The monocoque curve in the frame probably imparts some strength as a structural member with camber. The new frame which is straight maybe relying on some internal structure for that strength. The overall geometry is different and the bottom bracket appears to sit lower. Would be nice to have a side by side comparison with the Birdy 3 frame and this new one. The rear swing arm looks a little different and may have to be if the overall geometry is different in the main frame. All speculation for now until someone actually gets one and does a comparison. Without a dealer in the US and with only a few limited shops like Bfold that can help import a bike, those of us in the US may have to wait a long time.