AJW2W11E

I’ve use my present 3/8 inch KMC chain for one year. I’ve shortened it and lengthened it many times as I en swapped freewheels and chain rings so I decided to replace it with a new one last weekend. Identical model. The new chain made a harsh clattering sound but I bore through it for 20 miles figuring it would go away. Never did. Same thing next day.I put the old chain back on and the bike runs like a Swiss watch. Tension and chain slack set the same. I will add however I used Finish line wet lube on my old chain and the stock oil that comes on a new KMC chain with the new one.

davidad

3/8" ?

79pmooney

+1! You might find 3/32" works a lot better! (Chains come in 3/32" and 1/8" and all the newer, narrower 7-12 speed chains. Make sure a 3/32" chain is one for 5 and 6 speed freewheels.)

Seriously - how far and how hard has this bike been ridden since its last chain replacement? Chains "stretch" with time and wear the chainring and cog teeth down to match. The teeth now have effectively greater spacing than the new 1/2". Enough wear and the results can be what you describe.

Tooth wear is difficult to see. If you can see it, that cog or ring is VERY worn and only a stretched chain will work. Now a slightly worn cog will quickly stretch a new chain to fit (making it "old" quite fast). So, your choices (if indeed I have diagnosed your situation correctly) - see if you can live with the noise until your chain is stretched to match. (Enough wear on the cog and that won't be possible.) Buy a new cog (and maybe chainring). Or simply put the old worn chain back on if it is still working.

Troul 

if you slack the new chain tension slightly, does the noise change? If it does, is it less noticeable?

Iride01 

If you got the same chain as what was on the bike and the bike is only a year old, then I'd think you probably didn't run the chain correctly through the rear DR cage. There is a little tab in there between the jockey and pulley wheel. You have to be on the correct side of it or else you get noise all the time while you pedal.

Maybe you just routed it correctly with the old chain and messed up in your excitement of getting a new chain. <grin>

AJW2W11E

Oops forgot to say single speed ;single speed chains are 3/8” or 1/4”

shelbyfv

dedhed

Single speeds are typically 1/8" chains depending on how someone built the drivetrain.

cxwrench

OP's bike is a single speed.
SS chains are 1/8".

AJW2W11E

I am getting 1/8 and 3/32 all confused and somehow I derived 3/8 inch which is embarrassing.Yes it is a 1/8 inch chain. Thanks for the correction. Does the chain need time to break in, is it oil, or is KMC not meeting tolerances? I have heard they are a very good manufacturer.
The chain is about one year old and I am using a 6 month old White freewheel and I am an over oiler. I ride the bike 20 miles a day with lots of hills. I sure hope the freewheel is okay.Maybe I will get some pictures tomorrow.


Worn freewheel?

HillRider

A single speed cog wears pretty fast since it carries 100% of the drive load. If you kept the old cog with the new chain, the wear-mismatch may be your problem.

cxwrench

Obviously new chain with old cog/chainring is gonna be noisy. That WI cog looks worn for sure. Don't over-oil...it's worse than under oiling.

davidad

If you oil a dirty chain you are making grinding compound inside the pins and bushings. If you want your drive train to last, remove the chain periodically clean it and then oil it. Measure it for wear and replace it when the space between 24pins is 12 and 1/16". You could leave it on until it, the cog and chain wheel are worn out and then replace all three.

Troul 

What happens when you change the tension?

AJW2W11E

I called White today . Turns out you should not use 1/8 inch chain with 16 T, the chain won’t sit right. Can only use 3/ 32 chain. Bought a new gear with bearing 55dollars.

shelbyfv

So the new chain was actually not "identical" to the old one?

AJW2W11E

actually I was using the wrong size chain both times.

79pmooney

An 1/8" chain should run OK on 3/32" cogs. There are posters here who will swear to it. (I've never tried it. I ran 3/32" on my fix gear for many years then did the big switch to everything 1/8".)