{"id":39403,"date":"2022-07-23T13:30:00","date_gmt":"2022-07-23T11:30:00","guid":{"rendered":"https:\/\/www.bikeradar.com\/?p=627890"},"modified":"2022-07-23T13:48:22","modified_gmt":"2022-07-23T11:48:22","slug":"time-trial-bikes-everything-you-need-to-know-about-tt-speed-machines","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/cyclingplus\/rss_feed\/time-trial-bikes-everything-you-need-to-know-about-tt-speed-machines\/","title":{"rendered":"Time trial bikes: everything you need to know about TT speed machines"},"content":{"rendered":"

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By Simon von Bromley\n \t\t<\/p>

Published: Saturday, 23 July 2022 at 12:00 am<\/p>

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Time trials are the simplest form of bike racing \u2013 go from A to B as fast as you can, under your own steam.<\/p>\n

Unlike bunch racing, where the group dynamics of the peloton<\/a> mean that tactics play almost as large a role as the rider\u2019s athletic ability and you can save energy by drafting, time trials are about two things: power in and power out.<\/p>\n

Power in is controlled by the rider (and, to some extent, their gene pool). In simple terms, it\u2019s how hard you can turn the pedals. Power out is everything trying to slow you down \u2013 forces such as rolling resistance, friction, gravity and aerodynamic drag.<\/p>\n

A cyclist looking to improve their performance in time trials has two options; put in more power or reduce resistance to those forces.<\/p>\n

Due to the relatively high speeds involved (or the fact that you\u2019re trying to ride at a high speed), aerodynamic drag is usually the dominant factor in time trials, with research showing<\/a> that \u201caerodynamic resistance accounts for over 90 per cent of resistance a cyclist encounters on a flat surface\u201d.<\/p>\n

The problem only gets worse as you go faster too, because aerodynamic drag increases at the square of velocity. In order to double your speed, you need to produce four times the power.<\/p>\n

It\u2019s clear then that increasing \u2018power in\u2019 will quickly become unsustainable at higher speeds, even for the best athletes doing dedicated time trial training<\/a>.<\/p>\n

What is a time trial bike?<\/h2>\n
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Time trial bikes are designed with one thing in mind: speed.<\/span><\/figcaption> Simon von Bromley \/ Our Media<\/i><\/span><\/div>\n

This is where time trial bikes come in. Unlike road bikes<\/a>, which are designed to be versatile and perform well on a wide variety of courses and terrains, time trial bikes are designed with one major goal in mind: to be as fast as possible on straight, mainly flat, roads.<\/p>\n

To achieve this, time trial bikes use specialist geometry<\/a> and handlebars to coerce your body into a more aerodynamic position, plus aero-optimised tube profiles and components to cut through the wind.<\/p>\n

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Time trial handlebar extensions \u2013 sometimes referred to as \u2018skis\u2019 \u2013 allow the rider to adopt an aerodynamic position.<\/span><\/figcaption> Simon von Bromley \/ Our Media<\/i><\/span><\/div>\n

A time trial position compromises on handling and can be physically taxing to hold, but the positives typically outweigh the negatives.<\/p>\n

After all, the rider alone accounts for the vast majority of aerodynamic drag (around 80 per cent, according to recent studies<\/a>) in the rider plus bicycle system.<\/p>\n

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Time trial bikes are designed to be as aerodynamic as possible, to maximise straight-line speed.<\/span><\/figcaption> Andrew Legge<\/i><\/span><\/div>\n

What are the differences between time trial bikes and triathlon bikes?<\/h2>\n

Time trial and triathlon bikes share many similarities \u2013 primarily because the bike leg of a triathlon is often a solo time trial.<\/p>\n

The main difference is that, since triathlons are not governed by the UCI, triathlon bikes designed for draft-illegal events (those in which drafting competitors<\/a> is banned) are not constrained by the UCI rules.<\/p>\n

This allows triathlon bikes, and their designers, to be much more adventurous with design choices. This typically means deeper tubes and even frame shapes, thanks to materials like carbon fibre, that don\u2019t conform to the typical double-triangle design<\/a> bicycles typically used since their invention.<\/p>\n

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Triathlon bikes can look very different to time trial bikes designed under the constraints of the UCI\u2019s technical regulations.<\/span><\/figcaption> Simon von Bromley \/ Our Media<\/i><\/span><\/div>\n

With the importance of long-distance events, such as Ironman<\/a>, in mind, many triathlon bikes even take storage for food, drink, tools and spares into account. While road cyclists tend to carry things in their jersey pockets or in trendy handlebar bags<\/a>, triathletes are now able to carry their things in aerodynamically integrated storage compartments.<\/p>\n

It\u2019s all very civilised, and \u2013 if designed correctly \u2013 can even reduce the bike\u2019s aerodynamic drag. Bikes such as Canyon\u2019s 2021 Speedmax<\/a> and Scott\u2019s 2021 Plasma 6<\/a> are prime examples.<\/p>\n

