I was considering a Thudbuster ST. But I have 2 stokers at much different weights. How long does it take to change the elastomers? Or should I get a an air shock type and just change the air pressure? Sort of like the Sette Ryde ST-900 Air Suspension Seatpost. http://www.pricepoint.com/detail/166...n-Seatpost.htm Any recommendations or other ideas?