Everyone who rides compact (generally 50/34 chainrings) proclaims it is an improvement over traditional gearing (generally 53/39.)
I planned to, then rode, compact for the first time at this year's Tour of The Gila. Afterwards, Matt asked me what I thought - he was a bit dismayed with my report that "gears are gears." Caveat, I am one who jokingly refers to compact as "ladies specific gearing" and now that I have ridden it "senior specific gearing!"
Back up, to the genesis of compact gearing, as I know it. The compact "revolution" might be attributed to Tyler Hamilton. Apparently he figured the easier gears would allow higher cadence climbing. My cynical position was that he used it to prevent his riding away from the bunch on flat stages - that would draw attention to his doping!!
Prior to the compact gearing era, I was intrigued by a time trial Lance rode (and won, natch.) I believe it during his 2nd Tour de France victory. The course was rolling, say 25 miles, and his average cadence was 108! This has stuck in my memory to this day.
Conventional science has positioned the freely chosen cadence around 81 +/- 7, the energy optimal cadence at 73 +/-5 and the theoretical mechanical optimal cadence at 90. It seems Lance, by chance or science, had found a better way - his average cadence of 108 is way above any of these and he was known for his high cadence throughout his 7 victories.
Part of this reason this intrigued me probably has to do with my affinity for all things German. Those that know me know my preference for German - cars, foods, cycling teams, etc. For some reason. German cars run at about twice the RPM's of a comparable American car at a given speed. So maybe higher RPM's is better. It certainly is different.
To train my cadence I race crits and Tuesday nighters using a 25/15 cassette. I figure that this will force me to spin and I rationalize that if I ride in the 11,12,13,14 I am not "racing." I'm simply sitting in "just riding along." You never attack or chase from getting dropped in the 11, you spin your butt off when you are "trying."
Traditional training was to ride fixed gear in the off season, train your spin and don't push big gears. Then came the era of incorporating weight training into your training plan, particularly during the off season to build power.
I ran with this and have decided to push big gears in the winter ("off season") and spin in the spring and summer. I ride with an 21/11 cassette in the winter and 27/12 in the summer (now 28/11) and that is where I initially came up with the idea of using "junior gearing" 25/15 cassette for the Tuesday nighters and crits.
Here's what I'm talking about. Driveway crit w/ 23/11 cassette. Average cadence 92.
Driveway crit with 25/15 cassette. 102 average cadence. Limiting my "biggest gear" to 53 x 15 took my average cadence up 10%! After these type of training races I now find my "normal" cadence higher than before also, which is the goal.
Of course in our sport there are always those who must be different. Our friend Jason Sager rides only compact (teasing him I started referring to compact as "ladies specific gearing.") He now seems to feel that the optimal chainring combination is 52/38 (how that is "compact" relative to a standard 53/39 is beyond me, but hey, Jason is about 50% faster than I on the bike, so I have to let him have that.)
My conclusion is that compact gearing is indeed magic for us cyclists in that it saves us from ourselves. We don't have the discipline to keep the gearing "easy" when we get stressed on the bike, we subconsciously drop it in the biggest gear we have when we get into a spot of bother and this is counterproductive.
When in danger of getting dropped, if you make the gear easier, you enhance your chances of staying on. This is not intuitive or natural. When we increase our cadence we feel as though our heart rate goes up which will ensure we get dropped. Subconsciously we drop it into a bigger gear which paradoxically feels easier. We maintain contact for a very short time, but this seals our fate and we get popped.
My conclusion? Compact Gearing - Magic or Mental? Yes!!
Gears are gears. Ride compact, and don't put on an 11 tooth cassette, if you seek to race and do group rides at the best of your potential. Compact can save you from yourself and save you from losing contact with the bunch at crunch time (plus give you the easiest possible gear to spin when the road tips significantly upwards!) So if you want to maximize your potential, race and train with a combination of "Senior Specific" (compact chainrings, and "Junior Specific" (14/25 or 15/25 cassettes.)