Welcome to Pedal Science, the weekly bike fitting blog by Nick Thomas of The Endurance Coach. This week we look at the subject of TRI BAR LENGTH and cycling performance.
The aim of tribars is to minimise frontal drag and enable the person to ride faster at the same effort. It’s easy to fit someone in an aerodynamic position but a poorly fitting set of tribars can potentially result in a slower bike split, and certainly affect the following run split in triathlon.
The most common problem we see on time trial and road bikes is tribars which are far too long. The result is the rider over reaching and riding in an over extended position which can lead to the following problems:
- The closed hip angle can cause restriction as the leg passes over the top of the pedal stroke – this leads to an interruption in continuity of power throughout the pedal stroke
- The increased tension throughout the back can lead to discomfort and/or pain throughout the back, neck and shoulders
- Excessive rocking in the hips occurs as the leg passes over the top of the pedal stroke – this is inefficient and can lead to increased discomfort in the lower back, especially during long bike rides
All these factors ultimately lead to a loss in sustainable power and reduced speed but can be rectified with some simple adjustments.
When determining the correct reach on tribars the primary aim is to positon the shoulder at 90 degrees when the rider is using the tribars. By achieving this the upper body weight is rested onto the bars and tension is reduced throughout the posterior muscles. Most tribars provide some degree of length adjustability but this can vary considerably between brands and models.
Because a time trial bike positions the rider further forward it’s generally simple to achieve the correct tribar position providing there is some adjustability. On road bikes the problem is compounded by the fact that the rider is positioned further back due to the conventional frame geometry.
If you’re using tribars on a road bike it’s essential you choose tribars which allow the reach to be shortened several inches. Road bikes are not designed for tribars and as a result, it’s usual for correctly fitted tribars to only extend 1-2 inches beyond the end of the brakes and many tribars won’t provide this level of adjustability. To address this problem there are certain models which are specifically designed for use on road bikes. They’re much shorter than conventional tribars and are used by triathletes racing in draft legal triathlon.
When choosing tribars ensure they provide an appropriate range of adjustability. An over extended riding position will reduce your sustainable aerobic power and negate any aerodynamic benefits they provide.
Nick Thomas is the resident bike fitter at The Endurance Coach. He is a fully qualified bike fitter and expert in lower limb mechanics, holding a BSc (Hons) in podiatry. You can contact him using the email address: firstname.lastname@example.org or see more about his fitting services by GOING HERE.