I also have a 50 34 front, for riding in oklahoma, relatively flat with a few short steep hills i use an 11-23, but for going to colorado next month for triple bypass, long long climbs, i am switching to a 12-25. Last year i did the triple with a 53 39 front and a 12-27 rear. a 50 34 front and a 12 25 rear gives a little bit higher high gear than the 53 39 12 27. There is an excellent web site to help calculate this but i can't remember it, someone will probably post it here, but go to search engine and type in bicycle gear calculations that should get you there.