One of my worst rides ever happened in a heat wave where I left my filled-to-the-brim water bottles on the kitchen counter. About halfway through my rip on the local MTB trails my mouth felt like I was fuelling on sand and I could sense my energy flagging, fast. To say I limped home would be an understatement.

I knew I should have had water on that ride, but it felt like even more proof that we cyclists lose (and must replace) H2O throughout our workouts, because of sweating, breathing, and urinating. Sweat rate can add up to three to four litres of water lost per hour of exercise, especially if working out in sultry conditions. And all that fluid loss can certainly send you into the dehydration pain cave.

“Staying well hydrated is essential to proper body functioning and performance,” says Marni Sumbal, MS, RD, owner of Trimarni Coaching and Nutrition and author of Essential Sports Nutrition. “Replacing fluids inadequately during exercise can lead to a host of physical and mental issues, such as compromised digestion, poor body temperature regulation, irritability, fatigue, decreased sweat rate, and reduced blood flow.”

When your plasma (blood) volume shrinks from sweat loss, water from other areas comes into the plasma to compensate. This leaves less water available for body temperature regulation, which may make you feel like you’re frying and leave you with an increased risk for heat illness. One study in the Journal of Sports Sciences found that cyclists had increased perceived pain during a long ride when dehydrated. In other words, the symptoms of not consuming enough water certainly won’t help you crush any performance goals.

You should also know that a 2023 study published in eBioMedicine showed that adults who stay well-hydrated overall appear to be healthier, develop fewer chronic conditions, such as heart and lung disease, and live longer than those who may not get sufficient fluids.

What’s more: Decrements in skill and physical performance are more likely to occur when hypohydration levels reach 2 percent or more body mass loss, but the effect of dehydration varies by individual. Some research even suggests that a loss of as little as 1 percent body weight can impair muscle endurance, power, and strength. Men and women may also differ in how much body weight they can lose from fluid loss before their rides start to suffer.

All of this is to say that you shouldn’t take your hydration needs while on the saddle too lightly. But while it’s important to stay hydrated during exercise, it’s impossible to create one-size-fits-all drinking rules. Hydration needs vary by individual, and many variables including sex, climate, intensity, and genetic sweat rate can determine how much water you need during a ride of various lengths to stay hydrated. But that doesn’t mean you should leave your hydration plan up to chance.

There are some general guidelines worth knowing about and striving to achieve. And a study in Medicine and Science in Sports and Exercise found that cycling performance improved in subjects who drank according to a predetermined plan, compared to just taking in fluids when they felt like it.

To help you better pinpoint how to hydrate right, we tapped into the knowledge of our sports dietitian to help you figure out your optimal fluid intake plan, based on how long you want to ride. Here are your sipping points.

How to Hydrate for Short Rides: 1 Hour or Less

Focus on pre-ride hydration, aiming for 500-750ml two hours before heading out and another 250ml 20-30 minutes before riding. It’s smart to get some sodium in before you start pedalling, too.

Just because you are going for a shorter cruise doesn’t mean you should brush off your hydration. But for these rides, you can place greater emphasis on your hydration strategy before the ride, which can carry you through much of the workout. One of the best ways to limit the amount of fluid you need to take in during a brief ride is to drink enough before it.

“As a general guideline for one-hour workouts, riders should consume 300ml to 500ml of fluid two hours before exercise and another 250ml around 20 to 30 minutes before starting the workout,” Sumbal recommends. (The American Council on Exercise supports these numbers.) Do this and how much you take in during the workout becomes less vital.

One concern is that many people are at least mildly dehydrated all the time, meaning entering a workout already at a deficit, which can impede performance, even for shorter duration exercise and especially when riding in hot environments.

“Adding a pinch of salt to your pre-ride water may help with increasing absorption, while also helping with fluid retention,” says Sumbal. That’s because sodium in salt will activate transport mechanisms in the intestines for better absorption rates when at rest.

