If you simplify what a shifter does to its absolute bare bones, it purely creates and releases tension on a cable which pulls a derailleur cage. Withfriction downtubeshifters, you have to know where each gear is in the shift lever's throw. Too far in either direction can lead to a noisy drivetrain, but don't stop trying! Practice is key and you will learn derailleur and lever positions to keep your bike quiet and happy.
Downtube shifters are still popular with cyclotourists because of their simplicity and compatibility. Break a cable on tour? Throw out the old one, put a new one in. Break a cable in an integrated shifter/brake lever (brifter) on tour? Break out the pliers and magnet because you're going steel head fishing. Not#bikefishing, but #aaahhhhhhhF***thisbikefishing.
Friction shifters work all of the time and are compatible with pretty much every derailleur and cassette available. Want to mix Suntour and Campagnolo? Awesome. Shimano and Simplex? Done. Shimano, Campagnolo, Simplex, Suntour, and Microshift are pretty much all cross compatible with friction shifters.
In addition, downtube shifters are excellent for travel. Packing up your bike for a tour is significantly easier than brifters and bar-ends since there are fewer cables and housing lengths to worry about while positioning the handlebars.
Scott's rando setup on his Gunnar reminds me ofLance from his USPS days. One downtube shifter and one shifter on the bars. Having a right shifter on the bar-end makes it easier to reach the shifter which is used most often.
More recently, mid-80s on, indexed downtube shifters have made sprints and climbs significantly easier. Indexed shifting means that there is a *click* in the shifter for each gear selected. You can throw the shifter around and you'll hit a gear without worrying about being stuck between them. Most Shimano shifters and Microshift bar-ends even have a friction mode in cases where the derailleur hanger is bent or indexing isn't functioning properly. Keep in mind, you need to stay within component families (Shimano with Shimano/Microshift, Campagnolo with Campagnolo, etc...) for proper indexed shifting.
Plus, downtube shifters just look damn good.
Do you still use downtube shifters or am I just stuck in the Paleozoic era?