Each person is different and there is no perfect solution to cool weather dressing, but this list is a good place to start.
65-60 arm warmers
60-55 arm warmers, knee warmers
55-50 arm warmers or long sleeve jersey, vest, long finger gloves (light weight), ear muffs, knee warmers or leg warmers
50-45 long sleeve jersey with either a base layer top or a light jacket/vest, long finger gloves (medium weight), ear muffs or skull cap, toe covers, leg warmers or light weight running tights.
45-40 Base layer top with a long sleeve jersey and a light jacket, Gloves(heavy), shoe covers, pants (medium weight), Ear muffs or skull cap/balaclava
40-32 Base layer top with a long sleeve jersey and a jacket, Gloves(heavy), shoe covers, pants (medium weight), Ear muffs and/or balaclava
32-22 Still can ride starting with a base layer bottoms and pants with a wind resistant front paneling, wool socks, neoprene shoe covers, Base layer top, with jersey and coat. Heavy gloves, Balaclava and ear muffs.
22-0 Good day for the trainer and performing maintenance on equipment.