DIY Fifth Wheel Pin Box Bike Rack – pictures

As I wrote about before, there are various solutions to carrying bikes with fifth wheels. Each has its pros and cons. My previous solution was to lay the bikes on the dinette in a giant pile with waterproof sheets between each layer. It worked, but I really wanted to get them out of there.

I’ll start with that this isn’t your typical at home DIY. You need more than basic hand tools and do need a knack for welding. None of which I have, but I have a super-awesome father-in-law who has a friend with a full machine shop. That said, I have about $50 in parts and it took less than an hour of his time; you should be able to take this concept to any welder and he can build the hitch for you. After that it was a drill and bolt-on solution for the pin box.

Parts List

The $50 estimate assumes that you already have a bike rack. They can run quite a bit more.

1. If you don’t have one, you’ll need to buy a Hitch Mount Bike Rack
2. 12″ Receiver Tube (2″ x 2″) – this holds the bike rack to the vehicle
3. 24″ Angle Steel With 3″ Leg Lengths
4. Steel Sheet (enough for two pieces- about 2″ x 2″ and 3″ x 4″)
5. Spray Paint Primer
6. Rust-Oleum Semi Gloss Black Spray Paint
7. Eyebolt (3/4″ Eye Inside Diameter)
8. Bolts – you’ll need 4 for attaching the bike rack to the pin box
9. Lock washers – you’ll need 4 for attaching the bike rack to the pin box
10. If you have a pin box shroud/cover, you may need clips or bolts or something to reattach it

If you go to a welder, it is likely that they’ll have angle steel and steel sheeting on hand already. My father-in-law’s shop has a giant shelf of cutoffs that we could have used (and did for #4). I ordered #2 & #3 from Amazon (these links are the exact products that I bought). #4 came from my father-in-law’s shop. The remainder, I purchased from my neighborhood Lowes.

Tools List

1. Drill and/or drill press
2. Drill bits for drilling through metal (5 holes total will be needed – 4 in the pin box and one in the bike rack hitch that you’re fabricating)
3. Drill and tap set for the bolts that you purchase
4. Angle finder
5. Welder
6. Metal cutting saw
7. Grinder

The Vision

My challenge with most of the pin box installs that I was seeing is that very few accomplished the same with a pin box cover/shroud. All of the ones that I saw were just a plain pin box. Until, I found this post by lpxguy on rv.net/forums:

The Build

1. With the camper level, remove the pin box cover and check the angle of the pin box slope. This will be used later when cutting the angle steel for the hitch. Mine is 23°.

   

2. Test fit your bike rack to ensure clearance. Be aware of how close to the camper to get for 2 reasons – a) to ensure your bikes won’t hit the camper and b) to ensure that you can get your drill in under the camper’s overhang to drill the pin box.

   

3. Collect your raw materials.

   

4. Cut the angle steel into two 12″ pieces. The angle steel will go on either side of the receiver tube.
   

   

   

5. The angle steel will be flat to the pin box, so you need to cut the ends off at a 23° angle in order for everything to be flush at the rear of the receiver tube. (see the picture in step 9 for clarity)

   

6. Next you’ll cut off one the corners of each of the pieces of angle steel to be flush with the top of the receiver tube. (see the picture in step 9 for clarity)

   

7. Measure and drill 2 holes on each of the angle steel pieces (the opposite side to where you cut the corner off in the preceding step). These will be for mounting the hitch to the camper’s pin box. Their placement isn’t critical, but being symmetrical makes for nice appearances.

   

8. Sand down any sharp edges left from the cuts.

   

9. Dry fit everything into place. Double-check the angle.

   

10. Tack weld everything into place.

    

11. Cut plates for the 2 open ends and tack weld them into place.

    

12. Complete the welds.

    

13. If someone else is doing the welding, go for a walk in the machine shop.

    

14. Grind the welds and cleanup the final product.

    

    

15. Prime and paint the hitch.

    

    

16. Clamp the hitch in place on the pin box and mark holes to be drilled. Ensure that you have room to get your drill into place between the pin box and the overhang of the camper. I could possibly have moved my hitch some but I wouldn’t have been able to get in to drill the holes for the screws.

    

17. Center punch the holes and then drill them out. For drilling these holes, it’s best to drill a pilot hole with a smaller drill bit before drilling your larger correct-sized hole. Use a ladder for leverage, if you need.

    

18. Missing picture, but tap threads into each drilled hole.
19. Bolt the hitch into place.

    

20. Missing picture, but attach the eyebolt to the front (this is for your “oh-crap strap”)
21. Reattach the pin box cover/shroud. In our case, the shroud was previously held on by clips that broke while removing them. Rather than try to find long white clips, my father-in-law tapped the holes and we used bolts with spacers instead.

    

    

22. Add bike; fall in love.

    

Loading Bikes

When I loaded the bike in the above pictures, I backed the truck up so that the truck bed was below where the bike rack would flip up and extend out to. I was able to get into the truck bed easily and had my father-in-law hand his bike up to me. If I were alone or if it becomes that my wife can’t easily hand the bikes up to me, I’ll load them into the back of the truck first and then back it up into the same position to put them up there.

Protecting The Bikes

To protect the bikes, I have bought an ATV Cover that should be big enough to cover all of the bikes. I’ll put grommets across the open end to “lace” it closed. This will protect the bikes from the elements and the mess of bug guts all over them.

What to Watch Out For

My first towing was with just the single bike on the rack. Ultimately, we’ll have 3 or 4 bikes up there and I need to watch the clearance between the bikes and the back of the truck.