1986raleigh

If I did that regardless of temp if it was above fifty I'd be dead from heat stroke.

BoSoxYacht

I might not die if it was under 80 and dry, but why even try? Most bikes have room for 2 bottles, so why not use them both?

I once did a 70mile ride in under 3 hours(in 90+ temps), and only drank 50oz. I spent the day before hydrating, because I knew there would be no stopping for water. I lived, but after finishing my hamstrings cramped up so much that I'll never do that again.

wallrat

It really depends on who you are and if you're a sweater. I lose a bunch of water through sweat. I go through at least 1 to 1.5126 bottles per hour.

Also if you eat you'll need to drink more to help digestion.

Today I did 90 with 9000 get of climbing. I ate a sandwich and a bagel including 4 GUs. I drank 4 bottles of water, one Gatorade and a coke. It was around 75 to 80 degrees.

Machka 

The general recommendation is to drink one 750 ml bottle of water and/or sports drink every 1 to 1.5 hours while on the bicycle ... depending on exertion, weather, and general hydration levels.


For example, if you drank 8 glasses of water during the day at work, and therefore you were reasonably hydrated, you could probably do a 1-2 hour ride without water.

However, if it was a very hot day and you were about to do a century, you'd probably want to drink 2 or 3 glasses of water (plus electrolytes) before you go, and then start in with the 750 ml bottles of water and/or sports drink every hour during the ride.

FLvector

I go through at least 2 water bottles on a 50-60 mile ride. I'll top off one bottle if we break in the middle of the ride, since I don't like the feeling of having no water for the last 10-15 miles. I tend to drink less during the first half of the ride, then push the fluid during the 2nd half. During the cool winter months I have to remind myself to drink. During summer I'm pushing to replace the fluids as the day heats up.

bikerjp

Thanks for all the info. I do lots of rides of 50 miles or less and almost never drink more than two bottles. My concern is that if I'm losing that much water then the longer the ride the more behind on hydration I would get. Two bottles on a 50 mile ride might be okay but 4 on a century is likely going to be a problem. I probably went through 8 bottles (including some juice) worth of liquid on the 200km ride which clearly didn't seem like enough. It was a fairly warm day and very windy on top of the normal Colorado dryness. I was out for about 10 hours that day so I wasn't even drinking 1/hour. But at 2/hour that would be about 20 bottles which just seems like a lot.

On the weigh day I only drank water and did not pee between weighing. According to the bathroom scale I lost 2.8 pounds.

Bacciagalupe

Sure. But let's keep in mind that you can be adequately hydrated and still get heat stroke.

Lazyass

24 years in the infantry and I never saw a guy get heatstroke who was well hydrated. And I've seen many. Not saying it never happened, I'm not a doctor, but I don't know how it would. If it does then the person is probably pumped up on antihistamines or something. If you're hydrated you're gonna sweat. You're not going to get a heat stroke if you're sweating. Don't get heat stroke confused with heat exhaustion.

vfrjo

+1 on if you stop sweating, stop what you're doing and drink some water. 6-10 oz every fifteen mins or so. Saw a guy at work who was way overheated, dehydrated and tired. Stopped sweating, knew it, and chugged about 60 oz water. Needless to say, it bounced, so did his head when he passed out about 5 mins later. Ended up ok, but had a IV overnight. You know your body, drink what you need to stay hydrated. I drink about 24 oz in 45 mins when it's 85+. 6'3", 215 lbs.

UnfilteredDregs

I did 70 miles yesterday with a bit of climbing, 5200 ft, 80 degrees, 60-70% humidity... 5 bottles of water, 75oz.

rode 50 miles today, flattish... 60oz.

I'm 204#@5'10"

cbresciani

I live in Phoenix and did a 30 mile ride today with about 900ft of climbing with partly cloudy skies. Average temp of 89.9 max temp of 104 and a min of 80.6 and drank 2-24oz bottles of water and 1-24oz bottle of 3/4 coconut water mixed with 1/4 juice, which is about average for me, but our humidity was less than 10%.

hamster

I did some googling, and it looks like your reported sweating rate (1.1 L/hour) is quite normal for described conditions, at least early in the ride. The problem is that you can lose this much in sweat, but you probably can't drink this much because your stomach can't absorb liquid at this rate.

