Originally Posted by
secret_squirrel
I doubt they will try again which is a shame because the frame design gives plenty of places to hide a battery.
R&M afaict currently uses exclusively crank motors, not hub motors. This is generally the most efficient option since it benefits from the bike's gears. And it gives a sportier response as soon as your pedals move, rather than having to crank half a revolution before a hub motor starts pulling. And you get the full benefit of suspension, and a better weight balance and freedom to choose whatever rear gearing you want, including internal hub gears. Crank motors are more expensive though, and the frame has to be built around them. And that's a problem for the Birdy - how to fit a motor in that frame, without blocking the fold? If it is possible at all, the end result may not look much like a Birdy.
They could go for a hub motor like Pacific, but that would compromise with what they clearly believe an e-bike should be. (They can't install throttles to work around the hub lag, as those are not allowed for EU pedelecs, only for mopeds and upwards. The motor must be controlled by crank revolution.)
As for batteries, the frame has some volume, but not enough to easily fit a 500 Wh I think. Both frame and battery would need a peculiar shape which makes them more expensive. They could use the lumpy standard shape Bosch battery, I think that will fit on top of the frame, but it will look ugly and may affect folded dimensions a little bit.
All together this may be why they have given up on the Birdy and instead made the Tinker, a small-wheel ebike. Mostly non-folding, only the stem folds it seems.
https://www.r-m.de/en-gb/bikes/tinker/
But it reminds me, I did test ride an electric Birdy at the SPEZI bike show in 2013. I don't remember now what kind of motor it had. Only that it had the nuVinci Harmony automatically shifting stepless gear hub, a great ride. Probably this means it had a front hub motor, which I would say is generally the least good option for a motor, all else being equal. Bad on icy/gravelly ground, wears out tires fast, affects steering. Anyway, this confirms they were testing it, and dropped it.