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Duthie XC Tutorial

2K views 14 replies 10 participants last post by  woodway 
#1 ·
Ole Westra put out the call. Them XC trails are in desperate need, but maybe you're not too sure what to do? Well here's a story and a guide explaining what, how, and why.

Stardate yesterday probey wanted to come along, but the Mothership needed to stay home, this was all about giving love to the trails. Of course Westra forgets to mention there is no longer a combination lock at the gate. No problem i simply drove across Omar Visquels lawn and parked in his back yard.

The trails are all completed, current usage already has revealed problems, so my mission is clear. Locate, identify, and "finish" them.

ACK! a puddle!!!! We'll start of with a simple one, picture below is a dip in the trail. Water settles, organics accumulate and the tire wear combined with the erosive powers of water will continue to make this puddle deeper as years go by.



i've drawn arrows to show where the water was intended to go, also note the little drip, a drainage had been dug out to the left. But obviously the trail tread is now lower than the drainage leaving a puddle. You can see i scooped out a couple buckets of really good mineral soil with lots of rock in it, perfect soil for this application.



And here's the final shot showing the fixed trail. Spreading and packing the dirt into a nice slope, so water will now have no problem finding it's way into the drain like originally intended.



Next up is an example of small stretch of trail that is caught in a neutral state. The arrow shows that water from one side drains where it's intended, but the dotted area shows a dead zone where it's practically level with the mouth of the drain, so water just sits there. When that happens organics build up, tires will eventually erode this section and cause ruts. If you also notice a bump that the yellow McCleod is sitting on, i created that a few weeks before, but didn't finish the fix.



So since water runs down downhill we're looking at the + signs to help us envision a border, the + signs are the high spots.. Inside this area we use the yellow McLeod to scrape all the organics out, into the X pile, later we always throw this clutter off the trails broadcasting it out to feed the bushes. Our minus sign shows us where we need this water to go, the negative is our low point, our drainage. Already i've stacked some larger rocks to serve as a base for the soil build up we're about to put in.



Couple bucket loads of that really nice rocky mineral. Dump them out in a couple of lines to get a basic shape of what we need to do to make a slope for the water to shed off the trail. You see the McCleod is being used with the rake side to groom the shape, as well as take out rocks that are too big.



So here's the final shot we now have a nice slope so the water will now shed off the trail, and we'll have nice solid tread. Where before we just had film of standing water and gloop, now the arrows show the where the water runs toward the drip drainage, and we're good to go.



Ok this next fix is moving into more of an advanced area. But it's something that's real important to understand when doing trail work. You can first look at his picture and say, "i don't see anything wrong. There are no big puddles here!?" Well at first glance you would be right (even though the drainage did need to be cleaned of all those sticks and organic matter).
But the problem isn't the drainage here, the problem lies in the "flow" of this corner. You can tell by the frowny face this big high berm was intended to take the downhill rider to come out onto a sharper turn. But the blue dotted line shows that most riders don't take the berm as high as the builder thought, and they are winding up going left of the trail after the dip.



"Well so what?" you might say as this picture shows all the plus's and minus signs show the drainage is working good, water going toward the drip. Well the problem is the area i show in the dots. That section where riders are winding up is a section of trail that does not have a firm tread base. The edge of the trail there had alot of duff mixed in, so after a while there will be a rut. More riders will deepen the rut as they come down fast off the downhill corner, and brake and skid on it, and it will get worse and worse as years go by.



So the solution is to make a bump on this section. Berms are fun, but are not necessary for flow. This bump puts a nice inward slope to the trail (inslope). Generally you want to avoid inslopes because they prevent water from shedding off the trail, but in this case it's on the high side of the dip, so water drains fine. The dotted lines again show the common path of mt. bikers, only now the bump is there to help get the wheels back to the center of the trail with no trail damage done. This is an example of "flow", when speaking of the relationship of how a trail rides and responds to wheeled traffic.



A look from the other side. Dotted lines show path of bikes as they come around the downhill corner up from the drainage dip, and now onto this bump. The bucket shows the level of the inslope.



Ok let's examine how to make a bombproof bump. First after digging out duff to get down to the hardpack pack i piled up a nice pile of softball sized stones for a base. You can think of this like a skeleton.



Next we dump a pile of crushed gravel. The gravel will fill inbetween the rocks settling them in, as well as create the basic shape of the bump. You can think of this like a the cartiledge and tendons.



Ok this part is a bit overkill but i still was close enough to harvest this really nice rocky soil. So we can think of this step as adding extra muscle, we're giving this bump tread some steroids. Think of this as the muscle.



And a final "skin" layer of mineral soil, pack it down, and you have a solid tread that should last forever.



Ok the final problem we see has a combination of all these issues. After a downhill we have a dip drainage that is not draining well, and the arrow points to the log which is creating a visual obstacle which is pushing riders to the outside of the trail. The outer part of this bench was built over duff and organic and is breaking down on this climb.



So we show a puddle developing on the trail, the trail now rides over ferns, and above the edge of the trail breaking down. This trail isn't even a half year old, so this section needed attention right away.



Dig out all the crud. Throw in a bunch of heavy rock and bury that with a wheelbarrow full of crushed gravel to reinforce the tread.



And after a nice topping of mineral soil we have a tread that looks and rides way better.



