Ive tried to get forums going before..some with success and some that didnt work.. one thing i know is... people from other forums may sign up... but your competing for their time... i have multiple projects on the go..and im in more then one forum... but this is my only atv forum.... and i dont even get enough time to post here between the lexus forum, my pop up forum,iphone forums, the gardening forums, and on top of that facebook....
If your serious.. you need to make sure the forum has enough content..to keep the users, so they dont sign up..then never return cause they are busy at the other forums they have used before...