I also have the velcro instead of the zipper set up. I have velcro or hook n loop (the hook side) on my bars, the loop on the leaders. I baste my backing on my leaders with a long stitch on my machine. Others have been known to pin the backing on. Which ever way is easiest for you. The magic of the zippers and velcro is that you can take your leaders any where and load your backing and/or quilt top in comfort instead of leaning over your frame. With the zipper system you have to have a section of leader taped or permanently fixed to your bars, with the velcro you only need to have the velcro secured to the bars. For me that means less leader winding on the back bar and more room for the quilt sandwich. Also, I always float my batting and top and only use 2 bars. Floating means to leave hanging loose over the front bar.