We changed our 4 speed Brompton P line to 5 speeds

From 11/13/15/18T sprockets

To 11/13/15/18/21T sprockets

Before making the change we did a test ride with power meter pedals so we could compare the effort required (hoping to reduce effort with lowered gearing)

0:00 | Intro
1:49 | 4 speed loop
3:57 | 5 speed loop
7:37 | End summary
9:07 | Outtakes