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Dick
For the lower:
39x28 is 37.1 GI (standard 53/39 lowest gear with 11-28)
42x36 is 31.2 GI
42x32 is 35 GI (you could even go 11-32)
34-25 is 36.3 GI (so basically you can live with a compact and 11-25)
For the higer:
53x11 is 128.7 GI
42x11 is 102 GI
So the issue is not hills but sprint/flat.
53x11 at 70rpm is 43kmph
42x11 at 90rpm is 43kmph