Triathlon/TT

At first glance, it’s pretty difficult to know exactly what the differences are between a triathlon bike and one made specifically for cycling time trials; however there are a number of things that set them apart, mostly concerning geometry, build and fit.

Dedicated triathlon bikes often have a steeper seat tube angle, which pushes the hips forward and saves the hamstrings for the run. TT bikes have to adhere to International Cycling Union (UCI) rules, which requires that the saddle nose must be 5cm from the centre of the bottom bracket. 

Bikes that fall within the UCI’s rulings previously had to adhere to the 3:1 rule, meaning that no part of the bike can be any more than three times longer than it is wide at any point. These rules have been relaxed from January 2017, however, which means the line between tri and TT bike may be blurred even more in the next few years.     

A triathlon bike that doesn’t have to adhere to UCI rules is designed to be as aerodynamic as possible, but the rider may seek a less aggressive position on it to cope with the demands of running after the bike leg.  In contrast, a UCI-legal bike can only be as aero as the rules stipulate, but a TT rider will seek the most aggressive position that their biomechanics will allow.

This is perhaps the most obvious, visual factor that sets a tri bike apart from a TT bike, as tri bikes will more often than not have additional storage boxes and equipment needed to tackle a triathlon, either integrated or added on as aftermarket products.

Time trial riders will usually require a small amount of nutrition and two water bottles, assuming they are well-trained; whereas in long distance triathlons, even the pros will get through a considerable amount of food and fluid to fuel themselves for an all-day event.  

Tri-specific accessories vary greatly between bikes, depending on how the bike is built and what the athlete prefers to use. Many more high-end triathlon bikes now come with top tube boxes and hydration systems bolted and slotted onto the frame, and integrated solutions in other areas of the bike for storing tools in case of a puncture.  Bikes that don’t come with these accessories as standard will have space for the rider to attach their own.

In a time trial, a cyclist’s only concern is getting to the finish line as fast as possible, leaving them completely spent after an all-out effort when they get off the bike. A triathlete has the run to deal with afterwards, which often means a more forgiving set-up. A triathlete will generally want their forearms wider apart on the aero extensions, and bent at a slight angle at the shoulder down to the elbow. Having the seat tube further forward also puts less pressure on the hips and hamstrings. 

The add-on accessories needed to tackle a swim/bike/run race and achieving a position that helps the triathlete to save their legs for the run are the things that ultimately set apart a triathlon bike from a time trial bike; and it goes without saying, it’s always worth getting a professional bike fit to optimise your own position if you’re looking to buy your first tri bike.