My tip for keeping warm is to ride to anywhere that has here at home (Guyra 1350 mtrs) in the side mirrors......

. But really
I have access to good quality cold weather clothing but rarely use it....even riding here on the coldest of days....like some clear winters days with a light southerly breeze we don't get up to 0 deg, and simply don't ride anywhere in the ice and snow by choice

I still find if I keep my gear inside the house (21 deg) and am warm when I put it on the following keeps me warm enough.
Merino wool socks, Long sleeve T-shirt, DriRider textile Defender coat & pants with the liners in and vents closed, DriRider Alpine gloves (without the heated grips on) and my helmet. The ST is a perfect cold climate bike with the screen and faring......in fact these where the very reason the ST1100 hit the top of our list a few years ago.

We carry with us or have at home Icebreaker NZ Merino 200 thermals, neck warmers, Polarfleece 300 mid-layers, Gortex outer layers, even snow boots.....but don't use any of it on the bike. Now watching the young bloke play soccer in the snow on a Saturday morning all that sh!t gets put on.....just not needed for the bike.
But natural fibres, and multiple light layers comprising Base, Mid and Outer (wind/waterproof) is the secret to staying warm.
Cheers
Chris