Keeping It Cool
Carrying refrigerated items on a multi-day tour is tricky even on fair weather days - and darn near impossible during hot summer rides. In my book The Grocery Store Packed Pannier, I discussed using an inexpensive Mountainsmith The Sixer bag (under $40) to carry a handful of items; a small carton of Egg Beaters, a tube of tomato paste, opened bag of bacon bits, and possibly a chunk of cheese. The reality is that 2/3 of the space was dedicated to ice - my refrigerated contents were only "lunch bag" sized. This led me to think....would adding an even cheaper insulated lunch bag ($5) to The Sixer aid both organization AND refrigeration? Would double insulation make any difference?
This idea demanded rigorous testing and careful evaluation, which I wasn't going to do. Instead, I settled for an anecdotal approach leveraging my handy dual-prong temperature gauge.
The two bags were tossed in a freezer to get them nice and cold. Then a ziplock bag of ice was added to the Sixer and the insulated lunch bag was squeezed in next to it. One probe slipped inside the lunch bag, the other outside it, between the walls of the two bags but not up against the ice. The Sixer bag with its dangling wires was taken outside for what I would call the worst-case scenario - a 90-degree-plus day with massive humidity. The temperature gauge was turned on, initially only registering that both bags were under 32 degrees, the lowest reading the gauge will display.
After about half an hour the gauge for the probe measuring only the inside the Sixer bag had already reached 49 degrees, while the probe in the lunch bag was kept to 33 degrees.
Another hour later and the inside of the lunch bag is still keeping things cooler than if just the Sixer bag was used.
Overall pleased with the results. In the field I'll add a small bag of ice to the lunch bag since that still leaves enough room for my refrigerated items. And an even larger bag of ice would fit inside the Sixer to help lengthen overall refrigeration time.