Many cyclists who use both road bikes and Keiser Spin Bikes notice a significant difference in perceived exertion. Even when maintaining the same power output, a workout on a Keiser spin bike often feels considerably more challenging. This raises the question: why does a Keiser spin bike feel harder than a road bike at the same wattage?
One cyclist decided to investigate this phenomenon through a personal experiment. Using the same calibrated power pedals and ensuring identical bike fit measurements – even using the same seat – they compared rides on their road bike and Keiser Mi3 spin bike. Both sessions involved continuous pedaling at a steady state, eliminating any freewheeling. Despite maintaining the exact same wattage on both bikes, the spin bike ride felt significantly harder.
The key difference likely lies in the static nature of a spin bike compared to the dynamic movement of a road bike. On a road bike, there is inherent side-to-side motion. This motion allows for some upper body engagement and a transfer of energy across different muscle groups. In contrast, a stationary Keiser spin bike restricts movement to a vertical plane. This fixed position isolates the leg muscles to a greater extent. Consequently, while the power output might be identical, the spin bike workout places a more concentrated demand on the legs, leading to a sensation of increased difficulty.
This observation prompts a further question for cyclists: is training on a static spin bike, like a Keiser, ultimately more beneficial, or is the dynamic nature of a road bike preferable? If forced to choose only one for training, which would be the better option and why? Furthermore, should cyclists adjust their training intensity when switching between a spin bike and a road bike to account for these differences in perceived exertion and muscle engagement?
The experience suggests that a watt on a road bike and a watt on a spin bike might not be directly comparable in terms of perceived effort and muscle recruitment. Generating 200 watts on a road bike engages a broader spectrum of muscles throughout the body, whereas achieving the same 200 watts on a Keiser spin bike isolates the effort more intensely in the legs. While both provide effective workouts, understanding this distinction is crucial for tailoring training and interpreting perceived exertion levels across different types of cycling.
