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CAROL Bike With AI Technology Review

Quick Summary

The technological developments associated with fitness equipment these days is truly amazing. And now, up to the line rolls the AI-powered CAROL Exercise Bike. The acronym CAROL stands for Cardiovascular Optimization Logic. Designed around the idea that 8 minutes of highly-personalized, intensive bursts of exercise can actually yield more benefits than 45 minutes of jogging, the CAROL Bike brings with it a unique programming package in addition to a great bike. Priced between $2,395 and $2,795 depending on the package, the CAROL promise is that its proprietary system of training can yield real results with just eight weeks of 8-minute and 40-second rides performed three times per week. From a pricing standpoint, that puts the CAROL in roughly the same zone as the NordicTrack Commercial S22i Studio Cycle. Check out the details below in our full review of what’s turning out to be one of the most discussed bikes rolling onto the market this year.


Model CAROL Bike
AI Powered

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List Price

Suggested retail price, typically higher than the price you'll pay with our recommended retailers.

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The flywheel in an exercise bike is what creates resistance. You can choose the level of resistance to increase your workout intensity.

Resistance Type

The type of resistance shows what kind of flywheel is being used (if any), and its weight if the manufacturer provides it.


Type refers to the style of the ride: Recumbent bikes allow you to lay back, while Upright bikes are more like road bikes (lean forward).

Indoor Cycle
Drive System

The bike's drive system is how your pedaling interacts with the rest of the bike (flywheel) to give you a good workout.

Poly-V Belt

It's important to choose an exercise bike that will last, and the material of the frame determines how durable the bike is.

Heavy-Duty Steel

The most important part for comfortability during your workout, the seat should be adjustable and have ample cushioning.

Adjustable horizontally and vertically

Pedals are the driving force for an exercise bike, and should be comfortable, adjustable, and easy to control without slipping.

Toe clips and straps

Bike Programs allow you to complete a workout with changing speeds and inclines, without changing anything manually.

Heart Rate

Heart Rate programs allow you to track how many times your heart is beating per minute (bpm), and some control the workout for you.


Display refers to the screen you'll look at to monitor workouts. LED and LCD displays are similar to TV screens.

HD touchscreen
Max. Weight

Max. User Weight is the amount of weight, in pounds (lbs), that the bike can safely support, which can represent durability.

286.6 lbs

Dimensions are included to help you figure out if this treadmill will fit properly (Length x Width x Height and Height x Depth).

45.5" x 22”
Accessory Tray

Some bikes include an accessory tray for holding items such as water bottles, wallets, keys, or MP3 players like iPods.


Cooling Fans


Some exercise bikes can fold up and/or have wheels that make it easy to roll them around for convenience and to save space.


The warranty is a very important part of your investment. The longer the warranty, the longer you can get free/discounted repairs by the manufacturer.

Variable by purchase

Rating: 86%

Our Rating

Rating: 86/100. For those who think that a bike is just a bike, they might want to dig a little deeper these days. It might be difficult to find a home fitness fan out there without some kind of high-tech app or trainer-guided program at their screen. With the CAROL, an AI-powered exercise bike, comes not just a machine, but a different approach to fitness. To this end, it’s a little reminiscent of the MYX Bike, which brings a package geared toward heart rate zones. Other bikes come with programs aimed at increasing resistance levels. With the CAROL, the principle is glycogen depletion.

With any kind of resistance training, muscle fibers are broken down and rebuilt larger and stronger, per the principles of hypertrophy. But what powers the body through these workouts is a sugar known as glycogen. Stored in the muscles and used to fuel exercise once the body has pushed past the immediately available stores of energy, glycogen is that last burst of energy one has known as a second wind. The body can typically store glycogen sufficient to power up to 15 seconds of additional exercise before being depleted. Glycogen depletion kicks into effect the molecular changes associated with improved health and fitness.

The fight-or-flight mechanism associated with human evolution is a part of this process, and explains that extra burst of energy afforded when one last all-out performance is required. Any physical activity driven past that point of glycogen depletion improves one’s aerobic capacity and is the zone in which fat is burnt. Remember, glycogen is a sugar, and sugars provide immediate energy, whereas fat is a stored source of energy. Fat is tough to get to because most exercisers never reach that point of intensity where they blast past the immediately available sugars and get into the storage. All exercise programs associated with cardio health aim at the same general direction, but whereas others target heart rates or resistance levels, the CAROL program aims for glycogen-depletion.

The workouts are designed around the principle of supra-maximal sprints, meaning the computer-controlled bike will force users to pedal about three times harder than a traditional High Intensity Interval Training (HIIT) workout. Without the artificial intelligence associated with the machine, it would be difficult, if not impossible to do this alone. Finding the correct resistance level for oneself is one thing, but coordinating that with heart rate sensors and then timing the switches at those speeds would not likely happen with any frequency. The value to CAROL is that users can simply get on the bike, log into their personalized profile, and be guided through two 20-second maximum intensity sprints as the machine personalizes the resistance in between the warm-ups, recoveries, and cool-downs.

