# Berm Question?



## rossbourne14 (May 9, 2010)

I'm currently needing to build a berm for my trail. Now yes this isnt to difficult of a thing to do, but i want to make sure im doing it right. And i would like to get some opinions.

It's gonna be located on a near almost flat surface, with the trail almost completely switching back the opposite direction, so the berm will have to be angled sharply. The question i have is what would you use to support it? trees? rocks? alot of dirt? lol would it need to be tall? It's very possible to gain alot of speed coming into the berm itself, so i would imagine, the taller the better?

I don't really have that much dirt to work with, so the more fillers i could use would be great, but if thats detrimental to the longevity of the berm, then i wont. 

any pictures you all can provide of some switch-backing berms would be awesome! thanks!


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## bizgnar (Nov 6, 2009)

from my experience its always best to use all dirt when building things such as berms, rollers, or jumps. i would recommend digging down a bit and use that top soil as a base then find some quality mineral soil and cover the base with that. this technique will make building much faster. if dirt is an issue you can use rocks as a filler as a last resort. i really don't think the height is such a big deal, its more important to focus on the entrance and exit of the berm, making sure it is gradual. i'll try to post some pics of my trail i'm building.


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## Trail Ninja (Sep 25, 2008)

*If *you can get some rot resistant wood. You can build a log wall, not as fill, but to hold the fill in place. Then use rocks for fill, top with a good amount of dirt. You can get a lot of height that way. I'm going to find a thread that has some great pictures. It may take a while.


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## EXPERTRIDER (Feb 13, 2010)

Make sure you use a consistent radius arch for the berm. You don't want flat spots or lumps.
The steepness of the face is much more important than the height. I've built about 25 berms in the past 6 months, and the height has varied from 12" to 4'. 
The anticipated speed should determine how wide you make the radius. An 8' radius is very slow and tight... 16' radius is flat-out flying (like a downhill or very fast section)
The berm should almost start on the straight coming in, and should finish on the straight coming out. I aim for near vertical at the top of every berm. A push broom is my favorite tool for finishing a berm.
Build well enough for the occasional idiot that will go straight over the top....(I've seen it- a panic-stricken beginner grabbed his front brakes mid-berm and took a nice chunk of my berm over the top!)
The total beginner will ride the bottom and ride vertically thru the berm, so build it tough!
If you can make the berm visible well in advance, it will help with panic skids and other destructive behaviors....
(The beginner rider is WAY harder on the trail than an advanced rider!)


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## Fletcher-Love (Nov 14, 2009)

If your building your berm to act as a switchback...... (depending on where you live and how much rain you see) its a good thing to drain water at the top of your corner and at the bottom. I like to use large culverts at the bottom of some of my turns because they are easier to clean out and you don't have water running across the tread surface on your exit. It sounds like your coming into your corner with speed so I would make it a larger radius.


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## dk11 (Apr 30, 2010)

bizgnar said:


> from my experience its always best to use all dirt when building things such as berms, rollers, or jumps. i would recommend digging down a bit and use that top soil as a base then find some quality mineral soil and cover the base with that. this technique will make building much faster. if dirt is an issue you can use rocks as a filler as a last resort


Newbie trail builder question...is there a problem using rocks as fillers if there is enough dirt mixed through?

Also,what about building flat smooth rocks into the face of the berm to help reinforce it?


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## Trail Ninja (Sep 25, 2008)

dk11 said:


> Newbie trail builder question...is there a problem using rocks as fillers if there is enough dirt mixed through?


No, not at all.



dk11 said:


> Also,what about building flat smooth rocks into the face of the berm to help reinforce it?


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## dk11 (Apr 30, 2010)

Trail Ninja said:


> No, not at all.


Cheers Trail Ninja:thumbsup: :thumbsup: 
Exactly what I was thinking of!

My local trails are used sometimes by MX riders so the more stone the better I reckon


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## Trail Ninja (Sep 25, 2008)

No rocks? No problem.


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## dk11 (Apr 30, 2010)

Trail Ninja said:


> No rocks? No problem.


Thats just showing off 

It'll be a little less extravagant than that!

I'm lucky enough to have some dirt pulled up from the ground from some nearby fallen trees,and close to a large stream and fallen old boundary walls for the stone


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## Trail Ninja (Sep 25, 2008)

dk11 said:


> Thats just showing off
> 
> It'll be a little less extravagant than that!
> 
> I'm lucky enough to have some dirt pulled up from the ground from some nearby fallen trees,and close to a large stream and fallen old boundary walls for the stone


You've got stone fences you can use? That's flat rock that somebody else has gathered from far and wide and put all in one place? You can't get much luckier than that. I grew up in an area like that... 30 years ago.

Where I live now, all the rock is big river rock. Round and smooth and really hard to split with a sledge hammer (the only way to get a flat edge). Fortunately we have a lot of red cedar which is why we do so much wood work.


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## dk11 (Apr 30, 2010)

Trail Ninja said:


> You've got stone fences you can use?


Yep....loads...and loads of them!

The area is now a commercial forestry,but I think it must have been divided into fields many years ago.
The trail rides over the walls in sections in places where it has fallen,usually with some tree roots growing through them,so they can make a nice ride feature on their own.

The trail is in Ireland,so unfortunately none of that magic cedar here!
any wood structures will have to be pine with the bark stripped off


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## Trail Ninja (Sep 25, 2008)

No, use your rocks. It's way cooler. Plus, you know how old those walls are. Your trails will last longer because you aren't piling the rocks up like in the walls. You got any old Roman roads? Look how long they last.


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## cmc4130 (Jan 30, 2008)

I like to build berms with a transitioned face--like a skateboarding bowl corner--not flat bank....










There are other styles of berms.... this is kind of the clam-shell style that is ridden low-to-high-to-low....



















https://www.bikemojo.com/speak/showthread.php?75951-nice-berm


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## Cedar Branch Biker (Jul 28, 2010)

Ya'll's berms look like a cross between NASCAR high-bank speedways, and a skate rat's dream-come-true!


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## Fletcher-Love (Nov 14, 2009)

In the pics I chose to show that particular trail probably sees as much rubber as a nascar circuit.... ( thats a blatant exaggeration, but you get the point). Those corners can be ridden all year around, rain or snow....only because of the way they were shaped and the way they drain. In no means should all trails have corners like that. I was more pointing out a style of build for switch backing a turn. Carving the corner out of the hillside and making the tread a steep bank allows the berm to both hold its shape and drain water quickly. By digging down and into the hill ... in the area you intend to force your drainage.... you also generate fill material to build up the corner to your liking. I personally think the back slope on the inside of the corner needs to be laid back to the angle of repose. Much more sustainable than a trench. It will allow vegetation to grow back in towards the trail and looks better. A settling pit and large culvert at the bottom of the corner will allow the water to pass underneath the tread and eliminate tires riding on any running water. ok...i am done berm nerding.... for now....


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## Cedar Branch Biker (Jul 28, 2010)

Berm nerder? Is that anything like a nerf herder? (Ask Princess Leia, I ain't sure what that means.)


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