The triathlon bike leg is the longest part of any triathlon by distance and time, as well as being potentially the most expensive!

For a sprint triathlon, you’re going to cover 20km, which at an average pace of 25km per hour, means being in the saddle for 50 minutes, possibly twice as long as the run and 3-4 times longer than the swim, so it has more impact on your overall time and has the potential to deliver the greatest improvements.

It’s also potentially the most dangerous, simply because of the speeds involved, so there are a number of specific rules that you need to be aware of that are designed to ensure the safety of you and the other competitors.

There are probably more arguments over the way to squeeze extra performance out of the bike leg so let’s look at some of the key factors and discuss some of the myths and discussion points on the bike

The bike is the second leg of the triathlon and you will have your bike set up next to your kit ready to go and this will mean you need to arrive at the envoy in advance and have racked the bike before transition starts, so make sure you read your race briefing in advance so that you know when you need to be there by, and if there are specific rules and regulations you need to abide by.

As you rely on your equipment more on the bike than in the other two disciplines, it’s essential that you keep it in good working order and check it’s working properly before your event, especially as many events have a mandatory bike check before they let you race. Typically this is a brake check, but will often require that bar end caps are in place as well.

Helmets that clip-on are also likely to be mandatory.

Racking varies from race to race, so check whether you have a specific location or area for racking your bike based on your wave number, and rack your bike accordingly, then enjoy your swim!

After putting on your helmet, you’ll unrack your bike and walk/run to the mount line, jump on and off you go!

Depending on the length of the ride, you arrive back at transition, dismount before you enter transition, rerack your bike, remove your helmet and head out on the run. ( and yes, we have all forgotten to take off our helmets before heading out on the run so don’t worry about it!).

The bike is a good time to refuel if you’ve decided you need it, and take on fluids you need for the run, but don’t overdo it. 

Specific triathlon bike rules

Before any race, make sure you know the rules of the race and it’s governing body so you can avoid disqualification or penalties. If you are not sure, ask! The marshals at most events are there to ensure that you have a safe and enjoyable event and are more than happy to help with any questions you have.

They key bike rules will include:


Drafting means cycling close to another cyclist to benefit from their disturbed airflow and gaining a performance advantage. It’s a key part of the swim, and also road cycling, but its generally banned in triathlons. This means that you can’t sit on another rider wheels for the race so, if you are getting close, you need to either hang back or overtake, and will be enforced based on an imaginary box around the rider in front which you cannot stay in for more than 10 seconds or so, if you can’t overtake in the time set, you have to drop back.

Some races are draft legal, meaning this rule doesn’t apply, but in this case, tribikes may not be allowed, so it’s worth checking. These tend to be pro level races, but this change could migrate to age group races.

The mount and dismount

You are not allowed to cycle in transition and have crossed the mount line before you can get on. similarly, you have to get off before the dismount line when heading into transition after your cycle. Some federations and race Marshalls take this very seriously so make sure you know where the lines are.

Bike check

Keeping safe on the bike is one of the key considerations for race marshals, and often there will be a mandatory bike check as you enter transition to rack your bike before the race. This will generally involve a brake check and a visual check to ensure there are no obvious problems with the bike but can involve specific rules like ensuring that your bar end caps are in place. It’s worth check in the race briefing or rules, just to see if your race has specific requirements

Transition set up

The transition is a big and complex area, and to ensure that it runs smoothly, race directors will have assigned specific areas to specific waves, or even assigned specific racks by number in order to streamline the process and ensure fair and controlled racing. Your race briefing will cover this, and if not, then the marshals are there to help, so ask where you should go to rack your bike.


Safety is key and helmets are generally mandatory. In Ireland, it’s generally mandatory that you have your helmet clipped on before you even touch your bike, so you are required to clip your helmet on even when you rack your bike before your race. You are also expected to put on your helmet before you touch your bike, so check what the rules are for your race.

What type of bike is right for tri

The Bike leg will cost you more than any other part of triathlon with bikes costing from $1-10,000, so you need to make sure that you get the bike that is right for you.

Firstly and to the purist, most contentiously, what bike you do your first triathlon on doesn’t matter, as long as its comfortable enough to ride for however long you need to ride it for! 

These days cycling is a massive business that’s sailing a wave of high disposable income, later life activity and ecological thinking which allows it to sustain a vast range of microniches, providing more and more specialist bikes for each sub-genre of cycling and making choosing difficult.

