Thorn Cycles Forum
Technical => Transmission => Topic started by: Oggi on May 28, 2020, 07:20:40 pm
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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
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Sorry clicked the wrong button before I finished. The bike is my Thorn Mercury with the lightweight eccentric bottom bracket.
Doug
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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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How does a half link work?
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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.
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I think it's a shorter link . . . . . NOT just one side of the link . . . . .
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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)
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Thanks for all the advice folks. It sounds like I’m worrying unnecessarily. The sprockets are fine and I’m 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. I’m 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
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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 (https://www.sjscycles.co.uk/chains/kmc-12x18-z510l-12-link-offset-half-connecting-link/) does what it says on the tin and allows increasing or decreasing the length by half a link.
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I’m 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.
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Hi all
Apologies if I’m repeating what others have already mentioned but the KMC X1 chain is not just out of stock it’s been superseded by the KMC E1, SJSC part number 53243. I waited and waited for the restocking email and after a few weeks heard nothing so rang Thorns. Apparently it’s essentially the same chain and the KMC X1 missing link is compatible with the successor e1 chain so don’t throw away all your spare X1 missing links!
Regards
Tony
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Very much the same question as the OP. On my 18 month old Mercury II, I have reached about 5500 miles on the KMC e1 chain originally fitted. Using a Rohloff chain gauge I am approaching 0.075mm wear; there is no significant wear to the teeth on the chain ring or sprocket. I am running 45x19 which is one of the recommended combinations; when new the mini EBB had about 3/4 of the total adjustment available. I have taken up the slack once but still have just over half the adjustment still available.
The question is, do I replace the chain now or continue until all the adjustment is used up ?
Current prices on SJS are for a KMC e1 £26.99, sprocket £17.99, double sided chainring £49.99. Which I think makes replacing the chain unattractive in the short term.
Based on a comment up thread a new chain may not run smoothly with the 'little' wear I have. Which makes me minded to continue with the current chain. If the rate of wear does not increase I would hope to get another 5000+ miles before the adjustment in the EBB is taken up. After that I guess an option is to fit a half-link and run until the sprocket and chainring are really worn.
Any thoughts
Thanks
Robert
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The question is, do I replace the chain now or continue until all the adjustment is used up ?
The mini EBB does make it a little more complicated. You're not getting the full value of an expensive chain. When you get to the end of the adjustment, you could remove a link add a half and start again:
https://www.sjscycles.co.uk/chains/kmc-12x332-z510l-12-link-offset-half-connecting-link/
Current prices on SJS are for a KMC e1 £26.99, sprocket £17.99, double sided chainring £49.99.
Don't forget each cycle only costs 50% of the reversible sprocket and chainring. It might also be that the rate of chain wear slows, I'm sure some of the early elongation is settling in rather than wear.
The chain on my Mercury slipped a couple of times on a long ride last week, it still looks OK and I haven't been able to make it slip again on a couple of local rides, I'll monitor it, I have a new chain ready to go on. 23,700km, I'd like to round that up!
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On derailleur bikes, I swap chains at 0.75 percent elongation. But on IGH bikes, I wait until over a percent.
You said you used a Park gauge. The cheap gauges that only contact the chain at two spots are not very accurate, the gauges that have three hooks of the gauge are much better.
Park, Pedros, maybe by now others make the good ones, described here how to use:
https://www.youtube.com/watch?v=iOaFF_4CqJg
In the video, note at 0:57 that they use their fingers to put tension on the chain between two hooks, that is a key to this chain checker being more accurate.
Thoughts on that from Zinn:
https://velo.outsideonline.com/road/road-racing/measuring-chain-wear-accurately/
I use the Pedros one Zinn cites.
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I think it's a shorter link . . . . . NOT just one side of the link . . . . .
All links are a half inch.
The half link allows you to use an odd number of links instead of an even number. Looks like this.
https://www.amazon.com/KMC-Z410-OL-Half-Link-8-Inch/dp/B001CNC2UU/
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FWIW, I have the following for my Mercury Mk 3:
Connex 8-08 & 3 or 4 KMC Z-1. I bought these online in UK & Germany, cost around USD 15 each, if memory serves.
