UKH

Much of our outdoor adventures are spent in the Scottish North East and highlands between the months of September and April. I have been using my well loved -13C down sleeping bag for roughly 15 years now. Its 1.8kg and fills the lower compartment of my Osprey Atmos 65. I’ve never been cold in it and in warmer weather I open it up to use as a quilt. Great bag but would love to get the weight down. 
 

I’ve got my eyes on a direct replacement; a Thermarest Oberon -18 bag (1.2kg). But wonder if I should perhaps get a lighter and less insulated bag such as the Thermarest Parsec -6 (~800grams). This gives a warmer weather bag and a cold weather bag. 
 

So looking for some opinions and/or advice. A bag for each warmer and colder seasons? Or a one bag to rule them all? 

 I guess the classic answer is that everyone in the outdoor needs three sleeping bags: You have your expedition down bag for when it's really cold, something like a Mountain Equipment Lightline for the OMM and other occasions when weight is the issue and a three season, synthetic bag to doss in for 90% of the time when it's neither too cold or you dare risk your lightline.

Alternatively some say get the three season bag large enough so you can use the light down one inside so you don't need an expedition bag, but then some people say one Paramo jacket is all you need. They know nothing.

What sleeping mat are you currently using?

With a modern super high performance mat like a Thermarest NeoAir X-therm you can definitely get away with lighter sleeping bags than you could 15 years ago.

I'm pretty sure the additional performance means can now save c.150g on your sleeping bag and end up with similar performance as you would currently have with a much older bag/mat combo. 

As such, I'd definitely recommend looking at the whole system rather than just thinking about the sleeping bag.

However, two bags are definitely a much better option than trying have one that does everything. 

I have one bag for really cold weather that can be used open in warmer weather and one really tiny lightweight summer only bag.  

I've got two bags - a kompakt summer one c 950g and a PHD minimus 300.

The PHD goes inside the Kompakt for winter - so far been good enough.

The difficulty is the edge period between winter and summer - the PHD is a touch to cool, the extra weight of the Kompakt a mite too much.

maybe I do need three bags.....

Depends on your habits and how you use kit. Also depends on how much disposable income you have and how much of that you're willing to part with.

I use 3 bags for seasonal changes for 2 reasons. 1, I want to carry minimal weight, and 2, I find 3 bags offers me an option that is optimal for the season I'm using it in.

Have a look at the Spark range from Sea to Summit. IMO some of the best specced bags on the market right now in terms of weight vs warmth. You can pretty much get two of them and cover the whole year with a very minimal weight penalty. 

https://seatosummit.com/product/spark-sleeping-bag-spi/ 

I use the Spark SP1 for my spring/summer stuff (comfort 9c, comfort limit 5c) and paired with a decent sleeping mat I've happily used it down to 5c so far. A mate (who granted sleeps warm) has used his down to 2c whilst bivvying! It weighs 340g in a regular size.

The Spark SPIV (4) is rated to -8c comfort and weighs 880g. If you get this and either the SP2 or SP1 then you can pair them up and have a suitable sleep system for -15c to -20c comfort, whilst keeping the overall weight at 1.1-1.2KG.

It's worth pointing out that the Thermarest Oberon numbers quoted are for the comfort limit, not the comfort - this makes a big difference in terms of sleep quality. The comfort temp of the Oberon is -10c which then makes it a lot less attractive than the Spark series considering it weighs 320g more in a regular size than the SPIV despite only offering 2c more on the comfort temp - this is nearly the same weight difference as adding in the SP1 (340g) which offers far more warmth. 

The main downside of the Spark series is the thinner face material meaning you need to be a little more careful with zips and sharp things. They're also somewhat spendy but not stupidly so. 

Hope this helps  

Aye, I’m running an Xtherm mat myself which is also why I’m pushing towards a Thermarest bag to make use of the wee link system they have. I am constantly slipping about in my bag at night so see benefit in being strapped to my mat haha. 
 

