Time Trial Bikes: What Is A TT Bike?

If you’ve ever watched a Tour de France time trial stage or seen photos of one in the Sunday newspaper, you’ve probably caught yourself wondering: What on earth are those space-aged bikes they’re zipping along on?

The answer: they’re time trial bikes (or TT bikes for short).

They probably look – and cost – more like a NASA experiment than the rusting collection of nuts and bolts you’ve got sitting in your bike shed, and for good reason: time trial bikes are as fast and technologically advanced as racing bikes get.

To give you the lowdown on these lightning-quick speed machines, we’ll be walking you through:

  • What Is A Time Trial Bike?
  • 3 Defining Features Of A TT Bike
  • How Much Does A TT Bike Cost?

Ready for the debrief on these speed demons?

Let’s go!

What Is A Time Trial Bike: Title Image

What Is A Time Trial Bike?

Time trial bikes are built with one objective only: speed.

TT bikes are essentially racing bikes that are designed specifically for solo rides against the clock. They’re not much use for climbing or sprinting, and would be absolutely hopeless off-road, but for pounding through a 30 km time trial slog they’re second to none.

The main way they achieve this is by reducing drag. Aerodynamics plays a huge role in the speed at which you can ride, as any cyclist who’s ever powered into a vicious headwind is no doubt aware.

In a mass-start bike race, the ability to draft and ride as part of the peloton compensates against the additional drag from riding a regular road bike. But on a solo ride – such as a time trial – drafting is impossible, so aerodynamics become the all-conquering priority.

The faster you’re traveling, the stronger the effect of drag will be. So, at the speeds professional bike racers can reach, an aerodynamically-efficient bike can be the difference between hurtling to Tour de France glory and being left behind feeling like you’re cycling through treacle.

Let’s take a closer look at how time trial bikes achieve this.

Time Trial Bikes: What Is A TT Bike? 1

3 Defining Features Of A TT Bike

#1. The Frame

The frame of a time trial bike plays a massive role in achieving its purpose.

One of the first things you’ll notice on a TT bike frame is that all of its structural components are shaped more like blades than the tubes you’d find on a regular road bike, helping it slice through the wind to reduce drag.

The frame is usually made of carbon fiber, both to take advantage of its low weight and the ease with which it can be formed into the precise, angular shapes required for a TT bike.

The geometry of time trial bikes differs greatly from road bikes. The most significant departures are the shorter top tube, steeper seat angle, and the lower and longer front end. In combination, these have the effect of rotating the riding position forwards, making the rider more aerodynamic.

This is the single most important feature of a time trial bike. On the road, 85% of drag is generated by the cyclist’s body, with just 15% coming from the bike itself.

In fact, the riding position on a TT bike is so different that it actually activates the rider’s muscles in a slightly different way.

This 2015 study from the Scandinavian Journal of Medicine and Science found that the gluteus maximus is activated in the pedal stroke later and for less time in the horizontal aero position adopted on a time trial bike, resulting in a 3% decrease in power output and efficiency.

However, the effect of slashing drag is so extreme that – in the words of the study’s authors – ‘the aerodynamic gains outweigh the physiological and biomechanical disadvantages’ of riding a time trial bike.

Time Trial Bikes: What Is A TT Bike? 2

#2. The Wheels (And Brakes)

Though the wheels used on TT bikes and road bikes are interchangeable (they use the same hub spacing), in practice time trial wheels are very different from conventional road bike wheels.

The most important (and noticeable) difference is in their rim depth.

As a general principle, deeper rims result in more aerodynamic efficiency. The disc wheels commonplace in track cycling – and often found on time trial bikes – are the extreme example of this rule, ditching spokes entirely in favor of a solid shell extending all the way from the rim to the central hub.

In bike racing, choices around rim depth are a trade-off between aerodynamics and increased weight. Most road bikes used for professional cycle races compromise at around 40-60 mm of rim depth, which is enough to experience some aero benefit without adding too much extra baggage for big climbs.

On a TT bike, aerodynamics trump all other considerations.

Time trial bikes will often pair a disc wheel at the rear with a very deep front wheel of 70 mm or more, sometimes with tri-spokes. It’s uncommon to use disc wheels at both the front and back due to what’s known as the wind-sail effect, which can make the bike very difficult to control and vulnerable to blustery crosswinds.