UCI rules currently prohibit the use of such deep tubes or fairings, but cyclists taking part in time trials governed by the CTT (Cycling Time Trials \u2013 a UK-based governing body for time trials not regulated by the UCI) can take advantage because its rules are much less prescriptive.<\/p>\n

It\u2019s all about aerodynamics\u2026<\/h2>\n
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Aero all the way.<\/span><\/figcaption> Simon Bromley \/ Immediate Media<\/i><\/span><\/div>\n

Handlebars<\/h3>\n

Time trial handlebars consist of a bullhorn handlebar (often referred to as a \u2018base bar\u2019) with a set of armrests and handlebar extensions situated on top, in the central area.<\/p>\n

The extensions protrude forward, and, combined with the armrests, allow the rider to adopt and maintain a more aerodynamic body position<\/a> than would otherwise be possible.<\/p>\n

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Time trial handlebars help put your body into a more aerodynamic position. You rest your forearms on the padded armrests and hold the end of the extensions with your hands.<\/span><\/figcaption> Simon Bromley \/ Immediate Media<\/i><\/span><\/div>\n

The armrests and extensions should be adjustable for both width and reach, to allow you to fine-tune your position. There are many pages of rules dedicated to restricting the range within which the extensions and armrests can be positioned in UCI sanctioned events, though.<\/p>\n

If you\u2019re ever taking part in such an event, the commissaires may even use a complicated jig to ensure your bicycle fits within the permitted dimensions. Outside of UCI governed events, this is unlikely to be a concern.<\/p>\n

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The gear shifters are typically located on the ends of the extensions, but the brake levers are placed on the bullhorns of the base bar. This means you don\u2019t have access to both at the same time, as on a road bike.<\/span><\/figcaption> Simon Bromley \/ Immediate Media<\/i><\/span><\/div>\n

The downside of such handlebars is that the brake levers are typically located on the end of the bullhorns, so you don\u2019t have such immediate access to them while using the extensions.<\/p>\n

For this reason, time trial and triathlon bikes are generally not deemed suitable for bunch riding (outside of the team time trial<\/a>, of course).<\/p>\n

Tube shapes and geometry<\/h3>\n
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Deep tube profiles help the bike cut through the wind.<\/span><\/figcaption> Simon von Bromley \/ Our Media<\/i><\/span><\/div>\n

Aero is practically everything when it comes to time trial bikes, with weight being of only minor importance. Because of this, tube shapes are optimised to be as slippery as possible, within the UCI rules.<\/p>\n

While older time trial bikes used narrow aerofoil shapes<\/a>, modern machines have gravitated towards wider, Kammtail shapes<\/a>.<\/p>\n

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Narrow = fast.<\/span><\/figcaption> Simon von Bromley \/ Our Media<\/i><\/span><\/div>\n

These larger shapes are intended to trick the air into behaving like a much longer (and therefore more aerodynamic) aerofoil shape is present, and also provide benefits in terms of stiffness, weight and shielding water bottles from the airflow.<\/p>\n

The geometry of time trial bikes also differs from that of road bikes. The most notable difference is that time trial bikes typically have steeper effective seat tube angles (around 75 to 78 degrees) compared to road bikes.<\/p>\n

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The seat tube angle on time trial and triathlon bikes tends to be steeper than on road bikes, and some even offer seatposts that have multiple clamping positions to help fine-tune saddle position.<\/span><\/figcaption> Simon Bromley \/ Immediate Media<\/i><\/span><\/div>\n

This puts the rider further forward of the bottom bracket<\/a>, which can help prevent the rider\u2019s hip angle from being too tight and impinging on athletic performance.<\/p>\n

It does affect weight distribution, though, meaning more of the rider\u2019s weight is placed on the front wheel of the bike. This can negatively affect handling, particularly on descents.<\/p>\n

Wheels<\/h3>\n
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A solid rear disc and deep-section or low-spoked front wheel are generally considered the fastest combinations for time trials.<\/span><\/figcaption> Simon von Bromley \/ Immediate Media<\/i><\/span><\/div>\n

As with the frame, aero is everything when it comes to time trial wheels too.<\/p>\n

The use of solid rear disc wheels<\/a> and front wheels with ultra-deep rims<\/a> or low spoke counts (such as tri-spoke wheels<\/a>) are typical in time trials (front disc wheels are generally only permitted for use on the track).<\/p>\n

There\u2019s a balancing act to be had between using the deepest, most aerodynamic wheels you can get your hands on, and the negative effects such wheels can have on the bike\u2019s handling on windy days.<\/p>\n

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Disc wheels are heavy but, ultimately, very fast.<\/span><\/figcaption> Simon von Bromley \/ Our Media<\/i><\/span><\/div>\n

It\u2019s rarely too windy for a rear disc wheel. In fact, according to Xavier Disley of AeroCoach<\/a>, using a rear disc wheel can \u201chelp to stabilise a bike\u2019s handling in strong winds, as it moves the centre of pressure rearwards, away from the front wheel\u201d.<\/p>\n

However, at the front of the bike, choosing the most aggressive wheel you can find won\u2019t be the fastest option if it means you can\u2019t control the bike.<\/p>\n