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Discussion Starter · #1 ·
Is there something wrong (bent a little?) wrong with my XT 750 9spd cassette causing my PC-99 Hollowpin chain to separate?

I've suddenly experienced a rash of chain failures. Upon inspection, I find the chain plate(s) bent and trying to slip off the end of the pin(s). Yesterday it happened with the chain on the 3rd (28 teeth?) cog. I think it has always happened on the 2nd or 3rd cog.

Of course, I don't see an obvious fault with the cassette.

Thanks,
Terry
 

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Old man on a bike
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With a new chain each time? Or are you repairing the same chain and, if so, how?

A tooth on the cassette bent enough to damage a chain should be fairly obvious. You shift smoothly? You check the chain rings as well?
 

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Discussion Starter · #3 ·
Bikinfoolferlife said:
With a new chain each time? Or are you repairing the same chain and, if so, how?

A tooth on the cassette bent enough to damage a chain should be fairly obvious. You shift smoothly? You check the chain rings as well?
I've been repairing the old chain by discarding the bent parts and then carefully reassembling the chain and correcting any stiff links.

I am shifting the same as I have for years. The chain break does not occur during a shift. I did have a worn out middle ring but I replaced it some time ago.

My son and I rode today. Same obstacle where my chain broke yesterday. No problem. I was riding with a new SRAM chain and a different, but used, cassette.

Thanks for your response.

Terry
 

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Elitest thrill junkie
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Shimano chains have mushroomed shaped pins to prevent the exact situation you are describing (links sliding off of pins). This is why I use such chains, but there is no reason why a cassette would be causing that problem. Lots of torque and a poor chain is what causes that problem. Even sram makes a "special pin" for chain-reassembly, but virtually no one ever needs it due to the power link. If you break a SRAM chain, USE THE POWERLINK, or buy a NEW powerlink to put it back together. Otherwise, the chain will keep sliding off of the pins because you've made a weak-spot in the chain.
 

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Discussion Starter · #5 ·
Jayem said:
Shimano chains have mushroomed shaped pins to prevent the exact situation you are describing (links sliding off of pins). This is why I use such chains, but there is no reason why a cassette would be causing that problem. Lots of torque and a poor chain is what causes that problem. Even sram makes a "special pin" for chain-reassembly, but virtually no one ever needs it due to the power link. If you break a SRAM chain, USE THE POWERLINK, or buy a NEW powerlink to put it back together. Otherwise, the chain will keep sliding off of the pins because you've made a weak-spot in the chain.
OK, sounds like very good advice. I do have a couple spare POWERLINKS and always carry one with me. Anyway, if I do have another chain separateion I will definitely take your advice and replace the damaged link with a POWERLINK.

Many thanks!

Terry
 

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No, I meant just not having the chainrings indexed properly when remounted. I was also thinkin bout to big of a cassette gear for the rear derailleur might do that.
 
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