Richie...
Here's a thought (or for the price, two!):
I've found I tend to not ride bikes where there's a hassle to get them ready. For some reason, swapping accessories from one to another is enough to put me off and choose another, so each one is fully equipped with its own lights, computer, underseat bag, bottles, pump, etc.
I fear the same could be true if you found yourself swapping rear wheels very frequently (maybe you won't).
Wondering...where the "new" bike would be lighter, could you get by with something less than a Rohloff and thus less costly, but with many of the advantages...something like a Nexus or Alfine IGH?
Or...depending on terrain, perhaps a single-speed or fully Fixed-gear setup on the second bike? That would bring back the simple joy of your past BMX bike, but sized for a grownup and with better positioning to make speed and the same near maintenance-free advantages. That seems to be a large part of the appeal of SS and Fixed bikes for the college and uni crowd where they've simply exploded in numbers. They're lightweight, too.
The point being, if you have the second bike equipped with some sort of (less expensive) rear wheel, you could still quickly grab and use it without having to do the full swap thing on the Rohloff wheel. If you ride only one bike or the other for an extended period, it wouldn't be a problem to swap, but this would give options.
Best,
Dan.