If we ignore the mountain, gravel and commuter bikes for now ( and definitely forgetting ebikes!!), there are three main types of road bike

  1. Endurance bikes
  2. Climbing bikes
  3. Aerobics including time trial bikes

Endurance Bikes

Endurance bikes tend to have a more relaxed geometry and are designed to let you ride comfortably and fast over extended times, emphasising a comparatively upright position. They are not as light or stiff as Climbing bikes, but are lighter and generally much cheaper than aero bikes. Whilst they are a compromise between the two extremes not being as good at top speed or climbing hills as the other two ends, they are more flexible.

Climbing Bikes

The climbing bikes emphasis weight and stiffness over aerodynamics and comfort, but for the purist racer, they offer higher acceleration, better handling and significantly improved climbing performance than the other two types. This is the traditional racers bike that you’d see on tour.

Aero or TT specific bikes

The aerobikes are a relatively new phenomenon, thanks in large part to the rise in triathlon and Ironman events, where long distances at high speed require a much more aerodynamic bike and cycling position. These bikes emphasis front on aerodynamics, with slim frames, recessed bikes and deep-section wheels to reduce the drag and save a few watts in lost power which will save you time over the length of a race.

There are downsides, however. Firstly cost. A truly aero bike will be carbon fibre, as it’s difficult to build the right profiles needed out of anything else, and all components need to be specially made to comply with the frame geometry. Secondly, they are generally heavier. Canyon’s entry-level Triathlon bike is over 1kg heavier than it’s an equivalent race bike, a 15% weight penalty, which is massive in a sport that measures gains in terms of grammes. It’s also €700 more expensive.

However, with deep-section wheels, sleek lines, hidden cables and recessed they do look exceptionally good!!

How aerodynamics affects cyclists

According to Aerocoach, unto 80% of the drag that a cyclist encounters comes from the rider, with only 20% coming from the bike, and the bigger you are, the more you cause the drag when you are cycling, but what is drag and why does it matter?

A bit of a drag!

There are two ways that airflow, whether its windy or driven by your speed, affects the speed of a body through the air.

  1. Air pressure drag – this is caused by the shape of the body as it moves through the air and it similar to the effect of a wing in provides lift, because it relates to the differential pressure between one part of the body and the other.
  2. Friction. Air passing over the skin of a body exerts a limited frictional force in the same way that the ground does on the tyres, but it’s very small compared with the other forces acting on the bike.

Air pressure drag.

As a bike moves, it pushes the air out of the way, and in doing so, creates a high-pressure zone at the front and a low-pressure zone at the back and the difference in pressure acts like a vacuum and pulls the bike backwards, slowing it down slightly.

This happens on all parts of the bike to a greater or lesser extent, so anything that you can to minimise the frontal area of the bike or help the airflow at the back will help to reduce this. Bike manufacturers will offer a Kamtail shaped frame ( basically a teardrop with the sharp bike cut off), deeper section wheels, internally routed cables and installing brakes out of the way all of which will reduce the drag of the bike, making it more aerodynamically efficient, and requiring less energy to achieve the same performance at speed.

Aero position for fast efficient Triathlons

As mentioned above, 80% of the aero drag is caused by the rider, so anything you can do to drop the frontal area and make you more aerodynamically efficient will improve your performance more than changes to the bike. 




There are two key ways that you can improve your aerodynamics.

Aero Position.

The smaller the area that you present to the wind the less of a braking effect you get, and this is why you see a cyclist get as low as they can over the front of the bike, which allows them to present the smallest area to the wind without reducing the efficiency of their legs.

Tribikes take this to the extreme, with bar extensions and pads near the centre line of the bike to allow them to maintain a low position with the elbows inboard for long periods and pushes the hips forward which reduces the utilisation of the hamstrings during the cycle.

Riding in the drops and keeping the shoulders low at high speeds will allow you to achieve a similar effect.

Slippery clothing.

Tight lycra is common on cyclists and I think we can all agree it’s not for aesthetic purposes!! Keeping clothes tight to the body and using smooth materials reduces drag and helps you go faster.

A few things to remember

Aerodynamic efficiency is a critical determinant of ultimate performance, and you should do as much as you can to reduce the drag you and your bike cause when riding, but whether you need to go to the extremes is a matter of opinion, cost and personal circumstances.

  • It’s not your position that will determine your aerodynamic performance in a race, it’s how long you can maintain that position for. You see a lot of people with aero bikes racing out of the aero position, which means all they are doing is adding weight. You need to find the most aero position that’s comfortable for you.
  • Aerodynamic effects are dependent on speed, and the air pressure drag only really kicks in above 25kmph, so unless you are operating consistently above this level aerodynamics are less relevant.
  • Aero adds weight, so if you spend a lot of time on climbs, there will be a net negative effect go a more aero but heavier bike.

