When temperatures dip below 50, I add this underlayer to keep my core toasty. It also breaths well and does not collect sweat on climbs, so I never cold going down hill. I have this one and several short sleeve versions. I like the long sleeve so I can add or leave off arm warmers depending on how cold it is.
Definitely warm, down to at least mid-40's F and probably below that, yet with the dexterity needed to work the brakes and shifters. I have some XC skiing gloves which are very warm but too clumsy for cycling. And mittens, which would be even warmer, offer even less dexterity. Be aware that insulated gloves like these can't work on touch screens.