I had thought that actually, the modern -6 bag might actually be fairly comparable to my current bag due to its age. 
 

@jim Lanc - 3 bags sounds like a nice place. Fits well with the kit junky in me. 

That’s very helpful thanks! I hadn’t seen the StS bags before. Good catch on the comfort numbers. 
 

Looks like it’s time for a spreadsheet....

I have multiple but really only ever use two.  My winter Rab, no idea of the model as it’s about 30 years old and my summer ME. Summer ME only gets used in particularly warm weather when I know I’ll overheat in my Rab. Or when I want to limit weight. If I use it in colder weather I’ll just sleep in more clothes to offset the lower warmth rating, plus fluffy socks are a must.

I use the Rab in virtually every other situation. I’ve very rarely found it too warm.

I work on 3 bags:
- Winter down bag
- mid-range good synth bag (mostly car camping/sleeping at mate's houses)
- Lightweight down bag for high summer/cycle touring.

Don't discount the extra warmth of adding a liner to a light bag, and/or even putting it inside a bivvy bag. I came to the liner thing quite late, as prefer pyjamas to tying my feet together.

If I was doing more backpacking, I'd swap the synth for a mid-range down bag.

Starting to look more like a 0/-6 bag will be the first move I make. Then make room for a polar bag in the future. 
 

Anybody have first hand experience of the Thermarest bags? Specifically the synergy link system? 

My issues with liners as a tosser turner is, as you say, I end up waking in a panic with it knotted around my ankles. My merinos do a decent job of keeping the warmth topped up 🤷‍♂️

I always liked the idea of a light 2-3 season bag with a bigger outer bag to increase warmth or be used as a light summer bag. Since the late seventies (Northern Lights sac) I have considered this a good idea, but could have never afforded it then and now I have a PhD minimus and cope most of the year or take extra blankets in the winter for static camping.

PhD do make such a combination e.g. https://www.phdesigns.co.uk/minim-down-overbag

I use a super light (600g) Sea2Summit bag (I think its 1.5 season rated or something bizzare) which does me well spring thru early autumn (with addition of jackets at the edges of this) and then a chunky 3-season alpkit that I can use alone or with the S2S one inside.

I like leaving the chunky one at the campsite when doing 1-night loops out - you are guaranteed a dry warm bed waiting for you when you get back no matter what happens on-route

Should have added that a liner can range from gossamer thin silk to various weights of fleece for a range of temperatures.

They also keep your bag cleaner, so it lasts longer.

Weight is not the only consideration, between Sept and April has a lot of long dark nights, when you spend a lot of time in the bag.  To save weight lighter bags are often cut narrow to reduce fabric and fill, and can be quiet restrictive for a long Scottish night.  Fine in spring when you might be up and about till 10-11pm, but in winter you could already have been in your pit for four hours by then with another eight or so to go.

Measure your current bag in terms of width and the shoulders hips and knees and compare.

Personally if I was only using late autumn to April, and I'd get one bag with a zip, good hood and collar, and a drishell type outer. An extra couple of hundred grams for the zip and bit wriggle room can make a huge difference.

Also consider a quilt. I've just invested in a Thermarest vesper 0 deg quilt ( has the synergy link). Plenty warm enough for spring /summer and comes in at 440gms. I have a M H Lamina for sub zero conditions and the idea is to combine the 2 on really cold occasions if needed.

The synergy link helps to hold everything in place as I tend to turn a lot in the night. 

I've been using an Alpkit Pipedream 600 for the past decade, in all seasons. It's a 4 season sleeping bag but I've slept in it in hot summers, in cold winters, at sea level, at altitude, everywhere. Never been cold in it, never been too hot in using it as a quilt.

Thanks all for the advice. Decided to go with Thermarest Parsec -6 and a Thermarest Polar Ranger -30. Hoping this should cover everything I’ll ever do in Scotland and beyond. 
 

Now just need them to come into stock....