Building wooden jumps

GazzaPops

Likes Bikes
Here's a mini kicker I made for my kids. They are not up to jumping yet so they only roll over it but it's got enough of a kick to get them started when they're ready. I'm going to build some more features next year when we move into our new home.

I made this out of a single sheet of 12 mm plywood and a mixture of 70 x 35, 70 x 45 and 90 x 45 structural pine. The ramps are 1000 mm long and 300 mm high. It's 600 mm wide. The curve is a spline that comes in about 50 mm below the straight angle at 700 mm from the start of the ramp. I hope that makes sense, I don't have the drawing at home. The curve is not very aggressive so the 12 mm ply complied with the bend fairly easily. The tabletop is 400 mm long.

I haven't tried it out properly myself but it feels quite rigid to me when I walk on it. I got the idea from a couple of videos by Phil Metz and Seth's Bike Hacks.


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schred

Likes Bikes and Dirt
Looks awesome, lucky kids.

I only finished one today that looks pretty similar, the 15mm took some encouraging and I wouldn't be surprised to find it self destructed at any moment. Also regretting the super gradual incline, can see them snapping off.

Any suggestions on outdoor paint for ply?
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Flow-Rider

Burner
Looks awesome, lucky kids.

I only finished one today that looks pretty similar, the 15mm took some encouraging and I wouldn't be surprised to find it self destructed at any moment. Also regretting the super gradual incline, can see them snapping off.

Any suggestions on outdoor paint for ply?
Looks Good.
I nailed and screwed a fence paling to the start of the ramp then cut and sanded it to the same angle. I would imagine you'll need to do something for grip if you want to paint it, otherwise your kids might face plant when they have slightly wet tyres.
 

pink poodle

気が狂っている男
I reckon that feature is heaps of fun.

Did you do the new drop on the enduro track ?
I think it should be a lot steeper, but it is probably perfect for a wider audience.

I'm not certain which drop you're talking about..? The tram were a bit different to when I was last there (over a year ago!). Near the last series of jumps on the dh trail I saw a sign that said "drop zone" as I was hustling out. I didn't hit it - I was riding solo and it was my birthday so I felt karma stakes too high...meaning I passed out. It looks very straight forward though and not much different to the first drop at Narra.
 

schred

Likes Bikes and Dirt
One set down, second set is cut but unassembled, has 5cm more height for a bit more pop.
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Little tacker coincidentally took first proper pedal today (kms vs prev. a few cranks down the driveway) so the jump was too tempting. He only ate it twice as the safety gear on the cranks got tangled on the table top approach and departure angles, grrr.

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hellmansam

Likes Bikes and Dirt
the 15mm took some encouraging
and
Any suggestions on outdoor paint for ply?
For thick ply to bend nicely you can "kerf" it using a circular saw, make a series of shallow cuts crosswise to the bend you want, and put the kerfed side downwards. About 50 - 70% of thickness should be adequate, too deep and it will split along the cuts.
There are anti skid paints made for boat decks that would work nicely, but a coat of epoxy resin underneath would be good for the longevity of the ramp. Hopefully you've used Exterior grade ply for its waterproof bonding glue so it won't start falling apart if it gets wet regularly.
 

pink poodle

気が狂っている男
So who did the circular saw? Not one of the kids...surely?

Ramps look good. Love the stained finish you've put on. It that the burnings "sprinkle of rain" or "touches of dampness" finish?

Ramps look sweet. Get amongst it and gap ramp 2 to ramp 1!
 
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