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I did some work on my Rohloff bike today, installing a new chain & chainring and reversing the sprocket. When trying out the bike afterwards, something in the drive train was making a loud cracking noise under load. First I thought it was the hub, but after a while, I tracked it down to the new chain I had put on. Putting on the old chain was the only thing that made the noise go away.

What would cause this kind of noise on a new chain? Did I break it or did it came broken out of the factory? Should I try to get a refund?

You can hear the cracking here:

  • Break it not brake it. I suspect too tight. – paparazzo Jul 14 '17 at 22:19
  • It sounds like the derailer is simply misadjusted. But it makes me wonder -- did you put on the right width chain? I would imagine that a too-wide chain could cause similar noises. – Daniel R Hicks Jul 15 '17 at 1:23
  • @DanielRHicks - there's no derailleur. It's an IGH (Rohloff actually). But there could be rubbing of the chain against the seat stay. The OP should look for wear marks. – RoboKaren Jul 17 '17 at 16:35
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This happens when you replace your chain but keep your old front and back sprocket. After extended use, the sprocket and cog will wear down from use and the "U" shaped hold will look like more of a "V" over time.

When you install a new chain, and you apply lots of pressure (like when you are accelerating) the round chain links a squeezed into the "V" shaped olds and the creak.

The problem does not happen if you replace the sprocket and perhaps the cog when you replace the chain.

  • You normally get chain skip if the cogs are worn and you install a new chain; as you note it tends to happen when you apply substantial force to the chain as when accelerating. But that's not the case in the video; the wheel is not in contact with the ground so there's really not anywhere near that kind of force being applied. – DavidW Aug 12 at 21:29
  • The "V" shape is not an adequate description. It's more that the shape between the teeth becomes slanted. The unloaded flank does not change at all while the loaded flank is ground away in a round shape that matches the rollers of the chain. If the sprocket has short teeth like chain-shift cassettes, this eventually leads to the chain slipping off the teeth on the slopes that it ground into the teeth. A sprocket with long teeth like IGH sprockets will continue working with an elongated chain until it starts loosing teeth. – cmaster Aug 14 at 9:48
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My guess is you have some tight links that are making noise as they go over the sprocket. Those can probably be fixed easily.

See this Park Tool video. Tight links are addressed at about 10:35.

It might be that you did not join the chain links properly. What method was used to join the chain? A master link or rivet?

You can also see the chain tensioning advice in the Park video to check if that is the cause.

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It sounds like too much chain tension. The new chain will be ever so slightly shorter (i.e., un-stretched). There are also slight tolerance issues when between a chain ring and cog (e.g., how a chainring is mounted) such that the chain will experience spots of high and low tension.

If you didn’t reset the rear wheel position after installing the new/reconfiguring drivetrain components you could a tight spot that is too tight. The length difference between the new and old chain may be enough to make the sound go away with the old chain.

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