To come back to the start of the discussion about the transmission, the gear range of the Birdy GT, it is interesting to note that all 3 models of Riese & Müller and all internal gear hubs of Pacific Cycles have longer ratio than the derailleur models of Pacific Cycles.

We already discussed the R&M Birdy touring that has 52x 9-32 which is 22% longer than the derailleur models of Pacific Cycles that have 52x11 as longest ratio. R&M choose this seldom seen and fully proprietary hub+cassette system to provide this longer ratio.

The Birdy Rohloff has 52x13, but the Rohloff multiply by 1.467 on 14th gear so equivalent to 52x (13/1.467) = 52x8.86

Last model of R&M, the Birdy City with a Nexus 8 and 52x16 but the Nexus multiply by 1.62 on its 8th gear so its equivalent to 52x(16/1.62) = 52x9.9

Then the Birdy Touring 3x8 of Pacific Cycles with 52x11-30 but on a Sturmey Archer CS-RF3 that multiply by 1.33 on its 3rd gear so equivalent to 52x(11/1.33) = 52x8.27