Power Hungry

I got an interesting insight into power output on the bike today on the Tuesday morning Front Runner ride.

I remember back when I first got a power meter it was amazing to see just how much difference to your effort things like head winds, hills and group rides make. Anyone who has done any riding will know that all those circumstances make a difference to the amount of effort required to make a bike go. However, what I found surprising when I got a power meter is just how big the difference was.

There is plenty of stuff online about how big a difference things like a draft make to the amount of power required. According to articles like this (Cycling Aerodynamics) the benefit is in the realm of 40%. It is one thing to read that, but for me, I didn't believe how big the impact was until I sat in a pack and watched my power output plummet. It is one of the reasons that I prefer most of my athletes to train without a draft. Sitting 10 deep in a big peloton means you are literally doing about half the work you would be doing if you were riding solo. For a sport like triathlon that has no draft, I don't understand why you would hide from the wind like that in training. Still, that is a topic for another blog.

I was similarly surprised by the impact that a big wind or a hill made on power output. Obviously these conditions make cycling harder, but I was surprised to see them adding on 50 or 100W onto my power output. When you take into account the detrimental effects of spiking power on running performance, it makes you realise how much damage you can do yourself in a race by smashing up hills or pushing into a headwind. If the idea of a triathlon bike leg is to keep you power profile as flat as possible, then hills and headwinds really make that hard.

The effects of all these factors on power output were certainly interesting at the time, but they were hardly shocking. However, today I got a new lesson on things that can effect power, body weight.

Anyone who has been around cycling for a while will know that while power is interesting, the really useful number is power to weight. A 85kg guy pushing out 400W is good going, however, 50kg woman pushing out 250W is amazing. In the end, if you weigh more you need to generate more power, typically a lot more power, to ride as fast as somebody who is lighter. That is the lesson I learnt today.

Today was the first time I have really ridden with my power meter since I put on about 10kg and boy what a difference it made today, particularly because the session today was all about hills. I needed at least 30W more to get up a hill at anything like the pace I used to, in fact I suspect the number was higher than that. With no more muscle to push with that extra power demand simply meant I was going to fatigue faster, no way around it.

Whilst I don't think it is healthy for triathletes (or anyone else) to obsess to much about weight, rides like this morning are a good reminder about why maintaining a healthy weight has great benefit when it comes to racing. Combined with the differences that lighter weights can make to running speed, losing a few kgs really can help make significant improvements in race times.