[Opus51569]

On a ride the other day, I experienced a loud "pop" that I could hear/feel coming from the chainring/bb area. Taking off the chainring bolts, I noticed that instead of grease, there was dried residue from what I assume is a thread locking compound. Is this standard for chainring bolts? When I reinstall the bolts, should I use something like Loc-tite blue or should I grease the threads instead?

 

[Kuma601]

I've not used thread locking agent on mine. These days I assemble with a small drop of oil and torque it up.

 

[wim]

There's no rotational force (torque) acting on those bolts, so they don't need Loctite if they are tightened sufficiently to begin with. I put some grease on the threads and on the all contact areas, including the spider ramps.

 

[Opus51569]

That was my thought as well. I'm not sure what possessed the LBS to use a locking compound in the first place, but I thought I should consult the collective wisdom of the forums in case there was a rationale I wasn't familiar with.

 

[frdfandc]

It might not be loc-tite. It could be liquid teflon that the manufacturer applied to them during initial assembly. Unless the chain rings were recently replaced by the LBS, they probably did nothing with the crank/chainrings except for maybe check the bolts.

 

[backinthesaddle]

Grease...

 

[jmlapoint]

Maybe it's marine grease.
I never heard of anyone using LocTite on Crankarm Bolts.
Most use liberal amount of grease, torque up appropriately and clean any residue.

I do check the bolts periodically for tightness, and I have seen them loosen occasionally.

john

 

[Opus51569]

I should have taken a picture of the bolts before I cleaned them and applied grease. The substance that was on them was green and crusty. I have cleaned dried-up Loc-tite off of bolts in the past and it was the same consistency, which led me to assume it was a thread locking compound of some kind. It was only on the first few millimeters of each bolt thread. Other than that, everything else was completely dry. Whatever it was, I think the bike is better off now with grease instead. Thanks everyone for your suggestions and input.

 

[wim]

Factory efficiency.

The substance that was on them was green and crusty..

You really don't want to know what gets put on threaded connections to speed assembly. With some slimy green stuff on the first few threads of the chainring bolts, crank output per work shift could well be 3.5% more compared to dry assembly work shift output.

 

[Opus51569]

Dang... I'm going to miss that 3.5%... Though I suppose I could shave my legs or paint the chainrings red to compensate for it.

 

[STARNUT]

The Cannondale SISLs come with loctitie on the no-nuts bolts. I've used the blue before on persistantly stubborn chainring bolts that will not stay tight.

Starnut

 

[Kerry Irons]

It's galling

There's no rotational force (torque) acting on those bolts, so they don't need Loctite if they are tightened sufficiently to begin with. I put some grease on the threads and on the all contact areas, including the spider ramps.

This is "best practice" whether the bolts are steel, aluminum, or titanium, but for the latter two, grease (or something equivalent) is required to prevent galling. If you've ever threaded together a completely dry aluminum chainring bolt/nut, you might have found that it seized before it was even tightened up slightly.

 

[wim]

If you've ever threaded together a completely dry aluminum chainring bolt/nut, you might have found that it seized before it was even tightened up slightly.

Never had aluminum chainring bolts on a bike, but used to fool around with East German single-lens reflex cameras. Some of these had aluminum lens mount threads mating with aluminum threads on the lens. It's exactly as you say.