Some of these have resistance units attached to them and some do not, which means that those without resistance units virtually have no resistance. Rollers are arguably not even in the indoor trainer category, but I included them as many people use them and they are great indoor training tools.
Using super fast microchips, the Tacx Neo trainer figures out how to reduce force across the bottom and top of the pedal stroke thereby making the feel of the ride and effort level nearly identical to riding outside.
One new direct drive trainer has really taken it to the next level. As a result of the lack of resistance across the bottom and top of the pedal stroke, you are able to produce very similar, if not identical wattages indoors as outdoors. The direct drive trainers have been largely successful in creating a more realistic road feel. When you stop pedaling on a direct drive trainer the rear flywheel continues to roll until it’s inertia is exhausted. By adding in a heavier flywheel, a simulated rear wheel momentum type action is created. The direct drive trainers were invented to overcome this issue and by taking the rear wheel out of the equation. As you become trained to this way of pedaling, this gap will narrow and quite likely go away. In general, until you are “trained” to ride on a rear wheel resistance trainer, your watts will be 20 to 30 watts lower on the trainer than outside. An easy way of envisioning this is to imagine trying to stop the rear wheel of your bike wheel when it’s spinning rapidly in the workstand by grabbing the tire with your hand versus trying to stop that wheel while spinning out on the road using the same technique.
To be clear, it isn’t just the momentum (stored kinetic energy) of the rear wheel that keeps us moving out on the road, but rather that of our body plus the bicycle as a whole. As a result, this reduces your ability to create the same wattages as outdoors. As a result of this inefficiency, more strain is put on your cardiovascular system. Because there is resistance around the entire pedal circle, your legs are not used to having to produce power throughout the entire pedal stroke. If you stop pedaling the rear wheel comes to an almost immediate stop. On a rear wheel resistance trainer, there is little to no momentum of the rear wheel. This lack of resistance to pedal against may even give the legs a micro-rest in each pedal stroke as the momentum of the rear wheel continues moving forward and the legs try to keep up with the rpm’s needed to move the crank. Across the bottom and top of the pedal stroke, the legs have little ability to create any meaningful force against the pedals because of biomechanical inefficiencies in body position due to being seated almost directly above the crank. This is one of the fundamental differences between riding indoors and outdoors.Īs you ride outside on the road, your bike continues to move forward with momentum from the force that you exerted onto the pedals from roughly the 1 o’clock to 5 o’clock position in the pedal stroke. All of these trainers create resistance throughout the entire 360 degree pedal stroke. Some of these also contain a weighted flywheel with the intent to help create an additional feeling of inertia similar to what you might feel on the road. The rear wheel resistance type trainer is the most common and has been around the longest and has different ways of creating resistance on the rear wheel, such as: fluid resistance, magnetic resistance, and electric resistance. There are generally four different types of indoor trainers: The type of indoor trainer you are riding on plays a significant role in “feel” and the ability to replicate outdoor wattages. Let’s examine these factors so that you can better understand some of the issues behind this phenomenon and also what you can do about it. Rather, there are multiple factors that play a role in making your indoor wattage lower than your outdoor wattage. I believe that there is no single answer to this question.
After asking why this is the case, the next question is invariably, “What should I do about it?” Not only do they say their wattage is lower, but they also say that it seems a lot harder as well. Many times cyclists will comment that their Functional Threshold Power (FTP) seems to be as much as 30 watts lower when riding indoors than outdoors. One of the first things you notice when you get on your indoor trainer is that it is harder to produce the same wattages as outdoors.