Gross Efficiency In Cycling - by Coach Michael Lyons
Gross Efficiency in Cycling -
Coach Michael’s take on Pedal efficiency, Triathlon Cycle Optimal Training Methods and Useful tools.
Gross Efficiency Definition (courtesy Journal of Science and Cycling)
Gross Efficiency, the ratio of work generated to the total metabolic energy cost, has been suggested to be a key determinant of endurance cycling performance.
There is a huge amount of scientific data on this subject and I’d like to summarize some of the key points for Triathletes with some of my own experiences as proof points.
I have been riding a bike now for 50 years in many styles and hundreds of competitive races. During my Velodrome racing days, pedal cadence was highly regarded as a key to success and I spent much of my base training riding a single speed bike, (even on the roads) with a fixed 42 x 19 chain ring averaging 110 to 120 cadence.
As a road racer, my average pedal cadence was 95 but I could comfortably hold 120 rpm for burst of around 1 min or so, this was highly useful as the nature of bike races is that the pace surges from high to low and back again as attacks happen frequently.
Also As a road cyclist, I did a lot of Time Trailing, almost weekly as a cyclist across 16k, 25k, 40K and 80k distances. My cadence was typically 90 rpm for the TT with average speeds of 43 kph for the shorter distances and 39 kph for the 80k distance.
Now turning the clock forward 30 years research now shows us that high cadence has a high metabolic cost and that for Triathletes racing up to 70.3 distance a lower Cadence of around 80 to 90 improves cycling economy and is less taxing on the energy systems whilst producing optimal wattage particularly given the fact that we have to run following the bike leg. (Iron Distance 70 to 80 RPM may prove efficient for most athletes).
Now here is the trade off – lower cadence requires a higher turning force or more torque applied to the pedal to sustain power so if 80 RPM is optimal then our job as coaches is to train you to produce more force per stroke. It will be no surprise to you to learn that we are already training you this way through the following -
- Riding big gears on Hills of around 8% Gradient leads to recruitment of more cycle specific muscle fibers thru out the whole pedal stroke resulting in increased strength. Sets on Mundai and Mount Faber are a couple of examples of this type of strength session.
- Turbo Training - we do these every week using resistance and big gears and also having you develop pure power through short sprints, single leg jumps and single leg pedaling.
- The Gym - Strength training examples above and in the gym reduces the oxygen cost of steady state Time trial riding thus raising your gross efficiency.
Other factors that influence pedal force are crank length and bike set up, longer cranks are not for everyone, however the longer legged riders our squad would definitely benefit from riding 175mm, as would the shorter but stronger riders.
Its great to see power meters becoming more affordable, they are not the first thing you buy when beginning Triathlon but a progress measurement great tool once you have all the basics ticked off. Questions - Check with your coaching team on any of these points
Finally, if you didn’t already, now you know the method behind the FBG sets.