I surprised my wife with a 24" rear wheel with a NuVinci 380 hub for Christmas. We finally got everything installed and setup her 2015 Traveler on our Kinetic smart trainer today. She loves the new hub and is anxious to try in on the trails with her new 24" Big Apple. We replaced her 20" wheel and her Sram i8 hub. She always struggled on hills. TT lists the gear inch range of the Sram as 20-62 (259% range), and requires one to briefly quit pedaling with each shift of the gears. This was always a frustration for her as she climbed even modest hills. The NuVinci 380 has a 380% gear range. If I figured this correctly, with the stock 32 tooth front sprocket and a 23 tooth (pilfered from old cassette) rear cog, I believe her gear inch range is now 16.7-63.3. Once she builds some leg strength, we can move the ratio up with cog or sprocket changes. Alternately, we could add an Efneo GTRO, Patterson, or perhaps a Schlump mountain drive.
Of course, the NuVinci hub has no gears, as it is continuously variable transmission (CVT). Nothing shifts like NuVinci. It's simply seamless gear-free shifting. It's simply smooth as silk as you change gear-inch ratios by moving the rheostat shifter.
Bigger wheels are more susceptible to flex compared to smaller wheels. So, I purchased a double walled Sun Envy 24" rim and and we used 36 really good spokes. We decided on the Schwalbe Big Apple tire (24" 50-507) for several reasons- excellent reputation for rolling resistance, passive suspension, wide pressure range (#35-#70), and availability.
Now, if I can only figure out how to get the Traveler and the 559 folded and in our Prius V with enough room to cram all the stuff we need for 2 months of leisure travel across the country, I'll be a happy camper! We leave the first week of February- wish us luck.