I have double sided SPDs on all my bikes...except for my Voyageur, which still has toe clips and straps. Depending on the bike, they are either 520s or 424s. 424s might be nice on your touring bike for the times when you just want to jump on the bike a ride a mile or two, the extra frame gives a little more flat shoe support. I wouldn't want to ride them that way very far, the SPD mechanism will press into the bottom of your foot eventually.