How to know when jump is set?

Discussion in 'Trail Building' started by fphmtb, Sep 20, 2017.

  1. fphmtb

    fphmtb Likes Bikes

    Hey guys

    Built a new jump in my back yard, how long do you think it when take the lip set enough so I can be ridden.
    It's mostly clay soil, and is still pretty wet.
    Should I be able to see tyre marks in the takeoff or is that an indication of it being to soft?

  2. johnny

    johnny I'll tells ya! Staff Member

    Get your little brother to hit it first. If he crashes and burns, wait longer.
  3. pink poodle

    pink poodle Clinically Inane

    This depends on a lot of things, you live in a dry hot area? If so it should dry pretty quickly. Did you do the jump properly and make it entirely from the earth or were you lazy like me and stuffed it full of sticks and rocks? 100% dirt will hold moisture longer.

    Ideally you should wait until it is set like a rock. This way it will hold the shape better for longer. This will take days or longer. While it sets it doesn't hurt to give it a good whacking each day with the shovel or other flat tool to maintain the shape. It shouldn't hurt to ride it before it is totally rock hard, provided you don't mind doing ongoing maintenance to keep it in shape. It's handy being at home with it as you can resurface it and water it without having "the man" come down on you. Unless your dad doesn't know about the jump...and doesn't like it when he finds it.

    Once set you'll probably have a surface that looks like a crumpet as the clay has shrunk without moisture. Throw a good layer of soil over it, light sprinkle with the hose, whack it into place with the shovel, and leave it for the afternoon and night. I suspect this will get some use over the holidays!

    Got a photo of the jump?
  4. bikesarefun

    bikesarefun Likes Bikes and Dirt

    If you keep slapping the lip enough during the build, you can often get to the end of the process and it'll be good to go. It's all about pushing out the moisture and air pockets before they end up deep in the structure.

    I always want to make sure I can stomp my foot hard into the lip surface without making any real deformation (tread pattern is OK; just not a change in lip shape). Then she's ready. If you can get it to that point before you put down the shovel, you're doing it right.
  5. pink poodle

    pink poodle Clinically Inane

    This thread needs an update from the op...given the length of transpired time I'm expecting some good crash pics and an X-ray of a collar bone!
  6. Knuckles

    Knuckles Burner

    Still not set....[​IMG]
    Last edited: Oct 11, 2017
  7. Beej1

    Beej1 Senior Member

    That is mighty f'd up
  8. pineapplehead

    pineapplehead Likes Dirt

    For real?! Poor bloke
  9. link1896

    link1896 Eats Squid

  10. pineapplehead

    pineapplehead Likes Dirt

    He looks better in the 'before' photo!
  11. Knuckles

    Knuckles Burner

    Link has me sussed. I'm about as reliable as a Chopshop assembled alloy Yeti...

    Sent from my HTC_M9u using Tapatalk
  12. link1896

    link1896 Eats Squid

    It was a sb66c frame and dropper and it was black and HARDLY ridden according to the listing I spotted the other day.
  13. the drizzle

    the drizzle Likes Dirt

    I wish i could stop seeing the picture of the mangled face in my feed.

    Sent from my iPhone using Tapatalk
  14. hifiandmtb

    hifiandmtb King of his castle

    Don't Google "grinder accident".

    As in the tool, not the other kind...
  15. pink poodle

    pink poodle Clinically Inane

    Well...I'm not so hungry.
  16. Nautonier

    Nautonier Eats Squid

    Shame on Knuckles for falsely catastrophising the impact of MTB jumps by using a car crash victim. You'd have to be going pretty hard sans hemet to do that sort of damage.

    I've been building jumps in loamy soil lately and the buggers never seem to set. Constant rain and people riding them in the wet makes the 'setting' process impossible with ruts being cut into the ramps and landers. Yes, bring out the miniature violin...
  17. Knuckles

    Knuckles Burner

    Just highlighting the danger cyclists pose to innocent motorists. The injuries were obviously caused by colliding his dumped VT commodore into an unregistered cyclist. Thems a menace I tells ya!
    moorey likes this.
  18. pink poodle

    pink poodle Clinically Inane

    - Build lander first, leaving the launch until the lander is ready for use.
    - Don't clear a run in or out until the jump is ready.
    - Pile up obstacles on the approach and launch ramp as well, people are usually too lazy to clear it for themselves. NEVER on the lander or run out! That's dangerous.
  19. Nautonier

    Nautonier Eats Squid

    Some quality advice. Problem I have is that I get impatient and want to hit them or ride the entire new track. Maybe I need to build B lines first and jumps last.
  20. pink poodle

    pink poodle Clinically Inane

    While I personally don't engage in any trail building, it is my impression that this can work really well or also very poorly.

    When it works well you are able to cut in new lines fast and rely on the adventurous b-line crew to bed the line in through the sheer volume of traffic. This stops the trail from growing back over while you're busy piling up the gnar!

    When it doesn't work you end up with a lot of problems. The trail erodes as it gets torn up by dick heads that can't ride (especially if you haven't built berms!), jerks offs decide it must be an up trail, people claim ownership and knock down your jumps/drops/berms/whoops and other obstacles they don't like, people mistake your new line (those jumps) as their new line...and leave big panic skid marks on your launch ramp or out the back of your berm.

    Alternatively you can spend hours, days, weeks, months, years working on a trail in secret. Starting in the middle, meticulously shaping each obstacle as you slowly form the trail into a work of art...only to have some simple minded pricks try and steal and finish it as a trail for simpletons. If you survive this you then face the b-line crew again thinking it is their right to skid down or up your trail because...well fuck it the trail is here and even though I have no chance of hitting that 5m gap and there is clearly no b-line I'll just trample over this kicker and ride on through. I deserve this!

    It's a fucking mixed bag and the more you build the more you repair. The better the stuff you build = the more people will want to ride it. Sad fate.

    Again though I don't engage in any trail building, so am just guessing that these things might happen. My only trail building experience has been on private land many many years ago.

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