After my last Ironman in Busselton on Dec. 3, 2023, I have asked myself one of the questions that many cyclists might have, once they started to join competitions: how can I become a better cyclist, how do I get a faster bike split? There are many different factors that have an impact on your pace & performance on the bike.
Before I discuss those factors, I want to present a very helpful tool that I have been using for many years which is “kreuzotter’s speed & power tool”. I have added some metrics that come close to the ones that resulted in my bike split of a bit less than 5:30 hours for the 180 kms in Busselton:
Here you can find my data from Strava:
My weighted average power was even slightly higher at 165 watts; but to even things out, I left the average power at 160 watts, since the calculated riding time was more or less correct with 5:27 h.
Biggest impact on better bike split
The most obvious factor to get faster on the bike would be the power output. Let’s say, I can hold 180 watts instead of 160 watts over the bike course, then the calculated finishing time is about 14 min faster! Instead of 33 km/h, I would reach 34.5 km/h. Interestingly, my body weight has only a pretty marginal impact; however, since my next race will be a triathlon event, the body weight will have a more substantial impact during the run.
Another important factor which is not too obvious, is the effective drag area, also abbrevated as CdA. In the image above, it is an estimated 0.286 m^2. It basically goes back to your aeroposition on the bike. Had I ridden the Ironman with a road bike (“hands on the drops”), then I would have cycled around 20 minutes slower! So, aerodynamics are another very important aspect, when it comes to bike pace.
Some further factors, apart from some others, are better wheels (aero wheels) with accurate pressure; then, a higher cadence (I try to aim for about 85 rpm), and a proper race nutrition strategy. If you want to cycle with more power, then you usually need to consume more carbohydrates. For my next race (most likely an Ironman 70.3), I am going to aim for about 80 grams per hour. A higher power output of about 200 watts for the 90 kms combined with a slightly higher intake of carbs is my most important approach to get a new PB on the 70.3 course.
“On paper”, this would give me a bike split of 2:32 hours for 90 kms – no idea, if I will be able to make it; but I will certainly write about it here;)