To beat the heat this summer, we decided to do something fun, creative and slightly extreme. Jumping the bike into our neighborhood pond seemed like a good candidate. In order to pull off this activity, we needed some sort of ramp to suit different riders, including those who want a higher jump, but also those who care for a lower ramp. Most ramps cannot do this, and are too small anyways. To solve this problem, we set out to design and build our own, adjustable ramp.
Step 1: Supplies and Materials
For the ramp, we used standard lumber sizes (2x4's and 2x2's). We also used a large, sheet of plywood that was about an inch thick, give or take a few 64th's. The hardware that we used consists of 2-1/2" screws, 1-1/4" screws, a dozen miscellaneous screws, and two 3" clevis pins. We also used two sets of two hinges. The size of these doesn't really matter, as long as they aren't super flimsy. The miscellaneous screws that we mentioned are used to attach the hinges to the large plywood, so make sure they are short enough so they don't poke out on one side of the sheet.
- 1.25" screws
- 2.5" screws
- Misc. fasteners (under one inch)
- 3" clevis pins
- 4 heavy-duty door hinges
- 2x2's supporting main sheet of plywood: 78" (x2)
- Large sheet of plywood: 74" x 26" x ≈1"
- Long, base 2x4's: 8' (x2)
- Base end stop 2x4: 26"
- Support brace 2x4: 26"
- Support leg 2x4's: 27" (x2)
- Cross beams on base 2x4's: 19" (2x)
- Stops for height settings: 3.5" x 3.5" (6x)
- Small plywood sheet (for threshold): 29" x 14" x 1/2"
- Threshold 2x2's: 15" (x2)
- Threshold support 2x2: 20"
- Drill bits
- Chop saw or hand saw
- Rotary tool (dremel)
Step 2: Construct the Base
The first step is to put together the base of your ramp. This provides the height settings and overall structural support. At the front of the base, you will want to install one of the two 19" cross beams. make sure it is flush with the end of the long board, as your hinges will mount to this. If you want, you can attach these with brackets, but we just screwed sideways into the wood. *NOTE: It is extremely important to pre-drill all holes so your lumber doesn't split.* At the other end, attach your end stop board (26"). Next, add the last cross beam somewhere in the middle of the base. It really doesn't matter, so just use judgement with that. Once you've done that, it's time to add the stops to your base. This part is a little tricky, as the measurements need to be somewhat accurate. The front of the first stop is 68.5" from the front of the base. The next stop should be 74" from the front. The last stop is 83" from the base. Once these are attached, your base is complete.
Step 3: Build the Top
The top half of the ramp is the easiest part to build. All you have to do to build it is attach your 76" long 2x2s to the sides of your 76" by 26" plywood. The main purpose of these boards is to keep the plywood from bending too much. We figure that we will also use the jump in the wintertime for snowboarding and skiing, so the 2x2s will also serve to keep snow on the ramp. Put at least four screws on each 2x2, again pre-drilling each hole. *NOTE: The 2.5" screws may be too long for the 2x2 and plywood, so you can use your rotary tool to grind off the tips sticking out of the bottom of the plywood.*
Step 4: Build and Attach Legs and Hinges
The legs are very simple to build as well. To build them, get your two 27" pieces and attach them together with your 26" peice. When putting the screws in, it is best to do it diagonally, as this will help prevent any twisting. At the top of the leg assembly, you will attach your pair of door hinges, on on each leg. Mount them on the side that is opposite of the 26" cross piece.
After you have attached the hinges to the leg assembly, you need to attach your two heavy-duty hinges to the bottom front end of the plywood. (The front end is the side that does not have extra 2x2 sticking off of it.)
Now that you have completed these steps, you can attach the leg assembly to the plywood. Make sure to attach it to the BOTTOM side of the plywood.
Finally, go ahead and line up the heavy-duty hinges on the frame. We find it easiest if you just lay the whole thing out to do this Make sure the height adjustment stops are at the opposite end that you are attaching the hinges to, and that the base is right-side up.
Step 5: Make the Threshold
The threshold of the ramp serves to make a smooth and seamless transition between the ground and the jump. This means that the pivot of the threshold has to somehow be independent of the rest of the jump, seeing as the height is adjustable. To do this, you will have to construct your last part.
First, attach your small, 15" 2x2's designated for the threshold attach these on the outside of the 2x2's on the jump. Now you can line up the holes for the clevis pins. Drill the holes one or two drill bit sizes larger than your pins so the threshold can rotate freely. If the clevis pins are too short, you may have to counter-bore the wood. (If you don't know what that is, then look up and instructable on how to do it.)
Once you have everything lined up, go ahead and attach the 1/2" piece of plywood to the 2x2's that are set up. The final step is to add the support bar to the bottom of the plywood.
All done! Stand back and be proud of your creation. You worked hard, and deserve to cool down...(see next step)
Step 6: Jump Into a Lake!
Time to have some fun! All you need now is a lake or neighborhood pond and a bike. Make sure the lake/pond is deep enough before jumping or you could hurt yourself. What we did is strap a life jacket to the bike so it doesn't just sink. Happy jumping!