19.3 miles
Distance
2,822 ft
Climb
-4,328 ft
Descent
1 mile
High Point
-1,509 ft
Altitude change
4,470 ft
Altitude min
5,980 ft
Altitude start
4,472 ft
Altitude end
-1.5%
Grade
-56.3%
Grade max
54%
Grade min
8 miles
Distance climb
9 miles
Distance down
2 miles
Distance flat

Big day. Prepare for 6 hours of moving time on the bike. Loads of food and a water filter. Awesome ride finishing with a massive descent into the South Yuba drainage. Great views all along the way to boot

Detailed Description
Geology Lesson is a 19 mile moderately popular expert route located near Nevada City California. This mountain bike only route can be used one direction and has a extreme overall physical rating. This route includes 5 trails. This route climbs 2,822 ft with a max elevation of 7,495 ft then descends -4,328 ft.

Trail Issues on Route

  • Minor Issue / Yellow: 2 trails (newest: Nov 1, 2023)
Local Trail Association
Local trail association
Bicyclists of Nevada County (www.bonc.org)
Please consider joining or donating to the local riding association to support trail development & maintenance.
Donate to earn trail karma!

Stats

  • Distance
    19 miles
  • Avg time
    5 hr 20 min
  • Altitude change
    -1,509 ft
  • Altitude min
    4,470 ft
  • Altitude start
    5,980 ft
  • Altitude end
    4,472 ft
  • Climb
    2,822 ft
  • Descent
    -4,328 ft
  • Grade
    -1.5%
  • Grade max
    -56.3%
  • Grade min
    54%
  • Distance climb
    8 miles
  • Distance down
    9 miles
  • Distance flat
    2 miles

14 Reviews & Comments


We hope you've been enjoying Trailforks!

Create a FREE account to view route comments and much more.

Create a Free Account

Trails in Route

Details

  • Riding area
    Grouse Ridge
  • Primary Activity
    Mountain Bike
  • Difficulty rating
    Black Diamond
  • Route Type
    Shuttled
  • Bike type
    AM
  • Direction
    One Direction
  • Physical rating
    Extreme
no votes yet
close
  • Basemap  Map 
    • Pro
    • Pro
    • Pro
    • Pro
    • Pro
    • Pro
3D
Trail Conditions
  • Unknown
  • Snow Groomed
  • Snow Packed
  • Snow Covered
  • Snow Cover Partial
  • Freeze/thaw Cycle
  • Icy
  • Prevalent Mud
  • Wet
  • Variable
  • Ideal
  • Dry
  • Very Dry
Trail Flow (Ridden Direction)
Trailforks scans users activity logs to determine the most popular direction each trail is ridden. A good flowing trail network will have most trails flowing in a single direction according to their intension.
The colour categories are based on what percentage of users are riding a trail in its intended direction.
  • > 96%
  • > 90%
  • > 80%
  • > 70%
  • > 50%
  • < 50%
  • bi-directional trail
  • no data
Trail Last Ridden
Trailforks scans activity logs to determine the last time a trail was ridden.
  • < 2 days
  • < 1 week
  • < 2 weeks
  • < 1 month
  • < 6 months
  • > 6 months
Trail Ridden Direction
The intended direction a trail should be ridden.
  • Downhill Only
  • Downhill Primary
  • Both Directions
  • Uphill Primary
  • Uphill Only
  • One Direction
Contribute Details
Colors indicate trail is missing specified detail.
  • Description
  • Photos
  • Description & Photos
  • Videos
Trail Popularity ?
Trailforks scans activity logs to determine which trails are ridden the most in the last 9 months. Trails are compared with nearby trails in the same city region with a possible 25 colour shades. Think of this as a heatmap, more activities = more kinetic energy = warmer colors.
  • most popular
  • popular
  • less popular
  • not popular
ATV/ORV/OHV Filter
Max Vehicle Width
inches
US Cell Coverage
Legend
cell carrier legend

Radar Time
Activity Recordings
Trailforks uses anonymized public activity data. ?
Activity Recordings
Trailforks uses anonymized public activity data. ?
Personal Heatmap
▶ Activity Types
all / none
▶ Options
2
Date range month
–
Winter Trails
Warning A routing network for winter maps does not exist. Selecting trails using the winter trails layer has been disabled.
Missing Trails
Most Popular
Least Popular
Trails are colored based on popularity. The more popular a trail is, the more red. Less popular trails trend towards green.
Jump Magnitude Heatmap
Heatmap of where users jump on trails. Zoom in to see individual jumps, click circles to view jump details.
BC Backroad Status

Service Road Atlas is a free to use, community-driven service for viewing and creating reports on the numerous back-country service roads around B.C. and Alberta.

map legend
Slope Aspect
Direction the slope faces
Flat N NE E SE S SW W NW
Trails Deemphasized
Trails are shown in grey.
disable
Only show trails with no bike usage.
Enable
Suggested Layers
Based on selected activity type

    Save the current map location and zoom level as your default home location whenever this page is loaded.

    Save
    Trail transparency
    view larger map
    • Singletrack

    Photos

    more photos »
    156
    137
    227
    358

    Videos

    more videos »
    Grouse Ridge | MTN BIKE Adventure
    Grouse Ridge | MTN BIKE Adventure
    3:50 | 997 | comments: 0 | favs:
    Sep 6, 2018

    Recent Trail Reports Along Route

    statustraildateconditiondescription
    Grouse Ridge Trail: Blue Lake Trail To Spaulding Lake Trail
    Nov 1, 2023 @ 7:34am
    Nov 1, 2023
    		It's definitely a red trail with badly eroded trail bed full of loose rocks and hardly any soil to be seen.
    Crooked Lakes Trail
    Sep 16, 2023 @ 8:41pm
    Sep 16, 2023
    		Many trees down across the trail that you have to climb over
    Grouse Ridge Trail (Lookout to Blue Lake Trail)
    Oct 31, 2020 @ 11:23am
    Oct 31, 2020
    		Super dusty but still running fast reporter
    Grouse Ridge Trail (Lookout to Round Lake Trail)
    Oct 5, 2020 @ 8:41am
    Oct 5, 2020
    		Yesterday
    Bull Pen Trail
    Aug 8, 2019 @ 3:53pm
    Aug 8, 2019
    		Very dry and dusty.
    more reports »
    • By truckeeridetime & contributors
    • #29602 - 514 views

    Hit the Trail

    Open in App

    Get this route on your phone instantly.

    Download Route

    Save to wishlist, Garmin & download.