Chain suck after installing new KMC chain – help!

Yesterday I fitted a brand new KMC X9-L chain onto my drivetrain before going on a ride. While the chain ran incredibly quietly and shifted smoothly, around 5 miles into the ride I began experiencing problems with chain suck. This would always happen when in the small chainring and in one of the lower gears on the cassette (i.e. the larger sprockets). The problem was worst under heavy load on climbs. I thought that the problem may be associated with the very sticky nature of KMC factory lube, so I applied some Finish Line Wet lube over it during the ride. This made the problem much worse!!! I began experiencing chain such every 2-3 pedal strokes on climbs, forcing me to use my middle chainring. However, by the end of the ride (some 30 miles) the problem almost disappeared.

Here’s some additional info:

– I was using a brand new KMC-X9 silver chain, which I installed with only the factory lube applied. The chain suck did not occur on any one part of the chain in particular.
– The remainder of my drivetrain (cassette and chainrings) is almost brand new, with less than 200 miles on it. The KMC chain replaced a 9-speed XT chain I had on before (installed at the same time as cassette and chainrings), as it snapped 2-3 times on previous rides. I did not experience chain suck with the previous chain.
– The chain suck always occurred on the same part of the small chainring. The chainring is of the Shimano SLX 9-speed variety. There are no visible imperfections on any of the teeth.
– Not sure that it matters, but the bike is a 2008 Orange P7, size large.

Will degreasing and re-lubing the chain resolve the problem? Do KMC chains require a ‘wearing in’ period before they reach optimum performance (perhaps that’s why the problem almost went away towards the end of the ride)? Could it be a more deep-rooted problem?

Thanks!

Look for damage on front chain rings or a stiff link on the chain.

The chainring appears true with nothing unusual going on with the teeth, although it does tend to catch in the same place each time – not a problem with the old chain though.

As I mentioned earlier, the chain does not catch in the same place every time, so it’s not down to a single stiff link.

New chainring time. Old chain and chainring have worn together and match each other. New chain links will have a slightly different profile causing the suck.

Had similar issue myself recently.

DISCLAIMER: ymmv. 🙂

After under 200 miles though? Probably not even 150.

Grrr, why does my bike have to keep on breaking?????!!!!! I sometimes hate this sport.

coolbeanz – Member
After under 200 miles though? Probably not even 150.

It’s not the quantity it’s the quality, what you been doing in those miles (keep saying it but distance is a rubbish measure for mountain bikes due to the variety of conditions)
How worn was the older chain when you changed the rings?
Most chain manufacturers state that the lube used on chains out the factory is good stuff and also reaches deep inside the links, if you remove it all all the internal moving bits will not be lubed until you can get more lube into those links (hard to do).

Bit confused by your OP but has the problem gone away now? See what the next ride is like but replacing the granny ring is probably the next option (and fairly cheap)

I recently fitted a new Shimano middle ring, rear SRAM cassette and a KMC chain (as LBS didn’t have a SRAM).

After years of no issues with a SRAM chain, the KMC one has been nothing but a royal pain in the arse. Poor shifting, chainsuck and then wrapping itself up so badly it twisted a link.

Can’t wait to get rid of it and stick a SRAM back on

Not had any of these issues with a variety of KMC chains (all tenspeed) on a variety of bikes due to chain.

I’ve had issues with things boiling down to free hub maintenance, loose/damaged/worn chainrings, bent hangers, incorrectly sized chains, incompatible chain lines etc but none that indicated the chain was inferior to say, SRAM.

I like SRAM chains and buy 971’s for my crosser. I dislike the 10sp power lock but that can be replaced. Ditto Shimano rivets. I simply went KMC a couple of years ago due to local pricing and stuck. All 10sp is cheaper now, but I have no reason to change.

I’m persuaded the WolfTooth spacing issue may exist although I’m dubious that’s the chains fault either (as it already existed although it is recommended not to combine i believe) but I’m not sure I see what could be wrong with the chain here as described. I’d be asking someone else to take a peep on the assumption I’d missed the obvious – which we all do! 🙂

I degreased the chain last night, removing the sticky factory lube, and applied a helping of Morgan Blue Syn Lube.

To my surprise, this simple procedure appears to have resolved the chain suck problem completely.

Having read around a little, the general opinion is that the purpose of the factory lube is principally to protect the chain during storage. Some will be quick to quote Sheldon Brown here, arguing the contrary, but I think that my experience, and that of many others disproves his point. Perhaps this is less true of road bikes, but mountain bikes are very susceptible to attracting dirt, thus choosing the right chain lubricant is crucial. Another observation is that that the properties of the factory lube are likely to change during prolonged storage, perhaps over time turning it more viscous and sticky, thus less appropriate for immediate use.

