Suspension seatposts

[Susan]

So what IS the point of rear suspension?

If you ride on difficult terrain, it will help by swallowing bumps, thereby adding more traction and of course making your ride smoother. While a suspension can swallow a lot of pedaling power when riding on smooth asphalt, it helps a lot going uphills on loose gravel or rocky terrain by providing more traction. Going downhill, it's often better to get out of the seat for a variety of reasons - you can shift your weight to avoid going over the handlebars, jump over roots or use your feet as suspension for instance - so a seatpost-suspension won't work. If you don't have great biking skills, a full suspension bike will help to ride more difficult trails. If you already have great bike handling skills it will swallow some of the impact when jumping for instance.

When you look at common rear suspensions you will see that they are built in a way that gives the rear wheel the possibility to move separately from the frame itself while absorbing the occurring forces. Therefore, a rear suspension works whether you stand on your pedals or sit on your saddle and helps to keep your rear wheel on the ground when the trail gets bumpy. This can't be provided by a seatpost-suspension.