I currently have a Shimano Dura Ace 10 speed rear derailleur with a 12-25 cassette. For some hilly rides I'd like to change to a 12-30 cassette.
The maximum the rear derailleur can handle is 28, so I'm thinking of getting a Shimano 105 RD. I'd like to be able to switch between these two set-ups but fear that breaking the chain each time is not a good thing to do.
Is it possible to change the RD without breaking the chain by taking apart the pulley wheels?
Also is it possible to fit a 12-30 cassette on a Shimano Dura Ace 10 speed short cage RD?