2 straps, through the frame above the footpegs. I use 2 short loops, cut from an old ratchet strap and tied in a knot, and 2 karabiners,straps through the krabs. Pick a hook on the truck slightly forwards, pull em down tight. Driven possibly thousands of miles with mine like that, never moved an inch.
Pulls out and down, so doesnt compress the foks at all.
Tried various places on the bike , around the yokes, bars, over the seat etc. Nothing works as well or is as easy to set up.