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January 14, 2010
Since Wattbike has been helping support this site we’ve been having good fun with their ergos. When I moved to Australia from Canada I swore that I’ve never train indoors again. However, the more elite level cyclists I get to know the more I see how many of them use ergos as a vital part of their training. My mate Andy (the guy in the video) had used ergo training 3-4 times a week for his build up towards the National ITT championships.
A common testing protocol for cyclists to define their training zones and gauge performance is with something called a ramp test. A ramp test will determine Maximal Aerobic Power (MAP) since the test is done aerobically from the beginning and reaches the maximum capacity of the individual’s aerobic system at the end.
Basically what happens is after a good warm-up we start the test by pedaling at 200 watts (a relatively easy pace for most people). We then increase the wattage 20 watts every minute until KABOOM! FAIL. The power that you reach on the very last step is what your MAP is.
There are a few variations to this protocol depending on the test subject:
The test seems very easy at first and then creeps up on you little by little. Even though the test is relatively short in duration, it requires the rider to push himself to exhaustion and therefore very demanding.
What we wanted to accomplish here is get Andy’s Maximum Aerobic Power output and set some training zones based on this. We can also approximate Andy’s VO2MAX (the highest rate of oxygen consumption attainable during maximal or exhaustive exercise). Just Google Storer or Keen/Pasfield to find these calculations.
You can see the graph of the test below. The red and blue lines are where his heartrate and power are increasing with time. The relatively constant line on top (in purple) is cadence. His maximum power topped out at just over 450w. World Class potential!
Using the variables in the test (weight, age, power, etc) it was calculated that Andy’s VO2max was approximately 74.66 ml/kg (Storer method).
The other graph we analyzed was his pedal stroke efficiency. On the graph below you can see every single pedal stroke during the test plotted out.
To explain what’s happening here, a single pedal revolution involves a push phase and a draw pull phase with each leg. The push delivers most of the force that generates forward momentum. The pull also contributes to overall power by the upward pull of your attached shoes.
The shape of the graph below has a diagonal lean with the greater power in the bottom left and top right quadrants (the PUSH phases of the left and right leg). This is because the angle of peak force (the PUSH phase) is just beyond the 90° point (or 6’oclock position on the cranks). The angle of peak force will vary from individual to individual but should be at the same angle in each leg. Ideally you’d like to get this polar graph looking like a complete circle, but most people’s will look like Andy’s below.
You can pick any individual pedal stroke throughout the test and look at it. For example you can see what a pedal stroke looks like at the higher wattages v.s. the lower wattages.
This graph above is representative of the pedal stroke efficiency at the 422 watt power output. If you look at the blue highlighted row at the bottom you can see that Andy’s left leg is contributing 49% and his right leg is contributing 51% to his pedal stroke (very hard for him to concentrate on during a exhaustion test). There is a bit of an imbalance between right and left legs. Also, if Andy could work on the dead spots in his pedal stroke and aim towards 80%-90% efficiency it would be a key area for him to improve his power output without increasing his fitness. This would take many weeks if not months of training to perfect. Personally I think 100% efficiency (a complete circle) is impractical. The amount of “PULL” in each leg that needs to be done is far too great.
In the end it’s simply fun to see your mate in serious pain. All this testing, analysis and bike geek talk is just a way to legitimize the satisfaction resulting in seeing your buddy’s eyeballs pop out!