For a while now, the premier suspension stoker seatpost has been the Thudbuster®. It is seen on a lot of tandems.
You don't have to be a far gone weight weenie to have some pause before installing a Thudbuster®. There are two models, the 570 gram Long Travel (left), and the 450 gram Short Travel (right). In comparison, the captain's Thompson seatpost on the depicted DaVinci weighs 193 grams. The Thudbuster ST and LT thus adds 257 and 377 grams (9 and 12.6 oz) respectively.
There are two new seatposts becoming available that may provide some stoker relief without a significant weight penalty.
The 220 gram Ergon CF3 Pro Carbon, which is listed as not yet available at Bike24 for 250 euros.
Edit: News about availability--Originally Posted by Bike24
Originally Posted by Ergon International FB
And the $200, 250 gram Specialized COBL GOBL-R carbon seatpost.
Originally Posted by Specialized
Don't laugh - the strange-looking Specialized COBL GOBL-R really works, and quite well in fact. The benefits vary depending on saddle positioning but even in the forward-most setting, it takes the sting out of bigger bumps in the road.
The COBL GOBL-R isn't available until September as an order item, but newer Specialized bikes are equipped with it. I rode one last Saturday, but it was difficult to compare on a different bike. The LBS offered for us to borrow the COBL GOBL-R, and I hope to put it to the stoker test on our ride on Saturday.