My advice: if you're not used to 40-50F, just go for it and figure it out for yourself, everyone has s different level of tolerance for wind and cold. Best bet is to dress with stuff that can be relegated to jersey pockets if not needed after it gets warmer. For example, balaclava, arm warmers, leg warmers and a light wind jacket can all be rolled up and put into jersey pockets.
Don't be embarrassed to ride with your back pockets crammed with stuff you take off, especially as you're figuring it out.
Some ideas since I have a lot of experience in the 40-60 range. At 60 or a bit above, it's just normal riding clothes, bib and jersey.
At 40-50F I'd wear a super light long sleeve base layer under my normal jersey and bib straps - or light arm warmers - or just a very light wind jacket over the jersey. I'd either put light weight wind pants over my bibs, or wear leg warmers. My tights are almost too warm for 50F, but they're in the realm of possibility. Probably the leg warmers at 50, maybe the wind pants or tights as it gets closer to 40.
I always wear a thin skull cap, even at 100F so that would be on if it wasn't balaclava weather. I have a variety of balaclavas, from very thin to thermal. At 50, I'd either stick with a skull cap or try the thin balaclava. 40, a little heavier one.
Gloves- the thin long fingered gloves probably at 50. I have a two or three levels of glove warmth, so it would depend. The stretchy fabric work gloves with rubber palms work great for riding, are inexpensive, and come in a variety of weights and would be great for experimenting until you decide to get some "real" ones.
Shoes and socks: no different than what I wear when it's warmer. 50F is not tough on the feet in my experience. Whatever you do, don't cram heavier socks into your shoes. Tight fitting shoes will only make your feet colder. If you need additional warmth, get some inexpensive toe or shoe covers.
Last edited by Camilo; 12-31-23 at 11:50 PM.