Author Topic: Chain replacement advice, please!  (Read 973 times)

Dave B

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Chain replacement advice, please!
« on: August 20, 2016, 11:37:47 AM »
Hi, just returned from cycle touring in France  ( Brest Nantes canal Loire Valley etc). The chain on my Nomad II was very loose ( KMC narrow Z), I attempted to replace it with SRAM chain ( 8 speed pc 850) as it had done approx 5k over the yrs. Obvious the new chain didn't mesh so I replaced with the worn KMC chain and dropped a couple of links , and works fine.

Questions,  how long could I be expected to run this chain? Will I need to replace the whole front and rear sprockets if I wish to replace the chain? Or, did I attempt to replace the chain with the wrong type?

mickeg

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Re: Chain replacement advice, please!
« Reply #1 on: August 20, 2016, 12:22:18 PM »
... Obvious the new chain didn't mesh so I replaced with the worn KMC chain ...

Not a lot of detail here. 

The Sram eight speed should have worked, as that is the right size.

But if you had to remove a couple links to get the worn chain to be the right length, it might be so worn that you might have already worn out your chainring and rear sprocket.

Dave B

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Re: Chain replacement advice, please!
« Reply #2 on: August 20, 2016, 01:11:32 PM »
Thanks for the prompt response.

BY mesh I meant  that when I fitted the SRAM chain it sort of grinded and didn't generally run smoothly,  only ran it for approx 10 miles.  Should I have run it longer?

Are pin lengthso an issue . KMC are 7.3 and SRAM are less

The sprockets look fine in my admittedly experience.

Is it case are having to reverse the sprockets and then fitting a new chain
?
thanks for you input.

mickeg

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Re: Chain replacement advice, please!
« Reply #3 on: August 20, 2016, 04:05:11 PM »
Since most chainrings are sold with even numbers of teeth, I am assuming that is what you have.

If your front chainring has an even number of teeth, every other tooth can wear a bit more than the others.  Thus, if you put a chain on the chainring so that the teeth that used to have links with outer plates now have inner plates, that could cause it to sound odd.  More detail here:
http://www.sheldonbrown.com/chain-life.html

Thus, it is possible you put the Sram chain on with the links out of phase so to speak, and then got lucky by putting the old chain back on in phase. 

I am only guessing that this is what happened, but I have no other suggestions for why.

I assume your rear sprocket is 17 teeth, as that is what SJS usually supplies.  Thus, only the chainring and not the rear sprocket would likely be the source of the odd noise. 

I cut a small notch in one tooth on my chainrings and in one tooth of my rear sprocket (I use a 16T rear sprocket).  When I put a chain on, I am careful to always put a link with an outer plate on the teeth with the notch. 

If you take your chain off, you might want to mark the chainring first on which type of link was on one of the teeth so you can consistently put your chain on the same way.

Have you measured your chain for length (or stretch)?  I usually replace chains at 0.75 percent stretch.

I have no suggestion on whether or not you need to reverse sprocket or chainring.

Dave B

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Re: Chain replacement advice, please!
« Reply #4 on: August 20, 2016, 04:11:54 PM »
Mary thanks, I will give it go.

pavel

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Re: Chain replacement advice, please!
« Reply #5 on: August 20, 2016, 04:46:40 PM »
Went to France and the chain became Tolouse?

Sorry.... couldn't resist ;)

Danneaux

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Re: Chain replacement advice, please!
« Reply #6 on: August 20, 2016, 04:56:47 PM »
Quote
Went to France and the chain became Tolouse?
Brilliant. I bow to your superior punmanship, Pavel, as I do my sister's.

On spotting an elderly man driving erratically in his large car, she said, "Oh! Look! Its a Cataract Eldorado!"

All the best,

Dan.

John Saxby

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Re: Chain replacement advice, please!
« Reply #7 on: August 20, 2016, 05:19:20 PM »
Quote
Went to France and the chain became Toulouse?

Sorry.... couldn't resist

Ouch!  Pavel, you're taking the Lau trec there ...
« Last Edit: August 20, 2016, 07:26:00 PM by John Saxby »

Dave B

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Re: Chain replacement advice, please!
« Reply #8 on: August 20, 2016, 06:05:53 PM »
I must be getting old as I found that joke hilarious  :)

Andre Jute

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Re: Chain replacement advice, please!
« Reply #9 on: August 21, 2016, 12:36:37 AM »
Went to France and the chain became Tolouse?

Ve, voo haff Gazelle Toulouse, are NOT AMUSED.