However, even mild dehydration is going to cut down the sweating rate, possibly to levels which could be manageable in the long run.

If the air gets too hot, one good approach is to pour some cold water directly on yourself.

NoviceJohn

It depends on the temperature for me. During the cooler weather, I only needed 48 oz of fluids for a 50-65 mile ride. Now, in the hotter weather, I drank the same 48 oz for a 30-40 mile ride.

Also, rule of thumb and medically speaking, 2.2 lbs (1 kg) = 1 liter of fluids in your body.

hamster

"It is widely recognized that active humans do not voluntarily replace all the water lost during prolonged exercise in heat (14). Known as voluntary dehydration (14, 28), this behavior is complex, involves psychological (i.e., alliesthesia) and physiological components, and results in increased core temperature and cardiovascular strain even when test subjects begin exercise in the euhydrated state." Thermal and circulatory responses during exercise: effects of hypohydration, dehydration, and water intake | Journal of Applied Physiology

The problem with extrapolating running advice to cycling is that we're talking about different timeframes. For a runner, 4 hours is a very long run that even the most trained individuals rarely do more than a few times in a year. For a cyclist, 4 hours is an easy Saturday morning outing.

It's pretty well established that dehydration of just 2% of body mass (3-4 lbs, depending on your weight) can mess with performance (reduce heart stroke volume, among other things). If you wait to drink till you're thirsty, you'll be at -2% 2 hours into the ride and you'll never get back to zero because, even at 80 F, you can sweat faster than you can absorb water. Which is not a big deal for a marathon runner, who's halfway done and has unlimited access to water all along the route, but may be a problem for a cyclist who has to keep going for another 8 hours with potentially irregular access to water.

I have no clue where they get the idea that you can get "overhydrated" (unless, by "overhydration", they mean sloshy stomach.) The example of the person who started the topic shows that, with his initial sweating rate of >1 L/hour even under mild conditions, overhydration just isn't in the cards. I did a quick review of articles on hyponatremia and they say that the most typical sufferer of hyponatremia is a female marathon runner who's running at 5 mph while drinking water at the rate of up to 3 liters/hour. Clearly, this person does not sweat nearly as much as you or me.

P.S. One important point in your links is that switching from water to a sports drink (e.g. Gatorade) does not fully prevent sodium loss. Gatorade contains ~0.4 .. 0.5 g/L of sodium. Others contain even less (if you mix HEED at 1 scoop/bottle ratio, you get 0.05 g/L of sodium). Sweat composition varies from person to person and depends on conditions but can go as high as 2..3 g/L.

Dave Cutter

I have one of those high tech scales that measure my moisture/hydration level/percentage. I think that's a better way to track your hydration than counting ounces via time passage. Are you starting out on your ride fully hydrated? How do you know? If you feel good when you return home after drinking two bottles of water while on a ride.... does that mean your properly hydrated?

BTW... when cycling I normally drink a gulp or two every four miles.

Looigi

In warm weather and riding with reasonable exertion I'll drink 24oz/hr without even thinking about it. It's not uncommon to stop and refill my bottles after a couple of hours.

GravelMN

It's surprising how dehydration can creep up on you. On a recent long ride on a cool, cloudy day, I went through about two 24 ounce bottles in 3+ hours and didn't feel a bit thirsty. A couple more hours into the ride and maybe another bottle or so of dilute Powerade later I started feeling tired and noticed I hadn't needed a rest stop for quite a while. There was a pretty strong headwind and I got tired, blaming it on a lack of conditioning. Still didn't feel thirsty and temps still hovered in the 60s and low 70s. After the ride the thirst set in and I started feeling rough. Several glasses of water and other NA beverages later I went to the restroom and my urine was still dark and concentrated. As I kept downing water I started feeling pretty good again and began kicking myself because if I had drank more on the ride, I could have finished stronger without the after effects.

Lesson learned, thirst alone is not an adequate indicator of hydration.

