Ask the Experts: Indoor Cycling Power vs. Outdoor Power

Why is there a difference between the power you can put into the pedals outdoors than the power indoors? The difference between indoor cycling power and outdoor power tends to be more pronounced with shorter, higher-intensity efforts, especially when you’re out of the saddle. The reason why comes down to a few different factors. Determining what the main reason is for your discrepancy in power is the first step in correcting it. 


Short answer, yes. If you try to take your indoor power zones outside or vice versa without being aware of your individual difference, your workouts can become either impossibly difficult or wastefully easy, neither of which is ideal.

Only by understanding “Why” your differences exist—and by paying attention to how efforts feel inside AND outside—can you figure out what adjustments you need to make when moving between outdoor and indoor workouts.


When you ride outside, the bike is free to move underneath you. This is most apparent when you get out of the saddle. Most people assume that this additional power comes from using your upper body to pull on the bars. While this is true there are other factors at play.


The force that makes sprinters loathe the mountains is the same force that adds a little extra power to their finish kick: gravity.

When you’re standing, all of the weight that is normally supported by your saddle is now added to the force you’re putting into the pedals.  To really take advantage of that boost, you need to shift your center of gravity over the pedal you are pushing down. That means rocking the bike back and forth.


Maximizing out-of-the-saddle power production is also a matter of proper alignment between your hip, knee, and ankle. Rocking the bike back and forth while standing maximizes your use of gravity, but that requires your ankles, knees, and hips to move dynamically so they stay in alignment.  

When standing on the trainer, you can access the extra watts gravity provides by moving your whole body from side to side, but at the expense of optimal alignment. This impact can be mitigated with the use of AXIS Action Feet on the KICKR Indoor Trainer. These feet allow for five degrees of side-to-side movement making the ride or workout more dynamic resulting in better body alignment.


While most cyclists see higher power numbers outdoors for big, out-of-the-saddle efforts, many will also see lower power numbers indoors for sustained, seated efforts.

This can be caused by a few factors, most commonly by poor hip stability, which is usually a function of limited hip flexibility and poor recruitment of the gluteus medius muscle (that’s one of the three hip extensor muscles that make up the glutes. This in turn impacts the alignment of hips, knees, and ankles. Athletes with poor hip stability compensate by synchronizing the rock of their pelvis with the rock of the bike to keep their leg alignment closer to optimal, which gives them a distinctive, weaving style.


Add some poor core strength to poor hip stability and you have a “Swayer”.  Swayers shift their center of mass over the downstroke pedal as they rock the bike back and forth to compensate and get more power, resulting in a swaying of the torso. This swaying motion is restricted when you’re inside on a trainer, which means restricted watts and lower indoor power numbers.


There’s another, more basic reason for why you can generate more power outside: Heat. 

Riding outside provides the benefit (usually) of a nice, steady flow of cooling air. Not so inside. As the duration of an effort increases, overheating starts to limit how effectively your body can produce power. This means you are better able to produce higher power and sustain that power for longer durations outdoors than on your trainer. If you want to improve your performance on the trainer, be like Fonzie. Cool. The simplest and most effective solution is getting a smart fan.

If you find that you struggle in the heat, it won’t be limited to just riding inside. When that next heatwave rolls through be ready to see your power take a bit of a hit outside.  If you’re really struggling, you can take a tip from the pros and make an ice sock to put in the back of your jersey on those really hot days. An ice sock is simply some store-bought panty house stuffed with ice that can be placed in your middle jersey pocket.



If you see consistently lower power numbers for efforts indoors, your first step is trying to identify what might be the cause.  Poor hip stability? A weak core? Inadequate cooling on the trainer? The next step is doing what you can to address your particular issue.


Start incorporating the yoga videos that specifically address hip flexibility and stability into your training. Hip Openers, Hip Openers II, and the Hips and Hamstrings yoga videos that are part of your SYSTM subscription are great for improving the range of motion and activation of the gluteus medius muscle.


A strong, stable core will dramatically improve power and efficiency, while also helping to prevent lower back pain (especially if you do a lot of seated climbing). Try the 4-week Yoga Core Training Plan, available in the Cross-Training section of the plan library. You’ll be amazed at the difference it makes.


Even though you might see lower power numbers inside, that doesn’t mean that indoor workouts are a bust. Far from it. One of the major benefits of riding a trainer is the ability to focus entirely on the effort at hand so you can completely empty the tank. When doing efforts outside, you have to focus on traffic, road conditions, changes in terrain, weather, and staying upright.  On the trainer, it is just you and the effort. That kind of training pays dividends.

As you start to incorporate more outdoor sessions into your training schedule, remember that power numbers can be affected by a variety of factors. Understanding why there may be a difference between your indoor and outdoor power numbers can help you identify how to address specific weaknesses and get more out of your workouts.

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