Gear chart using MPH @ 90 RPM
For 700 X 23 / 23-622 tire with 170 mm cranks
With 10-speed 12-13-14-15-16-17-19-21-23-25 Cassette
52-39-30 triple
HTML Code:
52 33.3 % 39 30.0 % 30
12 30.5 22.9 17.6
8.3 %
13 28.1 21.1 16.2
7.7 %
14 26.1 19.6 15.1
7.1 %
15 24.4 18.3 14.1
6.7 %
16 22.9 17.2 13.2
6.3 %
17 21.5 16.1 12.4
11.8 %
19 19.3 14.4 11.1
10.5 %
21 17.4 13.1 10.1
9.5 %
23 15.9 11.9 9.2
8.7 %
25 14.6 11.0 8.4
Gear chart using MPH @ 90 RPM
For 700 X 23 / 23-622 tire with 170 mm cranks
With 10-speed 12-13-14-15-16-17-19-21-23-25 Cassette
50-34 compact
HTML Code:
50 47.1 % 34
12 29.3 19.9
8.3 %
13 27.1 18.4
7.7 %
14 25.1 17.1
7.1 %
15 23.5 15.9
6.7 %
16 22.0 15.0
6.3 %
17 20.7 14.1
11.8 %
19 18.5 12.6
10.5 %
21 16.8 11.4
9.5 %
23 15.3 10.4
8.7 %
25 14.1 9.6
You can of course see what a traditional double looks like by ignoring the small ring of the triple. Compact gives up 1.2mph on the high side but gains two lower gears over the double. The triple gives you another gear or so on the low end over the compact.
A case made for the compact:
http://www.slowtwitch.com/mainheadin...r/gearing.html
Nobody says a compact must have nothing bigger than a 50T chainring, either.
http://sheldonbrown.com/harris/chainrings/110.html