If I was going to outer Mongolia with a derailleur bike, I might bring one friction shift lever that could be installed on a downtube boss by removing cable housing stop. If you really wanted to get something like this, see if any local bike shops that work on older bikes have a bucket of old parts in the corner. Low cost shift levers off of a 70s bike might fit the task nicely.
Originally Posted by
3speed
I have a friend with SRAM Double Tap shifters who is carrying a spare bar-end shifter on our Europe trip. One of those doesn't weigh much, so I suppose if it puts your mind at ease and worrying is an issue...
The advantage of a vintage friction shifter on a downtube boss instead of a bar end shifter is that bar end shifters may need a longer cable and housing. A downtube shifter can be used with a shorter cable and without additional housing.