# chainline



## MrGrumpy (16 Dec 2008)

Ok been told by LBS that my chain line is well out, this of course was after my chain came off and wrapped around rear wheel, twisting and bending as it did so, with a rear wheel lockup to follow. He tells me that the Langster is a big pile of poo of which I`m now in some agreeance. However he has suggested a rebuilt back wheel with a differant hub which will push out the rear cog further allowing, hopefully a straightish chain line, its 5mm out by the way ! Would I better buying a new front chainset and BB in the vain hope that I could get it more or less bang on ?


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## MajorMantra (16 Dec 2008)

Could you maybe do something simpler (and cheaper) with spacers? How bad is the chainline? If your Langster is stock, shouldn't it be possible to get a perfect chainline? I thought they were right-on from new.

Matthew


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## Amanda P (16 Dec 2008)

Bottom brackets come in different lengths. Could you fit one that's 5mm shorter?

There are also adjustable ones, where the axle can be shunted through the shell to get perfect chainline.

Does your chainset have a removable ring? What about putting it on the inside of the spider, rather than the outside (assuming it is on the outside now)?


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## skwerl (16 Dec 2008)

5mm out. Who cares? No one cares about chain-line on a multi-geared bike. A chain can easily cope with 5mm. It may not be perfect and may be noiser than if the chain-line was bang-on but it doesn't matter.

As Phil says though. A new BB is probably easiest/cheapest way to fix it, if it bothers you that much.

I'd be wary of a shop that immediately suggests the most expensive option of building a new wheel. Especially as a chunk of the cost is for labour.


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## MajorMantra (16 Dec 2008)

skwerl said:


> 5mm out. Who cares? No one cares about chain-line on a multi-geared bike. A chain can easily cope with 5mm. It may not be perfect and may be noiser than if the chain-line was bang-on but it doesn't matter.
> 
> As Phil says though. A new BB is probably easiest/cheapest way to fix it, if it bothers you that much.
> 
> I'd be wary of a shop that immediately suggests the most expensive option of building a new wheel. Especially as a chunk of the cost is for labour.



I agree about not rushing to build a new wheel but I think if he's already thrown the chain once (not nice I imagine!) then it needs fixing.

Matthew


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## skwerl (16 Dec 2008)

depends what caused it to throw. 5mm off-line I doubt was the cause or at least not on it's own. Likely the chain was loose and that alone, or coupled with chainline being out, caused it to unship.
After all. How often to geared bikes unship their chains? Usually only when going over a bumpy bit of ground which overcomes the rear-mech tension, i.e. caused by chain slack.


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## mickle (16 Dec 2008)

MrGrumpy said:


> Ok been told by LBS that my chain line is well out, this of course was after my chain came off and wrapped around rear wheel, twisting and bending as it did so, with a rear wheel lockup to follow. He tells me that the Langster is a big pile of poo of which I`m now in some agreeance. However he has suggested a rebuilt back wheel with a differant hub which will push out the rear cog further allowing, hopefully a straightish chain line, its 5mm out by the way ! Would I better buying a new front chainset and BB in the vain hope that I could get it more or less bang on ?



As has been said, the chain came off because it was too loose. Not because the chain was 5mm out. There are plenty of easy and cheap solutions, non of which involve replacing the chainset or the back wheel. The shop is totally taking the piss. 

In case you missed that; The shop is totally taking the piss.


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## MrGrumpy (17 Dec 2008)

no i`ve got you  You know it probably was loose come to think of it as keeping it tight seems an issue, however surely its always gonna try and run off if its not straight ? Its just a tad worrying especially going down hill. Just my history ith this bike is tiresome to say the least.


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## mickle (17 Dec 2008)

I have just one thing to say to you Mrgrumpy; chain-tugs.


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## kyuss (17 Dec 2008)

I'd agree, chaintugs rule. I know a lot of people who say you don't need them, but by god they make chain tensioning so much easier. Dirt cheap too. I wouldn't be without them.

I'd also agree with Uncle Phil. Have you tried mounting the chainring on the inside of the spider (assuming it's currently on the outside)? I have an FSA Vero crankset that should really be used with a 103mm BB for the perfect 42mm chainline, but the bike came as standard with a 110mm BB with the chainring mounted on the inside (I guess because 110mm JIS BB's are cheaper and easier to come by). It's not pretty but it works, and I've never thrown the chain.

Rebuilding the wheel seems like a pretty expensive option. Sounds like the LBS is taking the piss and trying to make some money. A new hub won't sort the problem unless the sprocket is spaced out somehow, and you can do that with the hub you already have. Hubs are fairly standard in their sizing, it's almost certainly a BB, chainset compatability issue. A shorter BB would be cheaper than a new hub and wheel rebuild, but trying the chainring on the inside of the spider costs nothing.


