Originally Posted by bikexpert

New BIRDY spec 52T chainring, 11-34T freewheel (11, 13, 15, 17, 19, 21, 23, 26, 30, 34)

The New BIRDY 3D forged stem has a function which not many people knows. The upper stem can rotate 180 to change the 21degree to 19.5, not sure if this info will help you but I wouldn't know this if I didn't visit Pacific museum. However Pacific also do offer the 10/21 degree stem as an optional accessory!

Pacific museum staffs also told me the reason they spec mechanical disc brakes is to prevent problems from folding & unfolding. I have the BIRDY standard 9sp model and the original components are good for me!

Hope these helps