I tried the CAROL Bike's AI-powered workouts — here's what happened

10 minutes to boost your fitness, but at what cost?

The CAROL Bike in a corner of a room surrounded by houseplants
Editor's Choice
(Image: © Future)

Tom's Guide Verdict

If you like short, to the point workouts, then the CAROL Bike's 10-minute routines are ideal. The bike uses Reduced Exertion High-intensity Interval Training (REHIT) and AI to help maximize your training, allowing you to pack in a high-intensity session when you're short on time. It's expensive, and the features are locked behind a monthly membership, but it's effective and a lot of fun too.


  • +

    AI-powered automatic resistance adjustments

  • +

    Time efficient workouts

  • +

    Quiet ride


  • -

    No workout classes

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    Bike is expensive

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    Monthly membership required for AI features

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CAROL 2.0 Bike specs

Size: 45.5 x 22 inches
Weight: 120 pounds
Flywheel: 30 pounds
Max. weight: 286.6 pounds  
Drive type: Belt
Belt Resistance: Electromagnetic

I was excited to try the CAROL Bike. It's an exercise bike powered by AI, so it gets to know your fitness level and automatically adjusts the resistance to help you train optimally and reach your goals. Plus, the company says that it can deliver the benefits of a 45-minute run in just 8 minutes and 40 seconds. 

As an avid runner who has trained for various distances from 10Ks to marathons, I know what a 45-minute run feels like during and after, so I was eager to see how CAROL’s science-backed theory of Reduced Exertion High-intensity Interval Training (REHIT) would work in testing. 

And of course, I wanted to see if this bike deserves a place in our guide to the best exercise bikes on the market right now. Here's how I got on. 

CAROL Bike review: price and availability

the CAROL 2.0 exercise bike in the corner of a room surrounded by houseplants

(Image credit: Future)

The cost bike costs $2,595 on the CAROL websste, which is $100 more than the Peloton Plus Bike but it does offer a cheaper membership. Financing is also available through Affirm, offering 0% APR for 12 months. 

On the topic of memberships, there is an additional $19.99 monthly fee you will have to pay for your CAROL bike which is what gains you access to the AI-controlled resistance and incremental progressions, which is pretty much the biggest reason to buy this bike. 

The monthly membership offers you and seven others access to all of the CAROL bike’s features including the AI optimization, the choice of 20 different workouts and fitness tests, and a personalized dashboard with detailed performance metrics to help you track your progress.

However, you can still use the CAROL Bike if you don't take out a membership, but you lose access to features, like AI-powered resistance. According to CAROL, without a membership, you can use "non-personalized resistance settings, standalone performance metrics and six science-backed workouts."

There is the option to buy extras for your CAROL bike experience like the heart rate monitor which costs $69 and connects to the bike to track your heart rate. However, this isn’t essential as their are heart rate monitors integrated into the bike’s handlebars. 

You can also purchase a CAROL mat to place under the bike for $59 and its a good idea if you want to protect the flooring underneath the machine. Lastly, you can purchase a phone holder for $49, which allows you to have your phone securely attached to the bike as you work out. 

However, given the initial cost of the bike and the monthly subscription, it's surprising that these convenience features, like a phone holder and a mat, aren't included. But this is in line with the Peloton Bike Plus, which retails for $100 less, but also has add-on packages for accessories. 

CAROL Bike review: Design and setup

the CAROL 2.0 exercise bike viewed from above with a tablet in the device holder

(Image credit: Future)

The bike features a powder-coated steel frame and heavy-duty plastic casing around the pedals and flywheel and overall feels and looks very durable, although since it stays in one place indoors, this is more for aesthetic reasons than because it needs to survive in rugged outdoor conditions. 

The CAROL Bike is pretty inoffensive in size, taking up less than 7 square feet in whatever space you choose to put it in. And, according to CAROL, the bike is suitable for users ranging from 4 feet 7 inches to 6 feet 7 inches tall and supports a maximum weight capacity of 330 pounds.