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## mickle (17 Dec 2008)

The event may have damaged the drive side spokes of course.


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## skwerl (17 Dec 2008)

mounting the chain ring on the inside of the spider looks pants. be much easier to get a shorter BB axle or even easier to just not worry about what is a minor amount of offset.
Hold your fingers 5mm apart. Not much is it?
Hold a chain at one end and extend it out horizontally. See how much it bends by? Chains aren't that rigid in the horizontal plane, they're designed to cope with chain-line offset


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## Amanda P (17 Dec 2008)

skwerl said:


> mounting the chain ring on the inside of the spider looks pants. be much easier to get a shorter BB axle or even easier to just not worry about what is a minor amount of offset.



Being a pedant here, I agree that a chainring on the inside of the spider looks pants (if you care about that sort of thing. Is this a fashion fixie, or a functional one?) 

But there's no way it's easier to fit a shorter bottom bracket axle than it is to move the chainring from one side of the spider to the other.

And depending on Mr Grumpy's consitution, it may not be so easy to stop worrying about it, either!


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## MrGrumpy (17 Dec 2008)

ok guys think chain tugs are the answer here and at £6 a pop not to be sniffed at, as for the BB its a brandnew one 103mm which is what the original was. Was actually thinking about mounting the chain ring on the inside but they`re aint enough clearance. Its certainly been a slack chain issue and nothing else, my fault end off.


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## Dave5N (17 Dec 2008)

What am I missing here?

What do chaintugs do that a properly tightened nut doesn't?

Are they for conversions?


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## spandex (17 Dec 2008)

on a single speed and fixed wheel the amount of force you put on the rear wheel is so much more and they all ways shift no matter how tight you do it.


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## Dave5N (18 Dec 2008)

Bollocks. I don't see why. Don't have them on our track bikes and there's a bit more force put through in competition than on yer average commute, I'd guess.


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## MrGrumpy (18 Dec 2008)

well I can tell you my rear wheel does slip, probably becuase it aint tight enough, however I don`t want to do it up too tight, for I don`t carry around a socket and wrench in my bag on my commute


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## skwerl (18 Dec 2008)

spandex said:


> on a single speed and fixed wheel the amount of force you put on the rear wheel is so much more and they all ways shift no matter how tight you do it.



again - someone please explain this to me. A high gear means much less torque. How can there be more force going through the wheel?
Pedalling in low gear is going to put far more torque through your wheel.
Geared bikes don't suffer slippage due to having vertical dropouts. Older bikes with horizontal dropouts used to have reverse chain-tug thingies I'm assuming to help prevent the wheel twisting and to allow easy set up of wheel position.
Track bikes don't have chain-tugs. The only purpose they serve, that I can see, is they make it easy to get wheel alignment and chain tension correct and mean you don't have to tighten the nuts as much to keep the wheel in place. You can certainly do without them though


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## mickle (18 Dec 2008)

Proper track hubs with decent knurly washered track nuts in nice clean straight drop outs don't move. 

And vise versa.


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## mickle (18 Dec 2008)

BTW has anyone seen the size of Spandexes legs? He's a freak of nature.


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## Dave5N (19 Dec 2008)

No. I've seen Staff's and I've seen Hoy's though.

Is Spandex as quick as them?


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## mickle (19 Dec 2008)

Faster, longer, harder. he doesn't like the limelight though so he keeps his light under a bushell.

I'm sorry but what the F is a bushell and why would one keep ones light under it?


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## Amanda P (19 Dec 2008)

The Bible: Matthew chapter 5 verse 15. The point is that you _wouldn't_ keep your light under it.


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## GrahamG (19 Dec 2008)

One more post to add a bit of mildly useful information (or useless trivia - I don't mind how you classify it ), whilst mounting the chainring on the inside 'looks crap', there are lots of cheap 'track/single speed' cranksets out there (anything less than £70!) that are basically doubles and a 42mm chainline is only achievable by mounting on the inside. Besides you really can't tell from a distance.


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## christian dieu (24 Dec 2008)

MrGrumpy said:


> ok guys think chain tugs are the answer here and at £6 a pop not to be sniffed at, as for the BB its a brandnew one 103mm which is what the original was. Was actually thinking about mounting the chain ring on the inside but they`re aint enough clearance. Its certainly been a slack chain issue and nothing else, my fault end off.



If there is not enough clearance to mount the ring on the inside then it suggests that your problem is not at the chainwheel end anyway.

Maybe just a twisted frame


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