Tony, it depend on your strength, the climb, temperature, and your nutritional state as to whether the 34x29 will be low enough.
Moons ago I used to think my 39x28 was a sissy gear and truth be told, I rarely used it but when I needed it.....I NEEDED IT!!
When the wind is in your face, it is 100F, you are bonking, and the climb is steep, you will look at the 11 (or 12) sprocket with utter contempt and as I did, you will long for a triple crank like the one on my touring bike safely tucked away in the garage far, far away.
If you think a 40 inch gear is sufficient based upon normal riding, put something closer to 30 inches on the bike just in case. What I am saying nicely is you are dreaming if you think a 39x27 is sufficient. I was not the strongest rider but at 6'3'', I weighed 165 pounds, rode sub 1 hour 40K TT, etc.
Get the Compact and the 29 tooth. It will almost be sufficient.
Last edited by Weatherby; 04-10-14 at 04:51 PM.