How Shifting Varies by the Type of Cycling
Track riding, for example, requires higher cadence and a high level of efficiency. While sprinters spend more time at higher rpms to train fast-twitch muscle fibers, ultra-distance cyclists and triathletes typically roll with a much slower cadence.
Cyclocross and mountain bike competition, on the other hand, needs a more brute power-oriented discipline with bigger, often explosive efforts, which require rapid continuous shifting to optimize speed over difficult terrain. Fine-tuning the shifting will also keep the rear wheel from spinning or hopping on particularly precipitous climbs.
Road racing is more steady state-power oriented but still requires a sort of flow-state shift to hold the heart rate as steady as possible for as long as possible.
Criteriums require more explosive jumps to close down and create aggressive race-winning breaks. If these jumps are accomplished in large gears with too few shifts, the effort will be sluggish and predictable to others. The element of surprise is best accomplished with rapid-fire shifting, which will certainly save energy and keep the muscles from loading up from too much power applied from over-gearing.
Don't ever forget that learning what ratios work best for your body type can save you energy that you can use later! Throughout this mix of conditions we have the consideration of crank length. Shorter arms will produce a faster rollover, but typically with less power. That is why you see the shorter arms on track bikes, and they are also a better call for the deep pedaling turns found in crits.
How to Ride More Efficiently Through Shifting
The evolution of the mechanical side of things, from heavy steel to lightweight alloy and titanium cassettes with 10 and 11 cogs, gives you the means to more accurately gauge the ebb and flow of the terrain. But are you really utilizing those cogs?
A recent innovation, Shimano's Di2, in my opinion represents a technical leap. In plain language, the Di2 electronic shifting system permits us to maximize our cadence. By maintaining a smooth steady speed, with an efficient personalized cadence, we can avoid overtaxing our muscles and cardiorespiratory system.
It is an oversimplification to say that increasing or decreasing rpms will improve efficiency. What I recommend is varying the rpms to train the muscles. This can span the range from rapid turnover—to work the neuromuscular through very rapid turnover, say 110-120-130 rpms—contrasted with a slow power coaxing "mash," in consideration of the different racing conditions listed above.
With this approach you can explore a variation of torque and power and eventually find your own territorial preference. This realm is essentially a function of your own percentage of fast-versus-slow muscle fibers. Every one of us bikers is a shade different, so exploration is a key element of training. While using my Di2, I find my shift rate is up. I'm actually shifting about twice as much as before, fine-tuning my rpms to every grade and wasting far less energy in the process.
Regardless of whether you use electronic or manually activated cables to shift your gears as you climb, I invite you to shift more and work less. Climbing, which is defined as anything that pitches up irrespective of the percentage, is our real test. I find that by shifting more, I'm less sporadic with my rpms. The tuning of cadence can complement your form in a big way.
Work on your shifting by signing up for a cycling event.