Review: The One Daily Workout You’ll Ever Commit To

CAROL Bike is the fastest way to get fit (scientifically)

September 16, 2025 2:41 pm EDT
carol bike collage on blue background
The fastest you'll ever get fit.
CAROL Bike/InsideHook

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Okay, listen. I love working out. I’m a pilates instructor, tennis player and weight trainer. That’s a full slate, couldn’t you argue? And still, I find myself only exercising an average of probably four times a week, though I would work out every day if I could.

Or would I? The gym is far away, and carving out time to take a class is difficult when you’re busy, or tired, or you just showered, or you’d actually like to stay in and start a new hobby or drink wine or stare at your phone. I mean, the excuses start piling up real quick.

Then I was told about CAROL Bike.

Discovering CAROL Bike, however begrudgingly, gave me the opportunity to prove my theory: Will I work out every day if it’s the easiest, most efficient and scientifically proven way to get and stay in shape, and it’s literally in my living room? Let’s find out.

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CAROL Bike provides a few options for delivery — standard with no assembly, room of choice with no assembly or room of choice with full assembly. I chose room of choice, assembled, because it’s quite heavy, and it was totally worth it. I also got their two accessories: the Heart Rate Chest Belt and the Phone Holder.

Once plugged in, I connected the tablet to my wifi and opened the CAROL Bike app. You will need to set up an account and membership with CAROL Bike. The membership is $19.99/month, and it gives you and seven other riders the full experience of AI personalization, your performance dashboard and a library of workouts to choose from. Once you login, there’s virtually no other set-up required (the Heart Rate Chest Belt will connect via Bluetooth automatically).

Now, CAROL Bike is not a Peloton by any means. The interface and riding experience are devoid of upbeat trainers and pop music — instead, you select your tune from a handful of options (choose Tiger first, and thank me later) and you’re done within minutes, if you choose the REHIIT class option. (If you do want to ride for longer, fear not, they have a few other class options to choose from — Fat Burn and Free and Custom).

Carol Bike Lifestyle Image
Easy as one, two, three four five.
CAROL Bike

The science behind CAROL Bike’s REHIIT classes is completely unique: CAROL Bike states that you can improve your fitness by 12% in just eight weeks, you can reduce your risk of Type 2 diabetes by 62% and blood pressure by 5%.

REHIIT, for the uninformed (I certainly was) stands for Reduced Exertion HIIT. According to the CAROL Bike website, it was “developed by scientists looking for the shortest, most effective and accessible way to exercise,” and was previously only possible in a lab setting.

Dr. Neils Vollaard states, “CAROL’s AI-personalization and Instant Resistance help you push to your limits during the sprints. Like in a ‘fight or flight’ situation, your muscles are forced to mobilize about 25-30% of muscular glycogen — your emergency energy reserve — which releases key signaling molecules (AMPK and PGC-1a), telling your body to get fitter and stronger. You develop more mitochondria, your blood plasma volume increases and your heart gets stronger, resulting in increased aerobic capacity.”

CAROL Bike is the only one capable of this technology, because it hinges upon each individual’s physiology.

What Works

It’s compact for a stationary bike, so it only takes up a slight bit of your precious apartment space, especially if you’re based in NYC like I am.

I enjoy the no-nonsense approach of CAROL Bike’s interface and ride experience.

The REHIIT workouts are only five minutes, which is honestly a foolproof way to guilt you into incorporating it into your everyday routine. And it’s right there, in your living room, staring at you until you do.

The data tracking features show your real progress over time, and the habit score in particular piles on more of the guilt factor (in a good way). The heart rate monitor is a necessary contributor here: You can keep track of your heart health over time (hello, VO₂ max!).

Another cool thing about CAROL Bike is that they offer a $49/month Commercial Membership that allows up to 25 users to enjoy the bike, making it a great option for your office.

What Needs Work

My heart rate monitor went askew in the middle of one of my rides, causing a message to pop up on the screen and leaving me unable to complete my ride. I clicked out of the notification, and the gear changed to one that was so heavy I could no longer pedal. Since I was almost done with the ride anyway, I just didn’t save that data. I wish it would simply stop logging the heart rate monitor data rather than interrupting the ride.

I experienced some bugginess when the system needed updates. Just make sure you keep the software up to date, and this shouldn’t happen.

The phone holder doesn’t feel necessary simply because the rides are so short, so I would save yourself money here.

It feels like the tablet could just open up straight to the CAROL Bike app, without having to experience the home screen of the tablet at various points, which feels sort of archaic in comparison to the impressive technology everywhere else.

Is It Worth It?

CAROL Bike might just be the easiest way to get an amazing workout every day. It tucks into your home, its technology conforms to your preferences and particulars and it makes you feel quite proud of yourself for committing to something on a daily basis. For these reasons, we feel it’s our sovereign duty to recommend it wholeheartedly.

Go on and check out CAROL Bike for yourself, below. It may just be the (five-minute) ride of your life.

Meet your guide

Shelby Slauer

Shelby Slauer

Shelby covers Goods for InsideHook, having previously contributed to Mashable, INSIDER, Funny Or Die, Reductress, And So Forth. She reports on all things sports recovery, wellness, tech and really anything that makes our day-to-day lives better. You can reach her at shelby@insidehook.com.
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