Rocky Terrain Suspension Efficiency: The Open vs. Locked Debate

May 7, 2026

Rocky Terrain Suspension Efficiency: The Open vs. Locked Debate; A Peavine Challenge

In November 2025, I conducted a “Physiology First” experiment on Reno’s Peavine Mountain to analyze rocky terrain suspension efficiency. This ride has since become the archetype and benchmark for my 2026 training season. The mission was simple: Two laps on the Halo Loop at the same target power. Lap 1 was ridden “Open,” and Lap 2 was “Locked Out.”

This benchmark serves as the foundation for my current 8-week VQ Velocity training block. Throughout this season, I am utilizing the VO2 Master and Moxy Monitor both indoors and out on the trail as much as possible to gather high-fidelity data. As these assessments reveal more, the training plan will evolve to meet the specific metabolic demands identified.

Benchmarking Rocky Terrain Suspension Efficiency (Nov 2025)

While the power meter saw nearly identical laps, the internal physiological cost was vastly different. This table illustrates the “Terrain Tax” paid by the body to maintain mechanical output when rocky terrain suspension efficiency is ignored by locking out the frame on rock and gravel.

SmO2 Gaps and Rocky Terrain Suspension Efficiency

The Moxy data on the steep technical pitches revealed the most dramatic story regarding rocky terrain suspension efficiency. During 350W surges, my muscle oxygenation (SmO2) bottomed out at a staggering 2.4% while locked out, compared to 3.6% when open. The lockout adds “isometric noise”—the muscles never fully relax as they fight to stabilize you against rocky chatter, creating a compression limit that restricts blood flow and slows recovery.

This is a critical metric I will monitor throughout the season to gauge acute intensity and recovery capacity, especially when navigating SmO2 Range Decay.

The Biomechanics of “Mashing”: Garmin Cycling Dynamics

While the power output was nearly identical, the Garmin Cycling Dynamics reveal a fundamental shift in how that power was delivered. The “Locked” lap forced a move away from a fluid, circular torque curve and toward a less efficient “piston” style of pedaling as the bike deflected off rocks and gravel.

The “MTB Traction Reality” is clear: on loose Reno dirt and gravel, a “piston” style creates micro-slips. A circular, smooth torque curve maintains constant tire-to-ground tension. By protecting the “flow” in the Open lap, the same 228W was maintained with significantly lower internal stress. This is exactly what we explore in The Power Illusion: why wattage is only half the story. You can also dive into the external research on metabolic cost by Bini et al. (2024).

Visualizing Rocky Terrain Suspension Efficiency on the Halo Loop

To see the exact rock and gravel terrain that generated these numbers, check out the video below. At markers like 02:10, you can see the constant micro-adjustments required to maintain traction—work that becomes a “cardiac tax” when the suspension isn’t aiding you against the rocky chatter.

Watch the video: Climbing Halo Trail, Reno, NV

The 2026 Path Forward

Efficiency is about protecting the human engine. Throughout this season, I’ll be using Moxy and VO2 Master to ensure that as I increase my threshold, I’m doing so without increasing the “Terrain Tax.” The goal is a smooth, circular torque curve and low autonomic stress—the true markers of an elite engine. This is the cornerstone of our 15-15 Micro-Interval Protocol.

Coach’s Note: Chase the efficiency, not just the wattage. If your heart rate is climbing while your watts stay flat on rock and gravel, you aren’t getting faster—you’re just paying a higher tax. Focus on your rocky terrain suspension efficiency to preserve your aerobic ceiling.

Coach Richard Wharton, Peavine Mt., Reno, NV