Cycling is said to be an efficient mode of transport, when compared to running or driving a motor vehicle. Agreed. Mile for mile, far lesser calories and energy is spent, far lesser pollution emitted. But might that idea topple upside down when the road heads uphill?
When road grade rises, there is a seesaw effect in the amount of resistance wind and gravity play. Wind drag now goes down resisting less, and gravity comes up slowing you considerably. All that matters now is how much weight you carry and what gearing you have on the bike. The same gearing that perhaps tripled your speed output on a given rotational crank input on flats will plunge on a steep climb. If you choose to go with a lower gearing, your speed drops. So there is an apparent tradeoff there.
But it stands out, I guess, that one of the obvious elements of cycling athleticism - this notion of how good a cyclist someone is - is by assessing how well they can climb steep roads. Some of us may have this thinking that we're a real cyclist if we climb, and climb steep. I think there's a certain attractiveness in this tiring act. It gives one a sense of accomplishment, and sets a certain level of worth among the people he or she rides with. Bragging rights, yeah that's what it is. Besides, there's always a great view or a downhill to be earned at the other end, isn't there?
Top races in the world are most often won on the steep climbs, when a competitor can easily put time on his rivals. Stars who often showoff their talent on the climbs gets us all motivated to climb, and do it without getting off the bike. Getting off the bike and walking is somehow regarded shameful, powerless. You're no good. You aren't born to do it. Now where a cyclist does show mettle and talent on high gradient climbs, I think more can be said about his physiology and mental faculties than about the efficiency of his activity.
Its interesting that throngs of cycling fans line up steep cobbled roads and alpine climbs in Europe to see their favorite hero drag along the climb at close to walking speeds. Say one casual observer stepped back for a moment and asked : 'How efficient is cycling uphill compared to doing the same on flatland?', what do you think he'd tell himself?
I think the above observer could determine that this cyclist, riding past him on such a steep hill at 3mph, heaving from side to side zigzagging across the road like a detracked choo-choo train, will be more efficient if he got off his bike and pushed it uphill. There's no shame in this. Its just the clever thing to do, for this observer could jog up faster than the cyclist dragging along uphill! I would think much lesser energy is wasted simply caressing the ground with your feet than having to go through the complex motion of pedaling in circles with a chain and derailleur system that ultimately transmits some power to the rear wheel after losses through friction and deformation of rubber tires.
But sporting activity wouldn't have that, would it? Its not considered sporting otherwise. There might be booing from the crowd. There's no athleticism is walking your bike uphill...c'mon now. You're a sissy. You lack mental prowess.
Cycling does have its inefficiencies (perhaps that is why our early ancestors didn't swim out of the ocean carrying bikes to land). But it is the level of efficiency inherent in the cyclist which he applies to get past the natural inefficiencies that come into play in this mechanical activity that ultimately determines his outcome in a race, a training goal or the worthiness and respect he has among his peers. But I'm not the guy is the white lab coat so I can't credibly tell you where this bodily efficiency lies or how to attain it.