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Need mechanic opinion on this pic

Old 04-25-09, 07:34 PM
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Need mechanic opinion on this pic

put old components on new frame. Is changing gears fine, but it doenst looks ok to me. Thinking maybe with the new frame, chain should be shorter.

set up looks ok?
Shouldnt be more like in line 2 ?
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Old 04-25-09, 07:39 PM
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You can't see the bottom to see if the chain is touching the cage, but in general yes, it looks like you could stand to take out a link. Old components, new frame....why not a new chain?
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Old 04-25-09, 07:41 PM
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Take the chain off and out of the rear derailler. wrap it around the big, big combo. add 1 link.


you can definately remove one link.
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Old 04-25-09, 08:03 PM
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Originally Posted by Jynx
Take the chain off and out of the rear derailler. wrap it around the big, big combo. add 1 link.


you can definately remove one link.
Thats what it ooks like to me also.
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Old 04-25-09, 08:29 PM
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You will get chain rub like that sometimes on extreme range rear cassettes with triples up front, and there's nothing you can do about it.

Post #3 was great until the last recommendation.

Last edited by cuda2k; 04-26-09 at 07:58 AM.
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Old 04-25-09, 08:42 PM
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Originally Posted by operator
You will get chain rub like that sometimes on extreme range rear cassettes with triples up front, and there's nothing you can do about it.

Post #3 was great until the last recommendation.
the OP's picture states that the chain is on the "39" in front, which probably makes it a double chainring. I'd agree that shortening the chain by one link will prevent the chain from rubbing itself, as will tightening the B-tension adjustment on the derailleur.
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Last edited by cuda2k; 04-26-09 at 07:59 AM.
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Old 04-25-09, 08:47 PM
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Originally Posted by Jeff Wills
No BS, buddy... the OP's picture states that the chain is on the "39" in front, which probably makes it a double chainring. I'd agree that shortening the chain by one link will prevent the chain from rubbing itself, as will tightening the B-tension adjustment on the derailleur.
39 is the small ring, not the big. Which renders minimum chain length needed to not explode the derailleur in big big, still unknown.

Last edited by cuda2k; 04-26-09 at 07:59 AM.
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Old 04-25-09, 08:58 PM
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Originally Posted by operator
39 is the small ring, not the big. Which renders minimum chain length needed to not explode the derailleur in big big, still unknown.
Well, you said:
"You will get chain rub like that sometimes on extreme range rear cassettes with triples up front, and there's nothing you can do about it."
That's absolutely irrelevant since the OP's got a double and a not-so-extreme cassette. His issue is due to either a difference in the derailleur hanger or shorter chainstays on the new frame.

In either case, verifying the correctness of the chain length is needed- as Jynx said, wrap around the big/big and then add a link. If that doesn't result in a fix, tightening the B-tension screw will put a little extra tension on the derailleur.
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Old 04-25-09, 09:17 PM
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Originally Posted by Jeff Wills
Well, you said:
"You will get chain rub like that sometimes on extreme range rear cassettes with triples up front, and there's nothing you can do about it."
That's absolutely irrelevant since the OP's got a double and a not-so-extreme cassette. His issue is due to either a difference in the derailleur hanger or shorter chainstays on the new frame.

In either case, verifying the correctness of the chain length is needed- as Jynx said, wrap around the big/big and then add a link. If that doesn't result in a fix, tightening the B-tension screw will put a little extra tension on the derailleur.
Please just stop posting.
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Old 04-26-09, 12:55 AM
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While operator can get a bit worked up, he also generally knows his shiznit.

I'd let him work on my bike...and I'm a pro.
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Old 04-26-09, 06:59 AM
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Originally Posted by Jeff Wills
No BS, buddy... the OP's picture states that the chain is on the "39" in front, which probably makes it a double chainring. I'd agree that shortening the chain by one link will prevent the chain from rubbing itself, as will tightening the B-tension adjustment on the derailleur.
Absolutely correct. The chain should not rub the chain going the other way as it passes under the guide pulley. He needs to remove *at least* one link and maybe more depending on the big/big situation.

Shimano RD's adjustment procedure is actually to set up big chain ring and little cog and then adjust chain length to make guide and tension pulleys form a perpendicular angle to the ground.
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Old 04-26-09, 07:04 AM
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Originally Posted by operator
... opinion without seeing the chain on the big/big combo. You will get chain rub like that sometimes on extreme range rear cassettes with triples up front, and there's nothing you can do about it.

Post #3 was great until the last recommendation.
1) the photo clearly shows a short cage RD and what appears to be a 23 or 25 tooth large cog.

2) the OP stated it's a 39 in the front. Yes we are assuming the other ring is a 53. But if the poster had some giant big ring, rather than what "just came with the bike", he would know and say "Hey I put a huge 58t chain ring on the front, does that make a difference?

3) At least one and maybe more links need to be removed. The chain is not supposed to rub itself through the pulleys.

Last edited by cuda2k; 04-26-09 at 08:00 AM.
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Old 04-26-09, 07:38 AM
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Originally Posted by Wordbiker
While operator can get a bit worked up, he also generally knows his shiznit.
Knowing your stuff is no excuse for being rude, crude and socially unacceptable.
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Old 04-26-09, 07:46 AM
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As long as the chain is not rubbing on the upper chain guide tab (or itself), there is no problem and no need to shorten the chain. This is how it should look, with the chain length set for maximum wrap capacity. The little/little combo is still useable, but we all know it should not be used. If the chain is actually rubbing itself or the RD cage, then it's 1-inch too long. The exception would be a drivetrain that was intentionally setup with more wrap than the RD can handle.

My new 11 speed RDs are both set with the chain length like this, so I can use any cassette from an 11-23 to 12-27 with a 50/34 and ONE chain length. The chain does not rub on anything even in the 34/11.

Some bikes have more ideal chainstay lengths than others, which can cause a gain of up to 2T of wrap, compared to a bike with the worst case chainstay length. Some users might get by taking out 1-inch of chain and others cannot. Shifting to the big/big combo will tell the story.

Last edited by DaveSSS; 04-26-09 at 07:55 AM.
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Old 04-26-09, 08:06 AM
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I agree the chain looks long. who took the pic John Madden?
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Old 04-26-09, 11:21 AM
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Originally Posted by Barry in GA
Knowing your stuff is no excuse for being rude, crude and socially unacceptable.
He hasn't been exposed to manners like we have, but we still love him.
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