Which bike to buy for my first triathlon

wouldn’t suggest going out and buying a new bike unless you are serious about a long term career in Triathlon or riding in general, but, if you are, there are a few things to consider.

Is weight or aero more important to me?

This will be driven by where you expect to spend most of your time. In general, minimising weight is the goal of cyclists. It makes climbing easier, lets you maintain higher speeds, improves acceleration etc. so going aero will require you to compromise that to some extent. So consider how much time you are going to be in the aero position

How much have I got to spend?

A full aerobike, whether a specialist tribike or an aero road bike is going to be a lot more expensive than the equivalent road bike. Using the canyon example again, the Race bike starts at €1599, the equivalent Tribike is €2299 and the Aero road bike is €2699 for similar kit.

Where am I going to be riding?

Terrain plays a big part in bike choice, especially hills and mountains.  Climbing is affected more by weight than aero, as, until you hit the downslope, you are not going fast enough for any aerodynamic effect, but added weight Will slow you down.

What sort of riding will I be doing?

If you are planning on using the bike for general road races, sportifs or charity rides, avoid tribikes as these are often banned from such events, as they are not suited to riding in packs. The same goes for commuting. If you need the bike for commuting, a specialist road bike isn’t the way to go!!


No matter how fast your bike is or slippery your position makes you, if you can’t ride it for a couple of hours in races or training, it’s no good for you! It needs to be the right size for you and have a geometry that suits you and your riding style otherwise you won’t enjoy riding it and will probably stop. Remember, you are supposed to enjoy this sport, it’s not supposed to be torture!

Ultimately you should be investing in a bike that you are going to use as much as you can, so an around makes more sense. If you want to climb, it’ll be light enough to get you up the hills, and stable enough on the descents. If you want to go aero you can use the drops or when you become more comfortable in that position, you can add clip-on aero bars which will take you 90% of the way to the same position.

Which pedals should I choose?

There are a lot of choices when it comes to picking the right pedals for your bike, but what are the differences and which one is right for what cycling you plan to do.


The key interface between you and the bike is the pedal, and a proper linkage will optimise the power transfer from the leg to the crank. However, the more effective pedal connections need practice and are not for beginners, so you need to consider your experience and performance requirements when choosing the type of pedals.

There are three different options.

Traditional flat pedals.

These are the simplest and safest approach which consist simply of a flat platform and the foot is free to move, but as the foot is not connected, you are only gaining power from the downstroke, and can’t benefit from circular pedalling.

Toe clip.

Toe clips are a metal frame and strap that are attached to the front of the pedal and allow the foot to be secured to the pedal, increasing power transfer as it allows you to pedal ‘round’ the crank. The efficiency of the linkage is dependent on how tight the strap holds the toe in place and the stiffness of the shoe.

“Clipless” pedals.

With Clipless pedals, the shoe connects to the top of the pedal via a springloaded mechanism which attaches to a cleat which is bolted to the bottom of the shoe.. The connection is much firmer than with clipless pedals, so they are much more efficient than toe clipped pedals, but clipping in and out takes practice, and there is a chance that you’ll fall off when you stop if you can’t get your foot unclipped in time!!  In addition, you need specialist cycling shoes, with stiff soles which are pre-drilled to attach a specific type of cleat. Proper cleat positioning is essential to avoid foot pain, and you need to match the shoe, cleat and pedal type.

Clipless pedals are the ideal as they maximise power transfer but if you are new to cycling or are not confident, then consider sticking to the basic pedals until you are confident on the bike, once you are confident, then you can swap to clipless pedals.

If you decide to stick to toe clips or basic pedals, then that’s fine too and there some advantages. Obviously, it’s a lot cheaper than investing in clipless pedals, cycling shoes and cleats, plus trainers are a lot easier to run in than cycling shoes which make running around transition a lot easier!.

Cleat choices. 

The interface between the pedal and shoe on clipless pedal is called the cleat, which is generally a plastic or metal lipped block which is held on to the shoe with 2 or 3 bolts. The pedals, cleat and shoes need to match and the decision will impact on what shoes and pedals you can pick.

The traditional choices are either the Shimano SPD-SL or Look Pedals, which are very similar but are not interchangeable. Both use a larger plastic cleat which attaches with a three bolt pattern, which gives a firm connection and a wide range of movement forward, back left right and rotationally, letting you find the best position. This cleat sticks out of the bottom of the shoe, making walking difficult. The pedal has a spring loaded clip that allows a limited amount of side to side movement and a very firm hold which ensures maximum power transfer.

