Hi Rob It seems to me that all you need is a protractor and lots of pictures of pythons. Then measure the angle of the mid part of the seat from the horizontal. This method gives the same results as a number of manufactures specs. Good luck Jan From: Rob Raymakers Sent: Tuesday, April 05, 2011 2:18 PM To: python@xxxxxxxxxxxxx Subject: [python] Re: Abs workout from python? Hello, i'm gathering specifications of the diffirent parts to build a python bike. I got all the sizes/angles/measurements but I can not find how to calculate/measure the angle of a seat. Searches on the internet only give me a range between 19-30 degrees, but not how to measure the angle. Can anyone explain it to me so i can finish my 3d model. Rob