Originally Posted by
goalieMN
I bike to below zero with a Illuminite rain jacket over similar base and mid-layers. The jacket has a rear-vent and loooong pit-zips that stay open. It is a non-breathable jacket, so the vents are needed. If it had no vents, I would be super-wet after my commute with just a base-layer under it at 20 degrees.
I wear a Showers Pass jacket similar to the one goalieMN has--pit vents that zip and a rear vent. If it's very cold, I'll start with the pit vents closed, but by the first significant hill, I unzip them at least half-way. The sleeve cuffs have velcro tabs so you can open them up and get air flow through the arms of the jacket. I can ride this way for hours and, if I'm not bone dry, I'm just a tiny bit damp. It makes [U]a tremendous[U] difference. It's also bright yellow with reflective trim, so it's an added safety feature. I wear it over a double capilene (two shirts) down to about 25 F. or so, with one long sleeve capeline up to 40 or a little higher, and, if it's gonna be a little wet, over a short sleeve dri-fit type shirt if it's around 50 (I don't own any cycling specific jerseys at the moment).
Do yourself a favor and invest in a cycling jacket like this.