Originally Posted by HillRider

The 105 crank and the matching road front derailleur may not be compatible with the XT front shifter. Road front derailleurs have different geometry from MTB fd's and the shifters take that into account.

Also, you cannot use a MTB front derailleur with a road crank as the cage curvature is intended for a 42 or 44T large chainring and is too severe to match the typical 52 - 53T large chainring of a road crank. You would have to mount it way too high.

Finally, MTB cassettes almost all have an 11T small cog. Can your wife really use a 52x11 high gear? I'd look for a modest MTB crank to go along with your other components.