Build a plywood bike jump
Riding bikes is a whole lot of fun for kids, and this jump will crank up the fun even more.
Although medium-sized, this jump could be made smaller for younger or less experienced jumpers or larger for more experienced jumpers. If you’re a beginner jumper this is likely a bit too large for you, though it’s possible for a rider who’s new to jumping to launch off the side, rather than the end of the jump.
The First Joints
Once the triangular sides have been cut to size and the cross rails have been cut to length, screw the cross rails to the side so their narrow edge is flush with the medium-length side of the triangle. Don’t install the cross rail near the narrow point of the triangle just yet. And the cross rail at the take-off end of the jump (that’s being installed here) needs to be positioned so its outer face is flush with the short edge of the triangle.
Install the Top
Screw the top to the cross rails, ensuring the cross rails are perpendicular to the side. Position the top so it overhangs the end cross rail by the thickness of the plywood you’re using. This will leave room for the end panel to sit underneath the top
Add the End Panel
Screw the end panel to the end cross rail. Though the jump is pictured upside down in this photo, notice how the top now overhangs the end panel.
Lower Cross Rail
Be sure to position the lower cross rail so its lower edge is in the same plane as the lower edge of both the end panel and the triangular side. This will allow the jump to sit flat when its complete.
To protect against racking, the end panel must be securely fastened in place. Blocking between the end panel and the two sides will go a long way to keeping the jump strong.
The Second Side
Screw the second side to the rest of the jump. Ensure ample screws are driven into the cross rails and blocking. Overtightening the screws may cause the screw to strip the cross rails, as screwing into end grain isn’t as strong as screwing into face grain. Longer screws can also help with this.
Front Cross Rail
The final piece to install is the frontmost cross rail. In order to support the rider when they first enter the jump, ensure this cross rail is positioned so its lower edge is flush with the lower edges of the sides. If you look closely you’ll see that the taper the lower edge of this cross rail had to be chamfered on an angle so the jump would sit flat during use.
Mark and Screw
Mark the locations of the cross rails onto both edges of the top, draw a straight line between these points, then drive screws to secure the top.
We used 5/8″ thick sheathing plywood for this jump. If the person using this jump is well over 100 pounds it would be a good idea to use 3/4″ thick plywood. Another option to add a bit more strength is to add more cross rails under the top to beef up the support.
You’ll need two 2×4×8s for this jump. You’ll also need slightly more than one half sheet of sheathing plywood. You could get away with purchasing only a half sheet for the top and sides, then use other material you already have for the small end panel. The only caveat is that the end panel provides all the racking strength in this jump, so ensure the material you use is strong enough and will protect against racking. Some sort of angled cross braces would work for this, though a piece of sheet good is much simpler.
To secure all of the parts, we used #8 × 2-1/2″ exterior screws. You can use exterior adhesive if you’d like, but we didn’t and our jump is very stable and strong.
Start with the plywood sides
A track saw will quickly and accurately cut plywood straight, but a circular saw that runs against a straight 2×4 clamped to the plywood will also work well. Even a jigsaw that runs against a clamped 2×4 will give you a straight enough cut. Just be sure to offset the 2×4 by the distance between the edge of your blade and the edge of the saw’s base.
It’s easiest to cut a blank that will provide you with enough material for the two sides, then cut the two sides from that blank. Cut your sheet to give you a piece of plywood 16″ wide by 48″ long. Next, cut that piece from one corner to the opposite corner, giving you two long triangles for the sides.
Next, cut the top and end panel to finished size. The end panel will be 24″ wide by the length of the shortest side of the triangular sides. In theory, this should be very close to 16″, but if not, adjust the end panel to be the same length. The top has to be the length of the second longest side of the triangle, plus the thickness of the end panel. This is because the top will overhang the end panel after everything is assembled.
We used five cross rails for our jump; four directly supporting the top and one on the bottom of the jump, at the end. If the rider is over 100 pounds, or you’re making a longer jump, add an addition rail (or two) directly underneath the top for extra support. This is especially true towards the entrance end of the ramp.
Cut the cross rails to length. They need to be equal the width of the top, minus twice the thickness of the sides. Although four will eventually be spaced out evenly to directly support the top, the one closest to the start of the jump won’t be installed until later. You can screw the other three to the side so the upper edge of each cross rail is flush with the upper edge of the triangular side. The cross rail at the take-off end of the jump will also need to be secured so its face is flush with the shortest edge of the triangular side.
Add the top and end panel
The top will now get screwed to the cross rails. It should be positioned so its long edge is flush with the outer face of the side, and so the take-off end of the top overhangs the cross rail at the take-off end by the thickness of the end panel. This will allow the end panel to tuck in nicely underneath the top later.
The end panel can now be screwed in place. Its long edge gets screwed to the end cross rail and will be weak until we add the next few pieces.
Second last cross rail and blocking
The lower cross rail can now be added. Screw through the side into this cross rail, then through the end panel into the cross rail. Height-wise, position the cross rail so its lower corner is flush with the lowermost edge of the triangular side. This edge, and the lower edge of the side, will sit directly on the ground in use, so they need to be in the same plane.
