well, I didn't want to make it hot & cause some kind of reaction with the plastic in the bottle. it's not made for hot drinks I don't think. just warmed it so it wasn't as cold as the filtered pitcher water on my counter, so that it would take longer to freeze. and I only sipped it to coat my throat, wasn't really like drinking a hot cup of coffee. but some riders do carry insulated bottles of hot coffee on their rides

I have an insulated water bottle but it doesn't insulate nearly as good as my camelbak! I guess I'll try my luck with it one of these days.

I start with hot water before my ride. One in my cage and the other in my pocket, covered from the wind. The cage bottle starts to cool fairly quickly and I enjoy the warmer water. For an hours ride I switch the bottles half way. By then the cage bottle is cold but the one in my pocket is still pretty warm. Holds up for half the ride back. These are regular bottles. I have just invested in an insulated bottle to improve the heat retention.

Wear a Camel Back then put your parka on over it?

I put a bottle in my middle jersey pocket under my jacket. Body heat & insulation stops it from freezing.

Also, I have a Contigo travel mug that I use on the bike. A tiny bit small for a bottle cage, but if your cage is metal, you can bend it a bit tighter. I also added a few home-made "grippes" to the gage to help prevent ejection on bumps.

https://www.gocontigo.com/16-oz-autos...clean-lid.html

daughter gave me an insulated water bottle. not for cycling but it fits in a standard cage so I tried it out in severe conditions. filled it & a standard cycling insulated bottle with warm lemon water. the cycling bottle eventually cooled off but this Corkcicle bottle stayed warm

Scroll down to the fourth answer, select your temperature, and do the math! If it’s really cold out, you’ll probably get a buzz.

https://van.physics.illinois.edu/qa/listing.php?id=1640