[jad3]

Agreed - The 39 is the key...check the gear inches and it becomes apparent ...
Gives you a lot more "Easy" for a small reduction in "Hard". Then again...all are pretty close so it isn't too much to stress about.

Description...
http://www.inlandempirecycling.com/Cycling/calculate_gear_inch_chart.htm


Front Rear Wheel Gear Inch Ratio
39 25 700 42.12 1.56
42 25 700 45.36 1.68
39 23 700 45.78 1.70
42 23 700 49.30 1.83
39 21 700 50.14 1.86
42 21 700 54.00 2.00
50 25 700 54.00 2.00
39 19 700 55.42 2.05
53 25 700 57.24 2.12
50 23 700 58.70 2.17
42 19 700 59.68 2.21
39 17 700 61.94 2.29
53 23 700 62.22 2.30
50 21 700 64.29 2.38
42 17 700 66.71 2.47
53 21 700 68.14 2.52
39 15 700 70.20 2.60
50 19 700 71.05 2.63
39 14 700 75.21 2.79
53 19 700 75.32 2.79
42 15 700 75.60 2.80
50 17 700 79.41 2.94
39 13 700 81.00 3.00
42 14 700 81.00 3.00
53 17 700 84.18 3.12
42 13 700 87.23 3.23
39 12 700 87.75 3.25
50 15 700 90.00 3.33
42 12 700 94.50 3.50
53 15 700 95.40 3.53
50 14 700 96.43 3.57
53 14 700 102.21 3.79
50 13 700 103.85 3.85
53 13 700 110.08 4.08
50 12 700 112.50 4.17
53 12 700 119.25 4.42