If you find that you are peeing frequently before your workout, your pee colour is clear, and there is no underlying health reason, Sumbal cautions that this can be a sign that you are either drinking too much water, not consuming enough sodium, or a mixture of both. But you don’t need much salt to do the trick, as Sumbal says just 1/16 to 1/8 teaspoon of salt added to each 500ml of water is sufficient for better fluid absorption and retention.

Another option to fill up before you ride is to drink plain water with pre-workout foods that contain some sodium. In addition to sodium, you can add a touch of simple carbs, like maple syrup, to your pre-exercise water to also bolster absorption rates. A half teaspoon of maple syrup for each cup of water should suffice.

Sumbal suggests still reaching for your bidon on occasion during short rides to make sure you are maintaining good hydration overall. “If you are a heavy sweater, aim to consume 200-250ml every 20 minutes throughout the hour, and if you are not a heavy sweater, you can aim for 100-150ml every 15 to 20 minutes,” she says. Drinking to thirst can work for rides lasting less than an hour, especially if exercising in cooler conditions and at low intensities, she adds.

How to Hydrate for Medium Rides: 1 to 3 Hours

Go for 700ml per hour or 200ml every 15 minutes. Include carbs (30-60g per hour) and electrolytes (500-700mg of sodium) per hour with your fluid intake.

Once you push past the hour mark, keeping on top of your hydration needs becomes more pressing. The longer you ride the more fluid you shed, making it paramount to drink enough. “Consuming at least 700-800ml of fluid per hour of riding is a good general guideline,” Sumbal says. That works out to 200-250ml every 15 minutes of activity. Sumbal suggests taking small sips more frequently to help with digestion and minimise stomach sloshing.

Standard-sized water bottles will hold 500-750ml of fluid, so a goal is to consume at least one of these each hour of your ride by taking long pulls off your bottle at a few regular intervals. Remember that this hydration guideline can vary depending on the individual, and factors like intensity and temperature.

“When it comes to longer workouts, drinking on a schedule instead of to thirst is more advantageous to performance and health,” Sumbal explains. “Thirst sensations and signals are not always accurate during exercise.” This is particularly true if riding at altitude or in dry climates. And thirst is a subjective measure. Some may drink only enough to take the edge off their thirst, while others may drink enough to meet hydration needs.

Plus, a study published in Medicine and Science in Sports and Exercise found that hypohydration can impair performance and the ability to regulate body temperature, independent of thirst. So even if you don’t feel like you need to drink, you could still be dehydrated and, in turn, underperforming. And certainly waiting until you are dry-mouthed and very thirsty means you are likely already entering the dehydration danger zone.

Also, for longer, more intense workouts, your hydration plan should include more than just water, Sumbal says. The carbohydrates from a sports drink will provide the valuable carbs that your muscles need for energy, while sodium in the bottle can help replace some of this electrolyte lost in sweat to improve water balance in the body.

“You will be losing more fluids and sodium throughout a workout of this length and depleting glycogen stores—all of which will compromise health and performance if you don’t consume a well-formulated sports drink,” notes Sumbal. Fast-digesting carbs, like sucrose, will also promote better water absorption by increasing the activation of fluid transport mechanisms in the small intestine. A solution of 2 to 3 grams of carbs per 100ml of fluid should allow for optimal water absorption rates.

If you struggle with the lack of flavour, making your drink more palatable via a flavoured sports drink or electrolyte mix will help you consume more. In general, your goal is to consume at 30 to 60 grams of carbohydrates for each hour of activity, which can come from a combo of fluids and food. And like water, there can be performance benefits to consuming smaller amounts of carbs in fluid form at more frequent intervals.

The baseline recommendation for sodium intake per hour of exercise is 500 to 700 milligrams, but this can increase if you’re unconditioned, training in steamy conditions, or are a heavy or “salty sweater.” Just don’t think that you need to have enough sodium in your hydration plan to replace all the sodium you lose in sweat during a workout, as this is not realistic or necessary.

In general, if your body weight is still a few pounds below normal by the end of your workout, you are very thirsty, you are craving salty foods, and have a dark pee the hue of apple juice the day after a longer ride, Sumbal says this is a tip-off that you did not adequately hydrate during and after your workout. In contrast, a stable body weight, not being overly thirsty, and a pee that is straw-colored shows that you are staying on top of your hydration needs.

