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Thunderhill West

Willows, California · 2.67 km · 1.66 mi · counterclockwise

Thunderhill West is the 2.67 km (1.66 mi) short course at Thunderhill Raceway Park in Willows, California, run counter-clockwise through ten numbered corners — seven lefts and three rights. The circuit sits between 85.8 m and 108.7 m of elevation (roughly 281–357 ft), accumulating about 33 m (109 ft) of climbing per lap, most of it packed into the uphill run through Turns 1 and 2. The simulated speed profile splits the lap cleanly in two: a faster middle sector where Turns 6 and 7 carry minimum speeds above 100 km/h (62 mph) and entries approach 159 km/h (99 mph), and a slow final sector anchored by Turn 8, the slowest point on the course at a 10.2 m effective radius and a 39 km/h (24 mph) simulated minimum, followed by the similarly slow Turns 9 and 10. Simulated lap times range from 83.0 s (liter bike) to 84.5 s (middleweight twin). All figures on this page are physics-simulation estimates.

All figures: physics-simulation estimates · generated 2026-07-08 · methodology & assumptions

COMPUTED LINE · THUNDERHILL WEST SIM
Thunderhill West track map with computed racing line
1.66 MI
Lap
10
Corners
109 FT
Climb

Track outline © OpenStreetMap contributors (ODbL)

Thunderhill West — quick facts

Motorcycle track guide · simulation estimates · 2026-07-08

  • Length: 2.67 km / 1.66 mi, run counter-clockwise
  • 10 corners: 7 left, 3 right
  • Elevation range: 85.8–108.7 m (281–357 ft), ~33 m (109 ft) gain per lap
  • Tightest corner: Turn 8, 10.2 m effective radius, 39 km/h (24 mph) simulated minimum
  • Fastest simulated corner entry: Turn 6 at ~159 km/h (99 mph, liter bike)
  • Simulated lap times: 83.0 s (liter bike), 83.2 s (supersport 600), 84.5 s (twin 650)
  • Simulated average lap speed: 112–114 km/h (70–71 mph) depending on class

Turn 1

Left69 m arc
EntryMinExitBrake startEff. radiusElev Δ
138 km/h86 mph107 km/h67 mph122 km/h76 mph75 m246 ft76 m250 ft+1.1 m+4 ft

Supersport 600 preset · simulation estimates · liter-bike and 650-twin figures for every corner ship in the all-access pack · how these are computed

The lap opens with a left of 76.2 m effective radius that climbs 1.1 m over its 69 m length. In the simulation all three bike classes arrive at essentially the same 138 km/h (86 mph) entry speed, but braking points spread widely with mass and power: the liter bike model begins slowing about 93 m out, the supersport 600 at roughly 75 m, and the lighter, slower middleweight twin needs only about 51 m. Minimum speed converges at 107 km/h (66 mph) for every class, and the uphill grade helps the models accelerate back to around 122 km/h (76 mph) at the exit. These are physics-simulation estimates, not measured values.

Turn 2

Right138 m arc
EntryMinExitBrake startEff. radiusElev Δ
123 km/h76 mph81 km/h50 mph112 km/h69 mph15 m49 ft44 m143 ft+1.9 m+6 ft

Supersport 600 preset · simulation estimates · liter-bike and 650-twin figures for every corner ship in the all-access pack · how these are computed

This corner's walkthrough is in the all-access pack — along with the other 6 locked corners on this track.

Unlock every corner · $59 lifetime →

Turn 3

Left282 m arc
EntryMinExitBrake startEff. radiusElev Δ
115 km/h71 mph76 km/h47 mph133 km/h83 mph54 m177 ft38 m124 ft+1.4 m+5 ft

Supersport 600 preset · simulation estimates · liter-bike and 650-twin figures for every corner ship in the all-access pack · how these are computed

A long left — 282 m at a 37.8 m effective radius, tighter than the first two corners, still climbing 1.4 m. Here the simulation brakes from about 54 m out in every class: entry speed is about 115 km/h (71 mph) after the slow Turn 2 exit, and the model settles at the 76 km/h (47 mph) minimum. The corner then acts as a launching ramp — the supersport and liter-bike models exit at 133 km/h (83 mph), while the power-limited twin manages 131 km/h (81 mph). In the simulated speed profile this is where the faster middle portion of the lap begins to build.

