I have a Nexus 7 speed I've been riding for a few months. I was thinking about chain and cassette wear recently and that made me wonder how well the planetary gears inside an internally geared hub wear. Has anyone encountered a worn-out internally geared hub?
I have 3000 miles on my Nexus-8 with no problems so far. I know guys riding SA 3-speeds that are 40+ years old. I know some guys that repair the SA 3-speeds so you CAN wear them out, I've just never done it myself -- yet.
I suspect that it depends on the hub design and quality of materials as well as the maintenance given.
Apparently early Shimano 3 speed hubs had both design and material problems which could lead to breakage and wear so many did fail in use. SA had at least one 3 speed hub design with similar problems.
If kept oiled the old SA AW 3 speeds were pretty well bullet proof.
Not sure of the current "permanently lubricated" hubs from SA, Shimano or SRAM as grease ages, hardens and gets contaminated eventually. Also hub life seems to be dependent on the torque it is subjected to. Too low an input ratio combined with a very athletic rider is not a good combination from what I have read.
In "Living With A Rohloff", a PDF downloadable from Thorn Cycles in England, it is claimed that one Rohloff hub has done 190,000 Km without a failure.