I find I'm most comfortable sleeping in a bag liner with my bag opened and over me as a blanket if it's cold or under me, for more comfort, if it isn't. I'm thinking of changing to a blanket instead of the sleeping bag ... but would definitely want something warm, light, and compact, so I was thinking something like fleece might work. Advice?

I would not recommend fleece, not much warmth there. Take a look at Jacks R Better and Go Lite for some nice down or synthetic blanket/bag. I almost always recommend down over synthetic. Down is more compressible, provides higher loft per weight of insulation, has a wider temperature comfort range, and last longer than synthetic. Yes if it gets wet it looses insulation. But the chances of that happening are pretty remote in real world condition if you take minimal precaution and sleep in a tent.

Look into quilts. A backpacking quilt is basically a sleeping bag without a zipper, meant for top and side cover. The theory is that the insulation under you is compressed so not effective anyway, and those zippers are sooo heavy

Wool, like an old army blanket - packs small, insulates even if wet, warmth when you need it, and pretty durable. Use an old twin flat sheet for a liner, and you also have your light weight cover.

I had a fancy synthetic mummy bag, and it was warm. I lent it to my sister, and she lost it, and since then have been using an old military surplus wool blanket. It might not be great in the middle of winter, but for other parts of the year, it works very well. It doesn't compress nearly as much as down, but it isn't fragile either, and since it's plenty light, I just strap it on top of my rack, where the bulk doesn't matter.
If I ever do winter camping again, I'll consider buying a sleeping bag, but I may just bring more blankets, since they're much cheaper.

Quilt, thank you espuma that is the term I was searching for this morning. Search around for down quilts.

I bought a fancy mummy bag, the zipper was a MASSIVE pain in the arse... and it ended up breaking, and I found it extremely cramped. I think i might take a few of these suggestions. i just wonder about camping in below zero weather.

Thank you everybody for your advice. Much appreciated. I haven't decided what I'll do yet. The wool blanket or down quilt are two very good options but I won't need that sort of warmth for this trip. The down quilts look great since they will go down very small, but they are quite expensive. The wool blankets, while cheap, are too bulky. I want to be able to put them in my panniers and warmth really isn't all that important for this trip.

Wool or fleece are both heavy for their warmth compared to down or most synthetics.

I like a mummy bag with a long zipper. I want it to zip almost wide open. That way I use it like a quilt when it is cool and like a mummy bag when it is cold. Synthetics aren't bad and some are pretty reasonably priced.

For 3 season touring at altitudes where it might get cold a 20 F mummy bag works well. I use mine as a quilt way more than I use it as a mummy bag, but when it gets below freezing it is nice to zip up in it.

I managed fine with an $80 Slumberjack Superguide on the Trans America, but we didn't have much cold weather that trip.

If you can count on really mild weather, a bag like the REI Travel Sack +55 sleeping bag is cheap and works OK. I find it fine for colder weather than it is officially rated for. I am fine in it down to at least 40F.

BTW, on the sheet thing... On the trans America we had 95-100F+ degree days, day after day. Three of us bought one queen sized sheet and split it into thirds. Lots of nights that was all we needed and some nights we slept on top of it. I have since been leaving the sheet home to save weight though.

You can change your sleeping bag to a quilt easily if you or someone you know,can sew.If your real adventuresome,you can make one.Look at Rayway(Ray Jardine) online to get some ideas.

The wool would be heavy and would nor compress like a down sleeping bag, it can be warm and added effect that it can retain heat well even when damp but it is heavy and bulky

I thought down would be expensive too. I got pretty ruthless with myself when I was shopping for a sleeping bag tho. I live in Wisconsin. I hate being cold. There's no way I'd willingly get out of a sleeping bag if it's below 40F outside. And there's no way you'd get me to sleep outside if it was supposed to be below 40F... which tends to start happening in October, and can easily continue til May 31. June, July, August and September usually won't have night time lows below 40F (tho hitting 40F is pretty routine). So I needed a summer weight bag.

Turns out a 35F or higher down mummy bag with a full zipper can be had for under $150, sometimes under $100. I ended up with a REI down Travel Sack, which is $110 at full retail.

If I was the kind of person who actually slept warm, I could probably get away with a silk or polarfleece bag liner. Full zip ones in a mummy shape seem to run about $50. If you're decent at sewing, you could probably cut that by over 50%. In this climate tho... there's no way I could live with just a liner.

A wool blanket comparable to either option would run about $100, minimum, and depending on how big a blanket you need/want, it could easily hit $300. I'd also pitch a fit the moment it dropped below 60F if I just had wool. Wool tends to be warmest when it's in carefully engineered fabrics, and most wool blankets are not designed for warmth.

