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Dura Ace CN-7801 stretch
#1
Just installed new Dura Ace chain and noticed when cutting to length<br />
it is just as stretched as old chain. Opened other 2nd box of chain and<br />
found same thing.<br />
Have used this chain for years and it always came tight and waxed,<br />
now Dura Ace CN-7801 is loose and oily.<br />
Checked with 2 chain gauges and found same thing, 75% stretch.
Does anyone have any word from Shimano on this?
Is this part of the switch to CN-7900?

  Reply
#2
10 speed chains have more side to side play than older chains might have. I think that is what you are seeing. "Stretch" usually refers to the length of the chain getting slightly longer. You can measure this by putting a ruler up against the chain. It should be exactly 12" between pins. If it is over 12 1/8", you need a new chain. I'm not sure what you mean when you say "75% stretch".
Side to side play on a worn chain will get looser, but that, in and of itself, is not an indication that the chain needs to be replaced.
I don't know that any chains came waxed, but they may have used a thicker grease in the past.

  Reply
#3
DaveM,<br />
Actually the Dura Ace chains came with a wax up to about 8 months ago.<br />
And yes I know what stretch is, the simplest way to check it is with a good<br />
gauge and most of them are calibrated in percent of wear. 100% would be<br />
the time to replace.
The looseness of these new CN 7801's is either a manufacturing error or<br />
for some reason intentional by Shimano. I believe it is an error at the factory.
I'm checking with a Shimano rep to find out more.

  Reply
#4
I didn't know Dura Ace came waxed. Neat. Sounds like you know what you're talking about. I haven't heard of many manufacturing errors by Shimano, but they should know the answer. Update us...

  Reply


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