Q+A: What’s the difference between a triathlon bike and a road bike?

Q. What exactly is the difference between a triathlon bike and a road bike?

A. There are several visible and important differences between a purpose-built tri bike and a road bike. These differences allow a triathlete to function in the most efficient and powerful way on the bike and run sections of the race.

Tri bikes are designed to create the most aerodynamic solution for the bike section. The better the aerodynamics, the less power is required to go at the same fixed speed. This is why they have sculpted aerofoil-style tubes and deep-section rims on the wheels.

Tri bikes undergo rigorous testing in hi-tech wind tunnels and companies invest a lot of money in research and development to create a machine that slips through the air. But that's just half of the story.

Aerodynamic position

To go at a fixed speed in the most efficient way, you must combine the aerodynamic features of the bike with the position and output of the athlete.

By building a bike with a very upright seat tube, the rider's position is rotated around the bottom bracket, upwards and forward (onto tri bars). The upper body becomes flatter and more stretched out, which decreases the total frontal area. The result is a reduction in aerodynamic drag.

With the body up and forward, the active angle at the hip is also increased. This opening of the hip in this position means that the leg is working in a stronger range during the pedal stroke. The rider delivers efficient, powerful pedal strokes without being cramped up.

Better transitions

When the bike leg ends, the rider can make an easier transition to running because the riding position adopted on the tri-specific bike is biomechanically closer to running than is the case on an ordinary road bike.

The tri bike may not at first make you go that much faster but the combination of aerodynamic frame design and body position will eventually make you more efficient.

Low cost add-ons

A popular, low-cost halfway house for the beginner triathlete who wants to improve performance is to modify the riding position of the road bike. Adding some clip-on tri bars is effective and pushing the saddle forward as far as it will go will steepen the seat tube angle.

You are pushed into a more streamlined position and the all-important hip angle is increased without drastically compromising your ability to control the bike.

Spot the difference in our triathlon bike vs road bike diagram.

Jim McConnel

Jim McConnel is a coach with Driven To Tri (driventotri.com), a sports massage therapist and an XTERRA triathlete. He has been involved in sport since school. He began with track running but moved on to bikes and now races on the XTERRA off-road triathlon circuit in Europe. In 2008 he qualified for the XTERRA World Championships. He did his first triathlon in 1996. His motto is 'Train smarter, not harder.'