A bit of infos about the Birdy folding bike designed by Riese und Müller in Germany and manufactured by Pacific Cycles in Taiwan.
Based on a 2nd-generation ("Mark II") City with a Nexus 8 SG-C6010 gear hub and Magura HS33 hydraulic rim brakes, and a Mark II Light with an eight-speed Shimano Capreo derailleur and v-brakes.
The serial number on the frame has the following format:
So for instance, xxx09100782 means 2009, week 10, lot 0782
Compared to a Brompton, it rides better dut to its fork + frame in aluminum and possibly Schwalbe Big Apple fat tires, is more comfortable, is available with either a Nexus/Rohloff internal gear hub or a full-fledged cassette, and with either v-brakes, hydraulic rim brakes, or disk brakes.
It folds a bit bigger than a Brompton, offers no frame-mounted baggage block in the front (but the adapter from H&H makes it possible to use a Brompton block), its seatpost isn't flanged at the end so can be removed when parked on the street, has even less retailers (but stores selling R&M cargo bikes may provide Birdy parts), and is even more expensive than a Brompton.
If the reach (ie. distance betwen the seatpost and the handlebar) is too long, turn the seatpost and the upper-part of the stem 180° each.
You can also try a bar with a rise and set it a bit further back.
IMPORTANT: With Magura rim brakes, after the wheel is removed you should no longer operate the brake lever. The brake pads will press together making it difficult to mount the wheel. After removing the wheel, insert the transportation safety shims to ensure a sufficient distance between the brake pads.
I found no information on how to actually remove the wheel on a Birdy with a Nexus gear hub and Magura rim brakes in the "INSTRUCTION MANUAL BIRDY" created 17 July 2017.
If the chainline is only slightly too close to the frame, it might be possible to only add a couple of spacers on the drive-side to pusth the crankset outward. Otherwise, a new bottom bracket/crankset with a wider axle is required.
Example of a Birdy with a 50/34T
Natively, on its rear wheel
https://www.youtube.com/watch?v=QGW7b5pAvtk
Birdy III Foldable PORTER EASYWHEEL ROLLER Rack (Multi-S)
https://www.bikegang.co.uk/bikeganghut/Birdy-III-Foldable-PORTER-EASYWHEEL-ROLLER-Rack-Multi-S-p95805532
Litepro
Easy Wheel Push Wheels
https://www.aliexpress.com/i/4000763446872.html
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Check if compatible with Mark I and II.
Birdy Roll Solution 2 wheels roller + 2 wheels Rear rack (Multi-S)
https://www.bikegang.co.uk/bikeganghut/Birdy-Roll-Solution-2-wheels-roller-2-wheels-Rear-rack-Multi-S-p118176104
Low-rise rear rack
https://www.carousell.sg/p/birdy-rear-rack-with-easy-wheel-1045841745/
Sideways (manufacturer unknown)
https://www.facebook.com/permalink.php?story_fbid=357732360982367&id=137449652966532