It all depends on how you feel on it. If you feel like you are leaning forward you can either buy the block, or just take 2 foot long pieces of a 2 x 8 and screw them together and that should be high enough (3"or so) to make you level. I did this for two years in my basement. I have since moved the bike upstairs, and my son bought me the block for christmas. I don't realy notice any difference between the 2 x 8's and the block. As far as the trainer being stable enough on its own. The cyclops I own is more than enough by itself. I just felt like I was always leaning forward without something under the front tire.