C2 vs. Assault Bike Calibration

It’s been a while since I updated this blog, but recently I did some testing at CrossFit Ignite on how to come up with equivalent WODs for those who want to or need to use the Assault Bike / Airdyne instead of the Concept2 rower. Here’s what I found, which corroborates the findings in this article. FYI: Set the Assault Bike to measure meters vs. miles for distance.

  1. Common level of effort can be reached by using the watts setting on either machine.  E.g. if level of effort is supposed to be 75% – you can feel what 75% is like on the C2 using the watts setting, and then go onto the AB and pedal at a similar watts level.  I tested at:
    • 200 watts – which is about 1000 cal/hr or 2:00/500m pace on the C2 – this is the range where most people will be working for most WODs.
    • 385 watts – which is about 2k pace for me on the C2.
    • Max – which is >750 watts on either machine.
  2. Rule of thumb for anything longer than 250m/10cal all-out sprints:
    • Multiply C2 distance by 2 for Ae.  E.g. 500m on C2 equals 1000m on AB in the same amount of time.
    • Multiply C2 calories by 0.5 for AB.  E.g. 50 cals on C2 equals 25 cals on AB in the same amount of time.
  3. For anything up to 250m/10cal intervals at all-out sprint intensity (>750 watts):
    • Distance rule of thumb is the same.
    • Calories become 1:1 – so 10 cal intervals on the C2 are also 10 cal intervals on the AB – but this is only true if you are revving the AB to absolute max. 
  4. I don’t know why the calories even out at high intensities. There is no way of knowing the differences in how each machine even calculates this. In general it’s possible to maintain a higher average wattage on a bike than on a rower because the cadence is much higher on the bike, although the absolute max attainable wattage is similar on both machines. My theory is that there is a limit to how fast a human can move arms and legs, and you reach this limit faster on the AB due to the higher cadence and shorter range of motion, so at a certain point you can pour more force into each stroke (calories) without being able to move the flywheel much faster (distance).

 

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