Welcome to Pedal Science, the weekly bike fitting blog by Nick Thomas of The Endurance Coach. This week our resident bike fitter Nick Thomas discusses how going low, can sometimes mean going slow.
Time trial bikes are designed to be ridden fast in an aerodynamic position, which often includes a short head tube resulting in a low basebar/tribar set up. This results in a low, aerodynamic riding position but is ineffective and counterproductive for most people for several reasons:
- Most people are not flexible enough to effectively ride in such a low position
- The cramped position can cause restriction in the hips which leads to a sticking point (and loss of continuity) in the pedal stroke
- The position causes unnecessary tension throughout the back
- Discomfort causes power to drop
- The increase in aerodynamics is negated by the loss of speed
- Running of the bike is compromised as hip flexors are shortened and the back is tight
Low profile frames are one of the most common problems we see and it appears many cycle manufacturers completely overlook the fact that the bikes simply don’t fit the majority of their customers. There are several ways in which the front end can be raised sufficiently to provide an appropriate bike set up:
- Riser kit:
These are spacers which can be added to raise the tribars to a specific height above the base bar which remains at the original height. This modification can be seen on professional time trial and track bikes where two ‘columns’ are visible separating the base bar from the tribar. The benefits of not raising the base bar are increased leverage riding out of the saddle and a lower – and more stable – position when descending. Ensure the accompanying bolts are long enough to potentially raise the bars by several centimetres: it’s not uncommon for people to need to require more than 8cm of risers
- Stem extender:
The stem can be lengthened so the entire basebar/tribar set up is raised with the tribars in their original position. One key advantage over riser kits is the raised basebar is more suitable for people with poor back flexibility: for anyone else the bars might feel too high and relaxed for a race bike. Stem extenders are practical but fairly unattractive!
- Adjustable stem:
For greater versatility an adjustable stem is a very practical option. The stem has two adjustable pivot points so there’s a considerable range of potential movement in terms of reach and height. The micro-adjustability ensures the correct position is always attainable and adjustment can be repeatedly altered to achieve the optimum position. As with the stem extender adjustable stems raise the entire basebar/tribar set up.
A time trial bike is useless unless you can achieve the optimum riding position. Riser kits would be the ideal solution for people who want to maximise the performance benefits of a time trial bike. For anyone who requires a higher basebar and wants more adjustability an adjustable stem would be worth considering.
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: email@example.com or see more about his fitting services by GOING HERE.