There are conversion kits you can buy from Thule and Yakima, but they are upwards of $40 and clip on to an existing rack system. If you want to mount to a truck bed or SUV floor, then you need to buy two components, totaling ~$80. I went to two local bike shops and a specialty rack shop and no one had what I was looking for so I decided to make a quick stop by the local hardware store and design this on the fly.
Step 1: Parts List
My Parts List:
(1) 1/2" diameter, Galvanized pipe "T"
(1) Base / pedestal floor mount
(2) 1/2" diameter Galvanized pipe, 1" in length (you the actual length depends on how tight you wrench it together and how much slop you want.
(1) 1/2" diameter, 2" length (this can vary a few inches depending how high you want it to be, keep it lower for less stress on the part.
(1) Base wood stand (I had a piece of 3/4 plywood (4" wide x 34" long) around so I used that. You could use a 2"x6" if you want. I would keep it at least 36 wide so stays flat on the SUV or truck floor.
(4) 3/4" wood screws
(1) Paint (optional)
(1) Fabric (optional, but it sure makes it look nice)
(1) length of 4" wide, 36" long male Velcro
(1) Spray adhesive (optional, used if you decide to cover the base with fabric)
Step 2: Assembly
After I was done, I used some sandpaper to smooth all of the sharp edges off and make it ready for paint. I happen to have some black textured paint around. I always keep the textured style around as it hides a lot of evil when doing projects like this and gives it a finished look.
Step 3: Create the Base, Then Attach It All Together
Surface - What surface you are mounting to (SUV carpeted floor or truck bed)
Stability - Bikes tend to move a lot so make sure it is tight and if you do a temp mount like I did, make sure the wood is wide enough so it does not topple over or move around when you drive those twisty roads to you favorite mountain bike destination.
Longevity - Temporary or permanent mount (I chose to mount to a removable piece of wood)
For me, I wanted to have it in the back of my SUV and wanted to have it look very finished. I spent an extra 20 minutes (that is all it takes to make something to be proud of...) and routed a 1/4 round bevel on the wood, sanded the base, sprayed it with 3M adhesive and then covered it in some old fabric I had from another project. I stapled the fabric onto the wood and viola, done. If you have a carpeted floor, then that is where I would add the male Velcro to the underside so it sticks to the carpet.
Done. ~1 hour, <$10.
Step 4: That's It. Done!
An alternate design would be to have the board wider and have multiple bike mounts added to it, but this is all I needed.
Enjoy and Happy riding!