I had been reading my replies on and off and just wanted to say thanksfor the input. I think I like the mentality of you ladies better than some folks I know. Last hard trail I rode, I was getting no where fast pushing my bike. But, there's another day. I checked out those websites, and did ask some more at the lbs. That's a good tip to ask for trail comparisons of ones I know how difficult they were for me personally.
I have a good case in point on this one. There is a trail that is built in a park called Borderland that was built by the local IMBA chapter. When I read this, I thought of some of the ones I had been on out west that were built by mtn bike groups. I got there and I was dumbfounded. I rode the first few hundred feet thinking "yeah this is great" then it stopped and turned into flatrock and just..no trail. I thought...great...You lost the trail..again (just like someone else said...you might not even be ON the trail) so I started hiking because I was by myself and well, I was trying to figure out where the trail went. So I went and went and went. I found the 'main trail' and rode around according to the map and then got back to car. I went to my LBS later that week and told them how I got lost. Then the proceed to tell me that I WAS on the trail...and I said..."what trail?!"
So like I said before, it's always an adventure. I had to laugh the other day talking to a guy out west on the phone about the trails here. What is the hardest thing for me so far? "Not hitting trees"..."what?" "not hitting trees!"...out west the trees are further from the trail (in most cases) and out here, there are some that I have been on where it's close to no room for your handlebars. See, that is what I mean. Right there that would make it harder...
I also agree that it can be very difficult to determine the difficulty of a trail by looking at topo maps and/or by getting advice from local riders.
I think that difficulty refers to 2 things. Grade and Technical features. The grade of a slope will make the ride a higher intensity ride or a lower intensity ride. So if cardio and muscle endurance are a problem, stick with the lower grades/the less steep stuff, but if you have great cardio but less experience or skill, go with something steeper but fewer technical features. Technical features include rocks, roots, single track, logs, jumps.
Now how do you tell which trails have what? I've found that most good books on cycling trails will have an elevation profile as well as a description of the technical features.
One series I recommend are the Falcon Guide books. I have the Falcon Guide: Mountain Biking the San Francisco Bay Area. It not only has a highlighted map of the trail and a step-by-step description and a easy to read elevation profile, but it also has quick easy to read blurbs about difficulty, trail surface, terrain, seasonal info, dog compatibility, schedule, etc, in the very beginning of each section. I've seen other good books out there, but this one is my favorite.
Funny, I think Falcon guides stink for the most part. Mostly its for their routes, and the fact that they allow nonlocals to ride a trail system for three days and write the guide. ( this is what happened in my area, the guide is a joke) Don't get me going on the charge for use Trails.com website...
Anyway-
The Kissing the Trail series is really good but that's only for Oregon and Washington
Two kinds of ratings can also be for technical difficulty and fitness/cardio level. Maybe what you refer to as grade?
We are working on map development and trail inventory for a local trail system. Rating trails is a lot harder than you would think. First, it IS relative to other trails in the area, which means we don't have a lot of "greens". Then, you have to put on your "what if I were a visitor and hadn't ridden this trail 100 times" hat, how would you describe it then? It's a good challenge to get it all figured out.
I guess I haven't read the ones for other areas. The one for the SF bay area was written by a local and is pretty good. Too bad they are not consistent.