What’s the best bike for tri – a focused triathlon bike or a super-aero TT bike? We delve into the differences.

Radical triathlon bikes and time trial bikes are both designed to go fast and cheat the wind, so they’re pretty much the same thing, right? Well not quite. While they are both designed for maximum aerodynamic efficiency, there are actually plenty of differences including frame shapes, geometry, brake technology and storage.

Triathlon and TT bike frame design

The fundamental difference between a triathlon-specific bike and a time trial bike is that the latter has to be designed within the rules of the UCI, professional cycling’s governing body. This means that during the time trials you see at the Tour de France, the bikes must adhere to the strict UCI rulebook, meaning elements such as tube thicknesses and saddle position are closely monitored.

Cervelo P3X
The Cervelo P3X triathlon bike revives the ‘beam bike’ design that was cutting edge before the UCI banned this style in the 1990s. (Photo: Cervelo)

Triathlon, on the other hand, is free from such constraints, so tri bikes can be designed purely in pursuit of speed, performance, comfort or practicality in multi-sports events. This can lead to shapes that completely eschew traditional TT bike design.

Take a look at Cervelo’s P3X – the latest in a long heritage of triathlon ‘beam bikes’ built without a seat tube. Meanwhile, the Ventum One and TriRig Omni both forego down tubes, borrowing cues from British world hour record holder Chris Boardman’s Lotus bike, itself made at a time when UCI rules were more relaxed.

At the most extreme end of the tri bike spectrum, you’ll find the enormous aerofoil shapes of the Dimondback Andean and the Ceepo Shadow-R’s horizontal fork.

TriRig Omni Triathlon Bike
The beautiful TriRig Omni’s fluid shape balances inspiration from past classics like the Lotus with cutting-edge integration and practicality. (Photo: Nick Salazar, TriRig.com)

It’s not always about exotic shapes though. In 2014 Cannondale relaunched its Kona-winning Slice tri bike, utilising pencil-thin but completely solid seatstays (illegal under UCI rules) for minimum drag profile and added comfort.

TT and tri bike setup

One effect of the UCI’s strict rules, where the nose of the saddle must be at least 50mm back from the bottom bracket, is that time trial bike geometry can make it difficult to achieve the extra-steep seat tube more suited to hamstring-saving triathlon bike positions. To make their TT bikes more tri-friendly from this point of view, some manufacturers use a reversible seat post or multi-point saddle clamp design allowing a steeper effective seat tube angle – so factor this in if you’re shopping for a new TT bike for triathlon use.

Bikes designed with time trials in mind tend to have short head tubes and low stack heights, meaning the bars are low to help achieve an aggressive aero tuck position. This is ideal for short time trials where aerodynamics trumps comfort but is less suited to triathlon where the run is still to come – and especially Ironman and Ironman 70.3 events where a slightly more upright position is more comfortable thanks to less craning of the neck and compression of hip flexors.

Spacers can often be added to both the steerer tube and the base bar to achieve a comfier position on a TT bike while many modern designs have modular stem and bar setups that allow a neater, more integrated-looking cockpit.

From this perspective, there’s little to pick between a TT and triathlon bike – the former may require more spacers while you might find it trickier to achieve a super-low slammed bar position on the latter. In either case, look at the geometries of the bikes you’re considering and think about the type of racing you’ll be doing so you know where your bike’s setup limits lie.

Brake technology

Disc brakes are being rolled out throughout the world of triathlon bikes, technology not yet widely used in the professional cycling peloton. Companies such as Cervelo, Specialized, Quintana Roo and Felt have all embraced the discs, which allow powerful braking performance that’s unimpaired by complicated cable routing thanks to hydraulic lines.

Cervelo P3X Disc Brakes
Disc brakes are now available on triathlon bikes from several manufacturers including Cervelo’s P3X. (Photo: Cervelo)

With a negligible effect on aerodynamics, the improved power means safer riding on hilly or technical courses as well as the ability to brake later into corners, which makes up for the slight weight penalty. Picking a tri bike with disc brakes will also allow you to take advantage of the latest wheel technology, with aero experts such as ENVE producing disc-specific designs that are faster than their rim-brake counterparts.

For those triathlon bikes utilising more traditional calliper rim brakes, expect to see a selection of hidden braking setups with the front brakes hidden behind farings or integrated into the fork itself. The efficacy of these kinds of brakes can vary hugely with some offering solid stopping power and others giving lacklustre, spongy braking performance.

The TriRig Omega X is a powerful aero calliper brake upgrade for frames without integrated brakes. (Photo: Nick Salazar, TriRig.com)

Rear rim brakes on TT and triathlon bikes are usually placed behind the bottom bracket under the chainstays to minimise drag. Complicated cable routing can sap power here too while depending on frame clearances, wheel rub is also more prevalent as the chainstays flex under high torque efforts.

Triathlon bikes – onboard storage

While time trials in the world of road cycling tend to be shorter efforts, triathlon bike legs can stretch to hours meaning storage for fluids, nutrition and spares is essential. Fitting all this to a regular TT bike can not only affect the bike’s aerodynamics but the handling due to weight distribution.

With this in mind, many bike companies’ triathlon bikes now integrate storage for drinks, gels and emergency supplies, making them ideal for longer triathlons such as Ironman 70.3 and full Ironman events. The 2011 Specialized Shiv, which featured a drinks bladder in its enormous downtube, was the first mainstream example of this while the Trek Speed Concept ushered in the behind-the-seat-tube storage box, which now features on bikes from a range of manufacturers including BMC, Felt and Qunitana Roo.

Canyon Speedmax Triathlon Bike
Canyon uses the same frame on both the TT and the tri variants of its Kona-winning Speedmax, the latter with storage, a set-forward seatpost and a higher basebar. (Photo: Canyon.com)

Today, many bikes marketed specifically for triathlon have a selection of storage accessories with toolboxes at the back, gel storage on the top tube and custom aero drinks solutions between the bars being some of the most common. Meanwhile, at the superbike end of the spectrum, the Cervelo P5X, Dimondback Andean and Specialized Shiv all feature compartments within the frames themselves to hold spares.

For some bike brands, these additional storage solutions are the only things that mark the difference between their TT and tri models. For example, the Canyon Speedmax used by both Jan Frodeno and Patrick Lange to win the Ironman World Championships has a UCI legal frame with reversible seatpost hidden under a wealth of accessories that provide storage and actually improve aerodynamics.

Tri or TT bike – which is better for triathlon?

It might seem obvious that a triathlon bike is the best option for triathlon events, but it’s not necessarily so clear cut.

Provided a TT bike can attain the steep, saddle-forward seat angle – usually via a reversible seatpost or multi-position seat clamp – it’s a great option for triathlon, helping you to run strong off the bike. This is especially true for shorter distance events where there’s less need to carry quite as many supplies with you as you race.

If you’re aiming for a longer event, such as Ironman or Ironman 70.3, the more bags, bottles and food boxes you add to your bike, the more aerodynamic drag you’re likely to create so if budget allows you’ll be better off with all the built-in storage solutions and associated time savings of a dedicated triathlon bike.

Whichever bike suits your needs in the end, don’t forget your choice of tyres can make a difference – check out our guide to Clinchers, Tubeless Or Tubular Tyres For Triathlon.