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TT Bicycles vs Triathlon Bicycles

TT Bicycles vs Triathlon Bicycles

Is it better to ride a TT bike or a Triathlon bike? This is a frequently asked question among long-distance Triathlon enthusiasts, especially for those new to this discipline.

In this guide, we try to offer a comprehensive overview of modern Time Trial and Triathlon bikes. Technical features, similarities, and differences of these authentic concentrates of technology and aerodynamics, were born to compete against the clock. 

Both Time Trial and Triathlon bicycles are made to go fast and cleave the wind. At first glance, TT and Tri bikes look quite similar. Even at a second glance, it would be hard to choose one over the other. But when it comes to geometry and saddle fit, they can be different.


The prototype of the new Colnago TT1 with disc brakes. The new Team UAE Emirates Time Trial bike. Credit: Cycling Tips

The first important consideration must be made to better understand the main features of these two bikes. If TT bikes are to be used, they must meet the strict guidelines of the Union Cycliste Internationale (UCI), cycling’s world governing body. Which sets everything from the width of the tubes to the length of the handlebars to the position of the saddle. In Triathlon races, athletes do not have to comply with the UCI regulations; Therefore, while aerodynamics remains key in the construction of a “Tri bike,” brands can sport a variety of design solutions, including creative ones.

So on the one hand we have the World Tour time trial stages, where all riders follow the same rules. On the other when you attend the Ironman World Championships in Kona, Hawaii, you will know that each rider has chosen his or her specific bike to fit in the most unique way possible.

The Trek Speed Concept SLR riding in the Ironman World Championship in St. George. Credit:


What is a Time Trial Bicycle?

The Cervelo P5 of Wout Van Aert of Team Jumbo Visma, in TT setup. Credit:

Time Trial bike (also called a TT) is an aerodynamic bicycle made to race against the clock, often on a straight and flat course. Time trial bikes put aerodynamics first. In practice, these bicycles use all the science possible to go as fast as possible: every gram is taken into account, and every angle on every surface is thought about in terms of aerodynamics. Time trial races can vary in length, but at the highest levels, they rarely exceed one hour. 

If we consider just the performance aspect, TT bikes offer indisputable advantages, both in terms of aerodynamics and stiffness. It is no coincidence that all professional athletes, and almost all advanced ones, race on a Time-Trial bicycle.

What is a Triathlon Bicycle? 

The new Specialized S-Works Shiv Disc. One of the ultimate expressions of aerodynamics and technical solutions specific to Triathlon.

Triathlon bicycles are developed specifically for triathlon races, where the bike course is between 20 and 180 Kilometers. As anticipated, compared to Time Trial bikes, there is no regulation for Triathlon bikes. These can be designed in any way to make the athlete faster and provide a little more comfort. This leads to sometimes radical frame shapes and geometries. For example, Tri bikes often have a steeper seat tube angle, which pushes the hips forward during the race and allows the hamstrings to be preserved for the walking portion of the ride. With the seat tube closer to vertical, the rider’s hips are exactly above the crankset, going to engage the quads more and the knees less in the power stage.

Time trial bike for long-distance Triathlons?

Considering the growing popularity of long-distance triathlons, such as the Ironman, many Triathlon bikes also take into account the storage of food, drinks, tools and spare parts. While road cyclists tend to carry items in jersey pockets or handlebar bags, triathletes can carry their items in aerodynamically integrated storage compartments.

In addition, there are important technical considerations as well. On a longer distance, a Time Trial bike may be uncomfortable. Both types of bikes have specific design features for aerodynamic efficiency, but the triathlon bike is designed to ensure ride comfort during hours of pedaling. In addition, its construction helps preserve leg muscles for the walking portion of the ride. Both types of bikes have handlebars with aerodynamic extensions to allow the cyclist to extend his or her arms and assume a position that reduces wind resistance. But the aero handlebar position on a triathlon bike is not as aggressive; the back and upper body are less stressed than the TT position. 


1. Aerobars and Extensions

The technological and aerodynamic integrated handlebar with extensions of the new Felt IA-2. Credit: Felt

The Aero Bar, the distinctive handlebar for Time Trial and Triathlon, consists of a base, called the base bar, and the extensions.

Brake levers are mounted on the base bar, while the extensions are the shifting control point. Base bars are also used for climbs, especially steep climbs. To get the perfect fit, you can adjust the stem length and angle, headset spacers, armrest height, and extension angle.

The extensions protrude forward and, together with the armrests, allowing the rider to adopt and maintain a more aerodynamic body position than would otherwise be possible.

There are specific regulations dedicated to limiting the reach of extensions and armrests in UCI races. Outside of UCI-regulated events, however, this is not a problem.

2. The Frame: Shapes and Geometries 

The futuristic Triathlon frame of the Cervelo PX 2022.

Aerodynamics is basically everything when it comes to TT bikes, and weight is only of secondary importance. For this reason, tube shapes are optimized to be as smooth as possible.  These also offer benefits in terms of stiffness, weight, and screening of the water bottles from airflow. The geometry of time trial and Tri bikes also differs from that of road bikes. The most obvious difference is that time trial bikes generally have steeper effective seat tube angles (about 75-78 degrees) than road bikes.

UCI rules establish many of the measurements of a TT bike; but beyond the regulations, both TT and Triathlon bicycles tend to have a shorter wheelbase to put the rider closer to the front of the bike, short head tubes, and a reduced stack height. Both also tend to use shorter cranks. Shorter cranks result in increased power and better aerodynamic.

