I haven’t biked in single-digits yet, or below 24 for that matter.
My winter gear (largely the office commute only, now that really cold weather has arrived; my last leisure ride was in December) has been changing gradually, as this is my first winter biking, learning what works, etc…
I wear my office khakis over SmartWool long-johns, and the corresponding SmartWool long-sleeve undershirt. Then on top of that undershirt, a lightweight zip-up windbreaker from REI (through December). I pack my dress shirt and work shoes, socks & a tee. I added Showers Pass 3-layer socks to the gear in late Nov. A half-balaclava (nose and below) plus gloves and ski-goggles (to wear over my existing glasses; what a transformation in comfort that made!!) However, once mornings got even colder deeper into winter, the light windbreaker didn;t seem to be cutting it anymore. I splurged on a Gore windstopper jacket with removable sleeves, during a sale at Spokes. It REALLY blocks the wind from getting through the front, beautifully. (And has a zipper you can easily operate one-handed with thicker gloves, unlike the REI windbreaker.) I also added over-shoe covers, to cut the wind penetration into my bike shoes. On Thursday’s super blustery ride home (about 24f) I realized my half-balaclava may need scarf assistance for better neck coverage — even with the SmartWool shirt fully zipped up (it has a slight collar up the neck, and the Gore all zipped up — wind was getting through to the front of my neck; I don’t think the balaclava’s “front scarf” panel is long enough…