Virtual riding has become the panacea riders need in times of need. Whether it’s poor weather, family life, or a pandemic forcing you to stay home, virtual riding platforms like Zwift help you to stave off cycling withdrawals and stay fit for when you can return to riding outdoors. When combined with new, high-tech smart trainers, the experience of riding indoors is more fun and engaging than ever before.
Zwift drops you into a virtual world with other riders who are riding indoors.
Unfortunately, the high cost of new smart trainers might deter cyclists who are more budget-minded or those who are just trying Zwift to see if they like it. So what’s a frugal rider to do?
"Dumb" trainers vs. smart trainers
Classic resistance trainers have been available for years. They use either a fluid, magnetic, or fan unit for resistance. Sometimes, with magnetic units, resistance can be adjusted manually. Otherwise, riders have to shift gears or pedal faster to make things harder. Beyond that, classic trainers don’t offer much else.
The advent of smart trainers coincided with the rise of virtual riding. Smart trainers measure a rider’s power (and sometimes cadence), broadcast the data wirelessly, and automatically adjust the resistance to match the virtual terrain. By controlling resistance in real-time, smart trainers help make virtual riding feel like outdoor riding. Smart trainers can also be used in ERG mode which controls resistance to hit power targets during structured workouts. Classic trainers lack these features and, as a result, many have redubbed them as “dumb” trainers.
That's a bit harsh, isn't it? A classic trainer is the most cost-effective way train indoors. And believe it or not, you can still enter the world of virtual riding with your old indoor trainer. An entry-level smart trainer usually retails in the $500 range and good classic trainers can be had for $100-300 less. They’re especially affordable when compared to direct-drive smart trainers that cost over $1,000.
To use a classic trainer with apps like Zwift, the only data needed is power. There are two methods you can use to get measure power on a classic trainer — a power meter on your bike, or by using virtual power and a speed sensor.
Using a power meter
A bike equipped with a power meter like this Quarq crankset is ready to go with any dumb trainer.
If you already have a bike equipped with a power meter, you’re in luck. Most new wireless power meters support both Bluetooth and ANT+ transmission. Put your bike on the trainer and pair your power meter to the Zwift app by searching for it under “Power Source."
If your power meter only transmits ANT+, you'll need a USB "dongle," typically about $40, to plug into your computer, which will receive the ANT+ signals. If you intend to use Bluetooth, make sure the device you're using to run Zwift is compatible with Bluetooth 4.0 /BLE or "Bluetooth Smart Ready." Many older devices aren't compatible with new Bluetooth standards, but inexpensive Bluetooth dongles can be used if this is the case.
Once connected, either via Bluetooth or ANT+, you're ready to ride.
Using virtual power
If you don’t have a power meter on your bike then you will need to use “virtual power.” Virtual power requires a speed sensor to measure the speed at the rear wheel. With classic trainers, there is a relationship between wheel speed and how much power the rider is generating. This relationship can be graphed as a “virtual power curve.” Riding apps like Zwift can then use the power curve for a specific trainer, take the wheel-speed data, and convert it to power in estimated watts within the app.
"Power Source" on the upper left is where you connect a power meter or smart trainer. If using a Speed sensor with a classic trainer, connect using "Speed Sensor" on the upper right.
Too use virtual power, pair a speed sensor to the Zwift app by searching for it under “Speed Sensor.” You will be required to select your tire size and then your specific trainer.
Zwift has power curves stored for a number of popular trainers. Check that your trainer is on Zwift’s list of supported trainers. If your trainer isn’t listed then you will have to select “unlisted trainer.” Because there isn't a known power curve, this could affect your ride experience. But it will still be a great way to try out Zwift and decide if you want to upgrade in the future.
Choosing a speed sensor
You will need a way to measure your rear wheel speed wirelessly to ride on Zwift with virtual power. The most popular option is a simple Bluetooth and ANT+ enabled speed sensor made by Garmin and Wahoo. These retail for $40. They attach to the center of your rear hub using zip ties or a rubber strap.
Garmin and Wahoo also have wireless speed and cadence sensor bundles that retail for $60. Cadence isn’t necessary for virtual riding, but Zwift does recommend it to improve the experience.
If you own a Kinetic Road Machine, you can upgrade it with Kinetic’s inRide 3 Power Sensor for $50. It’s a speed sensor attached to the back of the trainer which detects a small magnet installed in the roller. Using Kinetic’s Road Machine power curve, the inRide 3 sensor will transmit power data directly to Zwift.
It will connect to Zwift the same way a normal power meter would. For a complete package, Kinetic offers the Road Machine Smart 2 which has the inRide 3 sensor already installed.
Virtual power accuracy
Zwift has done extensive testing and has power curve data for a large number of trainers to ensure that they can produce consistent and accurate numbers. I used virtual power with a Kinetic Road Machine classic trainer and had a power meter on my bike to compare. In my experience, the displayed power was close, but at times it did read 10-15 watts off when compared to my Stages power meter. This was especially noticeable during punchy efforts and fast accelerations. In general, my virtual was slightly higher than what my power meter measured at the cranks.
I also found that I sometimes couldn’t keep the power as smooth for long durations compared to my power meter. Fatigue would force me to shift and cause undesired fluctuations in wheel speed and power readings. But overall, virtual power was consistent with itself, which is what matters most for regular riding and training.
