[KRob]

I'm all but finished with a five mile trail build. Now we just need to figure out how to get off this ridge. One side is loose, and erosion prone. The other is very steep, without a real obvious flatish landing for a swicthback.

It is mostly a downhill trail but I've been trying really hard to make everything on the trail rideable going up as well. I need to put one switchback in on the steeper sidehill option but, dang, I've dug quite a abit and still don't see how I can back it climbable. It's got a big enough arc to make it doable (but still a bit scary/dicey) going down without having to do the euro, nose wheelie/tail whip method, but can't figure out how to make it climbable.

Tips from the pros?

 

[Harryman]

This is a good place to start.

https://www.imba.com/blog/mark-eller/advanced-trail-building-introducing-switchberm

On a really steep side slope, you're going to have to excavate and build a substantial platform into the hill, so looking down on it, it's not a V or U shape, but more of an Omega.

Shaped more like this:

https://trailism.com/insight/switchberms-and-climbing-turns/

As you've found out, doing it right takes a lot of effort.

 

[DaveVt]

Didn't look at the links above but I have 3 thoughts. First off, never start "Building" until the route is complete. Time is our most valued resource and it's always under-estimated, particularly when hand-benching on steep side-hill.

Second, even with machines, digging a proper switchback requires a ton of material moved......actually a couple few tons. Some sort of cribbing/retaining will lessen the material needed.

Third, tight turns can work and flow if you bring the side-hill trail up hill enough to reduce rider speed....or even just give an up-hill section of trail just before the turn.

Allowing riders to brake on an uphill section of trail, even if it's a short piece, like 10-15 feet, will result in a more natural force vector. It will still feel flowy, press the tires into the tread instead of skipping, skiddering along on a down-slope. Even if the turn is very tight....if you provide an area to decelerate, it will flow. .

I think many folks think flow trail or flowy trail needs to be fast all the time. Natural slowing and accelerating is a much more interesting experience IMO. Bringing folks uphill when they have a ton of velocity to almost a stop with no braking....then throw in a little low speed tech like a tight, armored through the fall line turn can be awesome. The Flow State is reached by variety and irregularity. Over-stimulation. When velocity slows down...featured and directionally changing tread will keep your brain engaged which is the key to staying in Flow. Like a good tune.....the blur-speed sections will compliment the low-speed noodley, chunky sections.
$.02

 

[endo_alley]

Maybe some phots of the trail? Is it possible to avoid turns on the steep pitch and post pone them until the terrain flattens or until the terrain favors a climbing turn?

 

[DaveVt]

Maybe some phots of the trail? Is it possible to avoid turns on the steep pitch and post pone them until the terrain flattens or until the terrain favors a climbing turn?

Agree with this.....keeping it flowing side hill rides way better....even if you have to deal with stream crossings and such. Assuming this is not possible hence the switch-back.

 

[endo_alley]

Sometimes people make poor layout choices early on in mapping a trail and wind up painting themselves into a corner further down the line. Best to layout an entire trail wisely before moving the first shovel of dirt. And if you have yourself in a bind, explore all easier fixes before putting a switchback or two in on a steep hillside. I truly dislike them.

 

[epic]

I wonder what you can do with some wood. Maybe you can build half of the turn onto a wooden platform and build a ramp back down onto the tread.

 

[endo_alley]

Is the turn necessary? Why not cut a bench into the slope and follow the slope all the way along the side of the ridge until you hit less steep ground? That is the proper way to layout a trail.

 

[KRob]

Yes, pretty much necessary. If you just keep following the slope down you'll end up in a steep/v-shaped washed out canyon on one side of the ridge and the side hill gets interrupted with some ledges and deeper drainage cuts on the side we're working on.

We've got the switch back pretty well cut in now. It's very nice going down. We were able to make a pretty good patform/landing zone on the downhill side with a downed tree propped up against a sturdy tree fill in with bigger rocks and mineral based fill dirt. The climbing portion of the turn is still a bit too steep to climb so I'm thinking off angling the exit portion on top more to make the grade more doable. One of the problems we're facing is the dirt is fairly loose so no matter how much we dig out (so far anyway) it still doesn't seem to get down to a really firm rock/mineral base.

I uploaded some photos although it's hard to get an idea for the steepness of the slope from these images. The vertical drop from the top of the trail to the bottom is 8-10 feet.

 

[DaveVt]

You're in mineral dirt, it's just dry as moon dust. You need rain then go out and tamp like a mad man. Your vertical back slope is no bueno. You'll generate a good bit of material from cutting that back. Use it to build up the ramp and lower part of the turn so you're gaining vert over a longer piece of trail. Got yourself in a tough spot. That tread will always get chewed up either from #VanLifeBros roosting the tight, steep turn, or from folks climbing up it in light gears. Preemptive surfacing might be a good idea. Something wicked grippy might make it climb better. Got much rock around?

