So you've invested in some tri bars for your bike? Great! All you need to do now is get nice and low at the front so that your chin’s almost scraping on the road and before you know it you’ll be slashing minutes off your time trial times, all because you create less drag.
So clip them on and let’s get flying, I hear you say. Well, yes and no... It would be nice if it were that straightforward, but there’s a lot more to consider than just aerodynamics.
Yes, tri bars are the simplest and cheapest way of cycling faster for the same effort, because your body, and specifically your frontal area which meets the wind, accounts for over 60 percent of your total aerodynamic drag. By allowing you to get lower, they do more to improve the profile you present to the wind than other, more expensive components, frames or wheels will ever do. What's more, they're easy to fit to almost any bike and very adjustable.
It's important to spend some time getting used to new kit before you race and that's certainly true with tri bars. But you also need to be wary when adopting an aero position. The conclusions of a recent research study, which I conducted at Brunel University, suggested that riding while crouched low on your tri bars may reduce the amount of power you're able to produce.
Aero bar testing
We tested age group triathletes over a 20-minute cycling time trial followed immediately by a 15-minute run at self-selected 5K race pace. They cycled in a crouched aero position as well as in the more upright position of riding with hands on the hoods. We measured average power produced on the bike, as well as their running economy.
Not only did we find that the triathletes produced an average of eight percent more power when cycling in the upright cycling position, but perhaps more surprisingly they also demonstrated a four percent improvement in their running economy. We concluded that the narrower hip angle produced by the crouched aero position may affect muscle recruitment patterns, leading to higher oxygen usage, heart and breathing rates.
Hip angle
So does this mean we should avoid using aero bars? Certainly not. Aero advantages should definitely be on your hit list, but you should aim to achieve your aero position with as large a hip angle as possible. If you have a road bike with tri bars, it's likely that your hip angle is too closed. A well-fitted time trial bike with its steeper frame geometry is more likely to guarantee you increased cycling power and better running performance.
Not all of us can afford, or even want to have, two bikes though. So the key is simply to make sure that, through adjustment of your seat fore/aft position and handlebar height, you keep as open a hip angle as possible while still maintaining a crouched aero position so you can ride fast. So stick with those tri bars, be prepared to spend some time optimising your setup, and there’s no reason you can’t go out and get that new personal best.
Correct – Open hip angle
Incorrect – Closed hip angle