Although it’s part of the job of being a fitness writer, I often dread the delivery of bigger items I test such as an exercise bike like the CAROL bike that weighs a grand total of 120 pounds.

But thanks to the delivery team behind CAROL, the bike was safely transported by two of their team into the room I wanted to ride it in and the bike comes nearly entirely assembled. With the delivery drivers gone, the bike was easy to manoeuvre into its spot with the transport wheels tucked under the flywheel. 

The device holder on the CAROL Bike with a tablet in place

(Image credit: Future)

Once I got the bike in a position I liked, I just had to set the tablet up on the bike and adjust the seat and handlebars to suit my size.

I had a bit of a struggle with the tablet and the holder, trying to slot the top of the screen into the small handles before realizing it simply rests on the top of the holder. I was concerned this would make the tablet unstable during rides, but the design is clearly well thought out, as I experienced no slips or smashes with the screen. 

You can move the seat up or down, as well as forward or backward, allowing you to control how close or far your upper body is to the handlebars. Additionally, the handlebars can be adjusted for height and feature a five-position multi-grip design. 

CAROL Bike review: performance

From my experience working out on this bike, the AI-controlled resistance levels are remarkably intuitive and adaptive. From the initial fitness tests to the first few rides, the bike’s AI technology began learning about my performance and tailoring the resistance to match my current fitness level. 

This meant that each session provided a challenge, and as I progressed, the bike adjusted to ensure my workouts remained effective. One standout feature was how seamlessly the adjustments occurred without needing to take my hands off the handlebars.

CAROL’s AI processor handled all the resistance changes, predicting when to dial it up and how long to maintain it. This was a great way to stay focused and fully immersed in a workout.

The fitness metrics provided, such as overall fitness score, heart rate via the included chest strap, R-R intervals, HRV measurement, peak power, and energy output, were useful for tracking my progress. It also offered local and global leaderboard stats, adding a competitive edge to my workouts.

The CAROL Bike's flywheel

(Image credit: Future)

I did hit a snag with the bike while trying to complete the VO2 max test though. The machine offers an 8-minute test to estimate VO2 max, involving a 4-minute warm-up at a 30W target power, a 4-minute ride at a personalized submaximal target power, followed by an optional 3-minute cooldown.

However, my heart rate wasn’t rising high enough above rest, causing the bike to readjust the resistance and reset the 4-minute timer repeatedly. This resulted in a confusing cycle of alternating between very easy and very hard resistance levels. 

Perhaps the bike wasn’t familiar with me enough at this point, or the heart rate monitoring was a bit off on this occasion, or I am just such an elite level of athleticism that the bike can’t raise my heart rate (sadly, I doubt it’s the latter).

Although I can't say for sure what the cause was, it's a reminder that there will sometimes be technical issues with smart exercise bikes, and, in the CAROL Bike's case, that affects how the automated features work. 

The CAROL Bike app on a tablet display

(Image credit: Future)

In terms of how the bike felt to ride, the whole experience was comfortable and smooth. The bike made little to no noise, making it well-suited to apartment dwellers. One thing I noticed was that during the intervals, the base of the bike rattled from side to side at the front.

I didn’t have a mat underneath the CAROL Bike while testing and would recommend you invest in one or if you don't want the additional splurge, use an old yoga mat if you own one to protect your flooring.

The bike doesn’t have any workouts led by enthusiastic trainers on the screen like you'd get with the MYX II smart exercise bike, so that's worth keeping in mind if you like the support to keep motivated during intense training. 

However, the whole point of this bike is to get your workouts done in a short space of time, eliminating the need for a trainer to guide you. After all, it's easier to keep motivated for 10 minutes compared to a 40-minute high-intensity slog. 

And, because the tablet runs Android 13, it also has access to the Google Play Store, so you can download the majority of Android apps, including Peloton if you fancy using the CAROL Bike's free ride mode to join a class, or entertainment services like YouTube or Netflix.  

Should you buy the CAROL bike?

