IMO it's impractical to remove a layer every time you go up a 20m hill and then add it again when going down.
Which is where the traditional adding and removing multiple layers approach which comes from mountaineering falls down for cycling. You end up too hot, the multiple layers makes it harder for water vapour to escape (especially if waterproof on top), humidity builds up in the layers to the point of where the air within can’t hold it, it condenses back into liquid, the layers get wet, thermal conductivity increases by an order of magnitude, you get cold despite all the layers.
Fewer multi purpose layers (soft shell) that trap warm air and create a micro climate within, work over a wider range of temperatures and have venting options to prevent overheating uphill, then chilling downhill are much more effective for staying warm and dry on the bike. I don’t mean things like laminates such as wind stopper, they are not breathable enough and work over a narrow range of temps, but more the vapourise type soft shell, which are windshell with a thin fast wicking fleece liner.
Andy sums up soft shell well
https://www.andy-kirkpatrick.com/articles/view/cut_the_crap1
