http://www.rei.com/product/47942637....HP_CYCLING_TOC

this is the one I wear and no I don't seem to spend any time unzipping it! LOL It has vents in the upper back which is nice under a backpack plus it has a zippered back pocket that you can open as a vent, and then of course the front pockets and even the zip-off sleeves can by unzipped partway to vent. I just wear less Under the jacket and then on the rare occasion (like climbing) I just unzip the front partway. oh.....it also has a 2-way zipper.

and yes - it takes me truly 10-15 minutes to change clothes in the morning once I get to work - which is why I don't do any lunchtime riding in the winter! LOL