(Currently, similar chains in Canada are between C$16 and $20, so the reference points above are still valid.)
On my Raven, I used KMC 8x98, which cost a little less, and worked very well. I used to change my chain after ~4000-5000 km.
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I have experienced the problem outlined by the OP and others with my Mercury.
I tried the half link but it didn't work for me.
Messed around with the EBB and finally it worked.
Just ensure that you have the same number of links in the new chain as the old.
I use cheap 8 speed chains and run them until I can lift the chain off the chain ring.
YMMV
Mike
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I have experienced the problem outlined by the OP and others with my Mercury.
I tried the half link but it didn't work for me.
Messed around with the EBB and finally it worked.
Just ensure that you have the same number of links in the new chain as the old.
I use cheap 8 speed chains and run them until I can lift the chain off the chain ring.
YMMV
Mike
What's the FLA, YMMV, mean?
Thanks
Matt
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Thank you for you comments.
I was not aware of the 3 point Park chain checker. Looking on the SJS site they have an older Park design and a KMC design which give measurements on chain extension, rather than a go/no go result, which appeals to 'nerdy' mind. Will think about investing in one or more of these.
I think my plan will be to keep running the chain through the winter and see how the wear/ extension develops. I have some half-links somewhere, will have to dig them out to see if they are any use once I run out of adjustment on the EBB.
Robert
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I have experienced the problem outlined by the OP and others with my Mercury.
I tried the half link but it didn't work for me.
Messed around with the EBB and finally it worked.
Just ensure that you have the same number of links in the new chain as the old.
I use cheap 8 speed chains and run them until I can lift the chain off the chain ring.
YMMV
Mike
What's the FLA, YMMV, mean?
Thanks
Matt
YMMV = Your mileage may vary = you may disagree or have a different result.
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I have experienced the problem outlined by the OP and others with my Mercury.
I tried the half link but it didn't work for me.
Messed around with the EBB and finally it worked.
Just ensure that you have the same number of links in the new chain as the old.
I use cheap 8 speed chains and run them until I can lift the chain off the chain ring.
YMMV
Mike
What's the FLA, YMMV, mean?
Thanks
Matt
YMMV = Your mileage may vary = you may disagree or have a different result.
Thanks. And you know, FLA?
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I have no idea about FLA or who mentioned it.
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FLA: place in the States, long way south of here. Cycle references? Dunno. ;)
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I have no idea about FLA or who mentioned it.
FLA = Four Letter Abbreviation 😏
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...
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FLA = Four Letter Abbreviation 😏
FLA is three letters <insert chuckle here>.
I could not find that on my list of acronyms that I keep handy.
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TLA, three letter acronym. Standard NATO speak, oops that an FLA.
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FWIW, I have the following for my Mercury Mk 3:
Connex 8-08 & 3 or 4 KMC Z-1. I bought these online in UK & Germany, cost around USD 15 each, if memory serves.
(Currently, similar chains in Canada are between C$16 and $20, so the reference points above are still valid.)
On my Raven, I used KMC 8x98, which cost a little less, and worked very well. I used to change my chain after ~4000-5000 km.
I run on Connex 808 too. First 808 ran for 13,000km. Current 808 is approaching 9000km and still ok. It doesn’t need to be a single speed chain.
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I too used to run Connex chains until they became more difficult to get and I discovered the KMC X8, which I buy several of at a time. The advantage of the X8 (any KMC chain, really) is its factory lube, which I think is the best of all the proprietary factory lubes. This is important to me because I operate a near-zero maintenance bike, the operating procedures for which include minimising the times I have to bend over the bike, which leads to running the chain for its entire life on the factory lube. It works. If you haven't yet seen my factory be experiment, there's a summary at
http://thorncyclesforum.co.uk/index.php?topic=6813.msg42349#msg42349 (http://thorncyclesforum.co.uk/index.php?topic=6813.msg42349#msg42349)
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I have no idea about FLA or who mentioned it.
FLA = Four Letter Abbreviation 😏
When I ceased working full time I took a contract at a well known charity.
When I asked about frequent references to TSA in internal documents I was told that it meant The Salvation Army!