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Zwift Cog is designed to expand bike compatibility with smart bike trainers and introduce virtual shifting for Zwift. Instead of traditional gear mechanics, you shift gears using electronic buttons. Zwift then calculates the resistance based on the terrain and your selected virtual gear.
Below, you will learn more details. I have summarized the pros, cons, and motivations of Zwift to push Zwift Cog to the market.
How Zwift Cog Works
Zwift Cog replaces a freehub with a cassette with one gear and two bowl-like wheels. It’s delivered with Zwift Click buttons, which you pair with Zwift and use for shifting. So, you won’t mechanically shift your rear derailleur (you can shift the front one); you only shift virtually.
It expands bike compatibility because you can use it with 8-12spd bikes, unlike with an 11spd cassette. So it’s easier to use one trainer with multiple bikes. But, there are a few disadvantages, like a slower change of multiple gears at once, a less mechanical feel, and mainly limited indoor cycling app compatibility. Zwift was the only app that had supported virtual shifting for a long time, but then ROUVY announced its support for Zwift Click in February 2025.
Zwift basically managed to lock customers into its ecosystem. Using different apps with one gear makes no sense unless you use an ERG mode. And since other apps don’t support virtual shifting yet, you can’t shift gears virtually.
For a detailed comparison of advantages and disadvantages, check out Virtual vs. Traditional Shifting or the following table.
| Type of shifting | Pros | Cons |
|---|---|---|
| Virtual shifting (Zwift Cog) | • Improves compatibility with bikes that have different number of gears¹ • Eliminates cross chaining • Allows setting different gear ratios² • Quieter | • Less similar feeling to riding a bike outdoors • Slower when changing multiple gear • The position of the shifting buttons is not ideal • Not currently supported by applications other than Zwift and ROUVY |
| Traditional shifting (cassette) | • Faster when changing more gears at once • Realistic shifting • Ideal position of the shifters | • Higher risk of cross chaining • Worse compatibility with bikes that have different number of gears • Won’t allow you to change gear ratios³ • Noisier |
¹Assuming a Zwift Cog is used.
²Currently on smart bikes only
³Assuming you don’t change cassette or chainrings
Zwift Cog v1 vs. v2: What’s the Difference?
The first generation of the Zwift Cog had a significant drawback: it couldn’t be micro-adjusted. This limitation made it challenging to achieve proper rear derailleur alignment, often resulting in increased drivetrain noise.
Zwift Cog v2 addresses this issue with ten micro adjustment positions, making rear derailleur/chain/sprocket alignment easier and reducing noise for a better experience.
Conclusion
Zwift Cog v2 solves a few problems, like the compatibility of bikes with different gears and crosschaining, but it brings another. It makes the trainer unusable with different indoor cycling apps. Luckily, you can replace it with a freehub body and cassette and use the trainer traditionally, where you shift gears mechanically.
Remember that you don’t need a Zwift Cog to use virtual shifting. If your trainer supports it, you can use it with a normal cassette and shift with Zwift Click or Zwift Play Controllers.
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