The proprietary software package learns the user’s ability through past performance and tracks this for future programming. A computer-controlled magnetic braking system calibrates the resistance automatically. The CAROL team has designed ergometers with accuracy in mind, and a self-designed Octane Score is generated by way of the bike’s sensors and algorithms. As with most newer bikes, this one comes with an integrated heart rate monitor and built-in safety algorithms to detect a potential problem.

Engineering-wise, the CAROL brings a commercial-grade frame and freewheel clutch with acceleration and deceleration in mind. Measuring 45.5 inches in length, the bike has  width of 22 inches, and weighs 130 pounds assembled. Driven by a silent, poly-V belt with a freewheel clutch, it has a 1:4:9 gearing ratio, and 14-kilogram (30.865-pound) flywheel, making it among the heavier units on the market. Set up for 110-240-volt, the bike features an ergonomically sculptured saddle and dual sided toe cages and SPD click pedals. Bluetooth connectivity is available for both headphones and handlebar heart rate monitors, and the maximum user weight is a solid 286.6 pounds.

Programming-wise, the CAROL app has users input age, gender, height, weight, and tabulates performance data from the bike’s sensors. The first six rides are designed to acclimate the machine to the rider. Rides one through three are considered to ramp-up rides, where the user primarily accesses a main workout, with sprints lasting just 10 seconds. The fourth through the sixth rides are for calibration, where users choose between 10-, 15-, and 20-second sprints. This is where the machine’s algorithms calculate the exact resistance needed to reach maximum intensity. After the sixth ride, users have full access to the workouts and features of the bike, and the AI feature will continually re-calculate resistance to reflect the changes.

Priced with options to include warranty:

  • Essentials Bike Bundle: $2,395 (1-year warranty)
  •  Standard Bike Bundle: $2,595 (2-year warranty, chest belt, tablet holder)
  • Premium Bike Bundle: $2,795 (3-year warranty, chest belt, tablet holder, two water bottles and holder, floor mat)

Each bike features a 30-day return policy, 24/7 support by phone, chat, or email. A $12-monthly subscription is also required for the programming, but is free for the first three months.



  • Conveniently-sized at 45-inch x 22-inch
  • Solid 130-pound bike weight
  • Driven by a silent, poly-V belt
  • Freewheel clutch
  • Gearing ratio of 1:4:9
  • Heavy-duty 14-kilogram (30.865-pound)
  • Ergonomically-sculptured saddle seat
  • Dual-sided toe cages with SPD click pedals
  • Bluetooth connectivity
  • Heart rate monitors in handlebars
  • Interactive sensors for RPM and resistance
  • Computer-controlled brakes
  • Live-streaming fitness routines
  • The bike can work with other apps as well


  • Riders who enjoy longer rides might not like
  • The warranty plan varies with package purchased
  • Very specialized programming


CAROL AI Bike versus Competition

The CAROL Bike AI Powered is an interactive exercise machine specifically designed for extremely high-intensity workouts in short bursts. Equipped with artificial intelligence programming which personalizes the workouts and their progression to the user, the bike brings a heavy-duty flywheel of 14 kilograms, or 30.865 pounds). What really makes the CAROL Bike stand out though is the unique, glycogen-depletion style of programming.

One key point to note here, the CAROL Bike features a freewheel clutch, which is great for folks unaccustomed to spin bikes where the direct drive can be a bit of a shock. Price-wise, the CAROL Bike is rolling in the same circle as the NordicTrack Commercial S22i Studio Cycle.

Interestingly enough, the NordicTrack family of machines is likewise trending toward specialized programming by way of the iFit Coach program. Live trainers can control the bike from remote locations as users participate in their classes. This is a great comparison/contrast with the CAROL AI Bike where the machine itself adjusts the resistance to match individual user metrics. Meanwhile, the MYX Bike also brings customized programming aimed more at heart rate zones, as opposed to the CAROL Bike’s glycogen-depletion strategy.

Machine-wise, the S22i is a larger bike at 55 inches x 21.9 inches x 54.8 inches, and it does bring a whopping 350-pound user weight capacity, indicating it might be a bit sturdier than the CAROL, which maxes out at 286 pounds. The S221 offers 22 levels of silent magnetic resistance, and  large 22-inch HD touchscreen. The S221 also features heart rate monitoring via telemetry and grip sensors, which is designed to work with the iFit programming. Meanwhile, the big difference which jumps out is the lifetime warranty on the frame, with three years for parts, and one-year for labor, whereas the CAROL Bike offers between 1- and 3-year warranties based on the package purchased.

