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12-02-18, 09:34 AM | #11 |
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Re: Is this sprocket too worn?
I think everything wears together so if you put a new sprocket on the teeth spacing will be slightly closer than the original so the old chain will only really be in contact with one tooth at a time. Then instead of the load being shared by all the teeth it will be concentrated on each one individually so wearing them rapidly until they reach the same spacing as the chain (and old sprocket) when the load will once again be shared and the wear rate slows. Unfortunately I think that during this process the chain is also temporarily more stressed so increasing its wear rate until it all settles down again.
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12-02-18, 11:15 AM | #12 |
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Re: Is this sprocket too worn?
After getting a puncture in the back tyre repaired I noticed that the chain was too slack so I took the bike back to get it fixed. The mechanic (who is a biker himself) pointed out that the sprockets were wearing and that I should always replace both sprockets and the chain at the same time. So next time it is serviced it will get done. As the bike is on the original set and has done nearly 20,000 miles I don't think I have done too bad.
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12-02-18, 12:25 PM | #13 |
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Re: Is this sprocket too worn?
Fortunately the sprockets are the cheap bits (unless you go for something fancy of course) however I think the quality of the chain can make a difference on lifespan. 20k is pretty good and apparently with auto lubricators that can be stretched (pun intended) up to 40k.
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12-02-18, 12:31 PM | #14 |
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Re: Is this sprocket too worn?
I agree with the,"Leave it until you need to replace the chain" posts.A JT kit for my 1999 Curvy is only around £66 quid.I fitted a DID kit last year but might go with the JT next time as they seem just as good for less and the sprockets that came with the DID chain were JT anyway
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12-02-18, 02:56 PM | #15 |
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Re: Is this sprocket too worn?
As the chain wears the pitch gets bigger (clearances in the pins/bushes increases). As the sprockets wear the tooth pitch hardly changes, or with the front if anything the pitch gets smaller as the root of the tooth profile where the roller seats wears and the effective diameter gets slightly smaller. The net result whatever condition is that the loading gets concentrated on the take-up tooth. A new tooth profile is designed to meet the chain roller at an ideal angle, a worn tooth means the contact happens at a different angle so results in greater impact, making it less refined.
The bigger problem is often the hooking and the drag which can happen as the chain leaves the tooth on exit. I tend to work on the principle that front sprockets get the hardest time and are usually the least expensive, so fitting a new one roughly halfway through the chain life can be effective and certainly gives a better condition than a worn one. I know it isn't an ideal or perfect situation, but only a complete new set of bits will give you that. Entirely up to the individual, I certainly wouldn't suggest either as necessarily better.
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12-02-18, 04:46 PM | #16 | |
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Re: Is this sprocket too worn?
Quote:
There is also more force on each front sprocket tooth as less teeth so less chain rollers in contact to spread the load over. Front sprockets don't normally cost too much.
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12-02-18, 05:41 PM | #17 |
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Re: Is this sprocket too worn?
youre right its just that, as I say, Ive found the new sprocket has slightly different pitch compared to the partially worn chain so the load instead of being spread is taken on individual teeth. This drastically accelerates the wear on the new front sprocket (and maybe the chain) until its pitch matches the chain and then the wear rate returns to normal. Effectively you have gained very little and may even have reduced the life of the chain....
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12-02-18, 05:43 PM | #18 |
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Re: Is this sprocket too worn?
Can 'o' worms!
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12-02-18, 09:30 PM | #19 |
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Re: Is this sprocket too worn?
If it aint broke------Fix it until it is broke.
Or just ride it until it wears out then buy another one.
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13-02-18, 08:42 AM | #20 |
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Re: Is this sprocket too worn?
So yet another thread that concludes one thing.
We all do different things because we are all different people. DomP - If you can be arsed to replace it and you want to, then the people have spoken - do it. If you can't be fudged as other people have also spoken - leave it till it's all mullered. I know which one I'd do. (It is still cold in the garage and there are many other things that involve less swearing) |
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