Author Topic: Chain replacement  (Read 225 times)

Oggi

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Chain replacement
« on: May 28, 2020, 07:20:40 PM »
My chain has reached .75 wear on my Park tool gauge after 2600miles. I looked at SJS and the KMC X1 is out of stock so I called in my LBS and they had one. £7 more than SJS but they offered to fit it so good deal I thought.
They struggled for 2 hours and could not get the new chain to fit. It is the same number of links as the old chain, and the same chain. But it is either too tight on the minimum adjustment or so slack it falls off if we put an extra link in. Eventually they put the old chain back on and agreed to do some research and get me back in when they have found out what is going wrong.
Does anyone here have any advice I can use. Thanks in advance
Doug

Oggi

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Re: Chain replacement
« Reply #1 on: May 28, 2020, 07:22:45 PM »
Sorry clicked the wrong button before I finished. The bike is my Thorn Mercury with the lightweight eccentric bottom bracket.
Doug

Matt2matt2002

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Re: Chain replacement
« Reply #2 on: May 28, 2020, 10:29:58 PM »
Sorry clicked the wrong button before I finished. The bike is my Thorn Mercury with the lightweight eccentric bottom bracket.
Doug
Half link the answer?
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Oggi

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Re: Chain replacement
« Reply #3 on: May 28, 2020, 10:35:54 PM »
How does a half link work?

Matt2matt2002

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Re: Chain replacement
« Reply #4 on: May 29, 2020, 11:44:38 AM »
How does a half link work?
Sorry. Not sure but I've heard other folks here mention it. I'm sure someone will enlighten us soon.
Never drink and drive. You may hit a bump  and spill your drink

lewis noble

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Re: Chain replacement
« Reply #5 on: May 29, 2020, 12:42:29 PM »
I think it's a shorter link . . . . . NOT just one side of the link . . . . .
 

PH

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Re: Chain replacement
« Reply #6 on: May 29, 2020, 01:15:59 PM »
Putting the old one back was the right thing to do, .75 is OK for a derailleur, but if you're going for that on am IHG then use cheap ones!  2,600 miles!!! I begrudge the cost if it doesn't last 10,000. Even at .75 the sprocket is unlikely to play nicely with a new chain.  I don't measure my chain, I change it either when I run out of adjustment or the sprocket looks worn.  A decent quality chain will last the side of a sprocket. 
I really don't know what your bike shop is doing, it's a standard chain on standard size components, if an old chain fitted a new one will.  Or have you changed something else as well?  The Mercury has some recommended sprocket/chainring combinations required to take advantage of the smaller EBB (Now changed on the MKIII)
« Last Edit: May 29, 2020, 01:17:46 PM by PH »

Oggi

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Re: Chain replacement
« Reply #7 on: May 29, 2020, 01:47:30 PM »
Thanks for all the advice folks. It sounds like Iím worrying unnecessarily. The sprockets are fine and Iím only at 50% of the available adjustment. My LBS have been very good with my derailleur bikes but they admit that the IHG is a new beast to them. They are used with single speed so not too unfamiliar. Iím inclined to leave it a while and change when I run out of adjustment. I have tried SJS but they are obviously running on skeleton staff.
The sprocket and chain ring are a standard combination of 47 x 17 and I have not changed anything other than the chain.
Thanks again folks.

Doug

B cereus

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Re: Chain replacement
« Reply #8 on: May 29, 2020, 02:48:56 PM »
As PH says the early Mercury frames had a mini eccentric BB which only allows for a little more than a half a link of adjustment. For this reason certain combinations of chainwheel and sprocket are only possible by using a half link.
 
Has your old chain got a half link in it?

There's a list of recommended chainwheel  sprocket combinations for the mini eccentric BB in the mega brochure.

Normally its only possible to increase or decrease the length of a chain by one whole link. The half link does what it says on the tin and allows increasing or decreasing the length  by half a link.

PH

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Re: Chain replacement
« Reply #9 on: May 30, 2020, 12:36:48 AM »
Iím inclined to leave it a while and change when I run out of adjustment.
That sounds like the best plan.  It's what I tend to do, have done the same with an EBB with full adjustment so doing it with the Mercury still isn't getting close to maximising usage.  I keep meaning to remove a link then add a half link once I've reached the end of the adjustment, that would take it back to the start.  But when it comes to it I can't be bothered, a new chain and half life of a chainring and sprocket still comes to under £40, so still reasonable value and you always know there's plenty of life in what you're using.  I have a couple of times moved the used chain over to my Alfine around town bike, where I've got another few thousand miles use.