Originally Posted by
dr_lha
Cage size has no effect on chain length, so all the proof you need is given in the chain length calculator I linked to above.
For a 17.25inch chainstay:
52T/28T = 56 links (55.7in rounded up)
52T/25T = 56 links (55.01in rounded up)
Whatever the maximum differnence is likely to be no more than a single link, so no big deal.
That must be inches (inner link + outer link). Otherwise it would be an awfully short chain.