Originally Posted by
carpediemracing
+1
If your chain is barely long enough for the big-big with the 25, it might just rip your rear derailleur off or your rear wheel out in the big big with the 27.
I did just that with a 12-28 cassette. I knew I had exceeded the chainwrap capacity by 3, but I never cross chain. Still, I started from a traffic light and pieces of derailleur flew everywhere and I got to pretend my bike was a scooter all the way home.