39 tooth chainring lifespan

[LegendRider]

What do you think the lifespan is for a Dura Ace 7800 39 tooth chainring that has been well maintained?

I'm still riding 7800 on my two roads bike and both groups have many thousands of miles on them. After installing a new chain and cassette on one of them, I get an odd rhythmic noise in the small ring, but not the big. It seems likely the small ring is worn out but I'm terrible at eyeballing wear on chainrings and cassettes.

[Louis]

http://roadcyclinguk.com/how-to/maintenance/how-to-identify-the-signs-of-a-worn-drivetrain.html/2#g6iE4HHLqE8GW0Fh.97

http://cdn.coresites.factorymedia.com/rcuk/wp-content/uploads/2014/01/ChainringNewOld.jpg

[oldpotatoe]

What do you think the lifespan is for a Dura Ace 7800 39 tooth chainring that has been well maintained?

I'm still riding 7800 on my two roads bike and both groups have many thousands of miles on them. After installing a new chain and cassette on one of them, I get an odd rhythmic noise in the small ring, but not the big. It seems likely the small ring is worn out but I'm terrible at eyeballing wear on chainrings and cassettes.

Noise means worn but not un-servicable..meaning if ya can stand the noise, it probably won't 'skip'. Many times during a tune..eyeball small rings..looks good..test ride, that 'noise' in small ring, all cogs, that goes away when into big ring.

[shovelhd]

Also, check for hooking on the drive side of the chainring teeth. Once it is past the point of being able to feel it with my fingernail, I like to replace it.

[mister]

i had probably 12k on a small ring and it seemed fine
i doubt one is worn after a few thousand miles

i did put a new bike together with mismatched parts and i was getting that rhythmic pulse thing you are talking about
small ring, smaller cogs on the cassette, figured it was the cassette but it seems it might actually be the small ring. the ring was brand new...
i haven't bothered with it because i ride in the big ring all the time on that bike

[oldpotatoe]

i had probably 12k on a small ring and it seemed fine
i doubt one is worn after a few thousand miles

i did put a new bike together with mismatched parts and i was getting that rhythmic pulse thing you are talking about
small ring, smaller cogs on the cassette, figured it was the cassette but it seems it might actually be the small ring. the ring was brand new...
i haven't bothered with it because i ride in the big ring all the time on that bike

small ring on backwards?

[Mark McM]

Chainrings will always wear unevenly, because the power transmitted is uneven - there are large power spikes on the pedal downstrokes, and little power as the pedals go across the top or bottom of the stroke. The chainring teeth that engage chain during the power pulses will wear faster. The chain engagement may make noises as it transitions between the more worn and less worn sections of teeth. You may even feel a vibration through the pedals at the trasitions.

All else being equal, the small chainring will wear faster than the large chainring, and due the higher chain tension and greater articulation angle, a worn small ring will be more noticeable than a large ring. However, there are ways to stretch the life of a small chainring. The small chainring typically does not have synchronized shifting pins or ramps, so the small chainring does not have to be mounted in a specific orientation. If you periodically rotate the position of the small chainring on the spider, the wear will be more even, and you can get more miles out of the chainring before it needs to be replaced.*


*Unfortunately, periodically re-orienting the small chainring only works on cranks with evenly spaced spider arms. The new unevenly spaced 4 arm cranks from Shimano and Campagnolo don't allow mounting the chainring in different orientations.

[mister]

small ring on backwards?


I doubt it, but need to pull the cranks to swap bb so i will definitely give that a look.

[thirdgenbird]

Adding an obvious note:

The small ring will wear faster for the reasons above, but keep in mind that is based off chainring use and may not translate to overall road miles. Around here, you may replace the large ring before the small. Roads are flat and its not uncommon to only drop to the small ring for a short climb.

[lhuerta]

...a worn chainring may also result in chain getting snagged during shifts, which could lead to chain suck, which can damage your frame (especially a carbon frame). Why not just share a pic of your small chainrings and we can easily tell you whether it is indeed worn.