Here is a video about the ICE tadpole trike rear elastomer suspension system used on their Adventure and Sprint models. It explains the 3 different elastomers and how to adjust the suspension.
Help in determining which elastomer to use can be accomplished by use of this chart:
And from ICE’s website here are their written instructions:
Rear suspension elastomer adjustment
The front and rear suspension can both be fine-tuned to work well for you. The rear suspension can be adjusted by a combination of selecting one of three different hardness and five different fitting positions for the elastomer. The front suspension can be adjusted by selecting one of three different hardness elastomers. All trikes come with medium elastomers fitted to both front and rear suspensions. Other elastomers are available for purchase from ICE.
The adjustment is accomplished by the selection of elastomers and mounting positions. The elastomers are available in three hardnesses: Yellow/Soft, Red/Medium, Green/Hard. There are five mounting positions; the lowest/closest to the main pivot (numbered 1 here) will make the suspension feel softer. The highest/furthest from the main pivot position (5) will make the suspension feel harder. To setup the suspension you will need to select an elastomer and position it by using the table below.
Unclip the rear suspension by pulling the stainless steel clip on the left hand side over its pin. The purpose of this clip is to keep the rear swing arm from dangling when the trike is picked up; it is only unclipped when changing the elastomer.
The elastomer is removed by pulling and twisting it off the shock pin. With the back end hinged open, screw the shock pin into the required hole in the shock plate. Firmly push the elastomer back onto the pin and close the swing arm back onto the stainless steel clip.
The position you have selected using the table above will give you a good starting point. Your trike should perform properly like this; however, it is worthwhile spending a little time experimenting with settings to find one that suits you best.
The elastomers have different compression characteristics, and you may find other combinations of elastomer hardness and pin position which suit the roads you ride on and your riding style better; it is just a matter of trying different combinations. The elastomer system is simple and small enough that you can carry a couple of elastomers in your bag and change them when you are out on a ride if you like.
If you ride on rough terrain or ride aggressively, you may benefit from a harder elastomer. If you are a leisurely rider, who rides predominantly on smooth tarmac, you may be able to use a softer elastomer. If the setup is too soft the trike may not reach its optimised comfort setting.
If it is too hard comfort will be compromised.
You should generally get a better result with the hardest elastomer recommended for your weight, for example if your weight is 90kg use the green elastomer in position 2 rather than red in position 4.
If you are a light rider and have your suspension setup soft it is advisable to adjust it to a firmer setting; change for a harder elastomer if necessary before allowing a significantly heavier rider to sit on your trike, otherwise permanent damage to the elastomer may occur.
With rear or full suspension, tyres can be run at higher pressure while maintaining good comfort.
Contrary to popular belief, elastomers do not significantly change stiffness with lower or higher temperatures.