Brompton Extended Seat Pillar Steel Brompton seatposts are so long, they are called seat pillars. While the standard Brompton seat pillar is long enough for riders with inside leg measurements up to 33 inches / 84cm, this Extended Seat Pillar is 2" longer so it raises the saddle height for riders with up to 35 inch inside leg measurements. Note: this longer pillar will protrude 2 inches higher compared with a standard issue Brompton seat pillar.