Time Trial (TT) bikes are specifically designed for the demands of a highly specialized niche of the sport of cycle racing, where individual riders or teams compete against the clock on relatively short and flat courses. Time triallers pit themselves not against the tactics of the peloton or the pull of gravity in the mountains, but against the pure power of their rivals’ legs and lungs and the ticking seconds of the clock.
This purist pursuit, where the difference between winning and losing can be hundredths of a second, calls for a specific tool. TT bikes are aerodynamic, ultra-stiff machines with the emphasis firmly on lower wind resistance and direct power transfer over light weight, responsive handling or long-distance comfort.
TT bikes are also popular among triathletes, who appreciate the speed benefits they can offer over the often relatively short and flat cycle stages of triathlon races. However a dedicated TT bike is not a prerequisite for competing in triathlons – a ‘normal’ race bike with some adaptations can serve just as well for many – and the benefits must be carefully weighed against the disadvantages.
Read on to find out more about the characteristics of TT bikes and to decide if a dedicated TT bike is right for you.
Firstly, you need to decide if you actually require a dedicated TT bike. While TT bikes are designed for time trialling and also popular with many keen triathletes, their aero riding position, frame stiffness and specialised components such as deep-section rims make them unsuitable as all-rounders. They are really only one-job machines, so forget about group riding, city commuting or hill climbing on a TT bike.
If you wish to do an occasional time trial or triathlon you may find that your own bike, with some adaptations (mainly the addition of a set of clip-on aero bars or deep-section aero wheels) will serve just as well. Also, the use of dedicated TT clothing such as a skinsuit, an aero helmet and shoe covers will help.
However for racers and triathletes looking to step up to the next level, a dedicated TT bike may be the ideal option. Despite their sleek aero looks, the main benefit of TT bikes is not in providing better frame aerodynamics (yes, this is a factor, but not so much as you might think), but in allowing the rider to more comfortably and efficiently maintain the ‘aero tuck’ position for a long time. The TT bike resolves some of the positioning problems associated with just adding tri bars to a ‘normal’ race bike, with a shorter top tube and steeper seat angle reducing the amount the rider needs to stretch in order to get into the aero position. Other little touches like gear levers positioned at the end of the bars for easy access make staying tucked easier, for longer.
Of course, it’s up to you. If you do opt for a dedicated TT machine your choice will largely be determined by your budget. While all TT bikes will feature aero-focused frames and components, entry-level machines will generally have alloy frames and more budget-level kit. Spending more money will get you into the arena of lighter, more technologically advanced carbon fibre frames and top-end wheels (e.g. with deep-section carbon rims, tri-spoke or disc wheels), transmission (often with electronic shifting) and finishing kit. The choice is yours.
The main difference between TT bikes and ‘standard’ road racing bikes is in frame geometry. TT bikes feature a shorter wheelbase, steeper seat tube angle and shorter head tube, effectively rotating the rider forward around the axis of the bottom bracket to achieve a lower and more aerodynamic pedalling position.
As well as offering less wind resistance, this ‘extreme’ cycling position maximizes the rider’s ability to transfer power through the pedals through position of the back and core muscles.
These changes also result in the handling and comfort of a TT bike being significantly reduced in comparison to a standard road bike, but as these bikes are designed to be propelled along flatter terrain for relatively short bursts, sustained power output is the key consideration.
With light weight and stiffness taking precedence over comfort, TT bikes are almost exclusively aluminium or carbon fibre. Frame tubing is often extensively shaped and profiled in the pursuit of optimum aerodynamics, with the aim being to present as small a surface to the wind as possible in order to cut drag.
Components and gearing
Manufacturers use extensive wind-tunnel testing to figure out how to reduce resistance, and employ components such as integrated seatpost masts, disc or carbon-rimmed wheels and tri-bars. The latter help to reduce drag by making the biggest part of the rider – the torso – smaller. The classic ‘aero tuck’ position – back stretched flat over the top tube and elbows tucked into the body – is synonymous with time trialling, as is the ‘teardrop’ TT helmet and one-piece skinsuit.
Gearing on TT bikes reflects their intended use – and users – with big double chainrings for sustained speed over flat terrain.