Originally Posted by
dddd
I wouldn't count on more than 26t, but with proper chain length and with the axle positioned in the dropout slots to best advantage, 28t would likely be possible imo.
I usually get best shifting with the axle well foreward, but that has less to do with maximum freewheel cog size and more to do with crisp shifting performance.
These Torellis are classic performance bikes and I almost cringe to see one festooned with at-the-limit low gearing with Shimano's logo on the biggest cog. I would put on a Sunrace 7sp 13-25t freewheel or any nice older Shimano or Suntour freewheel with perhaps 13-24 or 13-26t.
I hope you are well size-fitted to your bike and enjoy it to the fullest.
+1 These older Campy type short cage DR's are speced to run 13/14 to 26t 5/6speed but will usually take a 28t and 7sp with a little tweaking. I would also suggest you go with a 13-25T Sunrace modern 8speed chain and friction shifting. The modern ramped freewheel with slightly narrower chain and spacing will make a world of difference and is a low cost way to go about $30 for both.