> dat bump thing for mtb i have to calculate the height, curve,

Do you want to make a pump track or jumps?

small jumps to learn the proper form

Go to track, measure height and width, take picture. Try your best to rough it out.

>>1210322
The ones in your image are using 24" diameter cement culvert pipe. They might have 0.5 inches of soil on the very top at most.

>>1210322
These things were so fun to make when I was younger. Just make sure you don't make the jump too steep and land on your testicles. It is not fun.

File: i-47gmLWV-L.jpg (65KB, 800x450px)

65KB, 800x450px

>>1210322
they're called "whoop"s.

You're going to have a bad time if you "just throw some dirt randomly" and hit it.
Approach angle, spacing between them, and landing should be even between them and appropriate for your vehicle.
And the dirt needs to be packed decently to hold together, not give way and pull your bike into it.

Track builders have a pretty good "feel" for what they should be. A good track is a work of art, built with dozers or groomers.
And watching the precision a good snowcat driver has with the snow is beautiful.

t. snowmobile racer

About 15 years ago when we were about 17, my next door neighbor had a front end loader so we made a jump and a down ramp. This consisted of a big fuck off pile of dirt as the jump, and then another equally big pile of dirt as the down ramp. My other mate who thought he was pretty decent on his RM125 hit it pretty quick and cased it on the down ramp, so my other mate on his KDX125 thought the best thing to do was to hit it even faster. He ended up flipping and the bike ended up on top of him, and he ended up with a punctured lung.
I was up in the front end loader bucket filming the whole thing but footage has been lost for ages unfortunately.

>>1210322
just make a jump and err on the side of caution. hit it and adjust as needed.

>>1210328
This.

Unless you are going pro op just do whatever is comfortable.

Also, get a spare wheel and tire, throw dirt where u want, and bounce tire on it to pack it good.

Alternatively you can build the track hiu u want it. Then get some buddys and shovels and rent a whacker packer from and equipment rental. I promise its a real thing. Google it.

DO NOT GET YIUR GEET OR HANDS UNDER IT.

>>1210322
Hell OP, i got like 3 or 4 junk colvert pipes like that here at work. They brought them to dump but i drug them out to form fiberglass and never did. They yiurs if u want them.

But they in Southeast Kansas.