Put everything you want to bring in a pile. Then put half of it back. It’s the cliché of bike touring and backpacking alike, but it has an element of truth to it.
I like to start by deciding what the coldest temperature I could possibly encounter and decide what I need for that temperature. For most winter trips, that means 2 layers of wool tops and bottoms (wear one, pack the other), my custom bike tights, a fleece jacket with a windproof front, my Steger mukluks, a pair of mittens, my earflap hat, a buff and my heat exchanger balaclava. If I have to stop, I add a down sweater over this to keep me from getting hypothermic while eating or fixing bikes. I bring a spare pair of socks.
It’s no secret that the low-hanging-fruit of bikepacking are the main components: sleeping bag, tent and whatever you carry them in.
I have pretty much settled on Porcelain Rocket bags for all my bikes. They are reasonably light, very innovative and uncompromisingly durable. I have frame bags for all my family’s bikepacking bikes as well as seat bags and handlebar bags that I move from bike to bike. Tania has micropanniers since a seat bag does not fit her bike.
I generally carry a backpack, but I keep the weight in it to a minimum when I have the bike to carry the heavier items. Though my backpack looks large, it generally only contains a sleeping bag, a bag of candy and my Delorme InReach.
There is no comparisson between synthetic and down when it comes to weight, down bags are much lighter, even after factoring in a dry bag to keep the down from getting wet. I find I can get away with a somewhat lighter bag than most, partly because I use a heat exchanger balaclava on cold nights (below about -20ºC). With the kids in tow, I don’t even think about scrimping on their bags.
My tent is a Hyperlite Mountain Gear Ultamid4 which holds our family of four and is lighter than most 2 man tents. For winter I will sometimes skip the net insert if it is just me and the kids, but I bring it if Tania is coming for the extra comfort of a floor. If I bring a pole and the net insert it comes in just under 3 pounds. The minimum, without the pole or insert is about 1.4 pounds.
I did a bunch of weighing of stoves and fuel last summer and now have different systems for different trips.
For trips in winter, white gas is by far the easiest to work with as well as being faster by a substantial margin than alcohol. Inverted canister stoves work down to -20ºC (some even colder), but standard canister stoves are not useful below freezing. So for winter trips I use my MSR Whisperlite with white gas.
In the summer, for trips less than 28 person-meals (about 3 days for the 4 of us) our beer can alcohol stove is the lightest option. For longer trips, the white-gas has a higher density and has a much lower starting weight. The average weight of the stove + fuel package is lower for trips of 5 days or so, but the initial weight matters to me a lot since as we eat food, my total weight goes down anyway. Canister stoves are a little lighter for long trips since their fuel is higher density still than white gas.
Though bears are few in the winter months, I am aware of several other creatures that will steal or spoil your food and so I tend to keep my food in an Ursack bear-proof bag even in the winter. So far it has resisted the rodents and weasels that have managed to make past trips less enjoyable.
On the topic of bears, carrying bear spray in a holster outside in winter means that the bear spray will get cold enough to spray almost no distance. When I carry bear spray in anything below 5ºC, I carry it inside my jacket.
For my last winter bike trip with Tadhg, my total bike and gear weight was 66 pounds to start including food and a book. For solo trips, I can easily take 10 pounds off that. Every time I think my kit is approaching light enough, I encounter someone who is running lighter still.
One day I hope to reach the point where I can keep a week’s worth of food and equipment in my pockets. I will be able to go further and faster than ever before. You will not want to stand downwind of me after a week-long trip though.