professional athletes like cycling.

[Cycling Commentator] It's a furious threat.

But it's not just human endurance

on the track that delivers the winning formula,

it's human ingenuity off it.

It's the world's fastest bike.

In an elite sport,

the difference between success and failure

is often the finest of margins.

This is base camp for one of

the most successful teams in global sport.

Great Britain's track cyclists have topped

the medals tables at the past three Olympic games.

And it's a team that keeps churning out winners.

We wanna be the fastest in the world,

we don't just wanna win the Olympics,

we wanna win in the fastest time ever.

In a sport where races

are decided by as little as 1/1000th of a second,

Emily and her teammates are obsessed with one thing:

marginal gains.

A little margin of half a percent

will make that difference on the day.

[Cycling Commentator] Turning the pressure on.

And one of the best places

to find those tiny margins is on the bike.

The team's key man for this is an aerodynamics expert

and ex-Formula One motor racing engineer.

My job is simply to use technology and engineering

in any way I can to make the team go faster.

Cambridge University Professor of Engineering,

Tony Purnell, designed the world-renowned

T5GB bike with manufacturer Cérvelo.

By dramatically reducing air resistance,

it helped the British team enjoy

its most successful Olympics ever.

It's the world's fastest bike.

The way those layers of carbon fiber are constructed

all makes for a lighter and a stiffer bike,

without compromising the aerodynamics.

All important milliseconds

were shaved off performance times

by making the tiniest of design changes,

even down to the chain.

When you cycle, a little bit of the power you produce

gets lost in friction in the chain.

If you can reduce that loss, it translates

into the athlete being that little bit more powerful.

Using that chain would have made the difference

in the games between the silver and the gold medal.

It's not just the bike

where aerodynamic perfection is relentlessly pursued,

it's also the person on it.

The precise position of the rider

can make all the difference.

[Cycling Commentator] Always ahead of schedule,

he was 45 seconds up after 40 kilometers.

In 1996, Olympic Gold medalist

Chris Boardman broke the one hour world record.

[Cycling Commentator] As Boardman

settles into the superman position, arms stretched

in front of his head, for smoother aerodynamics.

By pioneering his legendary superman position.

Today, this legacy lives on at the state-of-the-art

Boardman Performance Center, in Evesham, England.

Bike design can absolutely help,

but we see that the most significant portion

of the aerodynamic effects and the drag

is coming from the rider themself.

Sit down, tell me a little bit more about

the direction we want to take, what do we want to look at.

Today, Jamie is helping

professional cyclist Dan Bigham decipher

his optimum body posture for an upcoming team pursuit race.

In the wind tunnel, Dan is battling winds

of over 60km/h to simulate the drag conditions

he'll face on the track.

His performance, and ultimately success,

could depend on a series of almost imperceptible

tweaks to his position on the bike.

Okay Dan, let's go for our first change,

we'll do this on the fly.

Let's move the hands, please.

By moving his hands slightly forward,

and adjusting the gap between them by just millimeters,

Dan speeds up by nearly half a second per kilometer.

We're operating at a world record place here.

So we've found some gains there,

particularly from the hand open position,

which is absolutely worth having.

Come race day, subtle changes like this

could add up to a big advantage for Dan's team.

Me personally, I'm about 4/10ths quicker just for my turn,

and if that gain was for everybody in the team,

then we're one and a half to two seconds quicker overall.

Cycling's reputation

has been damaged by doping.

But its pursuit of legitimate marginal gains

still sets the pace for many other disciplines.

Britain's world-beating cyclists

face ever more intense competition from rivals

who are quickly learning how to innovate.

The pursuit of marginal gains

is about to get even more marginal.