Technical aspects of hydration systems / hydration setup in triathlon

Hydration and nutrition are crucial in triathlon, especially on longer distances. In addition to the much-discussed questions of what, how much and when, there are some technical aspects to consider:

• Where to put all the bottles?
• What effect have these bottles on the aerodynamics and weight of my bike?
• Will hydration affect my position on the bike?
• How can I conveniently ensure a regular intake?
• What is the best set-up for the bike course?
• What is the best way to master the aid (or water) station?

We present the common types of hydration systems and provide information on the advantages and disadvantages as well as tips for optimal use. The importance of the individual factors varies from person to person. For example, leaving the aero position to drink leads to greater disadvantages with very optimized riding position than with a more upright position that thereby changes only slightly.

Above or between / below the arms / aerobars?

Hydration systems placed on the aerobars, slightly above the arms, can help to close the space between the head, arms and body. The position is therefore aerodynamically efficient. Most systems are not suitable for all inclinations due to their elongated design and the position of the refill opening. You should therefore use a balancing wedge if the extensions are positioned at a steeper angle.

Systems between and below the extensions are automatically part of the frontal area. The aerodynamic design is therefore particularly important and can have both advantages and disadvantages. The lower position leaves the cockpit cleaner, which many athletes find more comfortable. This also applies to the position of the bike computer.

For both types, it is important that the shape of the hydration system and the mount / cage are compatible with the lateral positioning of your aerobars (narrow / wide). As the cockpit setting affects comfort, power transmission and aerodynamics, you should avoid any restrictions. Bear in mind that your optimal cockpit setting can change over time.

Computer mount - with or without?

Front hydration systems and bike computers occupy roughly the same space around the aerobars. If you want to keep your existing computer mount, you should make sure that your hydration system is compatible and that both products remain easy to use in combination. Some hydration systems and BTA mounts also offer computer mounts that solve this problem.

If you want to monitor your data continuously, a display position in the front area of the aerobars, i.e. in the natural field of vision, is ideal. Many athletes are more comfortable with a slightly greater distance to the eye.

Refill opening with splash guard or closed lid?

A splash guard with insertion slots is always accessible and does not need to be opened before entering the aid station and closed afterwards. To refill, you insert the mouthpiece of the refill bottle through the slits into the hydration system without closing the mouthpiece. These systems are therefore only suitable if the refill opening is freely accessible and not blocked (e.g. by particularly tightly adjusted aerobars).

A closed lid offers a little more leeway when adjusting the cockpit, especially if the refill opening is large and easy to hit. Once opened, the mouthpiece of the refill bottle does not touch the system during filling and therefore cannot be closed unintentionally. The larger the opening, the easier it is to refill. The sealing is mostly better with these models. However, no variant is usually completely leak-proof, as otherwise a vacuum would build up when drinking through the straw.

With or without bite valve?

Without a bite valve, the residual liquid in the straw flows back into the bottle after drinking. With a bite valve, it remains in the straw if used correctly and therefore does not have to be sucked up the next time you drink. However, most bite valves lead to a significant tightening of the straw. As the flow rate depends on the smallest part, the effect is comparable to using a smaller straw.

Example: an inner diameter of 6mm, like the coupling section of many bite valves, instead of 9mm, as with most drinking tubes, reduces the flow rate by 56% (exponential change of the cross-sectional area). The outlet of the bite valve usually forms an additional constriction. This makes suctioning significantly harder and correspondingly uncomfortable under physical stress.

How do I adjust the straw?

The straw should touch the bottom of the hydration system so that you can empty it completely. Make sure that there is no kink in the straw inside the bottle that could impede the flow of water. Most straws can be easily shortened with scissors. The optimum length is crucial to ensure a comfortable supply.

And this is how it works:

• Get into your comfortable aero position on the bike (extreme positions usually can't be maintained permanently and are an additional challenge when drinking)
• Look ahead as you want to keep an eye on the road while drinking (this is often forgotten when setting up at home, e.g. on the bike trainer).
• Leave a little leeway so that the straw initially seems a little too long. Test the length in practice and repeat the process until you have found the optimum length.