$.02

 

[ki5ka]

What Dave says

 

[Cotharyus]

Yep. Like Dave says, clean up that back slope and use the material to build up the low side of the turn. Then either wait for rain or carry a bunch or water in and tamp that down. It's a steep hillside, and if you have to turn across it, it's always going to be challenging. It takes a lot of work to build a good turn on something like that even with a machine. There are a couple of places I've ridden where there are certain turns that you just resign yourself to "I'll try it every time, and maybe I'll make it one day" and it's not because it's a crappy build, it's because it's the only thing you could do on the side of the hill. When you start to run out of options, you're sometimes left with less than idea choices, but if you can put something solid there that will last, it may be the best you can do.

 

[endo_alley]

It looks as if you need to widen the bench along with stabilizing the backslope. When we have built over soil like that, you can easily lose a third or even half your bench over a the first winter as the hillside sloughs into the trail and the soil tries to stabilize. If you can keep both approaches to your turn fairly flat, that will let the riders set up for the turn. Find a lot of big rocks and boulders for the apex and bottom of the berm, it will probably hold up better in the long run. Batter the rock wall so that he rocks roll into the hill. Hammer (shatter) smaller rocks into the gaps. And finally cover the whole thing with mineral soil. That kind of soil may need a lot of grade reversals and nicks to hold up during a monsoon season.

 

[twd953]

Third, tight turns can work and flow if you bring the side-hill trail up hill enough to reduce rider speed....or even just give an up-hill section of trail just before the turn.

Allowing riders to brake on an uphill section of trail, even if it's a short piece, like 10-15 feet, will result in a more natural force vector. It will still feel flowy, press the tires into the tread instead of skipping, skiddering along on a down-slope. Even if the turn is very tight....if you provide an area to decelerate, it will flow. .

I think many folks think flow trail or flowy trail needs to be fast all the time. Natural slowing and accelerating is a much more interesting experience IMO. Bringing folks uphill when they have a ton of velocity to almost a stop with no braking....then throw in a little low speed tech like a tight, armored through the fall line turn can be awesome. The Flow State is reached by variety and irregularity. Over-stimulation. When velocity slows down...featured and directionally changing tread will keep your brain engaged which is the key to staying in Flow. Like a good tune.....the blur-speed sections will compliment the low-speed noodley, chunky sections.
$.02

This x1000!

I don't care if it's a machine built flow trail that can be ridden at a 20 mph average or an old school hand built technical trail that is ridden at a 4 mph average, I don't want to be going 20 mph or 4 mph the whole time.

Despite the type of trail (and I like both) those momentum changes keep it interesting, and if you can use the terrain to achieve those momentum changes without having to use heavy braking, that is by far the best from a rider experience and trail builder's perspective.

In the KRob's case, using the terrain to scrub the riders speed without heavy braking in what appears to be dry/loose/non-cohesive soils will keep the trail from blowing out so badly under heavy use.

Also, since it is intended as a two way trail, putting a short bit of "uphill" after the turn (when ridden in the downhill direction) or at least a short bit of flat will give climbing riders a bit of a rest before climbing a switchback that may be a bit too steep.

You don't need so much elevation change that a downhill rider needs to pedal out of the switchback, but it's amazing what a couple of pedal strokes of rest before grunting up a steep switchback will do on a long climb.

 

[endo_alley]

Yeah Dat.

 

[Schulze]

Are there no washes? Those are perfect to build a switchback into because the sides are already angled.

 

[KRob]

It did rain the past couple days and I got up there this morning and tamped it down best I could. I also pulled some dirt down from the inside of the turn to the bottom and tamped it down to build up the run up. I see what your saying about the steep climbing section. It's almost impossible to descend it without dragging the rear wheel a bit or climb it without spinning out.

So when you say the vertical back slope, are you talking about the berm? That dirt is very fine and loose. I can't see how pulling it into the trail will help. I think I need to dig the top part down more and pull that rocky, more mineral based dirt down onto the bottom where it starts to ramp up, no?

There are rocks about but not big paving type rocks. What about actual pavers like I see at some parks out West here (Northstar and Mammoth)?


Sent from my iPhone using Tapatalk

 

[DaveVt]

The back slope is the uphill edge you left when you cut into the slope. In your photo it looks almost vertical. That will not be stable. You should cut it back with your hoe to be slope as shallow an angle as you can, although it will always be pretty steep as the slope you're working on is steep.

Pavers could work, but also smashed rock will settle in if the rock breaks up enough. It might be a bit loose at first. If you mix dirt into the rock as you smash it it will settle in.

 

[endo_alley]

Are there any local mountain bike clubs or trail advocacy organizations? I think you would be well served by letting someone with trail building experience look at the sight and help you with the difficult sections. Easier to get it right early on than to rehab a bad design later. If you don't yet understand the basic terms of trail building, you need to read up some of the pertinent literature or such as IMBA trail book, or USForest Service handbook better yet take a course from IMBA.

 

[DaveVt]

Another option for improving the riding characteristics of an over-tight turn is a very steep berm. Might not be a durable shape for you considering soil type. A steeper berm would allow riders to roll through the turn with more speed, so less braking potentially.

Be interested to see how the interlocking pavers work. Never done it but have seen photos.