Saw this over on the BikePackers magazine blog by Jefe Branham. Looks like his TD sleeping kit for this year is sorted:

http://bikepackersmagazine.com/jefes-bivy-bag-project/

[Also featured on the front page is an Alps bike packing trip by some bloke called Gairy]

That looks like a really good idea and well executed but looking at the picture below, I can't help wonder how much of a gap there is berween the insulation and the mat (or where the mat will be)?

That looks, erm, cold

I'm slightly intrigued by the concept of "waterproof breathable cuben"...

I've not googled it yet, but my understanding was cuben was very unbreathable?

In this pic it seems the insulation and the pad meet, but perhaps some overlap would be better to eliminate a cold spot/edge?



It's very comfy in this armchair

Standard Cuben is obviously not breathable but there's a new type that is a bit breathable, I've never seen an figures on permeability rates though.

Zpacks use it to make jackets and sell it by the half yard!