Ultegra / XT casette interchangibility

[Gonz]

road bike needs better hill climbing gear ... I replaced the Ultegra cassette with a XT, no change to the chain or deraileru (105) ... now the drive train makes a funny chain noise, especially when the chain is on the larger cogs ... original chain is Shimano something ...checked the chain tension and the deraileur action - looks OK. Upper pulley is not contacting cogs. is the Ultegra casette interchangible with an XT cassette in terms of chain ?

[Hecubus]

The road derailleurs don't handle cassettes larger than 27t too well or at all. You also need a medium cage derailleur minumun for that cassette. The small cage can not take up enough chain slack to run such a wide spread.

[VT no 1 2 or 3]

May also need to adjust the chain length. My road bike is setup using an 11-32 mountain cassette and an XT long cage rear der. Works just fine. I like to ride in the mountains 16% + grades- 39/32 low is a lot better than the typical 39/25.