The chain split!

by Richthornton   May 13, 2013  

So my chain split whilst out on a ride today. Had a chain splitter and missing link, so got it repaired no problem. After repairing it, the chain was 1 link shorter than it had previously been.
I should have picked up on the warning signs, the chain had been talking to me for some time, seemingly trying to shift a gear of it's own accord and slipped off the small chainring once as well.
Now the funny thing is that after repairing the chain everything seemed better. Gear changes were sharper and neater, much less rubbing and chatter. I didn't alter anything else. Didn't adjust the indexing.
Could it be that I should have been using a shorter chain all along? I have always matched the length of the chain to the previous one when replacing it. Can a shortening of a couple of links really make such a dramatic difference or is it my imagination?
Do I now need to buy a new chain given that it now has 2 missing links in it or is it safe to continue to use?

Thanks to anyone who has something to say on this.

8 user comments

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Yep shortening a chain by one link can make that difference. Definitely replace the chain though and get another spare link

posted by crash144019 [47 posts]
13th May 2013 - 19:43

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Oh I'll definitely be getting more spare links, I would've been stranded in he depths of Cumbria, miles away from anybody if I didn't have one with me today!

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posted by Richthornton [94 posts]
13th May 2013 - 20:28

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Never measure your new chain against your old chain. Your old chain is worn out and stretched. This only makes your new chain to long. If you have changed your chain a couple of times your chain is only going to get longer and longer.
The formula for measuring your new chain is :-
Run your new chain over and around the two biggest cogs (chain set & cassette ) but not through the rear derailier. Have the chain overlap by 3 links. This should give you the correct length. Then put the chain on properly and join it. Once the chain is on run it on the two smallest cogs, the chain should not hit the rear derailier. Also run it on the to biggest cogs to make sure it's not to tight.
There are lots of good YouTube videos to watch which explain it.
Harry, owner of Glastonbury Cycles

posted by Harry.horler [2 posts]
14th May 2013 - 7:47

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Rich, forgive me if you know all this already, how old was that chain? How many miles do you think it had done? Do you own a chain wear indicator and do you regularly check to see if your chain is worn out? If the chain had done a few thousand miles you will have worn out your cassette too and if you just fit a new chain it will constantly slip over the worn sprockets on your old cassette. If you don't have a chain wear indicator already they are cheap and well worth having as you will be able to tell when to replace your chain before it totally wears out and save on new cassettes, jockey wheels and even chainsets if you replace in time.

Ah! Condor

posted by Bedfordshire Clanger [304 posts]
14th May 2013 - 22:38

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Bedfordshire Clanger wrote:
Rich, forgive me if you know all this already, how old was that chain? How many miles do you think it had done? Do you own a chain wear indicator and do you regularly check to see if your chain is worn out? If the chain had done a few thousand miles you will have worn out your cassette too and if you just fit a new chain it will constantly slip over the worn sprockets on your old cassette. If you don't have a chain wear indicator already they are cheap and well worth having as you will be able to tell when to replace your chain before it totally wears out and save on new cassettes, jockey wheels and even chainsets if you replace in time.

The chain and cassette were both replaced in mid-February and have done about 1000 miles since then so I doubt that either of them are worn. I do have a chain checker although I don't regularly check it, I guess I didn't consider that the chain could have been worn yet given the low-ish mileage on it.

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posted by Richthornton [94 posts]
15th May 2013 - 11:53

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Harry.horler wrote:
Never measure your new chain against your old chain. Your old chain is worn out and stretched. This only makes your new chain to long. If you have changed your chain a couple of times your chain is only going to get longer and longer.
The formula for measuring your new chain is :-
Run your new chain over and around the two biggest cogs (chain set & cassette ) but not through the rear derailier. Have the chain overlap by 3 links. This should give you the correct length. Then put the chain on properly and join it. Once the chain is on run it on the two smallest cogs, the chain should not hit the rear derailier. Also run it on the to biggest cogs to make sure it's not to tight.
There are lots of good YouTube videos to watch which explain it.
Harry, owner of Glastonbury Cycles

Thanks for the advice Harry, Although I don't doubt your knowledge, I was under the impression that the chain doesn't actually 'stretch' as such but the pins wear down causing the gaps between links to increase, but the length of the chain overall wouldn't change.
(http://cyclingtips.com.au/2009/03/how-to-check-for-chain-wear/)
am I mistaken?
However I will definitely be taking your advice for fitting the new chain as the length of the old chain will have no bearing on that method, thank you.
Rich

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posted by Richthornton [94 posts]
15th May 2013 - 12:00

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I'm yet to see a chain that's so worn that it's an entire link longer. Old vs new is fine as long as the old one was the right no. of links.

posted by racingcondor [105 posts]
15th May 2013 - 17:56

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Hope this link works.
This is the method I used when I first installed a new chain yonks ago.
I just count the links on my old chain now.

http://techdocs.shimano.com/media/techdocs/content/cycle/SI/SI_5X90B/SI-...

Have a look at centre-bottom of this Shimano pdf, there's a diagram showing correct chain length.

posted by Bing Bell [8 posts]
15th May 2013 - 19:58

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