3. Wheels: High Profile and Disc 

Team EF Pro Cycling tests Vision Disc and high-profile wheels, on the Cannondale SuperSlice Evo, in a special Rapha x Palace Tour de France 2022 color scheme.

As with the frame, aerodynamics is critical for TT and Triathlon wheels. In time trials we see the use of solid rear disc wheels and front wheels with very high rim depths. In time trials we see the use of low spoke count wheels (such as three-spoke wheels), front disc wheels are generally only allowed for track use.

A balance must be struck between the use of the more high-profile, aerodynamic wheels and the negative effects such wheels can have on the bike’s handling on windy days.  In general, the higher the rim has a high profile, the more aerodynamic the wheels are and the better they cleave the wind. Unless, of course, there is a side wind. In that case, the higher rims can act like sails and push the wheel, making handling the bike quite challenging. For this reason, many professionals have a variety of wheels to choose from, depending on the race they are competing in.

4. The Bike Fitting

Sam Long is in the typical aerodynamic position on the new Trek Speed Concept Disc. Credit:

While the aerodynamic position (arms spaced out thanks to aero handlebars) is most important, the position of the brake levers should not be overlooked. In general, when fitting a TT or Tri bike, one must consider all contact points: pedals, saddle, forearms, extensions, (when in the aero position), and the position of the hands on the base bar.

On Time Trial bicycles, aerodynamics reigns over comfort. In a time trial, a cyclist wants to go as fast as possible from point a to point b, even if that means contorting the body a bit. For this reason, the position is as backward as possible, with low handlebars and a greater distance from the saddle to the handlebars. In Triathlon, where races can be very long, comfort is the most important factor. Cyclists’ positions will be less gathered and a little more relaxed.

5. Riding Position

The riding position in TT and Triathlon is very similar. In both cases, the cyclist wants to reduce the surface area exposed to the wind. Imagine a wind tunnel: the cyclist wants as little resistance as possible while maintaining maximum watts. In the TT, this position is more extreme than on a triathlon bike, especially if the triathlon is quite long. In both cases, the cyclist wants to stay low in front. A short head tube allows the chest to drop. Some even recommend using a TT bike with a smaller frame to achieve lower elbow and thus shoulder height.

6. Brakes 

The aerodynamic fork with disc brakes and Shimano Dura-Ace Di2 braking system, from the Canyon Speedmax CFR.

Until recently, bicycle manufacturers struggled to find aerodynamic solutions to hide rim brakes inside the fork or under the bottom bracket. This resulted in compromised braking performance or complicated maintenance (or both), but was considered acceptable for aerodynamic gain.

Today, many triathlon bikes are switching from traditional brakes to disc brakes for greater control in variable conditions. Also, because the wiring can be hidden, disc brakes can make the entire bicycle more aerodynamic.

It is therefore too simplistic to say that traditional brakes are always more aerodynamic than disc brakes-it depends on how the components combine in the overall system. There is also no question that better braking performance can, on technical races, help you pedal faster. This is because it allows you to brake later and more safely, which, all things being equal, helps improve average speed.

7. Hydration and Storage

The new Argon18 E-119 Tri Plus, with disc brakes and integrated hydration and object storage solutions. Credit:

For TT races, athletes can often get by with one or two streamlined water bottles. But in longer triathlon races, it is critical to have a hydration and nutrition reserve (and even some gear) on board. The bike section is the best opportunity for athletes to focus on fluid and calorie consumption. 

So here on Aero bikes, we find solutions to store water, food, and gear that are easy for the athlete to access and do not compromise aerodynamics.

8. Drivetrain

The carbon single chainring on the Pinarello Bolide TT of Filippo Ganna, Team Ineos Grenadiers. Credit:

Time trials often take place on flat or undulating courses, so riders looking for every advantage can optimize their gearing.

This typically means large chainrings (up to 60 teeth) and widely spaced cassettes. The first allows for chainline optimization, while the second helps riders modulate cadence more precisely, which can be important when pedaling to the limit. 

9. The Saddle

The BMC Timemachine Disc Brake saddle is for sale HERE on Bike-room.

Given the aggressive nature of the Time Trial riding position, saddle choice is critical to maintaining comfort and preventing injury.

Therefore, it is a good idea to consider a saddle specifically designed to reduce pressure on soft tissues when riding in the aerodynamic position, because it allows you to move your hips forward and produce more power in the time trial position.

A saddle with a relatively long carriage will also allow for greater adjustability of position, which can be useful if the bicycle Seatpost is limited to a fixed position (this is in older Time Trial bikes).

10. Tires

Tire aerodynamics is also an important factor if the fastest configuration is to be achieved. For time trials, tire width must be optimized to maximize performance.

So it is just a matter of choosing a tire that is slightly tighter than the outer width of the rim. For example, if your rim has an outer width of 28 mm, a 25 mm tire will probably be the best choice aerodynamically.

Conclusions: what bicycle is suitable for Triathlons?

The Giant Trinity Advanced Pro TT. Credit: Giant

Time trial and Triathlon bicycles can both be used for Triathlon races. Especially for shorter races. Some people like the look of the TT bike, simple and streamlined. But if the section on the bike is long, especially if it is a 70.3 or a full Ironman, a triathlon bike will be much more comfortable. It will also allow more room for hydration and nutrition. While TT bikes keep the cyclist in the most aerodynamic position ever, triathlon bikes are the best way to stay aerodynamic while preserving leg muscles for running.

The choice is yours, the important thing is to beat the clock! 

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