I have gone down to -17F (no idea what the windchill was). I started having the grease in my free-hub prevent the pawls from engaging. It rarely gets that cold here. For clothing I used a ski helmet with ski goggles, balaclava, underwarmor base layer long-sleeve compression shirt, sweatshirt, Showers pass elite jacket, bike shorts, regular running tights, 3pl thermo wind/pants, ski socks, boots, ski gloves and bar-mits.

I feel like the stay-puff marshmellow man, but it keeps me cozy as long as I don't stop for too long or push it too hard and build up a sweat.