are so tight that I have never been able to get one apart without a Park master link tool. Quite different than my experience with SRAM links, which are easy to undo with my fingers.

Some of the kmc missing links come loose like that - there's nothing to worry about. Perfectly fine. We've had this issue on the 8/9 and 10 speed links and there's no way the link is going to come apart even if it was extremely loose anyways. Try it yourself with the link in various positions and forcing it apart just by simulating pedalling action. Not going to happen.

I have never been able to get one apart without a Park master link tool. Quite different than my experience with SRAM links, which are easy to undo with my fingers.

Well, I mainly bought the Missing Links so I could easily remove and clean the chain/drivetrain. Hopefully it is similar to the SRAM powerlink; otherwise, it will be pointless.


Some of the kmc missing links come loose like that - there's nothing to worry about. Perfectly fine. We've had this issue on the 8/9 and 10 speed links and there's no way the link is going to come apart even if it was extremely loose anyways. Try it yourself with the link in various positions and forcing it apart just by simulating pedalling action. Not going to happen.

Thanks for the input. Glad to know I'm not the only one who noticed. I will put a few miles on the chain and try to remove it again.

As operator said, kmc links seem to have a wide variability in tightness. This is probably intentional as some of them are spec'ed as "single use" (though you can usually take them apart with the Park tool or needlenose pliers), and others are touted as reusable. I've never had one come apart unintentionally though, even when the chain goes totally slack (e.g. dropped chain). In my experience, even the loose ones usually require you to squeeze the side plates together a little bit before the pins will move in the slots.

I've never had one come apart unintentionally though, even when the chain goes totally slack (e.g. dropped chain). In my experience, even the loose ones usually require you to squeeze the side plates together a little bit before the pins will move in the slots.

Well, as mentioned, mine definitely came apart when I shook it in my ziplock of lube. I know I've read that many have used the SRAM powerlinks on non-SRAM chains - I wonder if that would be a better fit if the KMC missing links don't work out.


This is probably intentional as some of them are spec'ed as "single use" (though you can usually take them apart with the Park tool or needlenose pliers), and others are touted as reusable.

I must say that the ambiguity of info on the single-use vs. reuse is annoying. Many say not to reuse at all, many say they reattach all the time without a problem, and others say the real spec is reuse is OK for the lifetime of the original chain. I made it clear to the mechanic at the LBS my intentions of using the missing links to regularly clean the chain/etc, and he acted like it was normal to disconnect/reattach.

There is a simple way to tell if a link fits properly. It should have about the same clearance between the inner and outer plates as the rest of the chain. Normally, this is in the .004 -.008 inch range, but up to .012 is acceptable. Much more would be a very sloppy fit. Get some feeler gages to check.

Well, as mentioned, mine definitely came apart when I shook it in my ziplock of lube. I know I've read that many have used the SRAM powerlinks on non-SRAM chains - I wonder if that would be a better fit if the KMC missing links don't work out.



I must say that the ambiguity of info on the single-use vs. reuse is annoying. Many say not to reuse at all, many say they reattach all the time without a problem, and others say the real spec is reuse is OK for the lifetime of the original chain. I made it clear to the mechanic at the LBS my intentions of using the missing links to regularly clean the chain/etc, and he acted like it was normal to disconnect/reattach.
Well, KMC is not the least bit ambiguous. They say, not reuseable. OK, that covers thier butt. That said, I re-use KMC links all the time with no issues, but I can't go back to KMC with an issue if I re-use one because they clearly say not to. See how this works?

Actually, some models say not reuseable and other say reuseable.

I've been using KMC X8 chains for the past year or so on a couple of my road bikes with 7 speed derailleur drivetrain. This is a decent quality chain that sells for about $14 at several web bike retailers. The outer plates are silver. These are a 6-7-8 speed chain and seem to work fine. The KMC quick link with the X8 chain is easy to disassemble for chain cleaning. I just use a chain slack holder and can remove the quick link in a few seconds. I've pedaled the X8 chains many thousands of miles with no problem.

Previously I used some Nashbar house brand 6-7 speed chains made by KMC. At one time, I bought a bunch of these for about $6 each. These also had a quick link, but as JanMM mentioned, these quick links were near impossible to remove.

I've used SRAM chains also, and usually had to use needlenose and play with their quick link a minute or so to get it to snap open. The SRAM, when closing the quick link would snap or click closed. The KMC X8 quick link does not snap or click closed.

I just put the newly cleaned and lubed chain back on the bike. It takes no effort whatsoever to release the missing link. I *barely* need to squeeze it together while pushing together, and the link is off.

I recently installed one of those Nashbar branded KMC 8 speed chains. This past weekend I removed and cleaned it with mineral spirits. Today I'm noticing with each chain rotation, when the master-link passes over the cassette cog, there's a tiny "slipping" feeling. The feeling is similar to when teeth on the cogs are worn. This happens more under heavy torque.

There is a considerable amount of play in the master link - at least much more than I'm accustomed to with SRAM powerlink chains. Not sure why this started AFTER my cleaning. I maybe have a couple hundred miles on it.