Search google "shimano rd-1055 pdf" for the docs on your RD. Look for the model # on your RD, change accordingly. PDF it will tell you how many teeth you can work with. You can bypass some headaches by switching to a long cage mountain RD. Long cage + 30 tooth rear cassette + compact crank = climbing machine. Compact crank may require a different FD, yours now is prob 14 tooth difference max. Search for a FD-xxxx, whatever your FD part# is. New crank may need a different BB as well.
Last edited by grizzly59; 07-20-21 at 08:15 AM.