You also need to use the proper material for the "trigger" mechanism. If the "hook" that goes through the eye bolt is too soft, you end up with problems. You need a material that won't bend each time you set the device. What that material would be, I don't know. I just know that I ran one of these for a day last year and it took a lot of fiddling to get the hook to release properly because the material was too soft and always bending. Otherwise, it worked well and was a ton of fun.
homebru