just reread and saw the bike model, its with 42t front and 19t rear,
with 700x32 tires, the 8 speed alfine gives 31.5 g.i low and 96 high.
31.5 would be horrible touring with, to give you an idea, in 1990 I bought my first nice touring bike. It had a low gear of 25 g.i. , not that I knew that at the time, and on my first tour with 4 panniers, tent , I went somewhere with steep long hills and it was very unpleasant.
I had to push up hills sometimes, and I had a knee problem.
after that trip, my bike shop explained to me how to change to a smaller "granny " gear, the small one at the front, from 28t to 24t, and showed me charts to see the actual "gear inch" change. It went from 25 to about 21 g.i, which on my next trip the following summer made all the difference.
I could ride up hills, I could downshift sometimes to my lowest gear and my knees thanked me.
years later I had a bike with 19.5 g.i. easier still on super steep hills or when tired.
years later, set up a bike with 17 g.i, easier still in super super steep hills and when tired, sure I didnt use it that often, but man its nice to have it.
and to repeat, this doesnt affect your average speed at all.
so bottom line is that you may want your partner to load up some panniers on the bike as it is, and go ride up hills to see how it is, and to see that 31.5 g.i is pretty bad for touring in hilly areas.
personally, pushing a bike up a long hill is not my idea of fun, but some dont mind. The problem is with a bike with not low enough gearing is that you tend to "try to ride it out", forcing a lot , so not great for the legs or knees.
there's a reason the old "20-100" range for touring is still a good real life range.
Im fairly certain that you cannot change the chain ring or rear cog very much , as it goes past the limits set by shimano, and can cause too much strain on the innards of the hub. You'll have to read up on it, but its fairly well known that these hubs are limited to changes that arent ideal for touring.
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Fully agree.
My expedition (Rohloff) bike has a range of 16.5 to 86.5 gear inches when I put on the 36T chainring that I use for touring. (Around home while riding unladen, I use a bigger ring.) At times I spin out on the downhills because I lack the bigger gears but I do not want to give up the low gears, so I just put up with the lack of higher downhill gearing.
My two derailleur touring bikes have ranges of 19.2 to 106.8 gear inches on the 26 inch wheel bike and 20.7 to 115.5 gear inches on the 700c bike. These ranges are in the ballpark of your suggested 20 to 100.
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Im pretty certain that a rohlof has a stock low of about 19 g.i.
The hub typically comes with a 16T sprocket, but the bike builder supplies the chainring. Thus there really is not a stock Rohloff low gear, you (or the bike builder) choose your chainring based on the gearing you want. For my touring gearing, I chose 16.5 gear inches as my lowest gear. With a cadence of 72 that gave me 3.5 mph (5.6 km/hour). I find that cadence is the lowest that is smooth and comfortable for me and 3.5 mph which is the lowest speed I find that I can easily maintain vertical and directional stability without over-steering.
That chainring combination has a ratio of chainring to sprocket of 2.25. Rohloff also has established minimum ratios to prevent over-torquing the hub innards. For most people on a solo bike (not a tandem) that ratio is 1.9, for people that weigh over 100kg, they have a larger ratio. Since I tip the scale at 80 kg, I could have used a lower gear if I wanted to.
Thorn usually uses a 17T sprocket instead of 16T but I bought my Rohloff separate from my Thorn frame so I am running a 16T.