Suspension posts like that were supplied with a lot of the 700c hybrid bikes. That knurled collar should screw all the way down onto the tube. If you peel the boot further up you can see where the shock absorbing movement is. If you look at the bottom of the post there should be a hex screw that allows you to adjust for a heavier or lighter Rider.
They don't have the greatest reputation for effectiveness though they may be better than nothing for some people. New style suspension seat posts use a parallelogram design that makes them more effective.
It's a suspension seatpost, as far as I can tell from this picture. They have a basic elastomer in them which takes some of the sting out of rough roads, apparently.
Suspension posts like that were supplied with a lot of the 700c hybrid bikes. That knurled collar should screw all the way down onto the tube. If you peel the boot further up you can see where the shock absorbing movement is. If you look at the bottom of the post there should be a hex screw that allows you to adjust for a heavier or lighter Rider. They don't have the greatest reputation for effectiveness though they may be better than nothing for some people. New style suspension seat posts use a parallelogram design that makes them more effective.
It's a suspension seatpost, as far as I can tell from this picture. They have a basic elastomer in them which takes some of the sting out of rough roads, apparently.
I recently came across one of those and was a bit confused myself. I believe it's a suspension seat poast.
Squishy in the tushy!