Winfried , a Dual drive hub will let you pop into a low gear when stopped , with the 3 speed IGH part
and the cassette part will give you a narrower difference choice within those 3 ranges.
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Other than the hub itself , the rest of the frame is just something to put it in.. separate choice Criteria.
Bike Friday offers the Hub in a variety of their models , Tikit and Silk offer a Belt drive option.
Not an Alfine buyer. I own a Rohloff.. It's in my Go To kit, now.
[snow melted , the studded tire Bike gets parked]