Originally Posted by ViperZ
True, but depending on the design and intended riding environment, you may really have to crank out the watts to keep warm, as all the body heat will dissipate out the back.
I have a Sugoi Team Radius Jacket that is exactly like that. I love that jacket, but it feels very cold when you start and if you stop. The breathable back and back of the arms really ventilates the body heat away. It was designed for very high aerobic intensity... I have used it to -9C, but I really had to keep my effort above 28km/h for the 100 km ride. There was a point when we were riding at about 24km/h and I felt very cold. It is more designed for late Spring, early Fall.
That's why I like the zip out back panel on my Canari. Low levels of venting when I want to stay warm, Much higher levels when I needed to cool off.
In truth, through Chicago winters, I went with the shell and sweater, but my commute wasn't very long. Had it been much longer, I would have personally went with feeling cold at the beginning in favor of the more breathable options, but that's me. I'd still pack extra layers, just in case.
The point that I'm trying to get across is that the original poster will probably be better off with several layers instead of going with the single layer softshell. Yeah, they work great in most conditions, but at the extremes, they don't work very well, and cycling as an activity happens to spend more time in those extremes than not. YMMV.