Climbing and riding against the Wind
Producing a constant power should feel the same whether it is on flat road, or with head wind or climbing or on a stationary bike in our pain cave.
300 Watt is 300 Watt and that is it ! Or is it not really ?
We know that for the common cyclist it feels harder on a steep climb. The reason for this can be given in a simple statement ; “When the pedaling stops you might roll back and downhill”
With a strong headwind you might be blown backwards when freewheeling.
When climbing or riding with head on wind it does not matter whether you pedal or not, whether you go slow or fast, there is a constant minimal push-back or reactive force. On a climb this minimal push-back force is proportional to your mass and to the slope of the climb. When riding in the wind the push-back force is proportional to your frontal surface and to the square of the speed of the wind.
This is unlike any other situation. As an example climbing a stair step by step may cost the same amount of force and energy but there is no danger for falling back when you stop stepping.
The question is , how much speed do we loose on freewheeling during 1 second, and how do we feel this ?
A little simple mathematics will help.
Let us take a cylist of 65 kg, riding a bike of 8 kg and who is able to develop 300 Watt in steady state at a comfortable cadance of 90 rpm.
When riding on flat road without wind, he will feel only the aerodynamic drag, and a small correction for rolling resistance. When in standard (non- aerodynamic) position, he will ride at a speed of 36.8 km/h. The combined effect of aerodynamics and rolling resistance accounts for a total push-back force of 29 N, or approximately 2.8 kg-force
When he stops pedalling this reactive force will cause him to slow down. The rate of slowing down is equal to the reactive force devided by his mass i.e. for one second of freewheeling he looses velocity amounting to Loss Of Speed LOS = 29/73 = 0.39 m/s or 1.45 km/h.
Because he was riding at 36 km/h this frational loss per second is %LOS = 1.45 /36.8 = 3.9 %
This is not a dramatic loss to say the least. He will barely feel it, keeps up easily by shortly pushing a little harder.
Things change dramatically when climbing. On a slope of 8 % the push-back force suddenly jumps from 29 to 65 Newton. His basic speed is now only 16.6 km/h and his LOS becomes 3.2 km/h which accounts to a dramatic %LOS = 19.2 %
Regaining his basic velocity of 16.6 km/h now will cost him a huge effort. Never will there be a moment for relative rest.
On steeper slopes the situation will be even worse.
The bottomline is that riding on flat road at 300 W allows for small but important variations in power and muscle tonus, while the same 300 W at climbing does not allow any relaxing.
Next table shows a few examples of the LOS and %LOS in various conditions of climbing and riding with head wind.
Table 1: Effect of riding uphill or with headwind. The basic velocity on flat and calm route is 36.8 km/h for our rider at constant power of 300 W. The 3th column shows the ideal gear ratio at the different conditions uphill or headwind in order to maintain 90 rpm at 300 W.
Column 4 is the approximate best practicable gear. Column 5 shows the total reactive or push-back force acting on the cyclist. Remark that 10 N corresponds to 1 kg-force. In column 6 is the loss of speed when the cyclist stops pedaling during 1 second, and column 7 shows the same loss of speed relative to the actual speed.
On a slope of 15% the basic speed has fallen back to a mere 9,7 km/h and a 1 second stop of pedaling will result immediately into a further reduction of speed to 4,2 km/h
Even worse would be riding in a storm headwind of 70 km/h where a dramatic drop in speed of 73% would be the result of this 1 second stop.
One remarkable fact is that riding on a flat road with a head wind of 40 km/h does have almost identical parameters and difficulty as climbing a 8% slope.
More generally, we may establish an equivalence between a head wind and climbing slope and even think of training uphill riding on a windy flat road. Low lying flat windy countries, such as The Netherlands or Denmark may even be good training facilities for climbing without having any hill of any importance. Just get out for a ride when all other people get inside because of the heavy or stormy wind.
Could this be one of the reasons the Netherlands have a surprising number of good climbers such as Tom Dumoulin, Erik Breukink, Bauke Mollema, Steven Kruijswijk, Robert Gesink, Joop Zoetemelk , Steven Rooks , Gert-Jan Theunisse …?
Uphill riding on flat road
A head wind of 7 Beaufort is approximately equivalent to climbing a 9% slope. The interesting wind uphill training zone is between 5 and 8 Beaufort.
The Dutch Mountain championship
Because there is no mountain of any significance in the Netherlands, they have a National championship for riding against the wind. The event is a 8 km long stretch on the Oosterschelde Kering and it is organized with a head wind of at least 7 Beaufort. Only 300 riders are allowed on standard bikes that are provided by the organizers.