Turn 4

Left108 m arc
EntryMinExitBrake startEff. radiusElev Δ
107 km/h67 mph85 km/h53 mph138 km/h86 mph84 m276 ft47 m156 ft-1.8 m-6 ft

Supersport 600 preset · simulation estimates · liter-bike and 650-twin figures for every corner ship in the all-access pack · how these are computed

Turn 4 opens the pattern: a 108 m left with a 47.4 m effective radius, gently downhill (−1.8 m). The simulation enters at about 107 km/h (66 mph) and starts slowing 66–93 m out depending on class — earliest for the liter bike, latest for the twin. Minimum speed is 85 km/h (53 mph), the second-highest minimum in the first half of the lap. The exit is strong in the model: 139 km/h (86 mph) for the two bigger bikes and 136 km/h (85 mph) for the twin.

Turn 5

Left171 m arc
EntryMinExitBrake startEff. radiusElev Δ
142 km/h88 mph80 km/h50 mph144 km/h89 mph9 m30 ft42 m139 ft+1.7 m+6 ft

Supersport 600 preset · simulation estimates · liter-bike and 650-twin figures for every corner ship in the all-access pack · how these are computed

This corner's walkthrough is in the all-access pack — along with the other 6 locked corners on this track.

Unlock every corner · $59 lifetime →

Turn 6

Right117 m arc
EntryMinExitBrake startEff. radiusElev Δ
158 km/h98 mph100 km/h62 mph115 km/h72 mph0 m0 ft66 m218 ft-1.4 m-5 ft

Supersport 600 preset · simulation estimates · liter-bike and 650-twin figures for every corner ship in the all-access pack · how these are computed

This corner's walkthrough is in the all-access pack — along with the other 6 locked corners on this track.

Unlock every corner · $59 lifetime →

Turn 7

Left168 m arc
EntryMinExitBrake startEff. radiusElev Δ
149 km/h93 mph108 km/h67 mph122 km/h76 mph12 m39 ft77 m252 ft-0.4 m-1 ft

Supersport 600 preset · simulation estimates · liter-bike and 650-twin figures for every corner ship in the all-access pack · how these are computed

This corner's walkthrough is in the all-access pack — along with the other 6 locked corners on this track.

Unlock every corner · $59 lifetime →

Turn 8

Left171 m arc
EntryMinExitBrake startEff. radiusElev Δ
147 km/h91 mph39 km/h24 mph103 km/h64 mph12 m39 ft10 m33 ft+2.2 m+7 ft

Supersport 600 preset · simulation estimates · liter-bike and 650-twin figures for every corner ship in the all-access pack · how these are computed

This corner's walkthrough is in the all-access pack — along with the other 6 locked corners on this track.

Unlock every corner · $59 lifetime →

Turn 9

Right174 m arc
EntryMinExitBrake startEff. radiusElev Δ
150 km/h94 mph41 km/h25 mph113 km/h70 mph0 m0 ft11 m36 ft+2.2 m+7 ft

Supersport 600 preset · simulation estimates · liter-bike and 650-twin figures for every corner ship in the all-access pack · how these are computed

This corner's walkthrough is in the all-access pack — along with the other 6 locked corners on this track.

Unlock every corner · $59 lifetime →

Turn 10

Left174 m arc
EntryMinExitBrake startEff. radiusElev Δ
114 km/h71 mph51 km/h32 mph145 km/h90 mph6 m20 ft17 m56 ft-0.2 m-1 ft

Supersport 600 preset · simulation estimates · liter-bike and 650-twin figures for every corner ship in the all-access pack · how these are computed

This corner's walkthrough is in the all-access pack — along with the other 6 locked corners on this track.

Unlock every corner · $59 lifetime →