Machka 

Just one reminder ... if you are drinking large amounts of water, especially on a hot day, don't forget the electrolytes. Take some electrolyte tablets. Eat salted almonds or potato chips. You'll feel so much better.

JamesRL

My best/worst day cycling, 2 and a half decades back, was 220kms, hills, on a touring bike with gear. It was 35 degrees celsius and nearly 100% humidity.

My consumption was twice the normal rate, 2 large water bottles per hour. I was riding solo, looking for small towns along the route, stopping at small stores just long enough to fill my bottles. I was mixing apple juice and water 50/50. I ate bananas and granola bars while rolling. I probably ate less(function of the heat) and drank about twice the normal rate.

Despite all of that, I bonked at about 180 kms. Took 20 minute rest with a sugary drink (orangina) and I was good to go.

In my experience, its all about conditions and each of us are different in how we react to them. I do know that hydrating before you get on the bike helps. And remembering to sip a little along the way, even before you are truly thirsty.

wphamilton

This is a logical analysis, but normally in these endurance type efforts we don't replace all of the water during the effort. So that's an upper bound, the most you might need.

I just finished reading "A Dog in a Hat", about an American who went to Belgium to race. The protagonist Joe Perkins relates that the European pros would only take one bottle for training rides, and along the way either stop for a soda or refill the bottle. Joe would carry two bottles, and take some ribbing for that. So it's reasonable that the range is between two bottles (55 ounces?) and your 78 ounces.

There are a few elite runners who don't carry any water. I assume that they've already filled up and that their bodies are somehow adapted to stockpile enough and still operate efficiently. So my question is what is the difference between carrying a certain amount of water in a bottle, or just drinking it first? Sports coaches in the 70's were always cautioning against drinking too much water, but they were full of crap about some other things, so I really don't know. Obviously you wouldn't want an excessive amount sloshing around, but maybe a better question is how to pre-hydrate and how much?

revchuck 

I'll add a data point. I'm 62, 6'2", 185 lbs. Yesterday I did a three hour endurance pace ride, 54 miles in three hours, just under 1k feet of climbing. According to my Garmin 500 (which usually reads high) it was 89 degrees F at the beginning of the ride and 104 at the end, and according to Intellicast it was 87% humidity at the start and 58% at the end. I went through two bottles of water with two Nuun tabs each and a bottle of plain water before I took a break at the 2:15 point, bought a 23 oz. can of sweet tea and drank it and filled a bottle with plain water at the break, and killed that bottle of water in the 45 minutes it took me to get home. Since my bottles are 24 oz., that's five bottle's worth in three hours. I wasn't bloated in the least when I got home; as a matter of fact, it was two hours before I needed to pee. I wasn't under-hydrated at the start, but I didn't preload either. Since the humidity went down so much, I got my first salt stains of the year on my shorts.

bikerjp

I did a bit of googling myself and found this.

How Much Water Should You Drink When You Exercise?

The recommendation there is to hydrate before going and then 8oz every 15 minutes. 32oz/hour is a bit low based on my calculations but if starting well hydrated it might be enough and stopping a few times for a juice or electrolyte drink would add to that.

banerjek

The amount you need varies drastically even for a single individual so it' not a good idea to get too hung up on specific amounts. I've gone through 3 gallons in a single day and had it not be enough, but I've also been out hours on one bottle.

Don't wait until you get thirsty to drink. If you do, you're already behind. That's fine for shorter rides but it will cause problems on longer ones. When you get dehydrated, you'll feel like crap and be much more prone to heat exhaustion and cramps.

waters60

I use my Camelback for long rides on hot days when I'm not sure of the water situation. Load it with ice cubes and water and it is very easy to drain the whole thing. Having the spigot so accessible also helps me drink more. The storage space is great for long rides. I use my water bottles for sports drinks, keeping the mold growing sports drink residue out of the Camelback!

Darth Steele

also, hydration starts way in advance of actually riding. I would also argue that you might be better off continuously sipping water in advance of being thirsty.

drink to stay hydrated as someone else said above

It's like hunger, you can't wait until you are hungry to eat, ideally you want 20 minutes in advance of needing energy.