zacster

I just replaced the big ring on my commuter, a 30 year old Trek 7000. It appeared to be the original. That took care of my chain skipping. No issue there, it was old, it was worn. But how long should they last? My road bike has a 12 year old FSA SLK compact on it, and while it doesn't exhibit any shifting problems, something up front just isn't quiet, and this is with a new chain. I hear a creak with each rotation, while the chain is otherwise quiet in the rear and shifts very well. I've tightened the saddle to the rails and the seatpost to the frame, I checked around all the other bolts. Could it just be a worn ring? It isn't new anymore and has a lot of miles on it.

We all know how frustrating it can be to find a creak.

Ericoschmitt

A quick search on "chain wear" or "when to replace a chain" will tell you what you want. I know, you said chainring. But here goes in short:

Depending on use conditions (muddy mtb to dry road, rider power), maintence and chain quality, it can last anything from below 1000km to 6000km.
Every 3 chains (some may say 4) change your cassette
Every 2 cassettes change your chainrings (it means the whole drivetrain at once)

If you use a chain too worn for too long it will start to bite and wear teeth, first and quicker on the cassette then on the chainrings too. Usually small cogs will start skipping. If your chainring is worn, probably the whole thing is worn too. Replacing chainring might fix it for a while, but the worn chain will wear the ring quickly too

"Years of use" is not a good measure. Some people ride in a week more than some others ride in a year!

LKA 

Instead of addressing wear, I'll address the creak [although I admit they may not be mutually exclusive.]
Creaks in that area of the bike I've had to deal with always entailed fasteners needing tightening or even replacement, and/or lube in places many would never consider.
EG, chainring bolts #1 , crankset fastening #2 , pedal attachment torque #3 , bottom bracket [the entire mess that comprises the BB ] #4 .

I'm not discounting wear, but I've never resolved a creak by replacing worn "stuff."
Coincidentally, the last creak I resolved was via removal of aluminum chainring bolts, substituting titanium fasteners @ the proper torque. Creak gone, peace restored.
Considering I had to drill the old Al fasteners out...good riddance.

Good luck!

zacster

I think the next thing to do is to remove the crank, although one issue I've always had with this crank is that bolt would loosen. This was a known problem with these cranks, and they added wavy washers and reversed the thread of one part in the next version. Now that I have a workstand this won't be so painful. I've already gone around and tightened the bolts. Oh, and why I didn't think of this while riding, TRY THE OTHER CHAINRING. DOH. And you'd think I'd have learned with the commuter, where I diagnosed the problem when I used the middle ring, stomped on it as hard as I could, and it was fine, but as soon as I put it on the big ring it skipped. I'll take it for a spin later and try that.

But I agree, it could be any of the above, except the chain part. I replace chains frequently and this is a brand new chain with under 100 miles on it. It was the silence of the new chain that made the creak all the more apparent. I put a new chain on the commuter too and it is dead silent.

fietsbob

speaking only to the subject line, how long to some extent depends on material hardness ..

lots of better chainrings use 7075-T6 aluminum

and can resist wear almost as well as the heavier but cheaper steel chainrings..

zacster

Mine is probably 7075 or even better. It is an FSA SLK crankset, and not one of the cheap generic ones. I replaced the inner ring, changing from a 36 to a 34, but not the outer 50. I wanted lower gears, but I can't remember the last time I was on the small ring other than to test it out. It is mostly flat in NYC.

imobilinpedalus

Until you break them in.

desmodue

Probably not. For the application, an aluminum alloy better than 7075 in a T6 heat treated condition doesn't exist.

zacster

My point was it is a high-end crank not a cheap one. Anyway, I'm in my cycling clothes ready to go and I'll see how it sounds today, and make a point of using the small ring as a comparison. The other thing I want to try is to swap my Assioma pedals to my commuter since the commuter is otherwise dead silent to eliminate those. These pedals are still new so they shouldn't be making noise. Just spinning them around they move freely without any kind of grab or looseness, either of which can translate to noise.

zacster

Riding on my small ring did not help, so I put the bike on the stand, removed each pedal and spun them around and checked the bearings by feel. No issue that I could detect. I undid the crank bolt and pulled the crank, felt the bearings. Smooth as butter without looseness. I shrug and put it all back together and go for another ride and I still hear it, but it starts to rain and I turn around and go home before I actually get wet. An hour later the sun is out again and it never really rained more than a sprinkle, so I go out again, and this time dead silence for the 20 miles.

My conclusion? It's the shoes and/or the cleats. I'll tighten the cleats before the next ride, and if that doesn't do it I'll just live with it, if the noise even comes back. The shoes are too new to replace, but eventually I'll need new ones.