Meanwhile, the MYX Bike comes in around $1,300 and measures 54 inches x 21 inches x 47 inches, and also offers a 350-pound user weight capacity. The MYX Bike offers a 41-pound flywheel with traditional friction-based resistance. This is significantly heavier than the 30.865-pound flywheel on the CAROL Bike, which is still considered quite solid. The heavier a flywheel is on an exercise bike, the smoother and more stable the ride.

The MYX Bike offers wireless heart rate monitoring, which also connects to the interactive programming. Here, the MYX Bike brings its own app and trainers, with the exercise strategy revolving around heart rate zones, as opposed to glycogen-depletion in the CAROL Bike. The MYX package offers hundreds of trainer-led workouts, plus new ones added regularly, whereas the CAROL system tailors the bike’s workings to suit the individual user. In terms of warranty though, the MYX Bike only offers one year. Check out our reviews of the NordicTrack Commercial S22i Studio Cycle and the MYX Bike for a specs analysis.


Workout Programs

The CAROL Bike’s proprietary programming is specifically-designed to induce glycogen depletion, which in turn facilitates both health and fitness improvement. The program features a number of unique routines.

  • Intense: The lead workout emphasizing maximum intensity in minimum time. Designed to be last just eight minutes and 40 seconds, CAROL will lead users through two 20-second maximum intensity sprints wrapped in gentle warm-up, recovery, and cool-down periods.
  • Energizer: Just eight minutes  and 20 seconds, the program is designed as more of an early-morning routine.
  • Fat Burn: Designed to generate a massive after-burn, riders can opt for the 30-sprint (15 minutes) or 60-sprint (25 minutes). Both options utilize eight-second sprints using personalized resistance followed by 12-second rests.
  • Constant Power: Users set a desired level of resistance and try to sustain it as long as possible. The bike will automatically adjust the resistance as the RPM changes. This program is designed to test one’s Functional Threshold Power (FTP).
  • Endurance: Riders can test their endurance and Maximum Aerobic Power.
  • Free Ride: This function allows riders to control the resistance manually using the touchscreen, or incorporate another fitness app.

Whereas other exercise bike programs focus on heart rate zones, calories-per-minute, or mileage, the CAROL utilizes short, maximal intensity sprints to trigger the body’s fight-or-fight response. By utilizing short bursts or supra-maximal pedaling speed, the bike creates a sudden demand for energy which forces the muscles to burn glycogen, of which it only has but a few seconds supply. Glycogen is a sugar stored within the muscle for quick fuel, and once depleted, the body begins better burning fat. Glycogen depletion results in improved aerobic ability as the process forces the body to adapt.

CAROL’s two 20-second sprints are designed to deplete glycogen stores by 25-30%. Compared to running, this result would require 45-60 minutes. Utilizing a principle called Reduced Exertion High Intensity Training (REHIT), the bike moves away from longer-term exercise as is typically found in HIIT.

The brand’s specialized eight-week plan promises to reduce metabolic health risks (MetS Z-Score) by as much as 62%, blood pressure by as much as 5%, blood sugar by 2%, and increase good cholesterol (HDL) by 6%. Granted, this all hinges on the rider’s willingness to commit to the program. That said, the company offers that the post-exercise oxygen and caloric consumption generated by the high-intensity rides has been tested.

CAROL Bike Features

The CAROL Bike is a relatively new entry into the world of indoor fitness machines, and with it comes a new concept designed around glycogen-depletion. The machine itself brings a commercial-grade frame with freewheel clutch. The bike features Bluetooth connectivity, which can be used for headphones or in conjunct with the heart rate monitoring program. The bike’s 14-kilogram (30.865-pound) flywheel makes it among the heaviest on the market, and the value to a heavier flywheel is found in stability and the smooth roll of the ride. The bike measures 45.5- x 22-inches and weighs 130 pounds fully assembled. Maximum user weight is 286.6 pounds.

Additional items can be purchased in bundle packages, to include tablet holders, water bottles, and chest straps.


Warranty & Guarantee

The CAROL Bike features a 30-day return policy. The unit is offered in bundled price form with a 1-, 2-, and 3-year warranty offered at different levels.


Is It Worth It?

A new entry into the market for indoor exercise bikes, the CAROL Bike brings a unique approach to high-intensity training, and it’s intriguing to say the least. The price puts it up in a category where it’s facing long-time producers like NordicTrack with its Commercial S22i Studio Bike. The basic bike and a 1-year warranty price at $2,995 with online specials cutting that to $2,395. Frankly, we’d like to see a better warranty for that kind of pricing.

Otherwise, the bike’s unique workout strategy utilizing machine intelligence either appeals to a consumer or it doesn’t. This is a techies’s dream, particularly if they’re pressed for time. Whereas the CAROL Bike wouldn’t appeal as much to those seeking long, leisurely rides, it provides everything a high-octane cardio fan wants in multi-second bursts. The fact that this bike is designed to make one pedal faster than they mechanically could on other bikes, all controlled by the computer system, makes it a “Yes” for the right person.

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