Note: if the straw is too short, you will not be able to look forwards when drinking, or only with difficulty. This makes the water supply uncomfortable, risky and often not executed as planned.

What is the optimum volume for hydration systems?

The volume of integrated and aftermarket hydration systems ranges between ca. 500ml / 17oz and ca. 1200ml / 41oz (ca. 1000ml / 34oz for front hydration systems).

A large volume offers an advantage at the start, as you need to refill later. From the first refill, the strategy is decisive. When riding through the aid station, it is very difficult to pick up more than 2 bottles. Refill one of them directly and place the second one in the bottle holder behind the saddle as a replacement. A volume of the hydration system of more than one refill bottle (usually 700ml / 24oz - 750ml / 25oz) has no advantage in this situation. The longer the distance, the smaller the advantage of very large hydration systems under this strategy. The situation is different if you want to stop at the aid station. In this case, you can take more on board with a very large system and possibly skip aid stations.

Additional volume means additional weight that has to be transported. This must be taken into consideration, especially for courses with relevant climbing meters. Due to the placement next to the handlebars, the volume of front hydration systems also has an impact on handling.

The same applies to the product weight of the hydration system itself. Depending on the model selected, considerable weight can be saved here. Compared to many other components, this is a very cost-efficient way of managing weight.

What should I fill into the hydration system?

As the liquid has to be sucked in through the straw, the liquid should not be thick. You should therefore not use any additives that reduce the viscosity (e.g. gels).

During the race, the hydration system will not always be completely emptied before. You should avoid flavors that you do not want to enjoy permanently during a competition.

What is the best setup for the bike course? Where to put spare bottles and carbohydrates?

If you want to use your own nutrition, the space will quickly become scarce. Strategic positioning is therefore an advantage. The optimum setup depends on many factors. These are, for example, the space available on the bike (especially with small frame sizes), your handling skills and your personal preferences. The following setup has proven itself and serves as a guide for designing or optimizing your own setup.

• Hydration system: Water
• Down tube / seat tube bottle(s): Carbohydrates - mixed with water (Slim aero bottles are ideal. Normal, round bottles have aerodynamic disadvantages here)
• Bottle(s) behind the saddle (BTS): carbohydrates – mixed with water (Very good place for 1-2 normal, round bottles / refill bottles, as it tends to be aerodynamically neutral)

Races usually start early in the morning and the temperatures are still relatively low at the beginning of the bike course. The hydration system is therefore sufficient to cover your hydration needs for the start.

As all the other bottles are initially used for carbohydrate mixes, you can add a little more water than you would with a single bottle for carbohydrates. The distribution over several bottles also reduces the risk of losing all your nutrition on bumps. You can use grip tape or sandpaper to additionally secure classic bottle cages behind the saddle during the race. To do this, stick a small piece over the small knob that secures the bottle to the top. The granular structure improves the locking effect.

Now the order of consumption is important. First use the nutrition from the always same standard bottle (i.e. not from an aero bottle) until it is empty. As soon as this is used up, you can dispose that bottle and replace it with a spare water bottle at the aid station. This gives you full access to liquids when the heat rises. As aero bottles are usually used on the down tube and seat tube due to the better aerodynamics, the bottle behind the saddle is ideal for this purpose. If the outside temperatures quickly become critical, you can make the carbohydrate mix in this bottle thinner. This means that the bottle cage is available earlier for replacement hydration from the aid station.

Approaching the aid (or water) station

Open the lid of your hydration system before you enter the aid station.

Check your bottles: Which ones need to be refilled? You can still use leftovers for cooling. Have the empty bottle(s) ready to throw them away right at the start of the littering zone.

Choose a volunteer, make eye contact and give a hand signal so that you get the full attention. This significantly increases the chances of a successful handover.

If you want to pick up 2 bottles, the optimal order depends on the situation. If the station is busy, it is safer to put the first bottle directly into the bottle cage behind the saddle to avoid collisions with other athletes and bottles lying around. If the station is empty and tidy, you can refill your hydration system first and then put the second bottle in the back. This allows you to accelerate again sooner.

It is usually better to pace yourself less aggressively in the station. The risk of a failed / missed bottle intake far outweighs the loss of time.