Damp and squishy

The original idea for a rear damper was to build an elastomer torsion suspension unit. The concept consists of two sections of square tubing, one inside the other, with an elastomer filling the corners providing resistance to torsion:


The original prototype worked well with only 30° of preload required for my weight. After several hours of work on the 'production' model I was disappointed to learn that the rubber inserts I used were too soft and getting 60° of travel for preload.


This won't be suitable and I'll have to consider finding an alternative rubber or filling them with urethane in future.