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I recently changed my chain and noticed it has uneven tension (probably my chain ring being out of rounds). I followed Parktool's video and set the tightest spot to have about 0.25 inch movement up and down.

I wanted to confirm that I did everything correctly, it’s been sort of hard for me to judge if the tension is correct. I’m also not sure if the noise that the chain makes is normal, or if it’s too tight. I have attached videos for the tension and noise.

I would appreciate it if someone could confirm if everything seems good? Thanks!

Chain tension (I start the video at the tightest spot) https://i.stack.imgur.com/PnAYP.jpg

Chain sound: https://i.stack.imgur.com/INx6w.jpg

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    I don't know anything about single speeds, but you might want to put your cadence sensor on the back side of the non-drive crank, so it doesn't risk nudging your ankle.
    – David Richerby
    Oct 8, 2018 at 16:08
  • A recently serviced (clean and well-oiled) single-speed chain should be next to silent. If you hear its links sliding on/off the teeth of the sprocket/chainring, you are hearing how it's being worn down.
    – cmaster - reinstate monica
    Nov 7, 2018 at 13:31

3 Answers 3

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I'm going to disagree with Mike and say that chain is far too tight. I race singlespeed MTB and have a fair amount of experience setting chain tension. In the fixie/singlespeed world; a loose chain is a fast chain, but not TOO loose. There is a "Goldilocks" tension to chains where the chain can freely move up/down along the drive line but not enough to jump teeth on the cog or chain ring.

All chains will "stretch" over time and require periodic re-tensioning but a chain that is set too tight will exacerbate wear on cog, chain ring, and the links.

FWIW, I run oval chain rings on my MTB and those are even more finicky to set up. Tension is set on those when the oval portion is at its widest position on the y-axis, then goes slack through its rotation, but never slack enough to de-chain or skip teeth.

Just an example of my chain after a race earlier this year where you can see how slack it was but still connecting and putting power to the tire.

enter image description here

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    Nice bike paint you got there ;-) And yes, that chain is near the maximum tension that single-speed chains should be ridden at.
    – cmaster - reinstate monica
    Nov 7, 2018 at 13:33
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For me the best answers is:

(taken from:) Why does the chain tension vary as pedals are turned?

  1. The chainring is "eccentric", either because of haveing been tightened off-center, being manufactured off-center (some defect or poor quality), or damaged. The best way to check is to suspend the bike or turn it upside-down, then slowly spin the cranks do see if it looks off-center. If it is badly assembled, you can try to loosen the bolts and recenter it manually;

  2. The sprocket might be off-center. This can be very subtle, but you can see the difference between the sprocket or the chainring being off-center depending on how many times per turn the chain reaches its tight spot, since the sprocket has a much smaller diameter;

  3. The chain itself can be unevenly worn out, or be uneven from factory. This can happen with very cheap chains, and can cause even a combination of slight unevenness of chain, sprocket and chainring to create a somewhat "random" pattern of tightening and loosening of the chain as the bike rolls.

P.S. In your case I'm not sure, if it helps, since on video the chain and ring are looking new.

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Nice bicycle.

I don't hear anything weird, it's the sound of fixie/single speed.

However the chain is too lose in my opinion. For your reference the total slack (up and down) should be less than USB type-A plug width and I get the impression that it's double in the tightest spot, to say the least.

My experience with chain tensioning is to "finger-tighten" (tension the wheel with one hand while operating the wrench with the other) it in the tightest spot gives you required slack.

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    I agree with jc allen: For single speed / IGH chains, slack is not a problem as long as it's not enough to cause the chain to fall off the sprocket/chainring. Single speed sprockets/chainrings have quite long teeth, allowing them to handle quite loose chains perfectly. Chain-shift bikes behave very differently in this respect, because their teeth are just not long enough. My chains always have at least two USB type-A plug widths slack, to stay within your measurement methodology. If I give them significantly less slack, their movement will start to be encumbered, and their wear be increased.
    – cmaster - reinstate monica
    Nov 7, 2018 at 13:23

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