Originally Posted by
The Smokester
If he has the long cage 105 rear derailleur, the capacity is 36 teeth so the first combination would be (26-12)+(44-22)=36 so this would work.
For the second combination, it's (26-12)+(46-20)=40 which would exceed the maximum capacity of the current available 105 rd. Using the LX rd, which has a capacity of 45 teeth would work and would be compatible with any shifters that suited the 105 and the cassette.
Those look like a nice set of gears for touring.
True you have to consider the RD capacity too. If the bike has a 105 short cage he'll have to go to a
105 long cage or a MTB derailleur to make best use of the triple. Even with a 105 long cage some combos would be unusable.