Tristar Athlete, you have done the training and have your race plan loaded and ready to go. When to ride hard vs ride easy is a science when racing. Wind sheer that greets you as your ride is exponential in nature, meaning it takes even more power to ride one mile an hour faster and especially true the faster you go. In fact, eventually there is a terminal velocity that even the strongest of cyclists will face.
Faster or slower run splits by distance using the concept of "wind sheer"
“...The hidden cost of riding fast is scary, the power you have to produce is proportional to the cube of your velocity. To increase your speed by 25%, you need to nearly double your wattage! ”
The purple area in the graph above shows the sum of all resistive forces that are not air resistance. This includes friction in the drivetrain of the bike, rolling resistance of the tires, friction in bearings, etc. The important takeaway is that all of these types of resistance increase linearly as the bike travels faster.
The gold area is air resistance. Air resistance increases at an exponential rate with speed. This means the amount of energy the rider has to expend, and therefor the amount of heat they produce (or TSS, training stress.), also increases exponentially with speed.
In order to have a faster day in triathlon and not tap into precious resources needed for the run we have taken the following key points from this athletes scatter graph and power-meter breakdown.
This athlete rode at goal power for much of the ride, when the speed was faster than their goal miles per hour of 21, they backed off and reduced the power using a larger gearing with low power output which helped to maintain momentum.
When speeds were slow they went up to their maximum allowable power output given by their coach. ( In this case for a half ironman advanced athlete ~90% of FTP) Placing power here had a greater impact vs placing power while at top speed. (Think more bang for the buck). Below we have outlined how this plays out at your next race.
So how does this play out? If your goal power for the race is expected to produce 19mph, then…
To create your own raceday strategy that incorporates power, speed, heart rate and rate of perceived effort please use our bike pacing calculator.
Pacing Plan
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