Rear rack for first-generation Birdy
I have a first-generation Birdy which doesn't have the mounting points that were added on the second-generation model for front (lowrider) and rear pannier racks.
I recently came across an "M-Wave One-4-All" rack for ~US$20. I was able to mount it as a rear rack on my Birdy without additional hardware. I needed to replace a couple of the provided bolts with longer ones from my parts bin, but only because my Birdy was already fitted with front and rear fenders/mudguards, and I needed the extra bolt length to go through the fender stays, rack stays, and frame. Once i had everything worked out, I cut the stays at the front of the rear rack to length with a hacksaw, and smoothed the end with a grinder, to save a little weight and make the fit cleaner. But I could have gotten by without cutting the stays if I had bent them to avoid interference with the top crossbars of the rack.
The "M-Wave One-4-All" is solidly made and rated for up to 25 kg / 55 lbs. It's heavy, but some of the weight of the package is extra mounting hardware that wasn't needed on my Birdy, and a set of angle braces (that make the rack into a rigid triangle that you might choose to leave off, depending on how much weight you plan to carry.
With the rack installed, the Birdy doesn't fold quite as small as without it, but it does still fold in the normal manner, and stands securely on the rack when folded. The rack sits level and high enough to hold two full-sized Ortlieb rear panniers without the panniers dragging on the ground. The rear derailleur hangs closer to the ground than the panniers.
Assembly and mounting was a bit tedious, but not per se difficult. I had lots of nuts, bolts, and fittings left over when I was done. The photos of the assembled rack on the package and online were more helpful than the written directions. There are a lot of bolts, sliders, and adjustments to accommodate a range of mounting methods and wheel sides for 20-29". Yes, the Birdy wheels are less than 20", but it still fits OK, with the rack sitting level and above the rear fenders/mudguards. The "M-Wave One-4-All" is *not* a quick-release or "folding" rack, but by pulling a few bolts (and removing the side stays, if you have installed those), it could be folded flat for shipping, if that would reduce the size of the baggage to satisfy e.g. airline checked-baggage size limits.
What appears to be the same model is sold under several brand names including by Amazon, Home Depot, and Walmart.
Your mileage may vary, but hopefully this may help others struggling, as I was, to find a suitable rear pannier rack for a Gen-1 Birdy.
Now if I could just find a way to fit *front* lowrider racks without drilling into the frame...