Downhill course

[tjp]

Our organization has a big project, our first, to get started on this spring, 10 miles of bike-specific (in that it will be intended to be fun for bikes, but will remain multi-use) singletrack, and a critical element is a dedicated DH course. It needs to be rideable for a wide range of riders, since Humboldt State will likely be using it for their race venue. Other than that, I think we're pretty open. There will be a steep section near the finish that will require switchbacks. A good test of tired arms... 1.7 miles, 1,000 feet loss or so.

Questions - max grade, min radius for the switchbacks, how steep to make jump faces, anything else to keep an eye out for as we plan??

Soil seems to drain well - chundery, for lack of a better description. Good loamy soil with lots of 2-6 inch rocks.

[sambs827]

Sounds like an awesome project. Posting so I can see updates and learn something.

[Davey Simon]

Our organization has a big project, our first, to get started on this spring, 10 miles of bike-specific (in that it will be intended to be fun for bikes, but will remain multi-use) singletrack, and a critical element is a dedicated DH course. It needs to be rideable for a wide range of riders, since Humboldt State will likely be using it for their race venue. Other than that, I think we're pretty open. There will be a steep section near the finish that will require switchbacks. A good test of tired arms... 1.7 miles, 1,000 feet loss or so.

Questions - max grade, min radius for the switchbacks, how steep to make jump faces, anything else to keep an eye out for as we plan??

Soil seems to drain well - chundery, for lack of a better description. Good loamy soil with lots of 2-6 inch rocks.

Start at the top and work down so the flow of the trail doesn't change. If you build it in sections this will happen.

[cmc4130]

Our organization has a big project, our first, to get started on this spring, 10 miles of bike-specific (in that it will be intended to be fun for bikes, but will remain multi-use) singletrack, and a critical element is a dedicated DH course. It needs to be rideable for a wide range of riders, since Humboldt State will likely be using it for their race venue. Other than that, I think we're pretty open. There will be a steep section near the finish that will require switchbacks. A good test of tired arms... 1.7 miles, 1,000 feet loss or so.

Questions - max grade, min radius for the switchbacks, how steep to make jump faces, anything else to keep an eye out for as we plan??

Soil seems to drain well - chundery, for lack of a better description. Good loamy soil with lots of 2-6 inch rocks.

Are you planning on the more traditional rugged DH trail?

Or are you planning on Flow-DH with freeride style obstacles? These days, the mountains like Whistler and Winter Park have both styles of DH trail.

I have more pics and explanation in these threads:

Vail, Keystone and Winter Park trip --cmc
Vail, Keystone and Winter Park

Seattle/Vancouver trip -- Colonnade, Duthie Hill, Whistler --cmc
Seattle/Vancouver trip -- Colonnade, Duthie Hill, Whistler


Rollers (spaced around 22' feet peak to peak) on one of Whistler's flowier trails (I think it was Crank It Up)


Berm radius depends entirely on how much speed you have at a given point in the trail.
Whistler:



Wallride to landing. Whistler:



Switchback at Vail. Originally a hiking trail, I presume---TERRIBLE for DH.


Nice S berm at Keystone:



High-speed 22-ish foot radius berm at Keystone.


DH jumps tend to be around 20 - 30 degrees.



20 degrees

30 degrees


Winter Park:

[HypNoTic]

What is your definition of "downhill"? The type of trail that would require a chairlift to enjoy or something that could be pedalled uphill but is more fun going down? If you're looking at "pure" downhill in the Whistler|Bromont|St-Anne sense of it, then a switchback on a steep section is most likely not a good idea.

What speed are you aiming for? Wicked fast or slower&technical?

Do you have a lot of natural elements that you can use? Rocks, rock face, big logs, steep sections, open sections, good amount of dirt, controlled drainage?

You might consider hiring a pro to guide you on the first few steps and make sure you optimize your trail experience while keeping it safe. Check out the PTBA for a few good reference. We're quite a few builders with a lot of experience building downhill/advanced trails.

[tjp]

Thanks everyone. Flagged it with Joey from Trail Solutions and a local DHer, but don't think we can afford much outside help this year. Some pretty accomplished racers will be putting their 2 cents in as we go through this process. Here are some more of my thoughts:

The s-berm photo above is kind of what I had in mind for the middle third of the course, which is a traverse through a drainage, connecting two ridges. There are rocks and old-growth fir trees in there that we will attempt to incorporate. The top third will likely consist of a mainline of tabletops and such on an old skid road on top of a ridge, with rocky technical options off to the side. The bottom third will be tricky. Starts on a big, flat landing, so we've been thinking some kind of rythm section or something. Then it drops steeply through the trees to the end. The only way to get down with involve some switchback-type turns - getting down this section without killing too much momentum will be the trick. Must learn the answer too "how tight is too tight?"

We want to avoid super-lippy, momentum killing jumps - think out, not up...personally, I love fast fallaways.

It won't be a pure dh, but it needs to be fun (and raceable) on a dh bike. We'd love to be able to use it for technical XC races too.

Edit: Love those keystone photos! Looking at them helped a lot with radius questions.

Think outdoor MX, not Supercross

[cmc4130]

. . .
It won't be a pure dh, but it needs to be fun (and raceable) on a dh bike. We'd love to be able to use it for technical XC races too.

Edit: Love those keystone photos! Looking at them helped a lot with radius questions.

Think outdoor MX, not Supercross

Glad you're stoked on building this But, really, though... the same trail raceable on a DH bike and an XC bike ?!?! . . .. that may be asking a little too much.

[HypNoTic]

the same trail raceable on a DH bike and an XC bike ?!?! . . .. that may be asking a little too much.

I totally agree with that. If you want a trail to be challenging enough to actually require a full-on DH bike, then most likely a XC bike will be out of his game. And a XC-level trail will be boring as hell on a big bike.

The only exception would be for the ultimate and perfect flow country trail with a strong enduro bias.

[tjp]

Now we're getting to a different discussion

My personal opinion is that the bike should not drive the trail design, and that for the big bikes to be "necessary" for a trail we'd either need bigger rocks than we have, bigger drops than we're willing to build, or steeper terrain than is sustainable. When all is said and done, it will likely be a fun, flow trail with a variety of optional tech features (probably no or minimal wooden ones), with the "target" being a 6 in bike. Makes it accessible for most riders, and the big bikes can still have fun. XC bikes just need to pick their way down a bit. We have a solid DH community who will provide input.

Seems reasonable in my head... Strong enduro bias. I like that!

The photos with curve radius and jump spacing - that is all great stuff. Taking notes....keep it coming