Keep in mind that your trainer's power curve can be affected by factors such as how tight you’ve attached the wheel against the roller, your tire size, or how much air is in your tire. For example, if you’ve tightened the roller against your wheel tighter or looser than before, the power curve won’t account for the change in resistance. You’ll end up working harder or easier than the power numbers might indicate. Try to keep these things consistent every time you attach your bike to the trainer so your experience is consistent every time you ride online.
The "dumb" trainer riding experience
For our own testing, we used the Kinetic Road Machine fluid trainer with an inRide 3 sensor to see how it compared to using a smart trainer. The subjects: Myself, an indoor riding regular, and our creative director, Dan, an indoor riding novice. The inRide 3 was very easy to install and calibrate using the Kinetic phone app.
Dan's trainer set-up has a black inRide sensor visible near the flywheel.
For both Dan and I, it took a few tries and some futzing around to establish a Bluetooth connection with our laptops (both Macbook Pros). My Macbook was unable to find the sensor and required a USB dongle. Once connected, we had no further issues. I was able to connect to my smartphone via Bluetooth first try. Using an ANT+ USB dongle was similarly easy.
With the inRide 3, power curve data is built-in so the sensor connects to Zwift as a “Power Source” rather than a “Speed Sensor." It required no further selection for tire size or the specific trainer we were using.
For Dan, the Zwift experience wasn’t life-changing. He uses his trainer to get through the dark winter months and will put in around 200 miles on it every year. But he prefers going outside and exploring on his bike. Zwift held his attention for a few sessions as he wandered around the virtual maps, but it just wasn’t the same. He has since reverted back to using his trainer without it. If he had used a smart trainer with controllable resistance, would he have been more engaged? He doesn’t think so.
With or without a smart trainer, Zwift was simply too much for Dan's sensibilities.
“All day I look at computers and programs and charts and graphs,” Dan says. “When I'm on my trainer I like to use the Kinetic app. It just tells me when to speed up, and when to slow down — that's it. Zwift was like an ADHD mass of information blasting me in the face and it was far too energizing for my tired brain. I greatly prefer a more dialed-down technology experience. I like my trainer experience to be simple.”
So Dan was not the ideal candidate for Zwift in the first place. If this sounds like you, then saving money by using virtual power on a classic trainer to try Zwift is probably the best option. The cost of a speed sensor with a classic trainer is pretty easy to swallow compared to a full-on smart trainer.
But what if you’re a tech nut? Or someone obsessed with training and fitness?
I’ve used Zwift extensively with both entry-level wheel-on and high-end direct-drive smart trainers. If I went back to the beginning, would I have kept using Zwift if I had started on a classic trainer? I think so. For me, riding any trainer on Zwift is still an interesting and engaging experience.
It doesn’t simulate outdoor riding at all. You don’t feel the resistance ramp up or decrease with the grade. So it’s almost an entirely different game. But it's still a worthwhile game. You watch your avatar move on the screen, and you generate the required numbers to make him/her move faster or slower. I could still explore the virtual world just as I could with a smart trainer, and I could even participate in group rides and races with no issues.
You have to think differently and change some of your ingrained riding habits. When climbing, you have to shift up to increase resistance and ramp up power to keep up with other riders. This is the opposite of what you do in the real world. You could not shift and just spin at the same cadence you were using when riding on the flats, but on extremely steep grades, not enough resistance can feel strange, and you will go very slow.
When descending it’s also easier to go fast because the resistance of your trainer doesn’t decrease. Zwift has built-in “trainer difficulty” settings that aim to equalize these sorts of variances between classic trainers and smart trainers, and they do a good job in most cases. But on steep descents, I can tell that classic trainers have an advantage in a race situation.
At the end of the day, using a classic trainer on any virtual course is going to be as engaging as you make it because you’re the one controlling your resistance with gear changes. You just have to pay attention and learn to shift into a harder gear when going uphill, especially when trying to stick with a group. Over time you will learn your trainer and figure out what ratios feel good for approximating different grades and you will have no problem keeping up with riders using smart trainers.
My trainer of choice is still my Saris H3 smart trainer.
There are a few reasons to upgrade to a smart trainer for Zwift. First, if you can afford it, it’s nice to use the app as it was intended, to simulate outdoor riding.
If you’re going to be using Zwift often, it might make sense to upgrade because the controllable resistance can help you keep things interesting You can do flat rides, climbing rides, and workouts, just like you would in real life. I ride indoors at least three times a week, so it made sense for me to use a smart trainer.
If you’re serious about doing races or group rides on Zwift, a smart trainer can make the experience more realistic and engaging. Because the resistance is controlled by your trainer, you just have to focus on going hard and riding like you do outdoors. And if you're doing a lot of structured workouts, a smart trainer can make hitting power targets easier by controlling the resistance in ERG mode.
But if you’re committed, a classic trainer can still do everything you need for Zwift. Trainers like the Kinetic Road Machine feel great and will serve you well if your goal is to simply keep pedaling through bad weather or survive long periods of stay-at-home riding.
If you look at the icons next to riders' names, you’ll notice many who don’t have to power symbol next to them. There are more classic trainer users on Zwift than you might suspect. So you definitely won’t be alone.
Are you a Zwifter? Do you use a smart trainer or a dumb trainer? Let us know in the comments!