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10% Additional Resistance Doubles Weekly Training Benefit

10% Additional Resistance Doubles Weekly Training Benefit

There are several limits to an athletes improving. Many of these are not physical limits either. The hardest part about improving performance is putting your shoes on in the morning. Once you have overcome this barrier, the next is making the time you have worthwhile.

The mental and human aspects to training are often forgotten for the more quantitative approaches of power and speed, time and kilometres. But even these quantitative measures are incredibly poor at translating training effect on a daily basis. One of the simplest examples of this is human natures inability to understand the laws of time and exponential changes.

We see the law of exponentials in compounding interest, population, house prices, and many other areas. For example, a 7% yearly increase in population in your city means the current population will double within 10 years, for a place like Sydney, which has a population of 5 Million people, 7% growth rate will mean population reaches 10 Million people within a decade. Imagine trying cram twice as many people on to overcrowded roads and public transport, everything seems fine now, but it will very quickly catch up on you. When dealing in Exponentials it’s hard to comprehend their numerical value on the surface, yet the implications are massive.

Let’s go back to cycling training. In an earlier post we briefly touched on Time to Fatigue, that description was wrapped up into a discussion about body size, CdA and many other areas. I would like to cover it again in more relevant terms. For training, the general rule is; for every 10% increase in power output your time to fatigue reduces by 50%. That means, if you increase the resistance on every ride by 10%, you have doubled your effective weekly training benefit.

With only a 10% increase in power, you total training time halves.

In the real world this means that if your training program requires you to do 6hrs at 200w, 3hrs at 220w will accumulate the same amount of fatigue. 1.5 hrs at 242w will also give you the same amount of training improvement. The value of only a few watts at this time scale can immensely change the duration you need to train for that day. This type of training is the core of every cyclists training program and probably some of the most important training you will do, yet much of it is left down to chance. Athletes forgo a few extra watts to train with a friend, reduce training speed because their partner wants to train slightly slower. Their new team bike came with only carbon wheels so they use them for training rather than their old heavier 32 spoke training wheels. These tiny psychological and accidental changes in someone’s training habits can have enormous effects on the outcome of someone’s career. A slight 20w or 10% reduction in riding power means you need to double your weekly training time to reach the same level of benefit. For someone who has a full time job this takes your weekly training from a manageable 10hrs, to the level of a full time athlete at 20hrs. A volume change that is impossible to match.

This is why we have spent so much time developing the AIRhub, our team recognized that even the slightest changes in average riding power will change the outcome of your career. We didn’t believe that leaving your life’s work to chance was a very smart career choice. Because these changes in wattage are so small it became rapidly evident that we needed a way not only to monitor these numbers but also a way to guarantee the execution. So delicate is the balance at the leading edge of performance that an imprecise load would very quickly lead to overtraining, heavier tires or riding faster simply wont cut it when the chaos of life gets in the way.

A common misconception about the AIRhub is that it is designed to make you go slower. This is incorrect. When training with the AIRhub, if you start to slow down to below what feels comfortable you are using it wrong and should pause it for a moment. The AIRhub is designed to increase your power at the times when your speed and power are disconnected, and not in their optimal zones. 


Cda mode is the nicest mode to train in. It perfectly simulates wind drag so it barely feels like it is there at all.

w/kmh mode is a sneaky mode that catches up on you slowly. The applied resistance tracks closely with the kinetic energy of the bike, so the resistance is hidden until many hours later when you suddenly realise that your friendly local loop had drained your legs of any energy stores that you thought you had. That few percent increase in intensity has wiped your endurance from the face of the planet and you are a withering mess until you realise that safety is the touch of a button away. As soon as you hit pause your old endurance resumes and you have a spare few hours of riding in the tank. This pace almost feels worthless now that you know the quality hidden in an extra few watts.

Heart rate mode is designed to keep you in your target zones when riding with others. Bunch rides, riding in a small group, this mode is not about speed or wind drag but uses your actual physiological parameters to deliver the correct training load. This mode is designed for rapidly changing environments and anything an exciting ride can throw at you, but still keeping you in touch with precisely what will make you improve; the scientifically tested training zones that have lasted for the past 60 years.

Power mode was built to take your indoor trainer outdoors. By listening to your power meter the AIRhub adjusts resistance to smooth out the lumps bumps and gusts that get in your way out on the bike. Especially good for timetrial efforts, tempo and anything that requires you to hold a specific power outputs for longer than your attention span. This will be the mode that changes cycling training for the next 20 years. Precise training dose in every environment.

Watts mode allows you to have fun and add quick and simple resistance to your ride. Very rarely do you get lumped with an arbitrary extra 100w when you are out riding your bike, so sometimes it feels a little strange to use this mode. We much prefer the smart modes which use speed or physiological data to better understand your environment and apply resistance accordingly

TIme to Fatigue

To find Power, Threshold and Time to Fatigue we use the following equations   

Excel plot of Power and Time gives us trend line equation.

The trend line equation will tell us how quickly your power drops off against time.

The data above is a 1 year sample from a national level racing cyclist. Data can be pulled from Todays Plan orTraining Peaks mean maximal power charts.

The trendline equation above is y=382.06x ^(-0.121)

Y = Required_Power (or power output.)

382.06 = athlete threshold calculated by the trend line.

(-0.121) = the exponent which tells us how fast power will drop off against time.

X = time in hours

That gives us; Required_Power = (Threshold) * (Time ^(exponent))

For our example we need to re arrange the equation to find "Time" 

Rearranging the equation we have; Time =(Required_Power/Threshold)^(1/exponent)

If we really want to get Tricky we can find the theoretical Threshold power of a rider based on a time to fatigue.

In this example we want to find "Threshold"

We rearrange to: Threshold = Required_Power/(Time^(exponent))

Giving us Threshold = 221/(20^(-0.121)

Threshold = ~317w