I will bring a Steripen in case I need to treat water.
I sure have liked mine in field practice. I use Eneloops to power it and charge them from my SON dyno/Cycle2Charge.
For the butane I was going to buy...
For the Eastern Europe part of my tour, I carried an alcohol stove as a backup to my preferred iso-butane, figuring I could power it with homebrew rakia (moonshine) found in "secret stores" along the way. Alcohol content can hit 80% in a strong homebrew. Didn't need to use it, as I found tall and short iso-butane cartridges in a Veliko Tarnovo BG hiking store that more than lasted my four-months on the road. Alky stoves can be near weightless and are small to toss in the corner of pannier, HB bag, or rear jersey pocket.
I primarily carry a self-made "penny-stove" made from a Heineken can. With all accessories (stove, penny, pot/cup with handle, lid, stand, windscreen, lighter, SA knife, P-38 can opener, pot lifter, 2 folding sporks, fuel bottle, carry sack), it weighs 460g, about 16oz. I considered it cheap insurance and have used it as my only stove/cook kit for fast, long (300k-400k) day rides and overnighters.
Best of luck and all good wishes, George, and what sounds like a wonderful tour!
Best, Dan.
The Steripen pen I have was deeply discounted by REI about a decade ago. Has an internal Lithium Ion battery. Once or twice a year, I top up the battery. Tested it a couple days ago, still works.
I have actually never used the Steripen, I bought it as a lightweight backup plan if I had to Wild Camp in Iceland a decade ago. I am well aware of the UV treatment for water systems, but the engineer in me has greater trust in a filter that blocks out the microbes that are bigger than viruses. I did not mention it before but I have yet another backup plan, theoretically two drops of chlorine bleach per liter should disinfect it, but I have used four drops to make sure if I was unsure. I bring a one ounce bottle. I was hesitant to mention, as I think that chlorine bleach is prohibited from airline transport, but I bring it anyway. There has been a couple times where I used both the filter and chlorine treatment.
https://www.epa.gov/sites/default/files/2017-09/documents/emergency_disinfection_of_drinking_water_sept2017.pdfThat said, I am certainly willing to try a Steripen as a tiny little contingency. Would probably also use the chlorine to make sure.
I think you already know that I use a Sawyer water filter for backpacking and canoeing, I put together a gravity system, takes minimal effort to filter two liters, attached photo. For those trips, I filter two liters per day, don't bother filtering water that I instead will boil (coffee, most suppers, etc.). But that is way tooooo much stuff to carry on a bike tour as a "just in case" contingency. Thus the Steripen and chlorine it is.
***
I have never had any interest in alcohol stoves, I have seen people use them in campsites. But I prefer stoves, of which I have too many to count on two hands. But thanks for the reminder of this option. I am confident that I have done enough research on where to find fuel.
The stove I am bringing cost less than $20 USD, works with both the mountaineering type canisters and the tall skinny ones. Thus by being usable by both common types of canisters, my chances of always finding butane is improved. Am bringing a cheaper stove because the UK airport security people on their website say they will confiscate any stoves that have actually been used, so if my stove does not make it back home, I am not out too much. Stove in photo attached, fuel canister is off to the right, this was on my last bike tour in Canada.
I brought a liquid fuel stove to Iceland and it was a major hassle to make it clean enough so that it would pass inspection by security, so I will never fly with a liquid fuel stove again. In Iceland I brought a butane stove as a backup and found so many half empty butane canisters left by campers before the left the country that I mostly used butane instead of liquid fuel.
https://cascadedesigns.com/blogs/msr-trip-reports/flying-with-a-camping-stoveThird attached photo is the liquid fuel stove I brought to Iceland, now it only travels by car or by bicycle, too much hassle to clean the fuel tank, pump, etc. to pass airport security. I had to keep moving the two pots back and forth for the single stove meal.