Everything You Need to Know About Spin Bike Resistance and Power

Understanding resistance and power metrics transforms spin class from random exertion into targeted training. These concepts, once you grasp them, allow you to customize any class to your fitness level and track meaningful progress over time.

How Spin Bike Resistance Works

Most spin bikes use one of two resistance systems: friction-based or magnetic. Friction bikes use a felt pad that presses against the flywheel when you turn the resistance knob. Magnetic bikes use magnets that create resistance without physical contact, resulting in smoother operation and less maintenance.

When you increase resistance, you are requiring your muscles to produce more force with each pedal stroke. This mimics the feeling of riding uphill or pushing against a headwind outdoors. Lower resistance with higher cadence emphasizes cardiovascular work, while higher resistance at lower cadence builds muscular strength and power.

Finding Your Baseline Resistance

A proper baseline resistance is heavy enough that you feel the flywheel throughout each pedal stroke but light enough to maintain a cadence of 80-100 RPM without straining. Many beginners ride too light, bouncing in the saddle with no control. If your hips rock side to side or you cannot smoothly stop the pedals, add resistance.

From your baseline, you should be able to increase resistance significantly for climbs and decrease slightly for faster flat road simulations. If your baseline leaves no room to increase, it is set too high.

Understanding Power Output

Power, measured in watts, is the objective measure of how hard you are working. It combines the resistance you push against and how fast you are pedaling. Two riders could have the same heart rate but vastly different power outputs based on their fitness levels.

Power equals force times velocity. Increasing either resistance (force) or cadence (velocity) increases your power output. The most efficient way to increase power is often a combination of both rather than extreme values of either.

Using Power Zones

If your bike displays watts, you can train with power zones similar to heart rate zones. Functional Threshold Power (FTP) is the maximum power you can sustain for approximately one hour. Your training zones are percentages of this number.

Zone 1 (under 55% FTP): Active recovery
Zone 2 (55-75% FTP): Endurance building
Zone 3 (75-90% FTP): Tempo and sweet spot training
Zone 4 (90-105% FTP): Threshold work
Zone 5 (105-120% FTP): VO2max intervals
Zone 6 (over 120% FTP): Anaerobic capacity
Zone 7 (max effort): Neuromuscular power sprints

To estimate your FTP, warm up thoroughly, then ride as hard as you can sustain for 20 minutes. Your FTP is approximately 95% of your average power during that test.

Matching Resistance to Instructor Cues

When an instructor calls out resistance levels like “add two turns” or “heavy climb,” translate these cues to your personal fitness. What feels heavy for a beginner differs dramatically from an experienced rider. Focus on achieving the intended effort level rather than matching others in the room.

Use rate of perceived exertion (RPE) as a guide. On a scale of 1-10, recovery should feel like 3-4, endurance work 5-6, tempo 7, threshold 8, and max efforts 9-10. Match your resistance to hit these target sensations regardless of what the person next to you is doing.

Progressive Resistance Training

To continue improving, you must progressively increase the challenge. Track your power output or resistance levels at specific efforts over time. If your threshold power was 150 watts two months ago and is now 165 watts, you have made quantifiable progress.

Periodically test yourself with standardized efforts. A 20-minute FTP test every 6-8 weeks provides benchmark data to adjust your training zones and confirm your program is working.

Common Resistance Mistakes

Too Light: Spinning with minimal resistance provides little training benefit. You burn fewer calories, build less strength, and miss the neuromuscular challenge that improves cycling performance.

Too Heavy: Grinding at extremely high resistance with low cadence stresses joints and can cause knee injuries. It also limits your cardiovascular development and burns you out quickly.

Never Changing: Some riders find a comfortable resistance and never adjust. Varying your resistance throughout each workout and across different sessions creates more complete fitness.

The Bottom Line

Resistance and power are the tools that sculpt your fitness. Learn to use them intentionally, track your numbers over time, and you will see improvement that random effort could never produce. The bike console is not just decoration; it is your training partner and progress tracker.