The alternative is SPD cleats from Shimano, which use a small metal cleat to attach to a two-sided pedal, making clipping in easier. SPD cleats were designed for mountain biking, where a hard plastic sole and large cleat are not suitable. This means that they can be recessed into the whole of the shoe, and can be fitted to shoes with rubber soles suitable for running and walking, which makes them ideal for commuting and touring.

There will be less power transferred and some additional weight, but they are a viable choice for people who are likely to be using their bike more for commuting than racing. 

Most triathlon-specific bikes and shoes will use either the SPD or Look format, but consider what you will spend most of your time on the bike.

Bike shoes for your first triathlon

Your choice of pedals will dictate the range of shoes available to you but there will still be a wide range of options available, and budget will dictate what kind of features you can pick from.

If you are going to cycling shoes ( as opposed to SPD cleats and MTB shoes for example), then the biggest decision is going to be whether to go for triathlon shoes or cycling shoes. The biggest difference is the fastening. Triathlon shoes are designed to get into and out of as fast as possible, which means they are likely to have a large opening and a single fastener. They will also have a loop at the heel which helps if you plan to do a flying mount. 

Cycling shoes are designed to hold you into the shoe more firmly, with multiple fastening points and firmer soles. They are designed for long rides so comfort and heat management are important.

The key difference is the speed at which you can get into an out of the shoe, so if you are planning on taking your time in transition, you are not likely to see much benefit from triathlon-specific shoes. However, if every second counts or you are planning to try flying starts on the bike, then triathlon shoes are a must.

Wiggle has a good selection here

What’s the flying mount and should I do one?

Cycling shoes are specialised for being on the bike not off it, they are not ideal for running through transition! To get around this, triathletes developed the flying mount, where the shoes are fixed to the bike and the athlete runs to the mountain barefoot, jumps on and slides their feet into the shoes whilst moving and tightens their shoes on the go.

This is by far the fastest way to get through transition, but requires triathlon-specific shoes and a lot of practice!!

The shoes need to have a large opening so you can get your shoes on easily and loops at the back that allow you to tie the shoes to the bike with rubber bands which stops them catching on the ground. The rubber bands need to be thin so they snap once you start pedalling.

The fasteners need to be easy to tighten as you will be tightening whilst pedalling, and you also need to be comfortable on your bike if you want to try this.

You’ll hear a lot of talk about flying mounts/dismounts being one of the marks of a “proper” triathletes, but they will still be pretty uncommon at most races and can cause so pretty spectacular crashes if you get them wrong, so definitely don’t feel like they are required.

What helmet do I need for my first tri?

At any triathlon, you’ll see a wide range of helmets, from simple bike helmets, alien-like aero helmets all the way to mountaineering and full-face motorbike helmets, but which one is right for the triathlon beginner?

A proper cycling helmet which clips securely under the chin is a must for triathlons, and most organisers won’t even let you get into transition without one. Full face, skateboard or mountaineering helmets won’t cut it, so you will need to make sure that you have one before you race ( to be honest, before you even get on your bike for your first training run! Cycling without a helmet is just about the stupidest thing you can do on a bike!)

There are two main types of helmet available and, as usual, it very much depends on what sort of cycling you are going to do.

Triathlon specific helmets are designed for riders who are able to sustain a full aero position for an extended period of time and their function is to minimise the drag caused by lift your head enough to be able to see forward.

There are two key features of the aero helmet which make them suitable for triathlons.

They are smooth, full shell helmets which minimise the drag caused by the cutouts in traditional helmets that are designed to cool your head and they have a long tail which removes the low-pressure zone behind the head, which reduces drag and relieves the pressure on the neck muscles this can cause.

They are definitely more aero, but can be heavier, hotter and are not the most attractive! Moreover, they are not effective if your head is offline which can reduce peripheral visibility

Standard helmets are designed to be very lightweight and provide adequate cooling to the head at all times. They will provide more drag than triathlon helmets, but obviously, are a more practical option as they can be used on training rides and commutes safely. They are available in much larger numbers, hence deals are more readily available so are going to be a much cheaper option.

One option is to have a standard cycling helmet and add an aero cover which is a thin neoprene cover that goes over the helmet and provides some level of aerodynamic improvement, although obviously not to the extent you would get from an aero helmet.

Online suppliers
Helmets on Wiggle

Some recommended brands




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