Most definitely armpit zippers, even for some winter days. For winter cycling, I make sure my jackets have this because of multiple layering. All my winter jackets for cycling and (mountain) snowshoeing have armpit zippers. I need that flexibility when temperatures change within a few hrs. /become very active. I must admit that cycling in rain at near freezing temp. to me, is way more unpleasant than cycling in much colder winter temp. @-20 C., but no rain. At least one isn't wet