I couldn't use a cover at all. It may have been the place in my driveway, or the placement of the driveway between my house and the one next door. The cover wouldn't stay on the bike. I was constantly retrieving it from the neighbors yard. Then I thought I would get smart and use the security grommets and solve that problem. I stopped using it altogether the second time the wind blew the bike over. I now have the bike in a shed in the back yard.
Good luck!