Taking some steps back viewing the entire climb, you'll see i used a pick to re-work the drainage as well as used that and a shovel to dig out the duff base. Then we can reshape and reinforce the tread with a couple loads of crushed gravel. All the signs are showing we're getting all the water off the trail now.



As our final shot shows that right above of the dip i added some inslope to help get the wheels centered on the trail. With our final topping of mineral soil we have an example of sustainably built singletrack trail that drains well, flows (rides) well, and will not suffer from erosion.



Cheers, now go dig!
 
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#3 ·
Rock Climber said:
Wow skooks, I feel like I just went to trail building 101! Thanks for the write up.

I got a little bit lost on the part about creating the bump and how that moves the rider to the intended line. Can you clarify a little for the slow people like me?
The bump has a flat surface and it is insloped. If you see the last picture where the bucket is leaning, you can see the trail and a line i drew behind it. Rider comes down a hill with roots, which is probably why they are not getting set up well to run the berm high, and that line is what appears to be the most used line.

When people come out from that downward turn at a fast pace they lean into the turn. The bump has a flat upper surface that matches the lean of the bike, so the level of the bike and the level of the tread on that bump are about equal. Same idea of a berm, but a berm is more pronounced.

Therefore your bike will carry speed better on a corner, and not slide out from underneath you.

So before you come down fast off that corner after the berm and you have a trail that is flat and/or outsloped at the bottom so it can drain water. But now physics is working against you so instead your turn radius is wider, therefore your bike blow out of the corner on the low edge of the trail.

So now you come down fast off that corner after the berm you still have the outsloped drain. But what's different now is you have an insloped bump that allows you to correct your trajectory.

Go ride it this part of the trail is open, it's the NE XC trail from the closure near Ryans/BT entrance toward Boot Camp trail. I still haven't ridden it yet to test, but i know it works, just because i do.
 
#4 ·
Thank you for that most excellent treatise! Printing off pics and all to take to a trail committee meeting tonight.... it's seemed a bit slow trying to communicate just how skilled and committed y'all have been on these projects, and that well built MTB trails don't all end up looking like a series of structures to huck off.
 
#6 ·
Wow, awesome explanation skookum. Definitely could have used this the first time I went out trail building, I was definitely lost at first but fortunately was with some more experienced builders. Hopefully reading this will encourage more people to get out there and lend a hand, as it will probably seem a little more reasonable/less intimidating than they may have though once they have some knowledge.
 
#8 ·
T-t-t-t-Timmehhhh!! Schoooooweeeeeet tutorial!! Thanks, man.

Can you do another one? This time out on Bootcamp on one of the flat areas that is far from a rock source:


Oh, and before you head out there, can you post it as a work party and maybe you'll get some peeps to sign up and help? :D ;) :) :p :thumbsup:

BTW, does anybody notice anything different about the above map?
 
#10 ·
mwestra2 said:
Oh, and before you head out there, can you post it as a work party and maybe you'll get some peeps to sign up and help? :D ;) :) :p :thumbsup:
Sure, ok, my lack of work from iffy weather is making these appearances sporadic and last minute. But i guess if people know when i'm out there with my intention of shoring up the XC trails before the opening deadline... Well maybe people would want to show to help out.
Whatever it takes man.

If somebody let's me in the gate i'll be out there today... But i want to finish out NE Dr. Phil.
 
#11 ·
verslowrdr said:
Thank you for that most excellent treatise! Printing off pics and all to take to a trail committee meeting tonight.... it's seemed a bit slow trying to communicate just how skilled and committed y'all have been on these projects, and that well built MTB trails don't all end up looking like a series of structures to huck off.
As Bob stated, there's a DVD you can get from the USFS that they put out with IMBA back in '06. It's pretty basic in nature, but might help with these concepts. PM me if you want a copy (I've got a couple left) and I can mail it over.

Also, the IMBA trail solutions book has lots of good info on trail tread, drainage, switchback construction, etc. It's money well spent and good to have even if it's just as a reminder.

You can see the USFS/IMBA on Youtube as well in a multi part series.

 
#12 ·
Yeah, I've seen the Youtube series and sent links and actually petitioned to host a group viewing session @ my office (I've got a BIG tv hooked up to a 'puter, ideal). It will happen, just takes time.

In the meantime we're talking about a group field trip up to sec 17 in Roslyn in the next couple months so I can take them through at least part of the race course and talk about what worked and what has required more effort to maintain (I'm not the expert Tim obviously is but we can discuss the most obvious stuff). It will also hopefully clear up some Mt Dew flavored fears about what 'mountain bike trails' are.
 
#13 ·
Thanks for all the help out on Bootcamp yesterday!

Re: the map... new trail name for the DWB line: "Paramount". And unfortunately we can't keep "2Hi" -- rejected by the man. Oh well... it's King County Parks land so they get to make the call on what is acceptable for a family park. HLC is coming up with a new name. The trail will still be the same :).
 
#15 ·
mwestra2 said:
Thanks for all the help out on Bootcamp yesterday!

Re: the map... new trail name for the DWB line: "Paramount". And unfortunately we can't keep "2Hi" -- rejected by the man. Oh well... it's King County Parks land so they get to make the call on what is acceptable for a family park. HLC is coming up with a new name. The trail will still be the same :).
Been there, experienced that. Out at PVCA FM still calls the trail we have been building on "Morning Wood", even though the name that the County accepted is "Cedar Run". So, you can have official names and unofficial names.
 
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