QUESTION: In summer I needed to drink at least four bottles to ride my favorite hilly 65-mile bike loop. Now that it’s 40 degrees cooler, I do the whole ride with one bottle. Is that OK? — Sam S.
RBR REPLIES: Probably not. You sweat nearly as much in the winter as when it’s hot and humid. But the sweat doesn’t show because of all your clothes, or it evaporates in the cold, dry air.
So, you don’t notice how much fluid you’re losing on winter rides. That’s a problem because performance deteriorates markedly when you’ve lost as little as 2 percent of your body weight as sweat.
Start that long ride with two bottles. Drink them in the first two hours, then reload during a quick stop at a convenience store. I bet your performance (and enjoyment) improves.
If you find that the liquid is too cold and that’s part of the problem that is keeping you from drinking, it can also be worth it to buy yourself some insulated bottles or at least carry a bottle in your back pocket so that your body heat keeps it from getting too cold.
From Mayo Clinic:
How do I know if I’m drinking enough?
Your fluid intake is probably adequate if:
You rarely feel thirsty
Your urine is colorless or light yellow
Your doctor or dietitian can help you determine the amount of water that’s right for you every day.
To prevent dehydration and make sure your body has the fluids it needs, make water your beverage of choice. It’s a good idea to drink a glass of water:
With each meal and between meals
Before, during and after exercise
If you feel thirsty
My own experience is that I need to drink a lot less on colder rides. A “5 bottle ride” in hot, humid weather turns into a “2 bottle ride” when it’s in the 50s (10-15 C). In my area, cool weather means high humidity so I experience limited respiration losses. If you like in dry areas, this can be significant but when the relative humidity is in the 80s and 90s percent and the temps are l0w, not so much..
Per Doug’s info from the May Clinic, your check for hydration can be either weighing yourself as you leave and when you get back (retrospective), having to pee every 2 hours or so during the ride (concurrent), or keeping track of past rides and how much you drank and drinking more this time if needed (prospective).
What is the basis for the statement that “You sweat nearly as much in the winter as when it’s hot and humid”? This makes absolutely no sense, since sweating is the body’s cooling mechanism, and is also directly contradicted by my own experience (and that of many others). At this time of year, when I get back from a morning ride with an average temperature of, say, 45F my skin is dry, my base layer is dry, my helmet straps and pads are dry, etc. because the cool air is providing plenty of cooling – no sweat required. And I am certainly not showing any signs of dehydration!
So no, you typically don’t need to drink as much in cool weather as you do in warm weather.
I suspect that the statement about sweating as much in the winter is a canard. It’s like the idea that you should drink eight glasses of water a day, an idea without supporting evidence. My experience is similar to yours; I need to drink less in colder weather. Go by whether you are thirsty, nature’s signal that you ought to drink.