Ultralightweight 2season sleeping bag?

[lookrider]

Could I have a little guidance on a sleep bag also
I'm inexperienced bike packing but keen on a go
The bags I looked at

ALPKIT PIPEDREAM 400
£230 750fp duckdown
865g packs to 25cm. X 18 cm

ROBENS CERAC 300
£190 600fp duckdown
845g. Packs to 26cm x 16 cm

I like the shark fin boot idea of serac
Theres a couple reviews say down was coming out too easily

I learned through advice on here too take the comfort markers with a pinch of salt


I'd likely be doing bothies and non winter camping in northern England and Scotland and maybe 3-5 times a year each trip a night or two
I know there's heeps of other bags that will get recommended but I have to narrow my buying options down or else you just search and read constantly

[sean_iow]

I've got a Pipedream 600 which I've had it for 15 years, great bag and well made.

Assuming the '300' in the title of the Robens is the weight of the down (the 400 in the Pipedream is) then the Alpkit bag will be warmer.

400g of 750fp down is much better than 300g of 600fp down.

In summary - buy the Alpkit bag.

[Dyffers]

Another vote for the Alpkit Pipdream; I've had a 400 for 13 years and it's still fine, used sporadically for 3 seasons use at reasonable comfort for a cold sleeper. I can force it into a 3l drybag if I'm feeling strong but a 5l one is easier.

[lookrider]

Thanks both
The serac 300 does have 300g of insulation

Could you advise what CUIN is as a measurement
I came across it in decathlons help to buy pages

Is it the same as Fill power but a different format for ultimate the same thing

[sean_iow]

I would think CUIN is Cubic Inches, imperial measurement of volume. Normally only used these days for the capacity of US V8 engines

1 litre is 61 cu in.

[whitestone]

Seems odd that Decathlon (a French company I believe) would use imperial measurements but Cuin does look like the abbreviation for cubic inches.

Remember that fill power is how much volume a specific amount of compressed down expands into so the bigger the number the better and the more you have the warmer the bag will be. There’s a slight fly in the ointment in that the US use a different test to everyone else but just subtract 50 from a US spec to get the international figure.

[lookrider]

Maybe this screenshot helps more
Says there's 800 CUIN and relates it to " loft"
If it is 800 Fill power then that seems an awful lot for £170

[Boab]

From https://www.alpinetrek.co.uk/blog/winte ... n-grams-or

Cuin, grams or %?

There are three different criteria that should you take into consideration when purchasing a down jacket.

• fill power (also: loft, cuin)
• the amount of down
• the down to feather ratio (e.g.: 95/5)

[sean_iow]

Further googling reveals that fill power, fp, is the volume of 1 oz (us) of down measured in cubic inches.

So 800 cuin is 800fp down, except as Bob said there is a difference between US fill power and European so you need to make sure it's a like for like comparison. Further details pasted below for the geeks

Fill power measures the loft of a down product, which is essentially the quality of the down. Maximum loft occurs when the down clusters are fully expanded. The fill power rating value is calculated by measuring how many cubic inches an ounce of down creates at its maximum loft. A down fill rating of 600, for example, means that one ounce of down can cover 600 cubic inches. The process involves putting the down into a Plexiglas cylinder and slightly compressing it with a weight.

It’s important to note that fill power is measured differently in the United States than it is in Europe due to the different types of cylinders that are used. In the U.S., the cylinder has a diameter of 241 millimeters and weights around 68.3 grams. In Europe, the cylinder is larger at 289 millimeters and weighs more at 94.25 grams.

When comparing the fp between bags you also need to take into account the fabric of the bag. A bag with a heavy fabric will compress the down more so it will not insulate as well (will feel colder) compared to a bag with a lightweight fabric. If you are using it in a bivi bag the weight of the bivi will also compress the down.

[lookrider]

That's all been very helpful
The fill power of the decathlon forclaz is 800 CUIN
equivalent to 750 fill power of the ALPKIT pipedream which is about £50 more I can only assume the ALPKIT must be argued to have better finishing materials. Zipps etc
Or maybe decathlon being larger company has better buying power coupled with they " may" work out of asia ....ALPKIT are UK manufacturers and worth supporting

[Hyppy]

ALPKIT are UK manufacturers and worth supporting

I'm not sure that's accurate. They do look to consider ethics, which is obviously a good thing, but their bags are made in China.

Screenshot 2024-09-23 at 15.35.58.png (77.81 KiB) Viewed 1317 times

[Boab]

If supporting UK manufacturing is important to you, and you can pay for the privilege, then you could get a RAB.

https://rab.equipment/uk/alpine-400

Hand-filled in the UK, all our down bags benefit from never having had their down compressed before use, maintaining the down’s loft and warmth.

[Hyppy]

Or, although not down-filled, Snugpak: https://snugpak.com/collections/sleeping