After spending time training on the CAROL Bike, it's an excellent choice for those with tight schedules, such as busy parents, anyone who works extra long hours, or those who simply prefer minimal yet effective exercise to stay fit. 

The bike's hands-free AI-controlled resistance and super-efficient workouts make it an ideal home exercise machine for maximizing cardiovascular health in minimal time. 

However, as someone who uses exercise as an outlet and enjoys longer workouts that allow me to fully disconnect from work and responsibilities, I found that the eight-minute sessions on the CAROL Bike didn't quite replicate the same post-workout feeling as a longer run or workout would.

While the bike claims to provide equivalent benefits in a fraction of the time, the experience may not satisfy those who value the effect of longer workouts. Your enjoyment of this technique also depends on whether you see exercise as a means to an end, or an activity and process in its own right.

Also, if you're someone who thrives on guided workouts and needs motivation from following a structured class, this bike may not be as stimulating for you. The focus is on autonomous, data-driven workouts rather than instructor-led sessions, so if you're looking for classes, the Echelon Ex-3 might be a better option. 

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Jessica Downey
Fitness Writer

Jessica is an experienced fitness writer with a passion for running. Her love for keeping fit and fueling her body with healthy and enjoyable food quite naturally led her to write about all things fitness and health-related. If she isn’t out testing the latest fitness products such as the latest running shoe or yoga mat for reviewing then she can be found writing news and features on the best ways to build strength, active aging, female health, and anything in between. Before then she had a small stint writing in local news, has also written for Runners World UK (print and digital), and gained experience with global content marketing agency, Cedar Communications.

Born and raised in Scotland, Jessica is a massive fan of exercising and keeping active outdoors. When at home she can be found running by the sea, swimming in it, or up a mountain. This continued as she studied and trained to become a PPA-accredited magazine journalist in Wales. And since working and living in London, she splits her time between weight training in the gym, trying new fitness classes, and finding scenic running routes. Jessica enjoys documenting this on her fitness-inspired Instagram page @jessrunshere where she loves engaging with like-minded fitness junkies.

She is a big fan of healthy cooking and loves learning more about this area with expert nutritionists she has met over the years. Jessica is a big advocate for building healthy relationships with food rather than building restrictive attitudes towards it. When she isn’t eating or running she also enjoys practicing yoga in her free time as it helps her to unwind and benefits her performance in other sports.

  • ron.grimes
    You list as "cons":
    No workout classes
    Monthly membership required for AI featuresBut, this is not exactly accurate. The CAROL Bike site states, "CAROL Bike also integrates with a wide range of training and fitness apps including Peloton Digital, Zwift, Kinomap, Rouvy, BKool and FulGaz." So, if you want to use the bike for both REHIT and classes, you can.

    Also, while CAROL has a monthly membership of $20, others also charge and so it's not really a con if everyone else also has a monthly membership fee.

    Ron Grimes
  • James Frew
    ron.grimes said:
    You list as "cons":
    No workout classes
    Monthly membership required for AI featuresBut, this is not exactly accurate. The CAROL Bike site states, "CAROL Bike also integrates with a wide range of training and fitness apps including Peloton Digital, Zwift, Kinomap, Rouvy, BKool and FulGaz." So, if you want to use the bike for both REHIT and classes, you can.

    Also, while CAROL has a monthly membership of $20, others also charge and so it's not really a con if everyone else also has a monthly membership fee.

    Ron Grimes
    We list 'no workout classes' as a con, as CAROL doesn't have its own library of classes, unlike Peloton, Echelon and others.

    Both those brands also require a membership, but you get access to live and on-demand classes as part of the monthly subscription. The CAROL Bike's subscription is mostly centered around the AI features — useful, but still not ideal if you like classes, which many people who invest in spin/exercise bikes enjoy.

    While CAROL describes the third-party apps you can use, these aren't baked into the bike. The display is an Android-powered tablet, so you have access to the full Google Play Store, including apps from Peloton, Zwift etc, but you would need a subscription to those apps to use the classes.