Review: Zwift Hub Smart Trainer

Zwift is not my natural habitat. Neither are any of the similar virtual training platforms that provide stationary runners and cyclists with on-screen routes through fantastic landscapes. As a Gen Xer whose formative years included the uninspiring video gaming of Intellivision’s Astrosmash, I spent most of my play time outside. When it comes to exercise, I still prefer the outdoors to any virtual world, but I also live in a northern climate where winter temps often dip below zero. It’s possible to ride in sub-zero air, but it might not be everyone’s idea of fun. 

Zwift is here to help you fight for your right to stay cozy. The company is best known for its virtual worlds—like the tropical archipelago of Watopia and its subsequent spinoffs—that provide creative and colorful distractions for runners and cyclists to explore while sweating through their training programs. Now, Zwift has moved beyond software and entered the hard goods space, offering its first-ever smart trainer, called the Hub.

The Hub smart trainer attaches to the bike you already own.

Photograph: Zwift

Direct-drive smart trainers have been around for almost a decade. These devices attach to your rear drivetrain, replacing the rear wheel. As you pedal in a stationary position, they transmit your real-world effort to the virtual training environment displayed on the app running on the phone, computer, or television in front of you.

The experience of riding on a smart trainer has evolved to the point that many of the frustrating connectivity kinks that originally defined the experience have been worked out. Most of today’s smart trainers provide a seamless, realistic-feeling ride. The most high-end smart trainers arguably provide a more calibrated environment than could ever be replicated outside. They can accurately measure your power output to within a percentage point, and they can register a maximum power output of more than 2,200 watts. They can provide such smooth connectivity that your brain almost fails to register that you aren’t really in the world displayed on the screen. Some even bump and shake as you ride over virtual cobblestones. These trainers cost in the realm of $1,400.

The new Hub costs $500. So what are you giving up by paying so little? And more importantly, what do you gain with the Hub, other than the hundreds of dollars that are still in your wallet?

One big difference: The Hub comes with a preinstalled 8-, 9-, 10-, 11-, or 12-speed cassette to match the cassette of the bike you’ll use on the trainer. This is a huge advantage, especially for someone like me whose indoor bike is a decade-old Specialized S-Works Amira SL4, which is a ten-speed. Most other trainers come with a preinstalled cassette or a multitude of options for more modern groupsets. But if your bike (like mine) has an older cassette that may not be compatible with the trainer, you’d need to first buy a cassette yourself and then secure it in place with a chain whip and cassette-locking tool. Either that or lug the trainer to the local shop and have them install the correct cassette for you. With the Hub, you can just select the right cassette option without installing anything.

Setting up a smart trainer can be mind-numbingly frustrating. While the Hub requires some wrenching, namely attaching the rear and front feet to the rear and front legs of the trainer with included nuts, washers, bolts, and a wrench, it’s a five- minute process. All the parts are color-coded, and the instructions are concisely spelled out in the accompanying manual, with some explanatory videos accessible via a QR code. After the legs are attached to the trainer and you take the rear wheel off your bike, the next step is to attach the bike by following the directions for quick-release or thru-axle hubs, depending on what’s on your bike. (Both adapters are included.) After mounting the bike to the Zwift Hub via the appropriate adapter, tightening the skewer, and aligning the chain, it's a matter of plugging the trainer in and waiting for the status LEDs to flash blue, which means that it’s ready to pair to Zwift so you can start exploring some virtual terrain.

One important note: The Hub does not lock you into using Zwift exclusively. It also works with virtual training platforms like TrainerRoad, Wahoo SYSTM, Wahoo RGT, and Rouvy. All of these are subscription services priced between $12 and $20 per month; Zwift charges $15 monthly, and a subscription is not included in the cost of the Hub.

A view of Watopia, Zwift's virtual training environment.

Courtesy of Zwift

If you do use Zwift, it’s important to download the Zwift Companion app to your phone and ensure that all of the Hub’s firmware is updated. If it is, follow the prompts to connect the trainer to the Zwift app via Bluetooth or ANT+. The last step before you set off on your Watopia ride—“Legends and Lava,” or whichever virtual route you choose—is to calibrate the Hub so the smart trainer can record your wattage numbers accurately. You should repeat this calibration process monthly.

While shifting gears on the preinstalled cassette was a little crunchy at first, I was able to fix that by lubing the drivetrain, then realigning my chain by adjusting the rear derailleur’s limit screws.

One other concern I had immediately after taking the Hub out of the box was its relatively light weight. The 33-pound Hub is 14 pounds lighter than the 47-pound Wahoo Kickr, even though the two trainers are almost exactly the same size. A good portion of that weight difference is in the Hub’s 10.3-pound flywheel, which is six pounds lighter than the Kickr’s. Generally, the heavier the flywheel, the more momentum the smart trainer can sustain and the more realistic its ride will feel. But the only time the Hub’s relatively light weight tripped me up was on the few occasions that I was standing on my pedals and accidentally turned my front wheel. That caused the rubber mat underneath the bike to bunch up, and I was forced to get off the bike and flatten it before I could continue riding. 

The issue could have been a result of the trainer’s light weight, but it could also be because the Hub doesn’t include the small plastic piece other smart trainers toss in to ensure the front wheel remains level with the back wheel. As an added bonus, that piece keeps the front wheel straight. When I borrowed the piece from another smart trainer in my basement, the mat stopped bunching up. Since then, the flyweight of the Hub’s flywheel hasn’t been a limiting factor on my rides, which have generally been in the 12- to 20-mile range. Also, I have never pushed more than 350 watts on my rides, thanks to a slow Covid recovery and my aging body.

One small downgrade from higher-end trainers I’ve ridden is that while the Hub’s ride feels smooth and solid, it can’t mimic the feel of riding on cobblestone or gravel by providing real-time haptic feedback like some other smart trainers do. This is not a dealbreaker for me.

One nice technology upgrade with the Zwift Hub, however, is that, unlike some more expensive trainers, it allows users to connect Bluetooth accessories like a heart rate monitor directly to the trainer. This is key, especially for users who run Zwift on an Apple TV. Because the Apple TV’s Bluetooth connectivity abilities are limited, heart rate data can get garbled or lost when the device is running a training program that relies on this data. That won’t happen if your heart rate data is being transmitted directly by the Hub.

Each Hub purchase includes a cassette to match the one on your bike.

Photograph: Zwift

Do a side-by-side comparison of the Hub and $1,300-plus trainers like the Wahoo Kickr or the Garmin Tacx Neo2T, and you’ll find some notable differences. First, the Hub can report your power output with an accuracy of plus or minus 2.5 percent, which is not as accurate as the plus or minus 1 percent found on the more expensive trainers. Also, the Hub’s max wattage is 1,800, as compared to 2,200 watts on the other two, and the maximum amount of road incline it can simulate is 16 percent, compared to 20 or 25 percent on the other trainers. 

If you’re an elite cyclist with serious training goals and have the quad strength to push thousands of watts and the time to spend hours on your smart trainer, these differences may matter. If so, a more advanced trainer may be worth the extra $900. But if you’re a cyclist like me who is looking to maintain a healthy fitness level on days when it’s too wet or cold to train outside—yet still wants a smooth and seamlessly connected indoor ride—the Zwift Hub is a good investment in foul-weather sanity.