Flexible seatposts for road-racing bicycles based on Carbon-Fiber/Epoxy Composites and designed according to patented principle (pseudo-parallelogram) have been developed by Canyon and Ergon.
Canyon: VCLS Post 2.0
www.canyon.com
www.canyon.com/technology/vcls2/
Ergon: CF3 Pro Carbon
www.ergon-bike.com
www.ergon-bike.com/de/de/product/cf3procarbon