Welcome to Pedal Science, the weekly bike fitting blog by Nick Thomas of The Endurance Coach. This week we look at the subject of HANDLEBAR HEIGHT and cycling performance.
The aim of tribars is to lower frontal drag and achieve the optimum position to enable the cyclist to ride as fast as possible. The last article discussed the factors which need to be considered when establishing the correct handlebar height for a road bike. These points are just as relevant when fitting tribars:
- The type of event the bike will be used for
- The ability of the rider
- The flexibility of the rider
- The cyclist’s confidence and bike handling skills
The faster and more flexible someone is the lower the tribars can be. However most people we assess have poor flexibility and/or restricted hip mobility which limits how low the tribars can be. The problem with a low front end is it causes more flexion in the back and hips, particularly when the foot is at the top of the pedal stroke – if someone has restricted flexibility or joint mobility a low front end can cause the following compensations, both visible when observing the rider:
- Rocking hips as the hip lifts to enable the foot to pass over the top of the pedal stroke
- Abducted knees (sticking out) as the hips open up to enable the legs to pass around the top of the pedal stroke
There are several potential consequences from these compensations:
- Pedaling efficiency is affected as a dead spot appears at the top of the pedal stroke which is visible when power distribution is measured using a spin scan. The inconsistent power distribution reduces average speed.
- Excessive movement in the lower back can cause muscular fatigue resulting in back ache. The longer the event the more debilitating the back ache becomes and therefore the slower the performance. For triathletes this is particularly detrimental as the bike is followed by a run: a tight, painful lower back will not enable the athlete to run to their potential and the loss in run speed can be dramatic, especially over a half or full marathon.
- Aerodynamic advantage is nullified if the knees as sticking out as frontal drag is increased
- Knee problems can develop in people who abduct the knees as the patella doesn’t track correctly (i.e. vertically).
Tribars should therefore be positioned at a height which improves aerodynamics without compromising the comfort or efficiency of the rider, and enables the cyclist to ride to their potential. If tribars are not improving bike (and run) speed they’re not achieving their intended purpose.
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.