We move deeper into the territory which this blog was designed to help discover: shit I don’t know a damned thing about.
Some reading has convinced me that these are the variables involved in differentiating one sleeping-bag from another: SHAPE – WEIGHT – SIZE – TEMP – MAKE – WATERPROOF – OTHER.
1) Temperature. That is, how cold it can get before the sleeping bag stops keepin’ you toasty. (Or, the corollary: how warm it can get before you flash-roast.)
Most sleeping-bags are rated with a lower bound of temperature. Common bounds are -10F, 10F, 20F, 35F, 50F. Any colder and you’re talking exposure suit. And warmer andyou’re talking birthday suit.
There’s also the occasional employ of the more colloquial tripartite division of “Winter,” “Three-Season,” “Summer.” Meaning, respectively, about 0F, 35F, and 50F. This terminology is disfavored because it is imprecise. Also because left-coast types buy lots of this stuff, and the left coast hasn’t had proper seasons since the Pleistocene.
I pulled a bunch of weather data for various points along the route (this is me being neurotic! this is me having fun!). Here are some of the better datapoints.
(Also, laying this out sucked, because WordPress. Bear with me.)
MAY (average high / average low / record low):
Plymouth, NH: 69/42/21
Burlington, VT: 67/45/24
Morristown, NY/Brockville, ON: 65/46/19
Ann Arbor, MI: 70/50/20
St. Ignace, MI: 60/45/x
Crandon, WI: 66/38/x
Elk River, MN: 70/46/17
Casselton, ND: 70/50
Glendive, MT: 70/45
Kalispell, MT: 64/39
Sandpoint, ID: 65/40
Wenatchee, WA: 65/45
basically adds 5-10 degrees to all totals
AS A RESULT
Statistically speaking, I am likely to encounter at least the occasional night which is in the 30s – especially starting out, where elevations will be high, winter nearest, and cruel New England undertire. It is possible, but unlikely I will encounter a cold snap of many 30 degree days. It is possible, but very unlikely, that I shall ever experience the 20s. It seems essentially impossible I will experience anything lower.
If the year is average of kindness, nighttime temperatures in the 40s will be commonplace through the month of May. Nighttime temps in the 40s and 50s will be the average throughout the entire trip.
Based upon this thinking, a sleeping bag with a 35 degree temperature rating is the bare minimum required. A 20 or 25 degree bag might also be of benefit.
1) If you purchase a sleeping pad, this can dramatically increase the temperature efficiency of a sleeping bag. This because you won’t be having your precious body heat stolen by the nasty nasty ground. Some sleeping pads are almost heat-neutral, whereas some boast a heating factor of 10 to 15 degrees.
2) A good tent will provide “dead air” of between 5 and 15 degrees of warmth, once you’ve sat in it for a bit.
3) Sleeping naked is less heat-efficient than sleeping in microfiber sleep pants and top. Which could be carried on the trip for just this purpose: one set, laundered every week or every other, just for sleepin’ warm.
All of the above, or averages thereof, are quite possibly calculated into temperature ratings assigned to sleeping bags.
WHAT HAPPENS WHEN IT GETS WARM?
I open up the sleeping bag and use it as a blanket. Failing that, I pick up a cheap blanket and use that. Failing that, I sleep under the stars like fuckin’ Pocahontas.
It seems best to purchase a sleeping bag with a 35 degree rating at minimum (maximum), perhaps as low as 20 degrees. This, and to go armed with a good tent, a mattress pad, and a set of PJs – just in case, and especially for the first week of biking.
2) Shape. Namely, whether ’tis a mummy or a caterpillar. I made that latter term up.
Mummy-bags are generally more heat efficient. This goes double for bald bastards like m’self. Probably a good idea to get – but not necessary.
Some mummy bags also have “pillow pouches,” wherein one can store a pillow – or, more easily, some wadded up clothing that shall have the same effect. This might be very nice. Otherwise, I’ll have to get a travel pillow, which is ‘nnoying.
3) Weight. Literally – how much the damn thing weighs. Important for one reason: one single ounce, pushed by human power some 10,000 miles, assumes princess-and-pea proportions.
Some sleeping bags weigh ten pounds. Some way one pound. Obviously the closer I can get to the latter is preferable. It’s not worth paying $100 for an ounce, but paying $50 for a pound might, actually, be worth considering.
4) Material. If it has its own implications. Some do, some don’t.
Down is best. 900-fill is the awesome, 700-fill is pretty great, 600 is acceptable. The higher the number, the lighter it’ll be, and the more long-lived.
Otherwise, synthetics are OK. Short-staple fills are better because they compress to a smaller size.
As far as I can tell, material really effects the temperature achievable at a given size (compressed) & weight – and price. By analyzing these factors independently, actual material is not important to me.
5) Size. The smaller the better. Because packing. Not worth significant dough to depart from the mean. But must be kept in mind.
6) Water-proof-ed-ness. Important on a planet that is mostly water.
On the other hand, my tent will be waterproof, and also my stuff-sacks. So the thing should never get wet.
On the other hand, PLANET THAT IS MOSTLY WATER. So waterproof is preferable if at all possible.
7) Weight. Lighter the better. Period.
In conclusion, what is preferable is:
A three-season (20-30 degree) bag, made of good goose-down or synth, waterproof, mummy-shape, lightweight and small.
Tomorrow I’ll go a-shopping, and see what I can see.