Chain Length ?

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Christine
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Joined: 9 Dec 2012, 12:40pm

Chain Length ?

Postby Christine » 30 Aug 2015, 4:00pm

How many links do I need for a 11 - 34 block & 44 outer ring on a triple, 9 speed block please ?
I saw a way to calculate not long ago but can't remember were & not really wanting to count the links on my old chain !
Chris
Last edited by Christine on 30 Aug 2015, 5:08pm, edited 1 time in total.

drossall
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Location: North Hertfordshire

Re: Chain Length ?

Postby drossall » 30 Aug 2015, 4:13pm

Why count the links? Unless your bike is unusual, any chain you buy will have enough links. Just lay the old and new chains out alongside each other.

The answer will depend somewhat on the frame, specifically the distance from the chainset to the sprockets. So I'd try fitting the chain and measure how many links to remove (I've never bothered with the comparison above). The aim, of course, is to have the chain feed round the largest sprocket and ring, with the rear derailleur swung reasonably far forwards, then to check that, on smallest/smallest, it can swing far enough back to take up the slack. If it's not far enough forward on largest/largest, it won't have the necessary capacity.

You don't want it as far forward as it will go - it's a matter of balance.

Christine
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Joined: 9 Dec 2012, 12:40pm

Re: Chain Length ?

Postby Christine » 30 Aug 2015, 4:35pm

Thanks for your reply, I have someone who is doing it for me & want to make sure I have a long enough chain in advance !
Chris

Valbrona
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Re: Chain Length ?

Postby Valbrona » 30 Aug 2015, 4:44pm

I do small/small method - chain on smallest chainring and smallest cassette sprocket simultaneously. Check out the first two pics you come to: http://www.parktool.com/blog/repair-hel ... gth-sizing
I should coco.

Christine
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Joined: 9 Dec 2012, 12:40pm

Re: Chain Length ?

Postby Christine » 30 Aug 2015, 5:06pm

Thank you, still scratching my head !
Chris

drossall
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Location: North Hertfordshire

Re: Chain Length ?

Postby drossall » 30 Aug 2015, 5:16pm

I really think that any chain will have enough links. It's just a matter of shortening it to suit the bike, which your friend/contact can do.

You do need the correct chain for the number of speeds (broadly, the more gears/speeds, the narrower the chain, because they are all crammed into the same width). Also, if there is a lot of wear to the sprockets and chain rings, a new chain may slip. However, you can't carry on with the same chain forever; if wear is very bad, you may need new sprockets and/or rings too.

Your friend who is doing the job should know about all this.

Christine
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Joined: 9 Dec 2012, 12:40pm

Re: Chain Length ?

Postby Christine » 30 Aug 2015, 5:25pm

Hi, yes I am ordering a new 9 speed chain & block, been having jumping in 2nd & 3rd sprockets & although it is not as bad as it was to start with after some tweeking, I think its probably time to do it ! I am paying someone, its not a friend & as the bike gets used regularly I can't just take of the chain beforehand to check the length !
Chris

resus1uk
Posts: 256
Joined: 12 Mar 2007, 9:28am

Re: Chain Length ?

Postby resus1uk » 30 Aug 2015, 8:00pm

Large - large method worked for chain length when I put a larger cassette on my trike.
That is on the Park Tools website as well.

Vorpal
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Re: Chain Length ?

Postby Vorpal » 30 Aug 2015, 8:14pm

I just put the chain on with a master link, and see if it looks right. Then, I try it out & see if it shifts right. I've never calculated, nor counted links.

I think any chain you buy for 9 speed will have enough links.
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old_windbag
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Re: Chain Length ?

Postby old_windbag » 30 Aug 2015, 8:34pm

I find shimanos method works well as shown in the shimano tech doc image below:-

https://images.duckduckgo.com/iu/?u=http%3A%2F%2Fassets.cyclingforums.com.s3.amazonaws.com%2F8%2F8c%2F8c48eec4_vbattach8966.gif&f=1

Also when buying chains online care has to be taken with some retailers where I've found the chain lengths sold are sometimes a few links shorter than ideal. A boxed item should have the number of links stated on it but sometimes chains are delivered in a plastic bag with no packaging or tech docs. Even then those retailers normally still indicate how many links on their website. Online chain calculators will give you a good figure for chain length in links so you can compare with what you're buying. I've used the chain off a manufactured bike to set the length of the new chain( copying no of links ) but found that the chain on the manufactured bike was actually a couple of links too long and my shifting improved when I used the shimano method.

BigG
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Location: Devon

Re: Chain Length ?

Postby BigG » 30 Aug 2015, 9:03pm

A 44/34 combination is far from extreme. Any 114 link chain will do - and almost all chains have at least 114 links. Why not count links? It is much easier than doing the calculation involving chainstay length, sprocket wrap and derailleur wrap.

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recordacefromnew
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Re: Chain Length ?

Postby recordacefromnew » 30 Aug 2015, 10:23pm

Christine wrote:How many links do I need for a 11 - 34 block & 44 outer ring on a triple, 9 speed block please ?
I saw a way to calculate not long ago but can't remember were & not really wanting to count the links on my old chain !
Chris


Since you know the 34 and 44, all you need to do is to measure the distance between the centre of the crank and the centre of the rear axle, enter all 3 figures into:
http://www.machinehead-software.co.uk/bike/chain_length/chainlengthcalc.html
and press the Calculate Chain Length button.

reohn2
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Joined: 26 Jun 2009, 8:21pm

Re: Chain Length ?

Postby reohn2 » 30 Aug 2015, 10:35pm

Christine wrote:How many links do I need for a 11 - 34 block & 44 outer ring on a triple, 9 speed block please ?
I saw a way to calculate not long ago but can't remember were & not really wanting to count the links on my old chain !
Chris


Simplest method:- with the chain on the largest chainring and the largest sprocket without going through the dérailleur ie;as if it were a single speed,pull the chain taught on the bottom run,then add two links to where they meet.
It will be spot on.
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tim-b
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Re: Chain Length ?

Postby tim-b » 31 Aug 2015, 6:37am

Hi

I think that's seven different methods! Try them all and take the average, but should that be the mean, the median or mode? And if it's a MTB with rear suspension it's possibly different again

If you really don't want to count I would use the calculator suggested by recordacefromnew ^^ for buying

The Shimano visual set up suggested by old_windbag ^^ has always worked for me for fitting, but NB the inset image for a triple ring. Make sure that the existing chain is correct and get counting :)

Regards
tim-b
~~~~¯\(ツ)/¯~~~~

Christine
Posts: 137
Joined: 9 Dec 2012, 12:40pm

Re: Chain Length ?

Postby Christine » 31 Aug 2015, 8:18am

Thank you all for your replies, I did get down & count links yesterday, but will re-check today !
I was hoping a simple solution would be out there , which I guess I found in the end !
I remember years ago when things weren't so complicated ( ha ha ! ) having to put more links in a chain from new on my Freddie Grubb touring/camping/did use it to race for a while ( less mudguards ! ) bike.
Again thank you for all taking the time to reply,
Chris