Either way, I know what I’ll be doing when it’s time to install a new chain: degrease and relube with a fresh dose of oil that will be regularly reapplied during the remainder of the chain’s life.

Yeah, that goop that is on the chains isn’t a ‘bike lube’. It’s to protect the chains post-manufacture. It is really viscous stuff and while I haven’t had a problem leaving it on before, it does gunk up very quickly. At the very least I use kitchen roll/rags to remove most of it from the ‘easy to reach’ surfaces of the chain before fitting.

Was going to say remove the sticky.

I had a very similar problem recently, after replacing a KMC X10 gold, with the same chain. I was using a Wolf Tooth N/W ring, and the bike had only been used in the dry, and the chain changed before 0.75% wear.
I’d washed off the sticky, shitty grease that it came with and used a small amount of wet lube in it’s place. But once I started riding, with every pedal stroke the chain would suck up just a little, not enough to jam anywhere, but making an extremely annoying noise, and wasting energy.
This didn’t get any better with a bit of use, so I’ve changed the whole setup to a MRP bling ring and chain guide, and I’ve had no problems (or dropped chains, which I had several of while on the N/W ring with no chain guide).

Any idea of the cause of this? The chainring, excessive wear or maybe the chain?

Sorry to bring this subject up again, but I recently went on a fairly muddy ride in Swinley Forest and the problem returned with a vengeance. Chain suck every other pedal stroke when in the small chainring pedaling uphill.

I really think it may be a problem with the KMC X9-L chain. In particular, the cut-outs in the links have a tendency to clog up with dirt, likely causing the chain to fail.

I had a Shimano XT chain on before, which never chain sucked, but kept snapping.

Any other chains I should try out???

turn the chainring round.

Seriously?

I really think it may be a problem with the KMC X9-L chain. In particular, the cut-outs in the links have a tendency to clog up with dirt, likely causing the chain to fail.

I have five X10L chains between my bikes and they work great in horrible conditions so it isn’t that. In my experience chain suck comes from worn or damaged chain rings. Look for bent or hooked teeth.

Interesting, I may swap out my SLX granny ring for an old Race Face one I have just as a test (it’s not actually that worn so should be OK).

er, yeah seriously.
the teeth wear, shark fin style, you can, sometimes, flip the chainring and get further use out of it, or at least prove to yourself the issue and spur you on to buy a new inner ring.

alternatively, take a file to it to remove the hooking profile which has come from wear from a worn chain.

running a new chain on a worn chainring will IME accelerate damage to the new chain….. so it feels like its ‘worn in’

how many chainrings do you have?

in my experience, if you’ve got enough chain to work on a triple, it can lead to chain-suck rearing it’s head when you’re in the granny ring.

(I’m not suggesting that running a triple causes chain-suck, but it can help summon the demon)

It’s a triple converted to a double (i.e. I replaced the large chainring with a bashring). I guess I could probably remove another link or two.

Try taking the granny ring off and rotating it round by either 90 or 180 degrees.
If the point that the chain suck occurs changes to match then you’ll know its the ring. If it doesn’t, then blame the chain.

OK, I think I’ll just get any new granny ring.

Any recommendations?

I don’t want to spend a fortune. I was thinking Shimano XT M770 or M771 (what’s the difference between the two by the way???). They’re both 9-speed, right?

hopefully someone can tell you which and why.

couple of things to consider,
BCD of the chainset (64mm) – obviously the holes in the ring need to match the crank
BB type – some ‘granny’ rings have tabs which would need filing to fit an external BB
probably find that a deore will be heavier than an xt, so will last longer (weight of a granny ring must be small anyhow)

Thanks for the advice.

For chain rings I tend to stick with steel over aluminium for two reasons:-
1) They’re thinner so less likely to suck
2) They wear much less.
I do keep the big ring alu as it tends to get less use, but it doesnt wear anywhere as much, middle granny are both steel.

The stuff on the surface of a KMC is more of a protective layer and is a bit gunky so the chain is stiffer, though never had chain suck with it and brief bit of riding and it’s flexible in no time.

However, degreasing, Sheldon is right, you will have removed the best lube the chain will ever have.

Personally I’d have wiped the chain down with water or a quick spin in a cleaner gadget with just water. Enough to scrub the sticky surface but shouldn’t remove the stuff inside.

Bear in mind lubrication is essential inside the chain really, not outside. Just when you stick lube on outside it works itself inside, but oil lubes will sit outside as well merrily attracting dirt.

If you’ve degreased though… Squirt. End of all your problems.