It looks like I get about 6,000 km of useful life out of the disc brake pads on the front of my main bicycle. That’s about 9 months for me (I ride all year round, about 8,000 to 10,000 km per year).
Two years ago I switched my Bike Friday Pocket Rocket to a disc brake on the front by replacing the fork and the front wheel. 1 1/2 years ago I received my Elephant Bikes National Forest Explorer (NFE), a low trail randonneur bike with disc brakes. 9 Months ago I switched the NFE from TRP Spyre mechanical disc brakes with metallic pads to Shimano hydraulic brakes with resin pads. These pads had now worn out, see picture above.
Along with the brake pads I also replaced the front rotor, as the old one had worn quite thin.
Most of the 7,000 km that I had done on the TRP Spyre brakes I had been using metallic pads, as the factory resin pads wore extremely rapidly: I had to keep adjusting the brakes after each Saturday long ride (typically 130-200 km). The metallic pads needed less attention but were very noisy in the rain.
My experience with the Shimano BR-RS785 brakes was much better. As hydraulic brakes their pads were self adjusting. There weren’t any noise issues. Wear is quite acceptable: One set of resin pads every 9 months is not too bad and I expect the new brake rotor will last even longer than 13,000 km / 20 months now that I am only using resin pads. On top of that the modulation on the hydros is great and they need very little effort. I could not be happier!
It is good to have real-life figures from actual use as to how quickly parts will wear on the bike so you can do preventive maintenance. It is better to replace a worn out pad at home when you know that it will be due for replacement soon, rather than finding out on a mountain descent that suddenly you’ve got nothing left to stop you!
Likewise, I regularly replace shifter cables (about once a year), before they wear out enough to break inside the brifters during a ride away from home, as happened twice to me before I learnt that lesson.
In the past I have been quite easygoing about replacing worn out bicycle chains, but a chain that has “stretched” will wear out your chain rings or cassette more quickly. Chains do decrease in robustness with increasing numbers of gears (from 8 speed to 11 speed) as they increasingly become narrower, so I will probably be replacing my 11 speed chain annually too.