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

Posted: 11 May 2011

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.'

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Discuss this article

If the tri position is so much better, why aren't all road bikes made with that geometry?
Posted: 11/05/2011 at 14:16

simply - comfort

if you are on a TT bike for a long time, then it can be a lot more uncomfortable than a standard road bike due to the position. holding a downward facing, arched back, bent neck, TT position hurts although you can train to overcome a lot of that. but it still hurts.

road bikes are designed for all round use so don't employ aggressive positions in the main
Posted: 11/05/2011 at 14:21

Hi Gregory,  This is simply down to rider comfort!
Posted: 11/05/2011 at 14:30

Theres no point in a road bike having that geometry as its used differently. Triathlons - you're in a low aero position. Road bikes you need to be more head up and its more about quick bursts of speed and fast handling rather than a steady speed.
Posted: 11/05/2011 at 15:05

about a £grand
Posted: 11/05/2011 at 15:12

Posted: 11/05/2011 at 15:30

Crumbs. I hope they're worth it! Looks like i may be about to win an ebay auction for one
Posted: 12/05/2011 at 09:25

I don't think you'd want to be on an agressive TT bike in the middle of a peleton.
Posted: 12/05/2011 at 10:35

I think it's a fair question - why aren't road bikes built with a much steeper seat tube angle - I know UCI rules dictate where the saddle can be in relation to the bottom bracket but it's not as if everyone has the saddle tip as far forward as the limit allows.      You'd think it's the same principle - open the hip angle and allow you to get lower at the front .    Pros do generally ride low - if you look most have the stem right down on the head tube these days - but they don't seem to ride a steep seat tube angle - I suppose they train to have the flexibility to do it.       I know Lemond used to talk about being further back behind the bottom bracket brought the glutes into play so there may be something to do with efficient recruitment of muscles as well as comfort.  

There's also the fact modern road bikes tend to have much wider bars than was the case some years ago - 44cm, even 46cm bars - it can't be aero to be that wide at the front.    

Posted: 12/05/2011 at 11:13

"it can't be aero to be that wide at the front"

problem comes when your shoulders are wider than your bars.....

you're right about pros riding low pops - I was looking at some of the bikes at the Giro and they have short headsets with the stems right on top - almost a case of the bars being attached to the forks! and when they go down on the drops then their hands are level with the fork tops. that's low!

Tri pros will say that a TT position doesn't shred the leg muscles for running like a road position does

anyway if we all wanted comfort we'd be riding recumbants
Posted: 12/05/2011 at 12:22

fat buddha wrote (see)
...if we all wanted comfort we'd be riding recumbants

Thats where i've been going wrong
Posted: 12/05/2011 at 12:26

I think there are a 'new generation' of cross-over road-bikes that offer more of an aero advantage.
Posted: 12/05/2011 at 12:28

I cant help but think thats marketing driven. Look at a head on shot of a cyclist. I'd say about 90% of the frontal area is the cyclist. The frame is minimal.

For road bikes you are meant to match shoulder width to bar width - I like my bars quite wide.
Posted: 12/05/2011 at 13:49

But they look nice.
Posted: 12/05/2011 at 13:52

^ while on a TT bike you match head width to bar width ... so most bars are quite wide
Posted: 12/05/2011 at 13:52

Is it not also the case that you don't need to be as aero when you are drafting in a peloton?  So that the more comfortable position doesn't cost much in terms of efficiency?
Posted: 12/05/2011 at 23:09

if you went aero in the peloton you're gonna get kicked off the bike by other riders - it's too dangerous. but otherwise you're right - pack riding is much more efficient for those behind the front riders - which is why everyone is expected to take their turn at the front to share the load
Posted: 13/05/2011 at 09:09

I've seen a few TT bikes converted to drop handle and road raced.

Got to say everyone is different and not all TT bikes are of the same geometry.
Road bike or TT bike it needs to fit you not a fashion. I can't use spez TT bikes no matter what, angles are fecked for me.
Posted: 17/05/2011 at 20:23

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