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8 to 9 speed chain length(5 posts)

8 to 9 speed chain lengthdddpt2
Jul 11, 2002 4:17 PM
I'm going from an 8 speed Ultegra set up to a 9 speed DA with 12-27 cassette. Any guidance on how much longer should the chain be, if any? Thanks.
Jul 11, 2002 4:35 PM
You didn't say what you were starting with so no one can really tell. If the gearing is all the same then there shouldn't be any difference in length between 8 and 9 speed - the onoly thing that's changing is the width of the chain on one more cog in the middle. If the 27 is lareger than what you were running then you may or may not need to add a link or two. Best method is to set it up and shift into big/big on the BIKE STAND and see if it's long enough. If you do this while riding and it's too short you run a very good chance of bending something.
Jul 11, 2002 9:01 PM
Sorry. The 8 speed has 12-25, su it's basically just adding the 27.
Thanks for the help.
setting chain length....C-40
Jul 11, 2002 4:42 PM
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 two links (one inch) 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. Two more links (another inch) 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 to avoid overextending 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.

If you want to see how much lower pulley movement will occur, without removing the extra two links, shift up four teeth (11 to 15 or 12 to 16). This has the same effect as removing two links.
Thanks for the help. nmdddpt2
Jul 11, 2002 9:04 PM