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Do I need to lengthen this chain.

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Do I need to lengthen this chain.

Old 07-17-13, 07:38 PM
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DOS
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Do I need to lengthen this chain.

A buddy asked me to swap out his compact for a standard double (53/39). The other couple of times I have done this there was plenty of chain to accommodate the bigger front ring. But the set up on this bike already looks pretty tight in the big/big combo. Based on picture, what are opinions on whether I need to add a link or two?
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Old 07-17-13, 07:41 PM
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DOS, You'll need a longer chain.

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Old 07-17-13, 08:00 PM
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If it's that snug in the 50/XX big-big, I agree you probably need a longer chain for 53/XX. Pull ALL the slack out and see if you can fold over two 1/2 links (1") of chain. That's what you will need for the additional 3 teeth.
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Old 07-17-13, 08:41 PM
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The 53t chainring needs roughly 3/4" more chain. To see if you have it to spare, pull the lower loop forward about 1" and see how it plays out.

What I usually do is pull the chain off the lower end of the chainring, then pull it forward 2 links and reattach it to the chainring. Back pedal a bit so the chain is well engaged. That allows me to gauge precisely how much I have to play with in the lower loop.

A variation on this works if the RD cage has enough travel for the lower pulley to rise above the line of a lower loop that's on a straight line. If so Pull the lower loop forward 3/4" for the larger chainring + 1" for the classic big/big + 1" guideline. So if you can pull the lower loop forward 1-3/4" you're home free with the existing chain.

Looking ar the photo, it'll be close, but may make the cut.
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Old 07-18-13, 05:46 AM
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That looks really tight, I think an extra link or two would make all the difference!
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Old 07-18-13, 07:46 AM
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Obviously, big big isn't where you'd normally be. Can you shift into and out of that combination and pedal backwards without jamming up the drivetrain? Can you still rotate the cage forwards a bit while in that combo? You should be OK if you can do all those things. Another link would definitely be better but the best solution would be to replace the chain if it has been on the bike for some time. Sram 9 or 1071s are cheap and work quite nicely. Al
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Old 07-18-13, 07:51 AM
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For pro mechanics with a lot of experience it's fine to rely on judgement when it's a fine line. But for me working on a friend's bike I'd err on the side of caution.
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Old 07-18-13, 07:31 PM
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So I went to LBS to see about getting pins I need to add links to the Dura Ace chain and the mechanic advised against breaking a dura ace chain, saying I should buy a new chain because adding links would compromise it. Are DA chains that fragile?
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Old 07-18-13, 07:39 PM
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Originally Posted by DOS View Post
So I went to LBS to see about getting pins I need to add links to the Dura Ace chain and the mechanic advised against breaking a dura ace chain, saying I should buy a new chain because adding links would compromise it. Are DA chains that fragile?
No. Shimano chains can be joined at any link (except do not use the same one twice), so there's no difference between a 1st splice on a new chain, a new splice in a new place on a used chain.

That said, I consider it bad practice to add links to a chain that's more than very slightly used. The new links will have slightly different pitch than the older ones, and I suspect that this will be harder on sprockets. I don't claim this as fact, but can say that you can often hear it as newly spliced links engage the cassette.

So it's a judgment call, and since it's your chain, you get to be the judge.
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Old 07-18-13, 08:15 PM
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Originally Posted by FBinNY View Post
No. Shimano chains can be joined at any link (except do not use the same one twice), so there's no difference between a 1st splice on a new chain, a new splice in a new place on a used chain.

That said, I consider it bad practice to add links to a chain that's more than very slightly used. The new links will have slightly different pitch than the older ones, and I suspect that this will be harder on sprockets. I don't claim this as fact, but can say that you can often hear it as newly spliced links engage the cassette.

So it's a judgment call, and since it's your chain, you get to be the judge.
as I understand it, my friend broke a chain not long ago, so chain is almost new. He's never been satisfied with the FSA compact that came with the cervelo he rides so when he cam upon an Ultegra 6600 crankset for 100 bucks, he bought it.
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Old 07-18-13, 09:21 PM
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Well, I installed the cranks and one thing is now for certain, the chain is definitely too short as is.
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Old 07-19-13, 04:31 AM
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Originally Posted by DOS View Post
Well, I installed the cranks and one thing is now for certain, the chain is definitely too short as is.
Well the solution is obvious isn't it? Pony up the cash for a new chain, size it properly and be done with it. I personally use cheap SRAM chains but you could use whatever floats your boat. You probably won't notice the difference either way. Al
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Old 07-19-13, 04:39 AM
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Originally Posted by Altbark View Post
Well the solution is obvious isn't it? Pony up the cash for a new chain, size it properly and be done with it. I personally use cheap SRAM chains but you could use whatever floats your boat. You probably won't notice the difference either way. Al
Well it's not my chain and is relatively new. Why not lengthen? But I agree, I use SRAM chains and don't spend a lot of money on them.

edited to add: I am, incidentally, feeling better about prospects of lengthening. I determined chain is 7800, the directions for which say "if it is necessary to adjust the length of the chain due to a change in the number of sprocket teeth, make the cut at some other place than the place where t chain has been joined using a reinforced connecting pin" . So if directions allow for it and chain is newish, I'll give it a shot. I had originally thoughtI was dealing with 7900 one way chain and I read online specific recs against breaking once installed.

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Old 07-19-13, 04:57 AM
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Originally Posted by DOS View Post
Well it's not my chain and is relatively new. Why not lengthen? But I agree, I use SRAM chains and don't spend a lot of money on them.
You've had two mechanics, one at the LBS and FBinNY, give you some reasons why adding links to the chain might not be the best solution. But you are free to spend the bucks on a link or two and a pin. I personally go for the easiest and most reliable solution when doing mechanical work. In this case, I think that the best route is to replace the chain. An argument can be made that a high end bike with a high end drivetrain should have a high end chain installed. However, 20$ bucks for a cheaper chain that will do the job equally well seems to be a logical compromise.

As mentioned elsewhere, you'd do well to remember that you are not working on your own bike. Don't cheap out. Keep it simple and replace the chain. That way your friend gets a very nice and reliable drivetrain assumming that both the cassette and chainrings are in good condition. Best. Al
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Old 07-19-13, 04:19 PM
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Originally Posted by Altbark View Post
You've had two mechanics, one at the LBS and FBinNY, give you some reasons why adding links to the chain might not be the best solution. But you are free to spend the bucks on a link or two and a pin. I personally go for the easiest and most reliable solution when doing mechanical work. In this case, I think that the best route is to replace the chain. An argument can be made that a high end bike with a high end drivetrain should have a high end chain installed. However, 20$ bucks for a cheaper chain that will do the job equally well seems to be a logical compromise.

As mentioned elsewhere, you'd do well to remember that you are not working on your own bike. Don't cheap out. Keep it simple and replace the chain. That way your friend gets a very nice and reliable drivetrain assumming that both the cassette and chainrings are in good condition. Best. Al
its precisely that I am working on someone else's bike that I am asking. As I said in response to FBinNY, it's a relatively new chain -- a few hundred miles max -- thAt he just spent considerable money on. Before telling him he needs to spend more, I wanted explore alternatives. All seems moot since I have been to two shops neither of which can provide the links or the pins I would need to extend the chain.
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