Chain Length

[CT Rider]

Question for you folks on chain length:

I presently have a 13-29 cassette (sory, I'm a wimp!) and plan to change over to a 13-26. Will I need to remove any links from the chain?

[flydhest]

Nope. The shortening would only help if you were going to have too long a chain. If you rig works now, you've been in something like the 26 tooth cog (probably a 25) and it worked, no?

The main reason to change the chain length would be to add a link if you went from a 12-25 or something to a 13-29 and it wasn't long enough for the big cogs.

Taking out a link would be necessary if your smallest cog and inner ring got smaller and you ended up with slack in that (crossover) gear.

[Dave]

With a Campy 13-29 cassette, you should have a medium cage RD. Changing to a smaller maximum cog should never be a reason to change chain length. One length will cover any cassette within the RD's wrap capacity. Here's how to correctly adjust chain length.

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 or the chain guide tab as it passes under the upper derailleur pulley. If you want to see how much lower pulley movement will occur, without removing the extra inch of chain, shift up four teeth (11 to 15 or 12 to 16). This has the same effect as removing two links. 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.

Second, the chain must be long enough to avoid over-extending 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 wrap capacity. If you deliberately exceed the derailleur's capacity and the derailleur is over-extended in the big ring/largest cog combo, then you must either avoid that combo or add another inch and avoid using the little chainring and the smallest 3 or 4 cogs (since the chain will hang loose).