Cold fingers are sometimes just a symptom that you are not really warm enough in general. That is, if you are loosing too much heat elsewhere, it will be signalled by blood being shut down to your toes and fingers first. Try a hat and maybe even another base layer.
Next check you have enough layers on your arms and your outer layer is completely windproof.
Then check your gloves. Once it's around freezing or below, your gloves must again be completely windproof. There are lots sold (including expensive ones) which don't stop the wind at all. Stretch a bit of the material across your mouth and if you can 'blow' through the material, they will never work. They are more suited to days when it's around 10 degrees or so.
If they are windproof, check they are big enough for you. You should be able to get a thin pair of gloves on under them. But don't do this! - just use it as a measure of how loose they need to be so as not to constrict your blood supply when gripping the handle bars.
After all this and you still have problems, then you need to step up a gear on the glove front and try lobster claw or true mitts which both are warmer than gloves and ultimately try slipping heat packs into the gloves across the back of the hand. But these are pretty extreme measures and aren't normally necessary till it gets a lot colder.
and I wear Endura Tundra)
