Hi Dirk, the triangle behind the pivot is not neccesary ( I think), because the weight of the body is translated into the pivot and into the reinforcement tubes in front of the rear wheel. There is the bending force. The points: wheelhub - Pivot upper - Pivot lower is a triangle, the little tubes betwen upper and lower tubes are just to reinforce the bike. First I planned to build extra tubes. With the next python I want to build I even want to leave out two front tubes. I ride on bumpy roads also and until now the frame is strong enough. I will rebuild the seat a little bit. The piece of wood is for no use. I am just hanging between the front and the back suspension. I will change it this week, then I will send a photo. (easier than to explain) It will be similar to a beach chair. Jürgen M. ============================================================ This is the Python Mailinglist at freelists.org Listmaster: Juergen Mages jmages@xxxxxx ============================================================