Do I need to replace my chainset?

[Shooter999]

Thanks everyone. All advice really appreciated.

 

[Yellow Saddle]

Not directly but if not all the teeth are making good contact, the force is applied through fewer links so there's a higher peak out-of-line force in each link as it passes and that's why it wears faster, isn't it?

Correct.

 

[Pale Rider]

On modern chainsets like the OP but not vintage?

Quite so, and there may be some modern rings that have teeth of all the same profile.

Shimano like their asymmetrical design, all their cassettes labelled HG have it, HG standing for 'hyper glide' - Shimano-speak for teeth of differing profiles.

 

[Blue Hills]

Chains don't skip on chainrings, only on sprockets (at the rear).e.

sorry, i am not techie but can confidently state that this is not true. I have a bike i don't live with and will soon be fitting a new chainring to (single chainring linked to 7 speed cassette mounted on 3 speed hub gear) for it is slipping like mad. My ridgeback hybrid/tourer 3×8 was recently slipping like mad. If your statement is true how do you explain the fact that a swap of the middle alivio front chainring immediately solved the problem? I am still puzzled by how that chainring wore so quickly but the swap definitely sorted things.

 

[Yellow Saddle]

sorry, i am not techie but can confidently state that this is not true. I have a bike i don't live with and will soon be fitting a new chainring to (single chainring linked to 7 speed cassette mounted on 3 speed hub gear) for it is slipping like mad. My ridgeback hybrid/tourer 3×8 was recently slipping like mad. If your statement is true how do you explain the fact that a swap of the middle alivio front chainring immediately solved the problem? I am still puzzled by how that chainring wore so quickly but the swap definitely sorted things.

Obviously, as I've stated, there comes a point when the chainring just cannot grip the chain and it will slide over the top of the teeth. This is called skating. Skipping is when a chain vacillates between two different gears on a cassette and this is caused by poor derailer adjustment or sticky cables or a bent derailer hanger. That gets me off on a technicality but I stand by my statement and its original intention.

The relationship between sprockets and worn chains is not intuitive. What happens at the back doesn't happen in the front. I've given the reasons for that. A reasonably worn chainring, even to the extent in the second photo, does not skate. You have to go beyond that and that is in the realm of severe neglect or ignorance.

You provide no photos or descriptive evidence nor reference you case against the two excellent photos provided in this thread. Therefore we cannot comment on your case. "Slipping like mad" doesn't really tell me much. I would imagine that yours was worn beyond the point of vibration, where any reasonably competent mechanic would have replaced it.

People assume that because a new chain skates on a worn cassette sprocket, the same happens in front but it doesn't. At the rear the chain skates because the chain enters the mismatched (worn) sprocket under slack and is not forced into the teeth. It therefore rides over the top and because of limited wrap, just skates over the top when you pedal hard. Moderate pedaling doesn't give the same effect. In front, the chain is forced into the worn sprocket under huge tension and it seats properly, albeit that only the first roller/half link is under tension. Only when the teeth are worn down (short), will it skate. In the rear it skates even though the teeth are still full-length.

 

[Blue Hills]

skating, skipping, whatever you want to call it.

 

[Yellow Saddle]

skating, skipping, whatever you want to call it.

I'll call it skating, thank you.

 

[EasyPeez]

Bear in mind the teeth are meant to be different shapes to aid shifting.

Some are more pointy than others and it's easy to mistake that for wear.

I had no idea, thanks for pointing that out. I was looking at my chainring just this lunchtime wondering why some teeth were showing signs of wear and others not, but I guess that explains it