i have an 09 CAAD 9-6 and was wondering if it is possible to change out the rear cassette to the sram pg 950 11-28. it currently has the sram 12-26 cassette that came from the factory. if it is possible will the tiagra rear derailleur be able to handle it?
2003 Specialized Hardrock, 2004 LOOK KG386i, 2005 Iron Horse Warrior Expert, 2009 Pedal Force CX1
Check the big/big combo out on a workstand before you find out the hard way out on the road that the chain is too short after the addition of a larger cog. It likely will have plenty of length to handle two extra teeth but you don't want to bet your frame/face on it.
'04 Serotta CIII, '01 Lemond Poprad, '10 Look 566, mid 90s Burley Rock N Roll Tandem, Old School Specialized HardRock
I swapped out a 12-26 to an 11-28 with a 105 short cage and it works fine with no chain swap (50-36 compact crankset). I did find some shifts to be slightly more noticeable that they were before, but all in all I'm happy with the result.