Is there any kind of rating system for how warm a glove or mitten is? I'm looking for something that I could wear winter biking in -15°F. I'm hoping there's a way to find out if a glove/mitten should pass muster.
Thanks for reaching out!
Generally speaking, gloves and mittens do not often come with a temperature rating. How warm a glove or mitten keeps you will depend on many factors, including whether you run warm or cold. Before moving back to Seattle, I lived in Fairbanks, Alaska for six years and rode my fat-tire bike year round. The system that I found to be best for riding in cold temperatures (down to -30°F, which is not much fun, if we're being honest) was a pair of insulated pogies, like the 45NRTH Cobrafist Bike Pogies, with a warm liner glove inside, like the Outdoor Research Protective Essential Midweight Liner gloves. What I appreciated about this system is that it kept my hands warm, gave me a lot of flexibility, dexterity, and room to operate my bike (gears and brakes), and also prevented me from losing a bunch of my hard-earned heat when I needed to pull my hands out of the pogies (to untangle my sled dog or adjust my goggles, etc.). I tend to run really warm, particularly in my hands, so a midweight liner glove was plenty warm enough for me. You'll want to consider something warmer than that if you tend to run cold.
If you wanted to go with a glove or a mitten, I highly recommend thinking about a 'split-finger' style like the 45NRTH Sturmfist 4 Gloves or the REI Junction GTX Split-Fingered Cycling Mittens. While not as warm as pogies, they will provide warmth and the dexterity needed to operate your bike and grip the handlebars.
Hopefully this helps, thanks!
Thanks! Both the pogie system you mentioned and the split-finger style look great. I think I'm leaning towards the pogies now. They super warm! Lot of good food for thought!