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Chain slipping/jumping on cassette Sora 9 speed

by roadgenius4
Wed, Feb 11, 2015 20:28
6

I have a Sora 9 speed set up with a 9 speed Tiagra Rear Derailleur. The gears were not shifting on the cassette around 3rd or 4th very well but were fine everywhere else.
I have only recently bought the bike second hand but I found that the original chain had nearly half an inch of stretch, so I replaced it immediately with a Clarks 9 speed chain. Since I fitted the new chain, the shifting is generally a lot smoother, however I still find it jumps on a few of the cassette rings. The jumping seems to be worse than it was with he old chain even though the shifting is improved so I don't know whether its the Clarks chain or the cassette which has probably worn as well. I know a tiagra/sora cassette is not a lot but I wanted to be sure my new chain isn't causing problems.

I had the exact same problem with 2 different MTB and Hybrid bikes I was fixing a while ago where I replaced the worn out chain, which actually worked OK, with a newer one and it ended up jumping on the old cassette. I'm guessing its because the chain and cassette wear at similar times and wear each other in places so that they don't work when one or the other is replaced.

If you're new please join in and if you have questions pop them below and the forum regulars will answer as best we can.

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6 comments

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stuartanderson | 9 years ago
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I recently changed my chain and the new one immediately started slipping on what I thought was the cassette so I changed that as well and it continued to slip. I was convinced the slipping was coming from the rear end of the bike so next I removed my aluminium jockey wheels and replaced with the original Shimano plastic ones, it still slipped! I eventually found some info on the net that it might be the front inner chainring although that didn't seem possible! I put chain on the big ring and the slipping stopped! I took off inner chain ring and as a short term measure I 'turned it round' the opposite way and the slipping was gone. Oredered a new inner ring and everything OK!!

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roadgenius4 replied to stuartanderson | 9 years ago
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that sounds odd, but interesting.
How does that make the rear slip though? that might be my problem but i dont know how it could effect the cassette.

Im thinking about upgrading to 105 10 speed soon so that should solve my problems. What do you think about 105?

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stuartanderson replied to roadgenius4 | 9 years ago
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I'll bet it is your chain ring! Try your bike in the big ring and see if it slips? Shimano 105 is excellent, I use it on my winter bike and it's (usually) completely trouble free!

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FullGas | 9 years ago
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Usually the cogs in the middle of the cassette wear faster than the other cogs simply because these are the most ridden with. Replace the cassette and everything should work work fine. If you want to make sure that's the problem watch this video https://www.youtube.com/watch?v=a-7SWfQeqXI

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Pete B | 9 years ago
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As the old chain when you got the bike was very badly worn, “stretched” to nearly half an inch ! (that is over four times the wear when the chain should have been replaced), the cassette will need replacing too. You are correct that the cassette does wear with the chain so a new chain will slip on worn cassette. Also with the bike running with a very worn chain on it, I would check the condition of the chain rings too.

I agree with the other reply that checking the chain for wear, (with a wear gauge or measuring with a rule), is a good idea. Some people advocate a new cassette with ever new chain, but if you don’t let the chain get too worn I don’t think you need to. I replace my chain at 0.75 on chain wear gauge (which is about 3/32" over 12 links ) and cassette every 3 chains.

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2 Wheeled Idiot | 9 years ago
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Yeah, sounds like your cassette may be knackered too (I assume the derailleur is tuned properly)....
But first you can regrease/oil the cables as their may be some sticking in the routing, this has happened to me a few times on my winter bike.
Clark's chains are also not great ime, so kmc or shimano at the same time you swap cassette.
Probably worth getting a chain stretch checker as this allows you to know when your chain is worn, early enough to not need a new cassette too so does save money in the long run.

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