Gear reflections: sleeping

Sleeping bags: Cumulus Quantum 350, Alpkit Pipedream 400

Ok I’ve got too many sleeping bags, seven at the last count (five down, two synthetic). On this trip I used two, the Cumulus Quantum 350 (just purchased) and the Alpkit Pipedream 400. The Quantum was used in the fells and the Pipedream at base camp.

At £250 list price (I bought mine for £220 from, the Quantum 350 is nearly double the cost of the Pipedream 400 (£130). I must give a little plug to They were very efficient. I rang them to see whether the Quantum was in stock. They took the order over the phone and it arrived (free P&P) the next day, less than 24 hours after placing the order.

Quantum 350

The down quality in the Quantum is higher at 870 vs. 750 fill power, but there is slightly less 350g vs. 400g. Calculating the fill volume, the Quantum is marginally higher at 10,150, compared with the Pipedream at 10,000 (how to calculate fill volume). The total weights are 727g for the Quantum and 740g for the Pipedream. It’s important to note that the weight advertised on the Cumulus web site is a very optimistic 665g. The swing tag claimed 695g. I’ve posted on this before, but I think it is very poor that manufacturers advertise inaccurate weights, when the weight is part of the selling proposition.

Quantum 350

On weight and effective loft, the bags are quite similar. However, there are some significant differences. Firstly, the shell material of the Quantum is Pertex Ripstop Quantum, which is a beautiful silky material. The Pipedream shell is a fabric from Toray. While it is perfectly pleasant to the touch, it is not as smooth as the Quantum. The Pipedream feels functional, whereas the Quantum feels luxurious. Interestingly, the Pipedream uses slightly lighter fabric (29gm/sq.m) compared with the Quantum (34g/sq.m).

For me the silkiness is important. I’m a side sleeper and tend to turn quite a lot in my sleep. In the Pipedream the bag tends to grip and turn with me. On the other hand, the Quantum allows me to turn within the sleeping bag, which I prefer. It also has a better “drape”, making it feel warmer.

Quantum 350

The second difference is the baffle construction. The Pipedream has a box wall construction throughout. Occasionally cold spots where the down is thinner develop. In contrast the Quantum has a trapezoidal baffle on the top and box wall on the base. I’ve found that trapezoidal baffles (also on the Cumulus Ultralight 350) to be very good at eliminating cold spots. Because it is easy to turn within the sleeping bag, I can also keep the trapezoidal baffle on top of me.

The different material, the drape and the baffle structure of the Quantum makes it feel a slightly warmer bag, in my view. I am sceptical about it being a -6c bag, but I sleep cold. I would expect it to be OK for me to slightly below freezing, but I can’t confirm this as the lowest night time temperature was +8c. The cut of both bags is quite similar.

The Pipedream has a generous neck baffle, whereas the Quantum has a small neck warmer baffle on the top side. I found the Quantum baffle to be adequate but the Pipedream is functionally better. The draw cords in the Pipedream are simple cord. The Quantum has elasticated draw cords, which I prefer.

Pipedream 400

Another reason for buying the Quantum is pack size. I found my Ultralight compressed to a smaller volume than the Pipedream. This is also true of the Quantum, which compresses to a smaller volume. I did find a couple of small irritations with the Quantum. Occasionally the zip would dangle in my face and I had to tuck it behind the zip baffle. The bag also had a slight smell of damp feathers (it wasn’t damp though).

Overall, I am pleased with the Quantum 350. It is a very pleasant bag to sleep in and compresses well. The colour is an attractive electric blue with a silver inner lining. Is it better than the Pipedream? There’s not much in it. The Pipedream is much better value, but I like the baffle design of the Quantum and the shell material is more to my liking. It will probably be the bag I go to first from now on, except in high summer or winter.

Sleeping mat: Exped Downmat 7, POE Ether Elite 6

I used the Exped Downmat 7 for base camp and the POE Ether Elite 6 on the fells. The Exped Downmat remains the Rolls Royce of mats. It is supremely comfortable and warm, but at nearly 1kg, it is more than double the weight of the Ether Elite.

The Ether Elite is now my mat of choice for backpacking. At 390g it is amazingly light for the comfort it gives. It also packs down to a very small size. I’m constantly surprised at how warm it is. I’m a huge convert to air mats as they are so much more comfortable than foam or self inflating mats. They do a great job of ironing out lumpy pitches.

POE Ether Elite 6

I thought the NeoAir was good but the Ether Elite suits me even better. One little tweak is to apply some lines of tent seam sealant to the underside of the tubes to give some grip on the groundsheet. The Ether Elite has some competition, though, if you are watching the pennies. Alpkit have launched the Numo, which is a bit heavier at 505g, but cheaper at £40. It is also slightly more generous in dimensions and doesn’t taper quite so much. I’m not going to buy one, but if you are in the market, it’s worth considering.


10 thoughts on “Gear reflections: sleeping”

  1. Robin regarding the total potential loft did you take into account that Cumulus use the US fill power rating which gives a slightly higher figure than the EU method that Alpkit use?

    1. I didn’t I just used the figures on the Cumulus web site. It’s not clear to me on the web site that they use US fill power although they use a US lab for testing. The fill volume of the Quantum is definitely 10,150 (on web site). If you add 100 to the Aplkit fill power (i.e. 850 rather than 750), then the fill voume is 11,330. My observation is that the fill volume is very similar for both bags. The down in the Quantum feels higher quality than the Alpkit down. If you read the Facewest explanation of fill power , the calculation used suggests that Cumulus are using the European method.

  2. I’d take that if the down is measured in a US lab it’s rated to US standards. I did e-mail them on the subject prior to finding out on their webite that they used a US lab but they didn’t reply.

    I agree about the ‘feel’ of the down used in the Pipedream range, it doesn’t feel as soft as that used in my Minim 500 although it doesn’t appear to affect performance to any great degree.

    1. I agree that it makes sense that a US lab would use a US fill power number, although it is “the International Down & Feather Testing Laboratory” so it might use the more internationally accepted European measures. It is a bit poor that Cumulus didn’t reply to your email.

  3. In the end specification is only a guide, if the bag is warm enough it’s good enough. Re. the e-mail, these things happen from time to time, I’ve had unanswered e-mails from companies who had previously always replied so it’s possible that they (Cumulus) simply didn’t get it.

    1. The Quantum bags are made by Cumulus in Poland. There used to be a UK company called Cumulus selling these Polish bags but they changed their name to Criterion. Some of the bags are identical to the Polish ones, some are specced specifically by the UK firm – but they use same materials like Pertex Quantum and the down, and use the same construction methods. But for some reason Criterion (was Cumulus UK) like to stretch the specs like using different temp ratings to make them look like they go colder and it looks like they use a different down rating system. So the EU site uses the EU cuin ratings. As far as I can work out, the UK Quantum bags are based on the Polish LiteLIne ones which use 850cuin. So I think the quoted 870 is probably EU 850 cuin.

  4. Robin – I have the 400. I agree with you that the bag tend to stick to you and I turn a lot at night and the bottom finds its way to the top and vice versa. ( happened last night on a overnight in the Southern Uplands). I am interested therefore on you comments re the Quantum. Apart this minor issue, the Alpkit bag is outstanding value – I only paid £95 3 years ago at the Outdoor show – so great performance for the price.

    1. The Pipedream is great value and is a very well made bag. The two advantages of the Quantum (as I said) is the cover material and the trapezoidal baffles.

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