Gorblimey! He don' arf know owto natter dunnhe?

I have a fleece neck gaiter from Columbia. I wear it round my neck and pull it up the back of my head to cover my ears, leaving the rest of my head bare (under the helmet) to keep from overheating. If I get too hot, I can pull the back back down without stopping to cool off, or pull the front up to cover my mouth.

I have a skull cap with ear flaps, it's lite weight so it doesn't get too warm but keeps the wind out. I also have a helmet cover which helps keep the wind out and keeps my head warmer. (bald)

Check out Earbags. I like them a lot for running and biking. Keep your ears warm without soaking up sweat from your forehead or interfering with your helmet fitment. https://www.rei.com/brand/Earbags

+1

I don't have that exact model but I have a simple Pearl Izumi headband that is good down to the 20's. When it gets colder (and I have 5AM wet hair from right out of the shower onto the bike) I wear a slightly heavier headband from goretex and a goretex helmet cover (good to at least 8 degrees (tested last winter) - probably colder

I enjoy using my Buff. Very versatile for cycling and other outdoor activities.

I use a balaclava, my girlfriend uses knit headbands (wool?). She knits them herself, they are fairly wide. For my climate a thin balaclava is plenty, the thick ones for motorcycle use are too warm. Headband isn't a bad idea for guys either, (I used to wear one when I had long hair so it doesn't seem odd to me, besides you're all Fred'd out anyway right?) I just haven't found a helmet cover I like and so the balaclava keeps the top of my head warm from the cold air coming through the helmet vents as well as keeping my neck, much of my face and my ears warm. I need to find the time to make my own helmet cover.

Some helmets , like Bern, perhaps others, offer a winter kit that includes ear muffs.
they have ski-bike -skate markets in mind .
consider a helmet for the winter, and another for the summer
(if you wear helmets)

VeloMuffs work great and the price is right.

Smartwool skullcap 100% wool. check online for best prices wash as needed and does not retain stink as poly does over time

+1 And I use a headband w/velcro clasp purchased from Target a few years ago. Got several of them for about 3.00 per as I recall. They keep my forehead warm at the same time. Do like the looks of the earmuffs posted here, though.

I have used a balaclava, skull cap and buff as needed. This winter I have used my helmet cover almost every day on my commute. It is bright yellow, so it helps with visibility. It has a loop that will support an additional light. It probably doesn’t do much to keep my ears warm, but it does cut down a little more of the air that would normally move through my helmet.

Ear warmer in your choice of fleece (my favorite) or neoprene.

That's what I did when militantly car-free and living in Colorado with occasional sub-zero temperatures.

If it's not too cold to ski, it's not too cold to bike and many of the same solutions work.

Nutcase now offers Ear Pads for the Street helmets, if you are into getting a new helmet. My girlfriend uses them with her helmet, And likes them a lot. That only works if you want to get a new helmet to. Nutcase has lots of cool designs for their helmets.

I use a Buff my self right now. I have very little space for extra, Big head, only to "clicks" extra room with my Giro helmet. But I would like to get a SmartWool Headband. I have tried it on and it seems to work well with a helmet.

I've looked at both the Bern and ski helmets and thought they were a good idea until I realized that mounting a helmet light to one would be very difficult.

Ski helmets also suffer from being too warm. While they would be nice for a 20 degree commute, they would be way too hot when the temperature rises to 40, 50, 60 or even 70 which is always a possibility around here.

Take a look at helmets like the Giro Fuse Ski Helmet. The GF has one.
It has a set of vents much like a bike helmet, with a sliding button which opens/closes the vents.

Saw one this weekend. Nice idea but the sliding closures would interfere with a helmet mounted light.

I also used two buffs. One around my head made into a beanie. It fits perfect under my helmet. I also keep one around my neck that I can pull up and over my face and ears.

I fold a bandana in half and tie it around my head so that the knot sits lower than the back of my helmet and the front is even with my helmet. I find that this deflects the wind from my ears quite effectively, but does not cause me to overheat.

When it gets colder I wear a fleece headband, but it's too warm for that this time of year so I stick with just the bandana until the temps drop below 15ish.

For my face, I wear a beard which is surprisingly effective at keeping me warm.

Giro fuse is the one I use for winter, under 20F. It's remarkably warm. I keep the vents open almost all the time. when it get's down to 0F I add a thin balaclava. Oh and it would be hard to mount a light on though.

I use ear warmers by LG. Fits nicely under my helmet and keeps my ears nice and warm.

I made something similar to these Dog Ears out of some fleece. I sewed it into a couple of triangles that slide over the buckles and straps on each side. Works perfect. No more overheating from a full hat under the helmet and my helmet fits way better than it did when I tried the head band style ear warmers.

I have a Sugoi insulated cycling cap. Helmet-wise, without it, I could actually fit in either a medium or large Specialized Prevail, but with the cap, I have to use a Large. So, and because I often wear caps even in the summer, I got the larger size of helmet.

Go to the MEC store or MEC.ca and check out MEC's Bolt or Charge toques or the CTR Mistral Vapor skullcap. They're all very thin but warm as helmet liners and the latter two offer very good ear coverage. Bring your helmet to check the fit.

Slipstreamz for cool or borderline freezing weather. They fit on your helmet straps and are designed to muffle noise but also provide a nice thin shield against wind thereby keeping your ears warmer.