Add two pieces of blocking (short pieces of 2×4 material) to increase the strength of the end of the jump. Cut two pieces to fit between the lower cross rail you just installed and the end-most cross rail. Screw through both the sides and end panel to secure the first piece of blocking at the junction of the side and end panel. The second piece of blocking will have to be screwed to the end panel so its outer edge is flush with the ends of the two cross rails.
Add the second side
The second side should fit nicely in place now, and can be screwed to all the cross rails and blocking.
The last cross rail
The final cross rail will support the take-off end of the jump. It needs to be positioned so it sits flush with the undersides of both side panels and sits flat on the ground when the jump is in use. Ours didn’t sit perfectly so we had to shave some material off one end of the lower edge so it sat flush with both sides. This cross rail will provide a lot of support while a rider first hits the jump, so it needs to fit properly. If you’re adding extra cross rails they should be installed now.
Ensure screws are added wherever possible, as they are what provide the holding power for all the joints.
Using the jump
A first step might be to look around your neighbourhood for things to jump off. You’ll likely find small rises here and there to get an idea of how your bike handles when it hits a jump.
If your plywood jump sits on a flat surface without rocking you’ve done a great job. If not, you might want to shave a bit of material off the lower edges of the sides and possibly the front and back cross rails and end panel. It doesn’t need to sit perfectly flat, but there shouldn’t be much rocking. Placing this jump on the grass might also help it sit still, though it might take a few runs over the jump to press it into the soil a bit. And let’s face it, if you happen to crash, grass is a lot more forgiving than asphalt to land on. And always wear a helmet when riding.
To use this jump you can start out by entering the jump at its thin edge but going off its side. The closer towards the end you exit the jump, the higher you will be, obviously. Working up the skills (and nerve) to exit the jump at its end might take some time.
Since this jump has a flat top it’s going to allow the user to go far (if they have speed) but it’s not great at getting a lot of “air.” Start off by lowering your seat slightly to give you a bit more room around your bike to work with. The main thing you want to avoid is for your bike to do a nose dive when you exit the jump. You can protect against this by pulling up on your handle bars just before your front wheel goes off the jump. You should aim to have your wheels equidistant from the ground while you’re in the air. You should also move your hips back over the rear wheel as you jump to help keep the front wheel from dropping downward.
Once you’re comfortable with this approach you can start to press into your rear wheel just before it goes off the jump. This will give you extra height and, in turn, distance. It’s at this point that you’ll be getting a better feel for how the jump affects your bike and what you can do to keep control of the bike when on the jump and in the air.
Riding a bike is a great way to get outside and enjoy the great outdoors. And a jump or some other obstacles can provide a fun challenge and allow you to take your skills to the next level.
More Fun Features
Mountain biking is all about the challenge of riding over obstacles while following flowing trails. Jumps are one part of the sport, but many other skills come together to make for a great ride. You can always go to the trails to practice, but there are times when being able to practice a single skill in a controlled manner will allow someone to get comfortable with that basic skill before needing to do it on a trail. These obstacles can be set up in a circuit so they can be practiced in your yard.
A fallen tree is a common obstacle on a mountain bike trail. With a bit of practice, it’s surprisingly easy to ride over a fallen 10″ diameter tree. A few scrap 4×4s coupled with a medium-sized section of a branch will give you a fake fallen tree trunk to practice on. Be sure to make this obstacle wider and heavier than you think, as it’s so much easier to ride over if it doesn’t move. The key to getting over a feature like this is to raise your front wheel onto the feature (with your weight back) then move your weight forward and ride over the obstacle. It’s critical to keep pedalling as you try to get over the feature. It might be best to start with a pair of 4×4s screwed together so you only have to clear a 3-1/2″ high obstacle, then adding another 4×4 or branch on top of that when you need a bigger challenge. It might even be best to start some young riders with a 2×4 lying flat on its face. Small tires make it hard to ride over large obstacles, and once small successes have been enjoyed, moving up in stages is a good approach.
A teeter-totter isn’t something you’ll often come across, though many man-made trails do have them. Even if you don’t find this feature on your local trail, the skills to be able to enter onto a teeter-totter and control your bike while riding over it are valuable to have. It’s also a lot of fun, especially with kids around. Using a 2×8 is going to be fairly easy, while a 2×4 is going to be a lot more challenging. A 2×6 is a nice middle ground. Fixing a shorter length of 2×6 on edge under it will provide the fulcrum. A few additional pieces of wood will be needed to act as blocking near the fulcrum. Add the fulcrum slightly off centre (lengthwise) so the teeter-totter will always return to the starting position so the next rider can enter it. It also helps to ease the front edge of the 2×6 so entering the teeter-totter is smooth.
Other Obstacles – A teeter-totter and a “log over” are a few other biking projects any woodworker can build. These obstacles will allow young or new mountain bikers to practice a skill in a more controlled environment before they tackle these challenges on trails.