IkeCan

For the last year I have had a persistent chain rub when riding in the higher gears. The noise would occur on almost every revolution of the crank. I adjusted the derailleurs as well as made sure the front cage was properly aligned. After that I chalked it up to being some sort of minor frame flexing.
Well I fixed the issue this week and feel somewhat foolish. The chainring bolts were not tight. The large chainring would actually wobble enough that when under load the chain would rub against the front derailleur cage. It was a simple fix that completely removed an annoying noise I have been hearing for a year. I thought that I would pass this on, in case others have overlooked checking the bolts on their chainring.
The only thing that makes me feel a little better is I had taken my tandem to my LBS to remove the chain rub noise and they did not notice the loose chainring bolts either.

Paul J

Add a little loctite helps keep them tight, we've had issues with our middle chain ring. I think Loctite Blue is the best if I'm remembering correctly.

IkeCan

Thanks, that's a good add.

LV2TNDM

Chainring bolts are systematically incorrectly installed at the OEM level. I have NEVER encountered a production bicycle with chainring bolts properly greased upon assembly. It's simply not done. The large diameter of the threads as well as the bolt head mean that they don't get tight enough dry. Add to that the terrible slot interface on the backside of the double, which can prevent achieving adequate torque. Even the proper tool tends to slip out of the slots when tightening. Then with the torque forces from the chainrings, things flex and the bolts eventually loosen up.

Threadlocker works, but it does not prevent corrosion or creaks as well as waterproof grease. Plus, the grease should be applied to the bolt threads AND heads to reduce friction while tightening to proper torque values. Plus, properly greased surfaces will prevent any pernicious creaks as well as corrosion.

30 years of greasing charinring bolts and I have never suffered a loose chainring bolt, whereas this is a somewhat common problem on pre-built bikes ridden extensively. And the shop missing the loose bolt kinda indicates that not much attention is paid to them.