Nautilus U618 Upright Exercise Bike review

The Nautilus U618 Upright Exercise Bike is ideal for smaller home gyms, and offers a wealth of workout modes, plus a built-in fan to keep you cool as you break a sweat.

Nautilus U618 Upright Exercise Bike review
(Image: © Nautilus)

Top Ten Reviews Verdict

The Nautilus U618 Upright Exercise Bike offers a variety of training modes and a wide number of resistance levels to help you lose weight, increase your cardio fitness and build stamina during your home workouts.


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    29 workouts built-in

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    Grip and chest strap heart rate

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    Heavy flywheel for quiet riding

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    15 year frame warranty


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The Nautilus U618 Upright Bike builds on the years of experience that Nautilus brings to the world of home workouts, and made our best exercise bikes guide thanks to its solid build, wide array of features, plus a great raft of modes combined with a decent price.

It's easy to setup, comfortable to sit on and use, and offers a simple yet effective workout system that's as good for newcomers as it is for spin class heroes. The Nautilus U618  Let's take a closer look at this upright exercise bike now to see if it's a worthy contender for your home gym... 

Nautilus U618 Upright Exercise Bike review: overview

The Nautilus U618 brings with it something that more affordable exercise bikes won't have: a reassuringly heavy 30lb flywheel. This is what offers resistance, meaning you'll get a more consistent, smooth and quiet workout ride than you'll get with other exercise. bikes. It's an often overlooked part of these indoor exercise bikes, with digital features pushed to the front instead, but it's actually one of the most important parts.

Nautilus U618: Specs

Design: Upright

Workout modes: 29

Supported weight: 325 lbs

Warranty: Up to 15 years

There are lots of others features to feel happy about too, such as the wide levels of adjustments, the many workout programs to dig into (more on these below), and decent heart rate monitoring options. 

Although, if you really want to accurately track your heart rate, as well as calories burned (and other data) when working out, we'd recommend buying one of the best fitness trackers to go with your new exercise bike. For the latest discounts, see our round-up of the best Amazon Prime Day Fitbit deals.

Nautilus U618 Exercise Bike review

(Image credit: Nautilus)

Nautilus U618 Upright Exercise Bike review: design

The Nautilus U618 is an upright exercise bike, meaning you'll get a nice high ride position for lots of leg extension and back freedom during your workout. The seat is fully adjustable , with multi-grip handlebars and comfortable support for riders weighing up to 325lbs. For taller users, the console is tiltable, making it easier to view.

The frame comes with a 15 year warranty, while the mechanical and electric parts are covered for three years. Labor is free for one year. While it would be nice to have that frame warranty extended to lifetime and the labor coverage for longer, this is still a good offering that tells us the Nautilus U618 is built to last.

Everything certainly feels solid, with chunky adjuster handles, a reassuringly heavy 83lb assembled weight, and a four-way adjuster for that gel-cushioned seat to enhance your in-ride comfort during longer or more intense workouts.

Nautilus U618 Upright Exercise Bike review: features

The Nautilus U618 features an impressive 29 workouts that come pre-programmed into the bike. That means you can easily fire up the console and get riding towards your fitness goals. It's all viewable on the DualTrack screens, which features larger and smaller displays so that you get maximum data clarity. This is also useful if you' have the accompanying app running on a tablet, which usually blocks one of these screens. The console unit even has speakers, so you can play music from your connected device out loud as you workout.

As the U618 comes with Bluetooth connectivity, simply pair it to your favorite fitness app and track your workout data so that it's pulled into the app. There's also a RideSocial app, via which you can 'ride' with others who are also using the same app. It's not Strava level, but it's a nice option to have. Another great app is Explore the World, via which you can virtually ride through real world locations alongside people from around the world. Your tablet acts as a screen. 

The bike's handles feature grips sensitive to heart rate, enabling you to track when you're in a fat burning zone. Or if you want to work in heart rate zones with a more constant reading, no matter where you move your hands, put on the included chest strap. 

If you're working out in hot weather, or really enjoy breaking a sweat when you exercise, the Nautilus U618 has you covered there too as it features a built-in fan to keep cool air flowing around you as you ride.

Nautilus U618 Upright Exercise Bike review

(Image credit: Nautilus)

Nautilus U618 Upright Exercise Bike review: performance

That 30lbs perimeter weighted flywheel is the real star of the show here. It creates a system that offers high inertia, making starting up nice and easy – presuming you don't have full resistance engaged – and enables you to enjoy a smooth ride. 

Smooth doesn't mean easy – there's plenty of resistance if you're up for it – but it's a steady realistic resistance that enables you to apply leg power evenly, working all your muscles comfortably without risk of overstraining or injury. During testing, this really boosted our confidence and helped us push through to new levels of speed and endurance.

The pedals are weighted and use a three piece chrome crank system along with foot support straps. All that adds up to a great fit that, when combined with height and seat adjustments, make for perfect comfort. How? Because you can focus on the ride effort rather than your position. 

The 25 levels of magnetic resistance are varied enough to suit most riders and training situations. While the top end is so hard that you need to build up to it, the bottom end is super-easy and ideal for getting started. Thankfully, slipping between these modes is easy too; use the buttons on the handlebars. You'll be able to carry out a varied workout, like interval training, with ease. Being magnetic, the resistance is also really quiet, which is good if you live in a shared house with paper thin walls or floors (for those who live in apartments).

While the gel-cushioned seat is fully adjustable, it's still a little on the hard side. That could be a good thing to propel you out of your seat to ride harder more often, but if you're buying an upright bike for comfort and this gel seat isn't comfortable enough for you, add in an extra gel seat cushion to boost saddle softness.

Nautilus U618 Upright Exercise Bike: verdict

For anyone looking for an exercise bike to undercut professional gym models on price, yet still retains some of their best workout features, the Nautilus U618 Upright Bike is the one for you. This exercise bike uses a heavy flywheel, features great handlebar controls, plus weighted pedals and a fully adjustable ride height and seat for a gym-like experience. By that we mean a solid base that's comfortable, with resistance that's smooth and quiet, but also with a wide enough range of workout modes to cover all riding needs.

Bluetooth connectivity and app support are useful, but for some this could be better connected with more modern apps that are now owning the home cycling market. Ultimately, if you want a bike that's solid, offers a decent warranty and keeps the price relatively low for the high-end quality it offers, the Nautilus U618 is perfect. 

Luke Edwards

Luke is a veteran tech journalist with decades of experience covering everything from TVs, power tools, science and health tech to VPNs, space, gaming and cars. You may recognize him from appearances on plenty of news channels or have read his words which have been published in most tech titles over the years. In his spare time (of which he has little as a father of two) Luke likes yoga, surfing, meditation, DIY and consuming all the books, comics and movies he can find.