You need to protect your food and drink from the cold; however, you also want them accessible. The more you cover up your nutrition to keep it from freezing the harder it is to eat and drink! Over a wool long-sleeved jersey I wear a thermal vest or jersey with a windproof front and pockets in the rear where I can keep my food protected from the wind.
Over these I wear a windbreaker or coat with a two-way zip--by unzipping the lower part I have easy access to my pockets. If it's colder I carry the food in my jersey pockets under the heavy jersey.
For fluids, if it won't be too cold I carry a couple of insulated bottles--the kind designed to keep fluids cold. I fill them with warm drinks: sports drink and tea with honey.
If it was colder, I used to put each bottle inside a heavy wool sock before putting them in their cages. I now have a couple of steel thermoses that fit in my bottle cages. Designed for cycling, by pushing with my thumb on a button the valve opens and I can drink one-handed. If it will be even colder, I wear a small hydration pack under my coat or even under my thermal jersey. Mine has an insulated hose. You can get a bladder with an insulated valve as well; I just blow back into mine after drinking so that there's no water in the valve to freeze.
More: When the Temperature Drops, Remember to Drink Up
Eating and Drinking Regularly
This is important year-round for a fun, successful ride. This is easy in the summer. You pull out a bottle or something from a jersey pocket and drink or eat on the bike. When it is colder and wetter your nutrition may be less accessible, but you still need it! Further, you may be wearing heavy gloves, which make it hard to grab food. I wear thin glove liners under my winter gloves so that my fingers are more dexterous but still have some protection if I remove a glove while riding.
If it's too hard to eat on the bike, then you need to stop to eat. I coached a MTB racer who enjoyed events like the Iditabike, well over 24 hours of biking (and hiking) in the snow. He learned that he needed to stop every 20-30 minutes to eat and drink or he'd bonk.
Some days riding on the plains in Colorado with the wind chill, it's too hard to try to eat on the bike. I stop, face away from the wind and eat and drink something. On longer rides I eat like I do on a bike tour. In addition to hourly snacks, I stop every few hours to go inside a store or café to get something hot to eat and drink and to warm up. Some riders do laps from the house so they are never more than an hour or two from hot chocolate!
In the winter you should be doing base training--the classic long slow distance--so follow these tips, take your time to eat and drink, and enjoy riding outdoors instead of grinding away on the trainer!
More: 7 Recovery Strategies Used by Pro Cyclists
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