It is probably best not to consider a sleeping bag as your only bedding, but consider it to be part of a ‘sleep system’ incorporating liner, pyjamas, down blanket or clothing for additional warmth in the colder months. The type of mat you use will also be a factor in how well you sleep and how warm you are.
The starting point is your sleeping bag. The kind that offers the greatest warmth compared to its pack weight will always be a down filled bag. Unfortunately down bags are more expensive, but the weight and bulk difference between down and synthetic filling can be considerable. Goose down provides better insulation than duck down and is consequently more expensive still. It is possible to find cheap goose down bags though, ours (below) cost just £55 each in 2017, bought from an eBay seller who was off-loading bankrupt stock.
These sort of bargains are hard to predict, but you can find them sometimes on eBay if you are patient. When searching for a down bag in this way you should be wary of any that say they have been stored in the stuff-sac, as this can damage the ‘loft’ of the bag and damage the heat retention properties. People seem to add ‘has been stored in its stuff sac since day one’ as some sort of selling point, when in fact it is the opposite. Down bags should always be stored hung up, fully unpacked.
Make sure you know the weight of the bag before purchasing – they vary enormously. Ideally you would choose one with hydrophobic down filling, meaning it had been treated to minimise moisture absorption, but as this is a fairly recent innovation these tend to be more expensive. It’s not essential, but it is nice to have as it means a warmer night and a lighter bag to carry in the morning, it also should mean less airing to prevent it going smelly on longer trips.
We use 3 season bags weighing around 900g. Obviously the warmer the bag, the heavier it will be, but some bags are heavy because they use cheaper material, zips and so on which add to the weight. Have a look at the stated weight of the fill and not just the bag. There are a lot of Chinese manufacturers selling very cheap down bags now via eBay or Alibaba. Some people say they are great, but you should be wary of stated weights, temperature ratings and fills. If your budget is very low and you have time to wait for them to arrive then they can be a good option though.
It is very difficult to accurately measure and compare sleeping bags using the stated temperature ratings as these can use different benchmarks. I find it better to look at the weight of down in the bag plus the fill power. Fill power is a measure of the fluffiness of the down – the higher the better. Sometimes this is referred to as ‘fluffy force’ by Chinese vendors. Our 900g sleeping bags have 400g of goose down inside – most bags made with lightweight materials will have a similar fill ratio.
Update 2019: I recently upgraded our sleeping bags to Mountain Hardware Phantom Flames, bought from Rock and Run for the excellent price of £190 each. I partially funded these by selling our old sleeping bags on eBay for nearly twice what I paid for them. The new bags contain 170g more down than our previous ones but are only 100g heavier. They contain 570g of 800FP down in a 1kg bag. They are a step up for us as they are filled with hydrophobic down and have a full-length zip, which makes them easier to use as a blanket when too warm. We have only used these a couple of times so far, but I have been very impressed with them. They are extremely warm, but as a cold sleeper, that’s how I like it. I will review them here in full once we have had chance to try them out properly.
You should always use down sleeping bags in conjunction with a liner as down is challenging to wash. We use a thick liner in cooler weather and a thin, lighter weight one in summer. For a thin lightweight liner that has a very small pack size and is quick to dry once washed, silk or faux silk is the best choice. The cheapest silk liner I have found comes from Decathlon at £25 each. Faux-silk liners are about half this price. We have one of each and to be honest I can’t tell the difference, except that the real silk one has ripped, whereas the faux one hasn’t. Both weigh around 150g. If the weather is very hot then you can unzip your sleeping bag and use it as a blanket over you inside the liner or just sleep in the liner alone. For colder times we use Lifeventure thermolite liners. These are a sort of stretchy t-shirt type material but perhaps lighter in weight. I don’t think they increase warmth by as much as is claimed, but they are still very cosy. They weigh 370g each and cost me about £12 each new on eBay, though they seem to be about twice that price now.
We have a down blanket each which we use to top up our sleeping bags in cold weather. They are fairly bulky and weigh 450g each, so they only taken with us on short winter trips. I have successfully used one of these on its own as a very lightweight sleeping bag in hot weather. Ours were from eBay at £20 each, but down blankets/quilts can cost many times more than that. Ours were a type that used to be sold by Costco as a down throw. You can still find them on eBay for around £25 by searching for ‘packable down throw’. They are large enough for two friendly people to share one to save weight. They will slip off in the night if you don’t fix them to your sleeping bag somehow (see below for a solution).
We also carry a Thermatex blanket. It is some sort of space-age fabric that is very thin and lightweight and also very warm. Measuring 1.6m x 2m and made from aluminized woven rip-stop nylon fabric it is highly breathable. The manufacturers claim it reflects 75% of radiated body heat. It comes with us more than the down blanket as it is much lighter and a lot more compact. It weighs only 200g and would just about fill a coffee mug I think. As a cold-sleeper I pretty much always carry one of these with me. It has saved me from many a sleepless night spent wide awake and shivering. They are quite expensive at £45, but you will occasionally find them second hand on eBay. As with the down blanket, it is essential that you fix them to the sleeping bag somehow to prevent them slipping off in the night.
To prevent our down blanket and Thermartex blanket slipping off us in the night we use these tiny pegs/clips to attach them to our sleeping bags. They weigh almost nothing and are ridiculously strong – despite their flimsy appearance we have never had one snap on us yet. Once you have some you will find yourself using them for a vast number of things, such as hanging out laundry, keeping food packets closed or pegging your led light string up on the inside of your tent. We usually take about 20 of them with us on a trip, with a weight penalty of only 26g for the lot. They measure 26mm x 10mm. You can find them on eBay by searching for ‘quilting wonder clips’. You can get 100 of them for a fiver.
Pyjamas and other clothing
We use merino wool pyjamas as they are very warm without causing you to overheat, lightweight with a small pack size and are naturally anti-bacterial so they don’t go smelly for ages. If you chose well (ie dark leggings and a plain top) then they come with the added benefit of being clothes that you can wear outside to ride or socialise in if the need arises (ie when you want to wash all your other clothes on a long trip, but don’t want to sit naked in the laundrette).
We also sometimes wear our down jackets to sleep in when we have been caught out and it is colder than we had expected and packed for. Once you can wrap your head around the idea of wearing your coat to bed it makes perfect sense – it is just an extra layer of down after all. This is very effective way to boost the warmth of your sleeping bag with something that you will carry with you anyway. Our down jackets weigh 200g each and are one of the most useful, versatile items we carry. Cycle clothing isn’t very warm once you stop riding, but pop your down jacket on over the top and you will be toasty in a matter of seconds. They also act as a replacement for a bulky, heavy fleece or jumper in our ‘civillian clothing’ setup. A down jacket is a bit of a lifesaver and considering they pack down to something around the size of a tin of beans and weigh only 200g you would be daft to leave home without one. It’s miserable being cold, so don’t risk it.
We use Exped Synmat HL M mats – they are tough, hard-wearing and lightweight with a small pack size but most of all they are very comfortable. They weigh just 365g. We used to have the down-filled Exped mats, but I don’t think it actually made much difference warmth-wise in exchange for much greater extra weight and bulk. Here are our mats packed – Tunnocks tea cake for scale….
….and pumped up ready to use… the yellow bag is the ‘schnozzle’ pump. It is also a useful lightweight drybag for keeping your gear dry en-route.