Time Trial Bikes
Time trial bikes provide an extreme, aerodynamic position, obtained through a short headtube and steep seat angle. This position, whilst also reducing wind resistance, maximises the rider's biomechanical ability to drive power through the pedals, locking the back and core muscles in place.
Leading time trial bike manufacturers use extensive- wind tunnel testing to improve aerodynamics through a variety of modifications. Tubes are profiled to reduce drag by reducing the size of the material presented to the wind and elongating it to reduce coefficient drag (the slowing effect that the wind has as it leaves your body or the bike). This allows the drag to leave the rider and the bike without creating areas of low pressure which suck the rider backwards (more commonly known as turbulence).
Tri bars make the biggest part of a cyclist (the rider itself) as aerodynamic as possible and therefore offer the best improvement in speed for your money.
Disc wheels offer an efficient surface to the wind but are only effective on still days. Similarly, an aero four-spoke front wheel helps cut into the wind and isn't influenced by wind from the side. As such it can be used in a wider range of weather conditions. A double disc is not currently allowed in time trialling.
A solid starter bike is likely to cost £1100-1800. The Trek Equinox is a good example and with its sleek aerodynamics offers complete bike affordability. The cost for a complete bike is around £1300 and includes a set of gear levers wired up to the tri bars.
A mid-range time trial bike is likely to cost £1800-3000. Felt manufacture the broadest range of models, all aimed at time trialling and triathlon. The Isaac Joule is a good example of the product of advanced wind tunnel tested designs, but is surprisingly affordable at around £1500 for the frame (including fork, headset and seat post).
At the high level of specification, prices can rise disproportionately high. The time trial bike used by a certain Pro Tour team retails at over £25,000!