Originally Posted by
PaulRivers
Any suspension you put in the back will reduce your power. Rear suspension on mountain bikes (until you get into expensive stuff but that stuff just locks out the suspension when it's flat and only kicks in when it gets bumpy) kills you power.
Suspension seatposts shouldn't have any effect on power (just more weight). Pedaling forces wouldn't compress the seat at all (if anything they lift you). Rear frame suspension is different because the downstroke also causes the rear suspension to compress. Even then its clearly possible to have modest suspension without much power impact (Roubaix, Domane, K8-s, etc).