Our site works best with JavaScript enabled.

Daring Deeds - real stories, expeditions, road trips and adventure

Nick’s Sleep Diary

By Nick | 14, Jun, 2013

Nick pushes his limit of comfort to the minimum on this year's Welsh Ride Thing.

The limit of comfort

I genuinely thought that the prototype sleeping bag that I would using for my mid Wales MTB trip would be just warm enough, but it wasn't until I unpacked it on a remote chilly welsh hillside with no other options to keep me warm apart from a synthetic jacket and a micro quilt, that I realised that I might have miscalculated it by a few degrees. These few degrees proved critical.

The term comfort limit is much used by manufacturers even though it doesn't have any scientific basis. What most companies are really referring to is the much more scientific sounding T Lim. The words comfort limit leads you to believe that you will be comfortable where as the term T Lim means that you are "just" not cold.

Limit Temperature (T lim)
Lower limit at which a sleeping bag user with a rolled-up body posture is globally in thermal equilibrium and just not feeling cold (related to standard man and in standard conditions of use).

After a lunchtime start and 6 hours in the saddle on the amazing terrain that mid Wales has to offer we found ourselves on the shores of Llyn Syfydrin. It had been a pretty clear day, it was certainly going to be a clear night and with a gentle breeze, just enough to take the midges away. The location couldn't have been prettier. I had plenty of calories and hot drinks and a brisk walk and a few star jumps to get the blood pumping. Then straight into the sleeping bag - 100g of Primaloft, a centre zip along with a taped shell. 

I'd picked this particular bag as I thought the night time temperatures would be about +5ºC with a small risk of a shower on the second night.

Almost from the off I felt the bag wasn't insulating, I was on a 3/4 size mat, but despite my feet being off the mat they felt warm. However it was the top half that I struggled to keep warm. After several fitful hours lying down where there was no sleeping involved I took a couple of layers off and used one as ground insulation for feet and the other used a duvet. Different parts of the body got cold depending how I lay, quite a lot of shivering, and occasionally I thought I was warm only to realise that I wasn't quite as cold as I was few minutes before. 
All night it was a losing battle, as the night wore on and as the ground got cold my feet started to feel it. But it was really the sheer lack of warmth in the bag itself meaning that I could never reach the equilibrium.

At about 3am I had to get up and go for a walk round, my shoes where already frozen. Looking at Kenny's sleeping bag there was already a frost on the bag, meaning that the insulation in the bag was retaining his heat. Mine was frost free which meant the bag was leaking heat. I was the radiator but the walls were made of paper. It was never going to work. As the sun rose I'd love to say that I stole a few precious hours of sleep but the reality was that it was warmer for me to make breakfast and get riding, the thought of brunch at a local trail center was too much to wish for. All I hoped for was that the next night would be a little warmer.

I already had a place in mind for the next bivvy, a lodge building on the edge of the Hafen forest with porches both sides, if the rain did come early, I was confident that I could stay dry, I couldn't face being wet and cold, that’s a dangerous mix. With almost an identical day behind me, great riding, perfect mountain weather and a sneaky beer with pub grub. We arrived at our bivvy stop. Hot drink, running on the spot and dived into the bag. I can say that I wasn't really warm but didn't start on this downward spiral of being cold. I was just not cold I guess I was at T lim which I think was about 3ºC warmer than the night before.

Conclusions
There are not many times you can get to analyse equipment like this. But these back to back nights really showed that once you tip over this knife edge, it is important to understand that just one degree beyond what you, as the heat source and the bag as insulation can cope with, means not being just a little bit cold but potentially feeling absolutely freezing. 

From now on I'm going to look at my ground insulation more, particularly my feet whenever it's close to freezing. The micro quilt is definitely something I'm keen to explore, I used a sleeve part so it was about a 50cm wedge, just enough to move around parts of the body as they got cold, which really suits my sleeping style. I'd take the same bag again just with a bit more thought on how to get the best out of it.

  • Google+

In pictures

No Comments

Share your thoughts about this article.

Daring Deeds

Taking on the Three Peaks Challenge
The three highest peaks in the UK in one day.
Al Humphreys - Suilven
Al Humphreys takes his new Brompton on a trip to Suilven
Rich and Tom Siepp Pre-Tour Divide ride
Rich and Tom's kit list and pre-amble for their Tour Divide route ride
The Proof of the Pudding
make sure you test your equipment
Highland Trail 550 - 2019
“Its not worth drowning to get free fish and chips” Alan Goldsmith
Body, Bike, Mind and Me: Part 2
Exploring mindfulness on the Highland Trail 550
Body, Bike, Mind and Me
Exploring mindfulness on the Highland Trail 550
Reccying The Dales Divide
The first one round the Dales Divide

More from Deeds

News

800 Mile Great North Trail Opens
New off-road cycle route
Join us for the long easter weekend.
come along and catch nature off guard this weekend.
Introducing Children to Mountains
Taking children on their first mountain experience
Glacial Retreats in Arctic Norway
Josh Leigh commences research in Arctic Norway
Ireland To Asia: A Year On My Bike
Tales from Sean Hoban's journey to Asia
Big Shakedown 2018
Round up of the Big Shakeout 2018
Alpkit Adventure Weekender
Join us in store for an adventure filled weekend
Teuchters on Tour
Fundraising cycle trip

More from News

Develop

Illuminating our Head Torch Development
Developing a new range of head torches
New UK Made Bikepacking Bag Range
UK-made bike luggage shifts up a cog
What’s So Great About Merino Wool?
What's all this fuss about Merino wool?
The low-down on Polygiene™
Wear more, wash less: you can't get simpler than that!
Designing the Argonaut Jacket
Creating premium performance without the price-tag
Branching out with the Rando Bikepacking Bag Range
New welded bike luggage
A Blank Canvas for our Tent Range
Good quality tents on a budget
Seat pack developments
2 new seat packs

More from Develop

Spotlight

Bivvying Top Tips and Kit List
Bivvy Essentials: What to take bivvying
How to choose a head torch
Buyer's guide: which is the best head torch for you?
Choosing a 4 season tent
Which tent should I buy?
Wild Camping Tips and Kit List
The guide to getting it right when camping out
The Highland Trail 550 2019
Stu Taylor returns to the Highland Trail
Long Distance Bikepacking: Highland Trail 550 Packing List
Pete McNeil tells us how to pack for endurance bikepacking events
Surviving 24hr bike races - Strathpuffer
Surviving 24 hours on a bike in northern Scotland

Be the first to hear about our newest products and promotions

Join AlpCol's Espresso newsletter for that hit of Go Nice Places, Do Good Things Greatness

CLOSE

By adding your email you consent to our terms and conditions