Are you prone to sweating?

I agree with dalava about layering.

I don't like riding in softshells at all. They're good for around town but they're too warm for aerobic exercise.

If you're comfortable when you leave the house, you're going to overheat for most of your ride. (And maybe sweat a lot and get clammy and chilled.) Better to dress so you're a little chilly for the first mile or two, that's usually the right balance, at least for me. You can drink a warm coffee or tea or something to keep you toasty for that first mile before the exercise starts to keep you warm.