How to fuel properly on the bike

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Nutrition is key to performing well and avoiding the dreaded “bonk”, whether you’re just training or actually racing. This has somewhat been a bit tricky to master for triathlon, since there hasn’t been a lot of research when it comes to long endurance events spanning across swim, bike, and run. What works in fueling for a single sport might not for the physical demands of two or three different ones.

With long-distance triathlon, the bike leg takes up a disproportionately large amount of time and energy. There’s greater opportunity to get your nutrition very wrong here and end up either under-fueled and hungry by the time you need to run, or over-fueled with your gut in deep distress. This is why we always encourage any of the athletes under our care to test their nutritional strategies in training; that process of trial-and-error helps you find what works for you individually.

Here’s what to consider to fuel better on the bike.

Type Of Fuel

Training and racing nutrition is available in many different forms. There are liquids, gels, dissolving tablets, blocks, and bars – and then there are also things like sandwiches, spam musubi bites, and even stops at roadside restaurants and cafes. Some people might respond well to carbohydrates and electrolytes both dissolved in fluids, while others may need to take their carbs as solids, and hydrate with electrolytes and fluid.

Practice with different ones to see which works best for you. The more intense the activity the faster you need the energy to enter your bloodstream; carbs are absorbed faster in liquid form like drinks or gels. If the rides are more easygoing, solid foods are great for a slow fuel release. (Higher intensity may also cause the digestive process to slow down because your body is channeling blood flow into your limbs instead of your stomach.)

Amount Of Carbs

Typically, you should be consuming around 30 to 60 grams of carbs an hour, which varies per individual (smaller individuals need less calories in general). These can come in energy gels, which contain 20 to 30 grams of carb per gel, or energy bars which contain 20 to 25 grams of carbs per serving.

Prepackaged nutrition usually comes with directions for how to take them, e.g. one gel per hour, one sachet per bottle, etc. How do you know if you’re taking too much? Vomiting or a bloated stomach will tell you that you’ve taken too much, too fast. How do you know if you’re taking too little? You bonk.


The more solid a food is, the more you need to take in water to help your gut to absorb it. There are some very liquid gels available which you won’t need to take with water, but more commonly you need to take a sip of water with each gel.

Water alone isn’t enough; to stay properly hydrated you need to replenish the electrolytes you lose in sweat. There are electrolyte-only powders or tablets if you prefer to take your calories in as solids and gels.


During a race, you can’t really take any nutrition while swimming. So you can take a gel in transition or in the first few kilometers of the bike leg, and then take succeeding ones at the proper intervals (based on instructions on the packaging as well as your personal trial-and-error).

Don’t wait until the last moment to top up. Unlike cars which you can keep driving until the tank is empty, the human body needs to keep its energy level constant to perform well. Many an experienced athlete can tell you the tale of forgetting to eat and drink during a race or dropping a bottle of nutrition and not stopping to pick it up, leading to a DNF or worse.

Fuelling properly on the bike leg helps you ride well while still leaving enough energy to run and finish strong. Staying on top of your nutrition on the bike sets you up for success at the finish line.


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