Got a truck?
Got a bike?
Need a way to transport your bike on your truck?
I got this idea from a local bike shop. It's pretty simple and pretty cheap too. I could easily see this modified to mount bikes inside a mini-van by using a piece a plywood instead of the 2x6 for a sturdy platorm to keep the bikes stable.
Cut a 2x6 piece of pressure treated wood to fit in the bed of your truck. Most truck beds have a built-in slot to hold the piece of wood.
Measure and mark on the 2x6 where you would mount the locking fork mounts and attach to the edge with sturdy screws. Remember to account for the width of the handle bars if you are mounting more than one fork mount.
If you want to secure your bike and the bike rack use a hole saw to drill a hole on each end large enough to fit a cable lock through.
I found a long cable lock at WalMart that I can thread through the bike rack and two bikes and lock them to the tie downs in the bed of the truck.