7.7 miles
611 ft
-607 ft
437 ft
High Point

In Albert Einstein's recently-discovered treatise entitled The Relativity of Mountain Biking, the first equation we see is called The Flow Equation. It is denoted by

Flow + Bike = Fun

We seek to optimize the right-hand side of the equation. In other words, have more Fun. By the iron law of equality, if we increase the right-hand side, we must increase one or both terms on the left. Since Bike is effectively a constant (we can only ride one at a time!), that means we need to increase Flow if we want more Fun.

Which is precisely what this route does.

The route offers the most concentrated flow with the least required mileage to be found in the Preserve. You'll enjoy a fun climb up Switchbacks (uphill-only, but watch for downhill riders). You'll roll through the surreal Tunnel 4. Then it's on to Singletrack Willy, which is mostly devoid of the cobblestones lining other trails, resulting in a hoot of rollers and jumps that's so much fun it's worth doing laps. (You can pretend you're in the World Cup Downhill when steering around the big jumps while advanced riders hit them). A quick climb takes you through the short but enjoyable Tunnel 7. Last up is Little Berms, whose banked turns add to the good times. From there, it's a downhill run back to the trailhead. Congratulations, you have solved the Flow Equation.

Some things to note:

1. The route is geared to intermediate riders and consists of green and blue trails.

2. The route is short enough to be a lunch ride. Consider The East Ender, which is this route on steroids, if you want a longer flow ride.

3. Please bring a bell. The trails are busy, and sightlines are often limited.

4. At the end of the jump area on Singletrack Willy is a large, left-hand berm that beckons you to steer into it. Don't fall for it because it ends in a dead-end of thickets and manzanita. Stay to the right instead to remain on the trail.

5. Optional add-on: Near the end of West Deer Canyon, you can veer right onto Santa Monica Ridge and ride The Shire (aka Tunnel 6). It's a fun trail but includes a TTF that can be risky for intermediate riders. Use caution when approaching because it appears suddenly.

6. All the trails are sanctioned and legal. Have fun!

Local Trail Association
San Diego Mountain Biking Association (sdmba.com)
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Trails in Route


  • Riding area
  • Primary Activity
    Mountain Bike
  • Difficulty rating
  • eBike Allowed
  • Bike type
    AM, XC
  • Physical rating
  • Ridelogs
More Stats for Flow Equation mountain bike route
  • Altitude change
    4 ft
  • Altitude min
    130 ft
  • Altitude start
    150 ft
  • Altitude end
    154 ft
  • Grade max
  • Grade min
  • Distance climb
    3 miles
  • Distance down
    4 miles
  • Distance flat
    5,003 ft
Avg: 4.5 (2 votes)

  • view (1)
Trail Conditions
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Trail Ridden Direction
Trailforks scans users ridelogs 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 riders are riding a trail in its intended direction.
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Trailforks scans ridelogs 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 rides = more kinetic energy = warmer colors.
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Radar Time
Trail transparency
trail: West Rim
9:45 | 5 | comments: 0 | favs:
Jun 25, 2021
trail: North Rim
9:45 | 8 | comments: 0 | favs:
Jun 25, 2021
trail: Tunnel 4
4:20 | 106 | comments: 0 | favs:
Apr 19, 2021

Recent Trail Reports Along Route

Jul 27, 2021 @ 3:40pm
Jul 27, 2021
Tunnel 4
Jul 5, 2021 @ 8:05am
Jul 5, 2021
Little Berms
Jun 20, 2021 @ 5:02pm
Jun 20, 2021
May 30, 2021 @ 9:46am
May 30, 2021
Tunnel 7
May 30, 2021 @ 9:46am
May 30, 2021
more reports »
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