I just took out the 580 and I noticed that if you stand on the back and give her a good hop she will lightly bottom out. Both of my other sleds have the ett suspension so I have nothing to compare it to. i believe thet the 580 only has 5" of play with the old style. If anyone has a zr580 and could check it out please let me know. I bought this sled so my nephew could ride with us. He only weighs about 120 lbs. compared to my 180. Should I worry?