The cadence or speed at which we pedal has a large impact on the type of workout we will receive.  Maybe larger than we think.  Often times, the only thing that separates one workout from another is leg speed.  This 4 part series will explore different ways cadence affects the type of workout and our body”™s response.

Part 1: Extremes and Limitations
Part 2: Cardiovascular or Muscular Emphasis
Part 3: Power Output or Strength Development
Part 4: Sprinting for Maximum Power

PART 1: Extremes and Limitations

There are two things to understand as we begin to explore the full range of leg speeds in cycling, (1) what is capable on a real bike, and (2) what is appropriate on an indoor bike.  Although the later may appear more to the point for the indoor cycling instructor, I”™ve seen instructors lose respect from outdoor riders because of uninformed, end-all comments.  Some of these comments sound like, “there is no value in pedaling faster than 110 RPM” or, “it is unsafe to pedal slower than 60 RPM — EVER!” or, “leg speed doesn”™t matter, just ride as hard as you can!”  Anyone who has hung around me long enough knows my thought on these comments is, “it depends”.

Why is the impact of cadence when riding indoors different than when riding outdoors?  It boils down to the lack of side-to-side and forward and backward movement (limitations) of the indoor bike. This limitation of movement has both mechanical and safety implications.

Natural Movement of the Bike

When we stand on a bike outdoors, it moves side-to-side (or should) as we apply pressure to the pedals. The bike may swing as little as 3-4 inches to greater than 10 inches.  What we often don”™t realizes is that the bike is also surging forward and backwards as well.  The overall movement of both the side-to-side and surges results in a "Figure 8."  Keep in mind that this movement is also present when riding seated.  We just don”™t notice it as much because the bike moves less.  So simply, a bike ridden outdoors moves much more than you may think.  This “natural” movement provides leverage for power production and aligns joints to apply maximum force. The lack of natural movement of an indoor bike can limit mechanical efficiency and power.

This lack of bike movement also presents safety concerns for indoor cycling.  Because the indoor bike does not move naturally, the body often needs to compensate by moving instead.  Regardless of how much one moves their body to compensate for the lack of bike movement, an unnatural amount of stress will be placed on the muscles and joints. This is the reason why certain movements and extreme cadences should be avoided.  Quick or explosive movements from a seated to standing position should be avoided.  These include sprints that start in the saddle and then force a rider to quickly stand with heavy resistance, and jumps (Spinning®) which encourage riders to move rapidly from a seated to standing position.  These movements will place unhealthy stress on the lower (lumbar) spine, because the body must compensate (not the bike) for the force.

Similarly, leg speeds faster than 110 RPM are discouraged on an indoor bike.  The lack of any movement on an indoor bike will place unnecessary stress on joints at higher speeds. The addition of a fixed, weighted flywheel only adds to the risk.  Conversely, pedaling slower than 55 RPM (with heavy resistance) on an indoor bike can also put a rider at risk since the bike is not able to move under the workload placing unnatural stress on joints.  Understand that it is not uncommon for riders training outdoors to perform cadence drills above 120 RPM or muscular strength efforts under 50 RPM. Are these beneficial — well, it depends.  More importantly, regardless of whether you are riding indoors or outside, appropriate resistance (gearing) and proper form should be maintained at all times.

NOTE: The limitations described above can also apply to “real” bikes ridden using an indoor (stationary) trainer.

Originally posted 2011-05-05 05:00:06.

Tom Scotto
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