KKBHH

Well, since the entire lightweight bicycle doesn't weigh very much then why not suspend the rider on the frame instead of suspending the rider and frame on the wheels ? In the first case the entire bicycle would be un-sprung weight while in the second case only the wheels and suspension would be un-sprung weight. But again the bicycle doesn't weigh very much against the total weight of bicycle and rider.

The problems would seem to be that a seat suspension would hinder pedaling while sitting in the seat. But then if there were only a handlebar suspension that would tend to pitch the rider's weight forward. If there were both a seat suspension and a handlebar suspension the rider would move more vertically. Of course there is a Specialized 20mm handlebar springing and dampening.

Now one bicycle developer has a seat compliance system that moves the seat mostly front and rear and not as much up and down. I suppose that the development has our attention. Well, it's the Cannondale Kingpin system that should be considered. They call it a suspension while I call it a seat-compliance-system. But another system is the Trek rear IsoSpeed. Then the Trek front IsoSpeed is a front-to-rear movement of the handlebars !

My solution is a stiff frame with a deflecting fork and deflecting seat post. Of course my sport is not long-range rides but short downhill courses like a paved sports-car track but relative to the 40 MPH speed of the bicycle.

Or maybe we should test the Cannondale Kingpin rear system with the Specialized Future Shock front system ?

Now we all know that a wheel suspension at the rear of a bicycle does reduce pedaling effectiveness.