I use a 48-36-22 setup on my touring bike with 13-34 in the back and shifted with an IRD Alpina-d front derailleur. I used a TA Zephyr crank in the past, but switched to a Deore MTB crank when I switched to a bottom bracket with outboard bearings for less bottom end flex. Same sized chainrings and cluster for both cranks.
It shifts well with Tiagra brifters.
If it's a touring bike, I'd question the need for a 50x13. If I spin out of a 48x13, I'm either riding a huge tailwind or I'm going downhill. Either way, I'll be coasting and enjoying the scenery.
Last edited by xyzzy834; 03-26-11 at 11:37 PM.