Triathlon Bike Guide


As one of the fastest growing sports in the world, triathlon pushes levels of fitness and stamina to the absolute limit. A properly fitting triathlon bike will provide the ultimate partnership for the section of the race covering the longest distance.

Triathlon bikes are unique in geometry in order to achieve the best performance and aerodynamics, although riders themselves will always create the majority of aerodynamic drag. It is worth mentioning that triathletes are not bound by International Cycling Union rules, so many triathlon bikes are UCI illegal. Some triathlon participants use modified road bikes with clip on aerobars which is a cheaper alternative for tackling undulating bike courses, but investing in a purpose-made triathlon bike will help achieve a better performance, especially for racing on flat and straight terrain.


Triathlon bike specifications



Unlike time trial bikes, triathlon bike do not not fall under UCI specifications meaning they can be designed with more pedal efficiency – especially for an athlete who is about to run a marathon. Notably, triathlon bikes have a steeper seat tube and slacker head tube. Placing the rider in a more ‘aero’ and efficient position. You can use a road bike for triathlon (most people do), but you can’t enter a time trial with a triathlon bike.


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A triathlon bike frame lowers the rider’s shoulders and rotates their torso so their back is almost horizontal, creating a comfortable, yet streamlined position. Usually, frames have oval or teardrop shaped tubing with a lower headtube, which improves the slick movement of the bike through the air and preserves running strength by working alternate muscle groups for pedqaling.

Triathlon bike frames are made of lightweight materials, usually aluminium or carbon fibre but can be made from titanium. Carbon fibre frames have good shock absorbency and are generally lighter, suiting less heavy riders and those who suffer from minor aches, but frame damage can be harder to spot as it is often internal. Light and rigid, aluminium frames are a cheaper option, but after time rigidity does wear down and frames are then liable to shake a lot on poor roads.




Aerobars (also referred to as tri-bars) can be added to conventional bars to allow you to adopt a lower, more aerodynamic position with your arms resting on the pads, either flat or slightly elevated. Aerobars need to be fitted so that your elbows are only slightly further forward than your shoulders, and far enough apart to allow easier handling. Aerobars can put strain on your lower back, so although helping with speed, can be worse for your posture.




Good wheels will be reliable and easy to maintain, stiff to avoid flexing, designed aerodynamically and weigh as little as possible.

Rim depth is important in providing aerodynamic benefit, with wider rims improving handling and cornering due to the casing shape of the tyre. As drafting is illegal in most triathlons, higher profile (larger) rims provide better aerodynamics as they are more conducive to the flow of air past them than traditionally thinner rimmed wheels.

As lighter riders are more impacted by side wind forces, wheels with less surface area are more beneficial, whereas bigger and heavier riders can have more depth in their wheels and still cope better with crosswinds.

Wheel material is determined by budget, which then affects weight. Carbon wheels can be very expensive, but reduce rotational weight and increase stiffness. Aluminium wheels make a cheaper alternative with more predictable and consistent braking surfaces than carbon.

Solid disc wheels can provide an aerodynamic advantage, but in an outdoor setting they need to be used on the back wheel of a triathlon bike as they make crosswind handling difficult on a front wheel. Disc wheels are now available with a dimpled “micro-vortex” surface for further streamlining.

700c wheels have been favoured in recent years and have the advantage of being more readily available alongside corresponding tyres and tubes, although 650c triathlon wheels can be a better option for smaller or slimmer riders.




The last thing you want during a race is a flat tyre, so choosing a good set of tyres is an important task. Tyres need to give the best performance in terms of puncture resistance, weight, grip and rolling resistance, and the more you pay, the better quality you will get.

Hooking onto the rim of the wheel and containing an inner tube, clinchers are the most conventional tyre and are cheaper and easier to install, but allow slightly lower PSI. Tubular tyres (tubs) reduce both flat tyres and tyre weight and have a sewn in inner tube which is glued to the rim of the wheel. Recent advances in technology have meant that there is not much difference between clinchers and tubs, however clinchers are better in terms of convenience and tubular tyres are better if only speed matters.




In triathlons, the usability of shift levers and brakes is crucial for success. Brake levers for triathlon bikes are mounted on the ends of handlebars and fine and dependable brake tuning is an absolute must for competitive cycling.




Triathlon saddles have unique positioning, with the seat angle being between 76-78 degrees (2-5 degrees steeper than a road bike) enabling the rider to place the majority of their weight on the front third of the saddle when riding in the aero position. To provide comfort whilst riding, triathlon bike seats have padded noses, supporting the pelvis as it rotates further downward. ISM (Ideal Saddle Modification) saddles are available for those with fit or comfort issues with standard saddles and significantly reduce or obstruct blood flow in the perineal area. The best triathlon saddle will provide the most comfort, and won’t necessary be a wider one.




Tri bikes tend to have high gears and large front rings. Novices will need to check the range of gears on their bike before they buy – a wrong choice will lead to some serious grinding if you hit a hill.


Choosing the right Triathlon Bike

As you might expect, the bigger the budget you have, the better the bike you will get. With prices for professional racing bikes starting at around £1,400 and top models priced at over £10,000, it really is a case of how much you can invest. Good quality wheels and tyres are also a must.

You will need to consider what distances you need to cover, what sort of terrain you will be riding on and much training you will are likely to do. Also, the types of race are worth considering, whether standard distance, Ironman or sprint triathlons, for example.

If you have any back problems, you might need a smaller or shorter bike to keep you in a more upright position, and aerobars might not be the best choice.

Ultimately, a good triathlon bike should be comfortable to ride and enhance your performance, so you need to ensure a perfect fit, looking at all aspects of the bike in relation to your body.


Triathlon Bike Accessories



Race organisers adhere to British Triathlon guidelines, so it is worth checking that your helmet is of ANSI Z90.4, SNELL B90, EN 1078 or an equivalent national standard (a CE mark is NOT an approval mark.) Your helmet will need to be the correct size and not move around on your head. More expensive models are lighter but contain more internal mesh which conforms to safety standards. In terms of design, triathlon helmets assist with aerodynamics and airflow and can also accommodate goggles or racing lenses instead of glasses.



Triathlon specific clothing is designed to enhance your performance and help gain you a better time. The best trisuits and shorts are seamless, equipped with padding for comfort and fast drying.



Easy to remove due to one large velcro strap and a soft heel cup to cut down on transition time, triathlon shoes are stiff, lightweight and provide necessary ventilation. Clipless pedals and shoes will greatly improve your bike speed, but take some practice to master, with the pedal attaching to the cleat on your shoe. Be sure to choose the same size as your normal shoes – they may feel a bit tighter but they need to be a snug fit.


-Water Bottles

Designed to assist performance and be easy to use, bottles for triathlons prevent any fumbling around or tilting to actually drink from them. Sitting between the aerobars or are held behind the saddle, bottles are designed with an aerodynamic shape or feature a straw.


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