Bikepacking and wild camping, with the best will in the world, can be a damp business and for that reason we have always preferred synthetic sleeping bags. Down, once wet, has a habit of losing the bulk of its insulation properties (unless you go for one of the moisture resistant fills that lasts longer in wet conditions) making synthetic a good idea. The downside is a slightly bulkier pack size and higher weight (for the warmth), but it's a worthwhile trade-off it if you're regularly wilding it in iffy conditions.
This excellent offering from Vaude is rated down to 1 degree centigrade in comfort and sports many features that make it a good option for bikepacking. A zip opening for arms adds not only the ability to sit up and cook or read from within the cosy cocoon of your sleeping bag, but also a degree of temperature versatility to the bag - when too warm we tend to just put our arms out when sleeping to lose some heat. A stretch panel for the knees also allows sitting up without tensioning and crushing insulation - again, handy for sitting up in the bag - but also good if you tend to assume the foetal position while sleeping.
One complaint we have is a relatively trivial one - the stuff sack uses a roll top and webbing loops to secure it which was a pretty inefficient and fiddly way to pack and unpack. We would much prefer a straightforward drybag approach with roll top/clip, so we spent an extra tenner and bought one which made it easier to compress the bag, and is waterproof to boot.
Overall, a great sleeping bag with extended functionality like zip out arms and stretch panels for movement, but we would have liked to see more thought given to the stuff sack.