A noteworthy side point is that the brakes on time trial bikes are notoriously rubbish.

Traditionally, TT bike brakes consist of modified rim brakes which are either integrated into the frame or tucked away behind the fork and chainstays respectively. These tend to need constant adjustment, be very fiddly to access to actually make those adjustments, and give you about as much stopping power as if you changed out your brake pads for wafer biscuits.

While the adoption by some manufacturers of ‘Mini-V’ brakes has improved things somewhat, a more radical solution has been to switch to disc brakes.

Conventionally shunned by time trial cyclists because of the additional drag they generate, some riders have started using disc brakes as they feel the benefits to stopping performance and safety outweigh the small aerodynamic cost, especially with modern designs which reduce their drag profile to negligible levels.

Time Trial Bikes: What Is A TT Bike? 3

#3. The Handlebars

In tandem with the geometry of the frame, the handlebars of a TT bike are crucial in maximizing the aerodynamic efficiency of a time trial cyclist’s riding position.

The key feature is the aero bars (sometimes referred to as tri-bars).

Aero bars consist of a pair of handlebar extensions extending directly forward beyond the stem and over the front wheel. They can be adjusted to a variety of angles depending on rider preference, and are usually equipped with foam pads to rest the forearms on.

First used in a major bike race by Greg LeMond in his era-defining charge to victory at the 1989 Tour de France, the purpose of aero bars is to draw the rider’s body forwards into an aerodynamic tucked position with the chest almost horizontal with the ground.

The gear shifters will usually be incorporated into the aero bars to reduce the need to lift the rider out of the aero position.

Aero bars are usually paired with a set of bullhorn bars, sometimes referred to on a TT bike as the ‘base bars’. The bullhorns are used for climbing (which bullhorns particularly excel at), turning, and any other function that would be near-enough impossible on the narrow, perpendicular aero bars.

The brake levers are almost always housed at either end of the bullhorn bars rather than on the aero bars, and are razor-thin to reduce drag

How Much Does A Time Trial Bike Cost?

With all that science-fiction styling and sleek carbon fiber, you’d probably expect a time trial bike to be hideously expensive.

And you’d be right!

The Entry-Level Choice

The market for TT bikes (second-hand models aside) bottoms out at around $1500 to $2000. Here you’ll find bikes that provide decent bang-for-buck without having to remortgage the house, such as the Trinity Advanced manufactured by Giant.

It’s listed at $2,680 on the Giant website, but as it’s a model which provides an easy platform for upgrades you’ll find a lot of variation in price depending on specifications.

For TT bikes at this price point, expect sacrifices such as exposed cabling, shallow rims, and additional weight compared to more expensive models. Nonetheless, there are some very decent options available at this price, which will massively outperform a road bike over a time trial course or a triathlon.

High-Performance TT Bikes

As the price point ticks up towards the $5000 mark and beyond, expect the time trial bikes on offer to be at or approaching professional standard.

Cervélo’s iconic P-Series Disc is considered the best of the bunch by many. The base model comes in at $3,400 on the manufacturer’s website, ramping up to $6,500 with the addition of Shimano Di2 gearing, 50mm rim wheels, and a host of other bells and whistles.

If You’ve Got Cash To Burn…

Once you push past around $7000, the prices can start getting astronomical.

The Specialized S-Works Shiv Disc is just about the highest-spec TT bike on the market, with a price tag to match: weighing in at an eye-watering $13,500 on the Specialized website.

For that price, you get Shimano’s flagship Dura-Ace drivetrain components including Di2 derailleurs, an integrated dual-sided power meter, and a whole lot of professional pedigree: Tour stars Peter Sagan and Julian Alaphilippe have both ridden the Shiv in Grand Tour time trial stages, among many of the sport’s other biggest names.

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Rory McAllister

Rory McAllister

Editor
One of the BikeTips editors, Rory has enjoyed a lifelong love affair with cycling. After a (fairly unsuccessful) period racing them in his youth, he eventually realized he had much more of a knack for writing about bikes than he ever did riding them. Though he’s always game to hurtle down an MTB trail or dive into the backcountry wilderness, Rory’s real passion is bike touring on Europe’s sprawling roads with his old cycling mates. Their most recent adventure was a ride from London to the Italian Alps; the next trip is already in the works!

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