[OriginalDonk]

I'm finally getting around to posting this resource that might help traveling racers/riders a bit. If you're hitting a trail system for the first time and don't quite know what to expect, the Web Soil Viewer (produced by UC Davis using National Resource Conservation Service soil survey information) may provide some insight into whether you're gonna be dealing with sandy loam (well draining, can be loose in the dry) or something like a silty-clay (poorly draining, will pack firmly in the summer) to help you with your initial setup (tire selection, pressure, etc.). Somebody could theoretically pull this into a Google API and load race routes. This may help explain why parts of your 12 mile loop are perfect in the spring while others are the nasty peanut butter clay that can be dicey.

Take a look here:

http://casoilresource.lawr.ucdavis.edu/soilweb_gmap/

 

[shiggy]

I'm finally getting around to posting this resource that might help traveling racers/riders a bit. If you're hitting a trail system for the first time and don't quite know what to expect, the Web Soil Viewer (produced by UC Davis using National Resource Conservation Service soil survey information) may provide some insight into whether you're gonna be dealing with sandy loam (well draining, can be loose in the dry) or something like a silty-clay (poorly draining, will pack firmly in the summer) to help you with your initial setup (tire selection, pressure, etc.). Somebody could theoretically pull this into a Google API and load race routes. This may help explain why parts of your 12 mile loop are perfect in the spring while others are the nasty peanut butter clay that can be dicey.

Take a look here:

http://casoilresource.lawr.ucdavis.edu/soilweb_gmap/

That is pretty cool.
I went to a riding area in Oregon I know well and for a ~7 mile square area there are 35(!) soils types listed.

 

[OriginalDonk]

Your soil variability is going to be determined by your local geology. In Oregon you may have more than a few dozen soil types given the setting. Somebody in Missouri may encounter only a few. So Shiggy, if you look at Sandy, OR and the new epic single track there, this tool has a ton of information.

Click on a soil class (in the upper right corner) like the Cazadero clay loam (0 to 7% slopes) for Sandy. You see the breakdown of soil components and a field for how well soils drain in the Map Unit Aggregated Data table. Cazadero is "well-drained." The tool has a ton more information that's probably a bit less relevant to the discussion.

Hope this helps some people out. It also may also be a resources for trail work planning as you can target work and amend (add or improve) some of the clay sections of trail with some larger aggregate (gravel) or focus drainage improvements on these areas.