Bicycle Mechanics - Are these gears worn?
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04-01-12, 03:37 AM
Following on from my other thread about my gear issues, I am going to recable my bike, however I'd like to know if these gears are worn out enough to justify a new cassette and / or chainrings. My chain is pretty stretched (probably over 1/16", maybe even 1/8") don't have a super accurate ruler at the moment.
Eventually I will replace the cassette and chain, however if by doing it now I can avoid a new cassette then I will do it now. If it is already too far gone, then I will ride it until it is unrideable!
Gah, that's ugly. When you get a new chain (and cassette, if your chain is more than 1/16" worn), just put a single drop of lube on each pivot and do your best to wipe it dry; that's all the lube you need.
To check for chainring wear, with a new chain, try to lift it off the teeth. If you can lift it by more than 5mm or so, your ring is prolly shot.
But the pics say your rings are fine, as there isn't a hint of shark fin to those teeth. You can see chainring wear; the teeth get a hooked profile. Sometimes you can feel it too, as a throbbing under power.
04-01-12, 11:19 AM
Clean the cogs and chainrings thoroughly, then replace the chain. If the chain starts jumping, especially in the smaller cogs, replace the gear cluster too.
I agree with Kimmo- the chainrings don't show much wear. Personally I'd give everything a good cleaning (chain off the bike, toothbrush and solvent on the cogs) and lube before passing judgement.
04-01-12, 11:25 AM
Yeah it is pretty dirty :D in that case I'm going to replace the chain (can clean it!) when I get it, and see how it goes.
The chainrings are in good shape, and I'd be very surprised if a new chain skipped on them. A badly worn chainring has a very obvious shark fin look to the teeth, and even then it has to be very bad to skip, except on smaller rings.
The cassette also looks OK but cassettes are more prone to skipping because of the smaller radius and because fewer teeth are engaged.
I'd replace the chain and cross my fingers about the cassette, hoping to get by, but be ready to replace it if the new chain skips.
As far as the accuracy of your ruler, I've yet to see a ruler that wasn't accurate enough to measure a chain for stretch.
04-03-12, 02:31 PM
Well I have now received the new cassette and chain and will replace the chain at the weekend as rain is due the next few days, then we will see about the cassette.
Why is your bike so dirty? :twitchy: I jumped a little seeing the second picture...
04-03-12, 08:29 PM
Even my commuter rarely gets that bad, and it's already cobbled together with old crap that I don't care about. Looks like way too much lube on the chain.
Clean it all up and next time wipe the chain down with a clean rag until only a thin film of lube is left. Looks like you were pouring it on by the bucket load.
04-03-12, 08:46 PM
Little ring looks pretty worn to me (the U shape between teeth is a little asymmetrical), big ring still looks good.
I can't tell cassettes by looking.
Little ring looks pretty worn to me, big ring still looks good.
usually you can wear chainrings until the crest width is reduced by more than half before they won't hold a chain. Neither ring is nearly that worn.
I'd post photos of the rings on my commuter which are much more worn, approaching the halfway mark at the crests, and still holding chains well, (so far) thank you. But I won't because I don't want to hear the "tsk tsk, you should clean your chainrings nagging".
Seriously, these rings are not not even in the same ballpark with the worn rings still running fine on thousands of heavily used mtn bikes.
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