How to Hydrate for Long Rides: 3 Hours or More

Consume 750ml to a litre of fluid, 60-90 g of carbs, and 400-800 mg of sodium every hour of your ride. Your goal should be small, frequent sips.

When out for the long haul, stay acutely aware of your hydration. The chances that you can keep up the pace for multiple hours when in a significantly dehydrated state is slim. For many athletes, the amount of fluids they believe they are consuming versus the amount they actually take in can be miles apart.

“For rides of this length, I would recommend between 750ml and a litre of fluid, along with 60 to 90 grams of carbohydrates and at least 400 to 800mg sodium as a good baseline for each hour of your ride,” says Sumbal. That is 1 to 1.5 bottles worth of fluid for each hour of activity. If you are not getting your carbs from solid foods, you most certainly need calories in your bottle.

Sumbal says that athletes should experiment with these guidelines during training and factor in the weather, terrain, and intensity/effort when devising a personalised hydration plan. Data shows that sweat rates can vary significantly among cyclists during a multi-hour ride, which would impact fluid needs. There will also be differences in needs among men and women, which research still needs to fully explain.

Drinking high amounts of only plain water for this duration without consuming sufficient sodium can lead to a potentially serious condition known as hyponatremia, or a dangerous drop of sodium in your blood. So make sure to have some salt with you. Sodium in your water bottle may also help you avoid those dreaded muscle cramps, at least according to one small study.

Again, our thirst mechanism isn’t the most reliable when we are exercising for hours. So think about using nudges to remind you to drink up. This could be as simple as setting a timer on your watch or GPS device to beep every 15 minutes to remind you to take a swig or two of fluid. If you know that your water bottles hold a litre of fluid and you return home with both of them drained or with them only half empty make note of this to give you a clearer picture of how you are hydrating and how you can make improvements.

An important note while working toward better hydration: If you normally drink 30ml of fluid per hour, but suddenly double this amount to stay better hydrated this could result in an unpleasant stomach experience. It’s better to ease into hydration by adding 100ml or two to your previous hourly intake for a few workouts, then another bit for a few more, until you get to your goal. This can gradually train your gut to tolerate the increased load.

For all-day rides, it’s worth remembering that all liquids contribute to hydration. So if you pull into a gas station for a bottled coffee drink or cold Coke you can count these toward your fluid intake. But Sumbal cautions that you need to be mindful that fluids like coffee and Coke are not formulated to meet physiological needs during exercise. “Coffee may increase the risk for heartburn and excessive caffeine may negatively impact cardio functioning. Soda may cause belching due to the carbonation and does not count as an effective sport drink,” she says.

To gauge your hydration efforts Sumbal explains that it can be useful to monitor your pee. If you notice that your urine is a very dark yellow with an off-odour then it’s time to get drinking. And, certainly, if you are hour 4 into a 6-hour journey and you haven’t had a nature break, that is also a tip-off you are not drinking enough. “If you are peeing excessively and your urine is clear, you have the opposite problem and are drinking too much,” Sumbal says.

One way to better estimate how much liquid you need to drink to side-step performance-sapping dehydration is a sweat test: Weigh yourself naked before a workout, then during a typical training session keep track of how much you drink. Weigh yourself naked again post-workout, then subtract your post-workout weight from your pre-workout weight. Add to that number however many millilitres of liquid you consumed. For example, if you lost one kilo but drank 500ml it means you sweated out about 500ml in one hour. On the flip side, Sumbal says if you are gaining weight during your rides, you are drinking too much, which can cause excess water in the bloodstream.

To determine how much you should be drinking every 15 minutes, divide your hourly fluid loss by four (in the above example it would be 175ml). Repeat the test in a few different environmental conditions and during different intensities of riding. The goal isn’t to match all the fluid lost during a workout, but to come reasonably close by slowing the rate of body weight loss. “This can be a simple method for addressing hydration status to better understand your fluid needs,” says Sumbal.