Triathlon vs Time Trial Bikes

Time and time again, we get these questions like, “What kind of bike should I get? Or “What’s the difference between this and that bike?” Well, it’s quite normal… and wise, to say the least. An outsider in the biking world would say, “Why should we bother about the differences? They’re all bikes, right? As long as we can ride them, it’s fine.” One can never be more wrong about this.

As a cyclist, you may already know that the slightest change on a bike could spell a massive difference in riding experience. These slight changes are what set the most identical-looking bike apart. An example of these bikes are triathlon bikes (tri-bikes) and time trial (TT) bikes, which look almost the same, but if you look closely, feel so much different.

a triathlete in blue helmet and black jersey riding his bike

The difference between these two bikes is too subtle that most manufacturers get no problem tuning the other bike to suit the client’s needs. For example, a TT bike (which is specifically designed for time trials) can be adjusted, fitted, and added with some accessories to make it suitable for triathlons. But what really are these ‘subtle things’ that set tri-bikes and TT bikes apart? Let’s find out in terms of these aspects: design, geometry and aerodynamics, features and accessories, and comfort.


One most basic difference between tri-bikes and TT bikes is the design. Although both bikes are designed considering aerodynamics, TT bikes adhere to the International Cycling Union (UCI) 3:1 standard rule while tri-bikes don’t. This rule imposes that no part of a bike should exceed in length three times than its width at any point. In time trials, the bikes’ components, such as tube thickness and saddle angle, are closely monitored. On the other hand, tri-bikes tend to deviate from the rule to get more aerodynamic possible for that long and fast ride.


Tri-bikes, as the name suggests, are bikes preferably used in triathlons. Typical tri-bikes have steeper seat tube angle to allow the hips to position forward while the shoulders and elbows are kept straight. This position keeps the hamstrings from working too hard while keeping a fast pace. As to why we must somewhat ‘reserve’ the hamstrings at this point is because you will need it later when you run. On the contrary, since TT bikes adhere to UCI rules, the seat tube’s saddle nose is positioned 5 cm from the center of the bike’s bottom bracket, which allows the rider to achieve an optimal speed with his leg power.


With its light frame and design, tri-bikes are meant to cover a long distance at high speeds with necessarily less effort. Being in an extreme, competitive sport, triathletes cycle for longer than in time trials, and not only that. They are not only meant to pedal their way through the finish line. They must unmount their bikes to run at some given point, which requires the endurance of the leg muscles. This explains why tri-bikes are designed as lightly-framed as possible – to offer as much comfort as it can for the hour-long pedal, without sacrificing the speed and aerodynamics. On the flip side, TT bikes can somehow trade comfort because time trials are speed races that require the rider to reach the finish line at a given amount of time. Hence, the rider opts to assume a more aggressive position in his bike and use his leg power and the bike’s overall aerodynamics just to obtain that optimal speed.


Nutrition and med kits, fluid containers, spares storage – you’ll never know when you’ll need them in a triathlon. As opposed to time trials covering a shorter distance and time with less to no effort on endurance, triathlons are on another level. Therefore, most tri-bikes are designed with storage features to accommodate these essentials. While these, of course, somehow affect the bike’s aerodynamics, they do not really pose a big issue since triathlons are more of a test of endurance than merely a speed race. TT bikes just can’t accommodate additional storage features because, in the first, the rider won’t need it anyway. Second, it will dramatically affect the aerodynamics and overall speed and maneuvering of the bike due to weight distribution.