It's not always easy to get a ride or to find a taxi, especially if you're out in the woods. It can potentially be a long walk. Usually it works out, but having equipment to cope with minor errors is a good idea.
To bring along:
Hose(s), pump/CO2, an extra chain lock, chain breaker/multi tool, patches (Park tool GP-2 kit and patches of glue sandpaper from Park tool VP-1), extra derailleur hanger, some cable ties. With this you should be able to do most things. Also consider having some Gorilla tape or similar, wrapped around the CO2 cartridge. A file for holes in tires is also good to have, if the hole in the tire needs to be repaired, you can file it up. Additional, a tool for opening a quick lock on the chain to be considered. It can sometimes be included in a larger kit, but there are several options.
Feel free to complete with a tool to plug a tyre, if you drive TL (tubeless). Stan's DART is the best. Park Tool TB-2C Tire Boot, for repairing tires. An extra screw for the SPD pedal is also good to have, preferably a whole SPD block, 2.5mm HEX for the pedal and a Torx, good for opening a worn screw. Tubolito are awesome extra tubes, if you ride them, remember to bring team patches for Tubolito, regular ones won't work. One piece of chain and TWO quick-links, can solve problems with broken chain. An extra valve core and tools for these, i.e. a valve core tool. Best is Stan's.
Fluid and energy in some form, and please plan for (at least) one coffee&snack along the way. It splits the tour and is very nice. It is a good idea to bring reinforcement garments, especially in spring and autumn or if you are climbing at higher altitudes (a rule of thumb is that it gets about 1 degree colder per 200m of altitude). A warmer cap/buff and a rain/windproof jacket are golden if there is a shower or if headwinds are encountered.
Medical kit in some form, Antihistamine, Paracetamol, and Ibuprofen takes no space, once in Tuscany we cycled into a wasp nest (it can happen anywhere), antihistamine is golden. Painkillers can help someone who is in pain. Better that the med-kit is included than that it is too big. Band-aids, bandages & some kind of antiseptic tissues gets you a long way.
