PatrickGSR94

Saturday I was out riding and noticed what looked like my small chain ring wobbling, or perhaps bent. I was also having problems with the chain getting pulled around between the rings when shifting down from the large to small ring. I think that's known as chain suck?

Anyway, I looked at it closer last night, and found ALL FIVE chain ring bolts were loose, and the small ring had pulled away from the spider arms in some spots (that explains the chain suck). One chain ring bolt was barely snug but not as tight as it should have been. The other 4 bolts were completely loose, and could be turned by hand. I feel lucky I didn't end up with a catastrophic failure while climbing or something.

Bike has over 6K miles on it, and I replaced the large ring over a year ago, but that's the last time I messed with those bolts. What could have caused them to all loosen up so badly? I guess I'll just start checking them every time I lube the chain from now on.

dsbrantjr

You failed to tighten them sufficiently. Once one loosens, the others have to take the (now asymmetrical) load; the closest neighbors likely loosened next, followed by the remaining ones. You are lucky, I have seen rings fold in half when one bolt comes out. Either get or use the little sheet metal tool Park Tool Co. » CNW-2 : Chainring Nut Wrench : Crank Tools to hold the nuts while you torque the bolts, or get a set of hardware with hex drive for both parts and hold them that way. De-grease the hardware and mounting surfaces and only put a sparing amount of grease on the threads.

dr_lha

When you replaced the large ring, did you correctly reinstall the chainring bolts in the right way and to the correct torque?

Lonesome rider

No matter how few or how many kilometers you covered, chainring bolts do loose due to stress/torque and vibration. I've had two bolts fall off. Result: bent small chainring (standing sprint). Check bolts every time before riding.

FBinNY 

Chainring bolts can and do loosen. The granny is especially prone to the problem as you'll see in a moment.

Consider how a chain drive works. The chain is pulling on the ring at a tangent, so as the crank rotates, the direction of pull rotates also. This changing pull can walk the chainring around in an oscillating motion, if there's any play at all. Larger rings on better cranksets are supported on close fitting shoulders specifically for this reason, but grannies aren't, so if the bolts aren't tight enough to hold the ring solidly, it's begin to shift and soon the bolts will loosen.

There's nothing you can do about the design, so make sure the granny's bolts are tight. If the problem recurs you can stabilize the ring and help prevent loosening by putting some medium grip lapping compound between the ring and crank mounting faces. The grit will bite into both parts and keep the ring from shifting under load.

PatrickGSR94

Nice Park tool, never seen it before. Yet another tool I need to add to my arsenal.

Bill Kapaun

You might want to tighten the bolts, ride it and then check them again.

PatrickGSR94

Will check them again tonight after I commute home. I suspect they're probably fine, though.

leob1

Loctite is your friend.

nfmisso

In this case BLUE or PURPLE thread locker; do NOT use red, unless you plan on drilling out your chain ring bolts.

fietsbob

At 40 years on riding and wrenching, I just get them Tight enough, Dry. But salted roads are nothing I encounter. there a little grease may keep them from seizing.

DMF 

Not really. Chain suck is when the chain won't release cleanly from the cog. It can get pulled into the mech where it's not supposed to go, and otherwise interfere with shifts. Usually a sign of advanced wear on the chain or the cog.

Your shift problem was from the cog not being where it is supposed to be. Gone walkabout.

PatrickGSR94

Yes correct, but the problem manifested itself in something similar to chain suck, where the chain was getting pulled up into the mech sort of in-between the rings.

rmfnla

A little heat from a hair dryer or a soldering iron will loosen up the Red Stuff...

nfmisso

Must not be the good stuff; two companies ago, we had to rework some bolts that had Loctite 271 (Red) used to prevent loosening; took MAPP gas torches to free up the bolts, propane torches would not do it.

rootboy 

Yep. They don't make Locktite like they used to.....

dscheidt

There are a number of grades of loctite, even in the "red" class. 262 will come off with hand tools on automobile sized parts (maybe not with a hex key on a chainring bolt). 271 is stronger, and will not come off with hand tools if it's properly applied, unless there's a lot of heat. There are a bunch of other grades as well, as well as other brands of htreadlocker.

skimaxpower

Much like un-lubricated condoms and non-alcoholic beer, red threadlocker should come with a "are you really sure you want to buy this product" waiver form at point of sale.

rmfnla

Huh, the other night I removed my Eggbeater cleats to install a pair of the SS shields. I had used the red stuff (Loctite brand) and was able to remove the bolts with just a t-handle allen wrench, no heat...

nfmisso

+1