Review Date
July 26, 2009

Overall Rating
 5 of 5

Aerobic Difficulty
 5 of 5

Technical Difficulty
 3 of 5

Ridden Trail:
Once a week

Reviewed by: stepenliem ,  Cross Country Rider

Summary:
I live around this park and hit the trails there a few times a week. Other reviewers are right in saying that these trails are non technical (with the exception of Corcoran Mine trail), but they will test your endurance though. I have been to many mtb trails in the bay area including Santa Cruz, Marin, Mt Diablo, Tahoe, etc, I can definitely say that Black Diamond is the hardest in term of physical endurance. For those who complain that they are not challenging enough, I dare you to try this:
Go ride the trails between January and March when there are a lot of rains and the cows trampled all over the trails. Its extremely technical to go down or up on a trail that have millions of holes half a foot or even a foot deep. Riding Black Diamond during those months is like riding the surface of the moon. Oh.. did I mentioned that those holes are all sticky mud? I usually switch my tires from 2.1 to at least 2.35 inch to ride during the winter months. If you can complete any trail during those worst months, I will buy you a beer!!

Recommended Route:
Go up North Ridge from the Frederickson street entrance, all they way up to the very top. When you descend from the top, take a trail that go to your right, and then another right up. Go follow that trail, it will take you to a wild, long and the steepest descent in the park. That will take you back to the gate. Total distance: 5 miles. Bonus point: do this route in February after heavy rain!

Review Date
April 28, 2007

Overall Rating
 4 of 5

Aerobic Difficulty
 4 of 5

Technical Difficulty
 2 of 5

Ridden Trail:
Once a week

Visitors rate this review
4.00 of 5, 1 votes

Reviewed by: rockymtnrider ,  Weekend Warrior

Summary:
Black Diamond has a lot of different trails. You can ride as far as you want. You can do a short ride of about 10 miles or go trail to trail and you can ride over 25 miles. You can make the ride easy or reverse it and make it even more of a climb. It is a great park to build your skills and muscles. I could bearly ride a hill when I started and now I can ride strong. Still have to walk part of the wall.

I ride Black Diamond about 3 times a week. I live near it and I am so glad I do. I started mountain biking back in January.

Recommended Route:
Old home stead loop to acorn, down the ridge trail. Right onto stewartville trail. Ride it to the wall then up to ridge trail to acorn then left onto old homestead loop finishing the loop.

Other recommended trails in the same area:
Check the trail maps. You have endless number of options. You can ride to clayton from antioch if you have the stamina.

Review Date
July 4, 2005

Overall Rating
 4 of 5

Aerobic Difficulty
 4 of 5

Technical Difficulty
 3 of 5

Ridden Trail:
Once a week

Visitors rate this review
5.00 of 5, 2 votes

Reviewed by: ElPedro ,  Cross Country Rider

Summary:
A mostly climbing or descending loop.

Recommended Route:
Short Loop From Frederickson Lane gate. Get over gate and take the trail off to the right. You'll ride a minute or so until you come across a trail called Old Homestead Loop. You take a left here. This is a moderate climb of about 30-40 minutes depending on your speed. About 20 minute in you'll come across another trail. Go to the right. When you get to the top of this hill there will be a trail to the left. Take that and it will lead you to the Ridge trail. When you get to the ridge trail you can go left or right. Left will take you down the Ridge and dumps you onto Stewartsville Trail. Turn left on Stewartsville and this goes back to Frederickson. Right will take you to top of the Ridge where you can look out and see “the Wall”. It’s a steep climb and fast descent. At the bottom of the wall is Stewartsville Trail. Stewartsville will take you back to where you started on Frederickson.

Other recommended trails in the same area:
Long Loop
Same as above with the right turn going to the top of the Ridge. When you’re at the top look right and you’ll see a bench before the bench there’s a gate. Take that and drop down into Black Diamond Mines where. At the bottom of that descent turn left onto the paved road (you can fill up with water if you are low by the picnic tables). Take the dirt road called Nortonville. This road will take you up by the cemetery. At the top of the hill go down Nortonville. At the bottom of this fast downhill turn left. This is a long climb up to a paved road. The road has some steep switchbacks and ends at as a short steep climb near a tower. Keep going straight onto the dirt path. This path will lead you back to the cemetery. Go down the cemetery and retrace your path back to the gate. Bring plenty of water and somthing to eat.

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Review Date
May 1, 2004

Overall Rating
 4 of 5

Aerobic Difficulty
 3 of 5

Technical Difficulty
 3 of 5

Ridden Trail:
Once a week

Reviewed by: daroy ,  Cross Country Rider

Summary:
Black Diamond Mines or better know as Contra Loma, I work out here a few days a week and would love to show you guys and gals around. It's mostly fire trails and I hate to say it but not the best and outstanding single track. The climbs are great and for sure will get you breathing heavy. The decents are fast and usually smooth. Just go and give it a shot, if you like climbing and decending fast you'll love it. It's also a great place to race around with you friend due to the wide trails!

Review Date
August 11, 2003

Overall Rating
 4 of 5

Aerobic Difficulty
 5 of 5

Technical Difficulty
 3 of 5

Ridden Trail:
Once a week