Building a huge portable bike jump that fits in my Honda

Building a huge portable bike jump that fits in my Honda


Last month we built a large wooden lip behind
a row of shrubs, for use with my airbag lander. And as it turns out, we use this airbag jump
a lot—basically any time we can. But as the season wears on, the ground tends
to stay mushy for days after it rains, and for hours after the morning freeze thaw. Riding the airbag in the wet is like riding
a slip and slide, so I’ve been thinking, it’d be nice bring this airbag someplace
else when it’s wet out. To do that, we need to build a portable lip
small and light enough to fit in the back of my Honda, with the airbag. That sounds easy enough but this lip can only
be so small and compact. The one we already have on airbag trail is
dug into the ground for stability, and features hardwood planks for weather resistance and
grip. It’s very big, and very heavy. So our portable lip will need a totally different
design. For starters, I want to make this lip a step-up,
which means it’ll be lower than the back side of the lander. I also want to use as tight a radius as I
can get away with to keep the length of the jump down. If you’ve taken 6th grade geometry you know
that a radius is half the diameter of a circle. Our garage quarter pipe has a 6 foot radius,
and it’s only 4 feet tall. On paper, that looks like this. Our backyard airbag jump has a 10.5 foot radius
and it’s almost 6 feet tall. On paper, it would look like this. To make a jump small enough to fit in my pickup
bed, I’m going with a 5 foot tall lip with a 9 foot radius. To draw that I’m using the lines in my driveway
as a grid to line up this sheet of plywood, then using a 9 foot length of string as a
compass. On one of the sides, I marked an arrow showing
the correct angle of the transition so that we can use a level to get it oriented correctly. I want this lip to be 36 inches wide, so I’m
subtracting the thickness of the plywood from that and cutting a bunch of beams to build
the frame out of. Since I’ve never built a lip exactly like
this, don’t follow my blueprint. I fully expect to make changes to this frame,
and maybe even rebuild it someday entirely. But hopefully it’ll be something we can
transport and ride tomorrow. 1/4 inch plywood can bend a fair amount, but
installing it wet helps to prevent cracking, so I’ll spray this down every so often for
the next 30 minutes and then get to bending it. Bending the plywood is always tricky business. So it’s best to do it… slow and methodically. Now that we’ve built our lip, it’s time
for a dry fit. Not quite ideal, but I’ve got an idea. To hold the
lip together we’ll use these latches, which seemed like a good idea in the planning phases,
but in actuality look super jank. With the lip in two pieces, it fits quite
nicely in my bed, with room to spare. And it’s more than light enough for one
person to lift. But then, there’s airbag. As it turns out, Kevin has professional experience
in the dispatch, transport, and inflation, of bouncy castles, which is essentially what
this airbag lander is. This airbag weighs….a lot. it actually arrived on a pallet. But by using the hand truck and blower as
a sort of staircase, one person can load it into a pickup. This whole setup packs into my bed so nicely,
that it’s actually not sketchy at all. In fact, nothing shifted at all during transport. Setting this up in Kevin’s driveway took
actually less time than setting up at my house. At my house we need to get the bag and blower
from the garage to the lip, which is more work than you would think. Here we can unload everything on site. Time to see if these latches are as jank as
they look. Step ups are really fun. You can easily see the landing on approach,
which is useful. And jumping a step up is very smooth since
you catch the landing at a higher point in your trajectory. Despite a few adjustments and a small learning
curve, we were getting really comfortable on this lip…maybe a little too comfortable. So it turns out that Dave can backflip. And that meant the session had officially
popped off. That was my first backflip attempt outside
of Highland Training Center, and I rotated way too slow. Looks like my flips need some calibration. With under an hour of daylight left, we were
trying to get in as many runs as we could, but Paul had never ridden a wooden lip this size, let alone a double. And so, it’s safe to say our portable airbag
launch worked out pretty well, or did it? As we started to gain confidence and ride
harder, it started to get way sketchier. Eventually we weighed down the center with
a big rock and that solved the problem, but I’ll need to take this ramp apart and redesign
it eventually. A redesign would include a harder angle on
the rear supports to keep the ramp from tipping, and a carriage bolt and wing nut solution
for holding it all together. We’ll do that another day, but I think it
is safe to say that the concept works. Anyone with a pickup of any kind can transport
this huge instant jump anywhere. I hope you enjoyed this build and should you
decide to build one of your own I’d urge you not to follow my blueprint save for maybe
the radius part. I’m really stoked on finally doing a big
backflip, and taking a 360 on something this big as well. It’s amazing how much you can progress when
you have a huge cushion to land on. Thanks for riding with me today and I’ll
see you next time.

Add a Comment

Your email address will not be published. Required fields are marked *