I'll soon start a rather long trip from Ushuaia in southern Argentina to Alaska in the north of North America. As I'm from Europe (France), I don't really know what to expect about spare parts for my bike in South America.
I'll ride a Kona Rove ST, a gravel bike with 650b wheels and 47mm wide tubeless tires. The train is 1x11 SRAM. How easy do you think it will be to get new tires, gear parts, tubeless sealant and other spokes?
I have around 1 year touring experience in South America. Mostly remote dirt roads and trails.
I would never ever purposely run tubes again.
As long as you are confident in your tubeless setup flats should be almost nonexistent. I only carry one tube for emergency that has never been used. A small bottle of spare sealant is pretty essential to top off if you start to get small air leaks. Needle and thread to sew small cuts, as well as tire plugs. A few patches if you are forced to use a tube.
All decently large size cities in Chile and Argentina should be fairly well supplied with bike parts (somewhat less so in other countries in my experience). If not, then it is usually easy to travel by bus somewhere bigger. If you are in big cities (especially capital cities) can be good to stock up or change parts, especially if you are headed to remote areas.
Tubeless sealant is becoming more and more ubiquitous, especially in MTB communities. Usually these guys are not running tubeless specific tires, and they make it work. 650b mountain bike tires will be easier to find than road or gravel tires (could be an issue, not sure what tire clearance a kona rove has?).
SRAM parts can be much trickier to find than Shimano. Old shimano standards are king. Dub and GXP bottom brackets/chainrings could be difficult (especially 1x). I believe Peru only recently has an official SRAM importer.
I would carry plenty of extra brake pads, they are light and depending on your brake model could be difficult to find.
Generally just keep an eye on parts. Be religious about cleaning and oiling your chain. Have a good idea for what is wearing and when you might need to replace it, and plan ahead.
I've just returned from several months touring in South + Central America. Tyres for 27.5" and 29er were the most common, and generally easy to find in cities or larger towns. I was running 700c and had difficulty finding decent tyres for this size (coudnt use 29er due to clearance issues).
Spare rims/hubs for anything upto 32h are also readily availible, however, as I found out in Mexico, spares for 36h wheels (rim/hub) are very hard to find, and only availible in major cities.
I was running 10 speed, gf running 9 speed - parts for these drive trains were generally easy to get hold of. I cannot comment on availibility of 11 speed components. I would recomend taking a set of friction bar end shifters for emergency use of you break a gear shifter.
Definitly take some spare brake pads - these were very expensive (often 3 times the price in the UK). Given they weigh very little, its worth taking some just for the cost savings, and they can also be hard to find outside of cities (depending on which ones you need).
I was using inner tubes, with several spare tubes on hand, and lots of patches! I would usually get a puncture every 300-500 miles on average, although some days would see multiple flats. I was glad I didnt go tubeless though, as my tyres picked up numerous cuts that definitly would not seal with sealant. I also met other cyclist who were having issues with tubeless set ups and finding hard to find replacement sealant. If you do go tubeless I would take at least 2 or 3 spare tubes for back up.
Make sure you know how to fix your bike before you head out, you need to be fairly self sufficient with bike maintenence. For anyone from Europe, its hard to comprehend how remote some of these places are. For example in Alaska and Canada, we regularly cycled several hundred miles between bike shops (on the Alcan), and there was no bus service or anything along this stretch. Similarly for parts of Patagonia and Northern Argenina - we cycled several days between bike shops or larger towns.
Finally, if you do pickup a serious mechanical, most people drive pick-up trucks and its usally possible to hitch a ride to the next town. Hitchhiking seems extreamely common in Argentina and Chile!
I suggest you plan your route through as many of the significant towns and cities as feasible. Then google up the addresses of bike shops in each town, and save that list somehow with you, either on thin paper or on your phone.
And you should carry everything you'd need to do a basic roadside repair and maintenance. Tools would be a decently specced multitool+chaintool, as well as cassette lockring tool and a lever for it (for spoke replacement).
For consumables, I'd suggest carrying this on your bike all the time: three tubes per bike, a pack of sticker patches, chain lube, one spare gear and one brake inner cable, four spare spokes and nipples, chain master links, and cable ties and some suitable spare bolts. Perhaps one spare chain in the group for emergency.
Expect do a significant overhaul at least once on your trip, where you replace brake pads and all cables and so on, but that would be in a town or city not in a little one-pub town or worse on the side of the road.
