The media coverage of that time trial and many pictures in the cycling magazines led to a wider interest in aerodynamics for the bicycle and thus began the revolution in aero bars and more aerodynamic bikes.

Thru the years all kind of strange designs of bicycles, handle bars, and aero bars have come and gone in the market. Frames became more advance, lighter and most of all significantly more expensive. Aero base bars became more “aero”; the aerobar extensions went from ski-tip bend to straight and then curved/bend again. Shifter/brake levers were mounted either on the base bar, still be able to use the SIS shifting system or on the end of the aero extension, using special bar end shifter also used in cyclo-cross, to stay more aero while changing gears. Armrests also received different shapes and even brake levers were mounted back wards. All of these changes eventually resulted in regulations in order to keep the bicycle safe for “normal” use.

As the popularity of triathlon grew so did the interest and the market for aerodynamic gear. Large numbers of people started to change their conventional handle bar too the aerobar and the famous “cow horn” or “bullhorn” base bars. In the beginning these base bars were made out of aluminum and mainly had a round shape. The industry reacted very quickly to the new market and with the introduction of carbon fiber all kind of different bars were presented to the public. In the late 90’s entire kind of futuristic all in one carbon bar were designed. 

The myth of the tri-bike.

Despite all the fancy designs, construction and materials, they all had one thing in common; the brakes levers were always to far away for the rider. Arms became too much stretch out what made it harder to turn the handlebars and the athlete had to lean further forward which resulted in shifting the center point of gravity forward. Bike handling and safety became an important point of discussion. However, it was the fitting of the athlete on the bike what became the main reason for the development of a new multi sport bicycle frame.

Brakes levers were now located to far away from the center point of gravity and this necessitated a re-design of bicycle frames for multisport. It was somewhere in the late 80’s that the tri-bike was developed. There was a large market, given triathlon’s rapidly growing popularity, for a new generation of bicycles. It was clear to the manufacturers that athletes were going to buy a new multisport bike, replace their road bike for the multi sport bike or even get a second bike for multi sport use.

Till somewhere in the early ninety’s, road bicycles were made mostly out of steel with traditional European-proven geometry. The handle bars was held in place by a quill stem which could be moved up in down in the steerer tube from the fork. The available length of these stems was amazing. It started at 50 mm and went up to 130 mm with increment of 5 mm. Today’s stems are made with increments of 10 mm.

If a bike fitting is done properly, the most aero dynamic and biomechanical efficient position is nearly always found in the drops of the conventional bend handle bar.

By placing the cow horn base bar with the clamp area on top of the regular bend handle bar, you will see that the brake levers position on the base bar is much further forward. The solid green line shows the position if the middle of the hand on the traditional bend drop. The dashed line shows the position of the middle of the hand on the base bar.

This difference can go up to 70 mm. As an example, let’s say the original stem was 100 mm long. Leaving the saddle in the same position as it was would mean that the length to the brakes would increase by 70 mm which in turn requires the stem to be 70 mm shorter which would result in a 30 mm stem to achieve the same position. A stem of this length does not exist. One possible solution would be to slide the saddle forward which would bring the knee further forward. Efficiency is compromised with this action so it is not recommended to do that. The knee joint (crossing point of the white lines) does end up in front (red dashed line) of the center from the axle of the pedal ( red line) which reduces the contribution of the hamstrings to the cycling movement and decreases the optimal downward power transfer between top and bottom dead center. Only the power transferred vertically to the pedal is the most usefull                                                      

The second option is to bring the head tube closer to the saddle. By doing this, using the geometry of a 700c wheel, the front wheel will then touch the down tube. If not touching the down tube, the resulting toe overlap will increase significantly.

After working through this web of “geometry” problem, it turned out that a frame building challenge emerged. The simple solution was to move the seat tube forward to 74 or 76 degrees and on some really small frames even to 78 degrees. This would give frame builders the option to make the top tube shorter and the use of normal size stems and a 700c front wheel with out the danger of excessive toe overlap.

The tri-bike was born. The end result is that this new bike was created out of two main limitations that are directly related to each other if it becomes to frame building:

The average length of the human torso and arms

The size of the (front) wheel. 

This whole procedure is not new. When bicycles were made out of steel, they were offered from size 47cm or 48cm to size 66cm with increments of 1 cm. With the introduction of the compact frame building, frames are offered from XS (extra small) to XL (extra large). Looking at the geometry chart of any bicycle manufactory, it will show that the seat angle does get slacker as the size of the frame increases. This has nothing to do with the potential rider of the bicycle; it was and still is done due to the size of the front wheel in relation to the length of the top tube. In the picture an example of the Colnago Master-X frame sized chart. All the way in the left column the frame size. In the column Sc shown  the seat tube angle. You will see that as the top tube get shorter the seattube angle gets steeper. 

Looking at the history of bike splits in Ironman results shows us that the more forward and deeper position did not made a significant difference. In 1988, Axel Koenders, who broke the world record in that year  rode on a regular bike with just an aero bar under 4 hours and 30 min. In 1997, nine years later Luc van Lierde rode in his world record race 4 hours and 28 min and in 2008, Ain-Alain Juhanson did the bike portion in 4hours and 26 min. In an interview  with Triathlete Magazine (300th Issue), Ain-Alar Juhanson said that he was not efficient nor comfortable in the aggressive aero and forward position. He moved the saddle back and the “cockpit” up and rode 10 min faster in the Hawaii Ironman in 2008 compare to 2007.

 Twenty years later, top athletes still ride nearly the same bike splits in Ironman races.

Tri bikes are designed with aerodynamics and aggressive riding in mind. To achieve this, head tubes were made really short in order to keep the handle bars low for an aggressive drop of the handle bar. This should support the athlete to be in a very aerodynamic position. In reality, most athletes cannot ride a bicycle in that deep position. The drop of the handle bar is not determined by the components ordesigns of the bicycle frame. It is determined by the sizes of the athletes body.

Who benefits from the tri-bike?

The aswer here is very simple. The bicycle market benefits from the tri-bike. There was a multi billion market out there for this new product and it was smart marketing that made the tri-bike a succes in the bicycle store.

In addition to that, during a bike fit the discussion is most of the time about being comfortable on a bicycle. If the athlete really wants to be comfortable on a bicycle, it could be  aerodynamics that will be compromised to achieve this. However, an aero helmet does contrubute more positive to aero dynamics then a shorter head tube on a bicycle.

Below are images from a local race in South Florida. They show that in most cases there is no purpose that the multisport bicycle has a short head tube. Many multisport bikes have a significant amount of spacers under the stem in order to raise the base bar or handlebar, sometimes up to sixty millimeters (60mm)!

The tri bike is the result of the introduction from a new type of handle bar; the cow horn or bull horn base bar. This handle bar made it necessary to make some radical changes in frame building; by making the top tube shorter and steepen the seat tube, it was possible to use these bars without too many limitations. Bicycle manufacturers started to dig in the this new multi sport market and all different kind of tri bikes, made out aluminum, titanium and carbon were rolled into the bicycle stores. The selling points used for these new multisport bikes were that the athlete does save their hamstrings for the run and that the tri bike it self and the position it created was much more aero dynamic. The popularity of the tri bike grow because of the enormous marketing behind the product and the individual result of an athlete in a big race, mainly Ironman Hawaii.