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Dura Ace 12/27cassette with 7701 chain(6 posts)

Dura Ace 12/27cassette with 7701 chainfofa
Dec 29, 2001 10:04 AM
I would like to know if it is possible to put a 7701 Shimano chain on a 12/27 D/A cassette. The instructions that came with the cranks say that a maximum of 25 teeth are allowed for a cassette on the largest sprocket. Will I need to add links to the chain? I've never done this before so some advice on this would be helpful. Thanks.
chain length...C-40
Dec 29, 2001 10:23 AM
Most new chains have enough links to fit just about any bike. What you must know is how many links is just right. Here's how:

Two simple tests will determine if the chain is the correct length. First, it must not hang loose in the little ring, little cog combination. If there is no tension on the chain in the little ring, little cog combination, remove one link at a time, until there is. When the ends of the chain are brought together, some movement of the lower pulley should occur, indicating tension is being applied. One more link may need to be removed, beyond the point of absolute minimum tension, to keep the chain from rubbing on itself as it passes under the upper derailleur pulley. Once this is done, the chain is set to the maximum useable length. Removing additional links will do nothing but reduce the derailleur's capacity. It won't help keep the chain from skipping or jumping.

Second, the chain must be long enough not to overextend the rear derailleur when shifted to the big ring and biggest cog combination. If the chain is set to the maximum length as described, it should always pass this test, unless your setup exceeds the derailleur's stated capacity.
chain length...fofa
Dec 29, 2001 10:32 AM
That was most helpful C-40, Thanks.
forget about the chain!!!Rusty McNasty
Dec 29, 2001 11:01 AM
There are 2 more things you need to consider before doing this swap:
1) Is the upper jockey wheel too close to clear a 27 tooth cog?
2) Is the cage of the derailleur long enough to handle the extra 2 teeth capacity?
If you have a 42/53 front ring, you are probably OK on #2, but if you use a 39/53 setup, you are going to need a derailleur with a capacity of 29 teeth. I believe that the DA derailleur has a capacity of only 27 teeth.
Works for meB2
Dec 30, 2001 9:08 AM
I've found that if I just follow the Shimano directions (chain length, B-Tension, etc.), the 12/27 works fine for me.
re: Dura Ace 12/27cassette with 7701 chainO
Jan 1, 2002 5:53 AM
I use a 12/27 cassette with a Dura Ace chain. The only problem with using this set up is that I chose to go with a Dura Ace triple rear der., because I could not set the double der. up to be used properly. While the chain was on the 27 cog, I found that the der. could not be set up to travel over the 27 properly. Thus, the chain rubbed on the der. I hope that I have explained myself....