Jacks-R-Better

Kifaru Woobie

If you are in mostly warm weather the US Military produces something called a poncho liner, or "woobie". Trust me, infantrymen get so attached to them they steal them from the service and keep them when they get discharged. It is basically a fairly thin insulated comforter in camo that is intended to go underneath a poncho to use as a waterproof sleeping wrap. They keep you surprisingly warm. On a warmer note, you can do the same thing with a thicker quilt.
I wouldn't suggest wool blankets or the like. They work, and work well, but are heavy and bulky in comparison to some of the newer things you can get.

For camping/backpacking (no cycle touring yet) I've used a 30 degree down mummy bag, a Hudson Bay wool blanket, a 55 degree poly fill travel bag, a homemade 45 degree poly quilt, and two cottage-gear-maker backpacking quilts: one 40 degrees and one 30 degrees.

All except the 30 degree quilt open out flat and that item just has a footbox built in. I hate sleeping in a bag, I like to have my arms and legs free to flop around where they will.
The wool blanket weighs far too much and not as warm feeling as any of the others. However, it will not melt when using it around a campfire. It stays home since it is unless I go car camping and want to be all cool and retro.
I rarely use the mummy bag anymore since the 30 degree quilt is warmer and compresses to a smaller package (higher quality down fill) and weighs slightly less since it does not have to completely enclose me as the mummy does and does not have the never-used zipper.
I've slept under the 40 degree down quilt (with extra clothes) to 31 degrees.
The home made poly quilt is OK, but it does not compress very well so it stays home. It is also heavier than comparable down items for the amount of insulation (how cold can I go) it provides.
The 55 degree poly bag unzips into a quilt-like item. It is perfect for central valley (california) summers.

I would suggest a backpacking quilt, a fully unzippable sleeping bag, or a woobie. All of those items will compress nicely: better than a comparably warm wool or fleece blanket. Down or poly is up to you. I prefer down since it "feels" warmer to me than poly. All in my head, I know!
Don't forget to insulate yourself from the ground as well!

here's a little link to show some kifaru stuff
https://www.asanacycles.com/Asana_Cyc...al_Forest.html
and the Kifaru Woobie compress down pretty small.

https://www.kifaru.net/woobie.html

That's not small,

THIS is small! 40 degree, 700 fill down sleeping bag. 20 ounces of warmth in a grapefruit sized package of warmth.

the OP should be able to get about the same type of weight from a semi rectangular bag from western mountaineering or marmot, or a topquilt from one of the prolifigate boutique makers out there.

This is a highly individualized topic. I'm fine in a mummy bag, but my daughter vehemently hates them (as do lots of people.) The sleeping bag's suitability depends a lot on the conditions you'll encounter. My last bag (synthetic) started out plenty warm, but lost some insulating properties over the years. It was fine during summer trips, but I went on a short tour to Zion Canyon in the spring where it got down to freezing, and I was cold! I put on every article of clothing I had brought with me (not comfortable) just to be barely warm enough. So I bought a down bag with more warmth.

Before I left on this summer's tour I debated which to take. The old bag would have been fine during the warm summer months, but after my experience at Zion I opted for the warmer bag. I'd rather be too warm than cold, right? It worked fine, although there were some times I woke up sweating.

Although I primarily use a Nunatak Arc Alpinist down quilt on my bike and kayak tours, I have used the Kifaru Woobie in warmer weather and found it very effective, durable, versatile and warm. Just another option to use as needed.

down vs synthetic
cold when wet, still stays warm when wet

I've used that Kifaru stuff down to 34F without a problem, even when wet it still stays warm
I choose synthetic simply for the wet factor

Man you've got me looking at the Kifaru website and lusting after a paratipi and little stove now.
Have you ever tried their packs? A friend of mine when I was in Afghanistan used a Pointman and loved it.

Western Mountaineering sells exceptionally lightweight expedition quality sleeping bags & they also have a down comforter that is extremely warm. However, I would recommend one of their semi-rectangular bags that could be unzipped and used as a comforter for warm nights. If it gets extremely cold you'd have the fall-back option of zipping up.

have not used their packs...yet.

I've got a bunch of Kifaru stuff on my website
www.AsanaCycles.com

Polar fleece wont compress much , down compresses a lot, Synthetic Fiberfill is in between.

this a tapered foot quilt. and the insulated sleeping pad you will have are reasonable
https://www.nunatakusa.com/index.html they have kits where you would wear your Down Coat
and just bring the bag for the waist down.

or the pad sleeve and bag/quilt combo :https://www.campsaver.com/itemmatrix....8&MatrixType=1