| Unit | Size | Supported weight | Resistance | Workout Apps | Warranty |
|---|---|---|---|---|---|
Nautilus U618 Check Discounted Price | L:38.5" W:24" H:58.3" | 325 lbs | Eddy current, 25 levels | 29, Bluetooth | Frame: 15 years Mechanical: 3 years Electrical: 3 year Labor: 1 year |
The Nautilus U618 upright bike was released in 2016. However, that was the part number 100493. At the beginning of 2018, Nautilus has released a new version of this bike, the 100653. It’s not much different than the slightly older model but comes with several improvements. Also, the older, 100493 model is still available. So, in case you want to find out more about it, you can check it out HERE.
The Nautilus U618 upright exercise bike is part of the Nautilus Performance series, along with the Nautilus R618 recumbent bike or Nautilus T618 treadmill. It’s a light commercial fitness machine with a sturdy construction and a slightly larger size than several models in this price range.
Technical Details and Specifications
- Assembled dimensions: 38.5L x 24W x 58.3H inches (98L x 61W x 148H cm)
- Assembled weight: 83.1 lbs (37.7 kg)
- Flywheel weight: 30 lbs (13.6 kg)
- Weight capacity: 325 lbs (147.7 kg)
- Handlebar: 2-way adjustable, with pulse sensors and elbow rests
- Seat: Gel-cushioned, 4-way adjustable
- Pedals: Weighted, with straps
- Resistance: Eddy current, 25 levels
- Performance monitor: 29 workout programs, Bluetooth connectivity
- Amenities: Sound system, cooling fan, bottle holder, media tray
- Warranty: Frame 15 years / Mechanical 3 years / Electrical 3 years / Labor 1 year
Frame construction
As we’ve mentioned above, the Nautilus U618 upright exercise bike is a light commercial fitness machine, designed to withstand a lot of wear within the premises of a gym club. It 
features quite a robust frame, able to support users up to 325 lbs (147.7 kg). Needless to say, its frame is made of steel tubing. Most of the bars within the frame construction feature a black, industrial quality paint coating, highly resistant to corrosion.
The bike’s construction integrates only a few plastic parts. These are the covers of the drive system, the covers of the base tubes, and the bottle/accessory tray which attaches to the console mast.
This Nautilus exercise bike offers excellent stability as both its base tubes feature large, rubberized stabilizers. The rear stabilizers are adjustable, offering the possibility to perfectly level the bike on any type of flooring.
Although this upright bike is slightly larger than other similar models, it still isn’t an extremely large fitness machine. When fully assembled, it is 38.6″ (98 cm) long and 24″ (61 cm) wide, while its highest point (the top of the console) can reach 58.3″ (148 cm) above floor level. These being said, it’s definitely a fitness machine that can fit a small apartment.
The Nautilus U618 upright bike isn’t extremely heavy. But still, when fully assembled it weighs approx. 83 lbs, which is more than twice as the average road bike. This weight adds to its overall stability. However, the bike isn’t difficult to transport once it is completely assembled. Its front base tube integrates a set of wheels which allow you easily change its location.
Seat and handlebar
The Nautilus U618 upright exercise bike features a seat with more comfort factors than the U616 model. To begin with, it’s a Nautilus Gel seat, which integrates two gel cushioning 
elements, one on each side, for an equal weight dispersion. It’s made of highly durable synthetic leather, also having a contoured surface to promote a healthy blood circulation.
The seat can be adjusted in four directions, up, down, forward and backward. Its upright post has 14 adjustment positions, offering an adjustment span that can accommodate users between 5’0″ and 6’7″ (153 – 201 cm). However, users shorter than 5’3″ (160 cm) may find it difficult to adopt a fully seated and completely leaned forward position, with the forearms resting on the handlebars, such as the model in the photo above, even with the seat adjusted all the way forward. But nonetheless, they should have no problem exercising while holding the handlebar in various other ways.
With regards to the handlebar, the one supplied with the Nautilus U618 is 2-way adjustable. It has a T-knob at the middle which allows the adjustment of its angle. The handlebar is almost fully covered by a sheet of Urethane in order to deliver a comfortable and secure grip. It integrates several elements that other bikes don’t offer, such as large elbow rests and resistance controls. It also features stainless steel EKG pulse sensors so that the console can read your pulse. However, the console is also telemetric.
Drive and resistance
The Nautilus U618 upright bike features a belt drive system, using a heavy-duty v-belt resistant to stretching. It’s equipped with a fairly heavy flywheel for an upright bike; it weighs 30 lbs
(13.6 kg), delivering a steady momentum and a smooth pedaling motion. It’s a free-spinning flywheel, which means that the pedals won’t continue spinning if you stop pedaling. This also means that if you pedal in reverse you will get no resistance.
This exercise bike is equipped with a heavy-duty crankset, with solid steel crank arms. Even though it’s not a spin bike, it should be able to support less heavy users in standing up pedaling routines. However, workouts of these sort or spin workouts are not recommended to carry out on this exercise bike as this may lead to severe wear and tear. It is, after all, an upright bike not a spin bike, designed for seated workouts.
The crank arms are equipped with weighted pedals which feature adjustable straps for maximum foot stability. They have standard threads; thus, you can easily find replacements for them, basically in any bike shop.
This Nautilus upright bike features a motorized magnetic resistance system. This means it must be connected to a power circuit in order to make available any resistance. Its operational voltage is 9VDC / 1.5A. An AC power adapter is included with the bike, rated 100V-240V 50/60Hz Input, 9VDC, 1500mA Output. Class 2. The cable of the adapter plugs into the machine close to its front base.
The bike’s resistance can only be adjusted from the control unit, or from the controls integrated into the left and right handlebars. The resistance system consists of a servo motor and a magnetic element. As you select a certain resistance level from the console, the servo motor will adjust the position of the magnetic brake pad in relation to the flywheel, resulting in more or less drag. The console also has several pre-set workouts. So, if you exercise by using one of them, the bike will adjust its resistance automatically.
The bike offers 25 distinctive resistance settings. The lowest setting (1) delivers almost no resistance, being perfect for users who require rehab training. Conversely, the highest resistance settings (23-25) offer the possibility to undertake intense workouts for strength and endurance development.
Console
This exercise bike comes equipped with a SightlineTM tilting console, almost identical to the one on the Nautilus R618 recumbent bike. It features two LCD displays which integrate LED backlight for easy reading. The top display is larger and shows the selected goal, the 
profiles of the current workout, its name, and your heart rate interval. The lower display is smaller and shows time, speed, distance, RPM, resistance level, calories burned and heart rate. Speed can be calculated in both MPH and km/h, while distance can be tracked in both miles and kilometers.
As we’ve mentioned above, the console unit is telemetric. It can track your pulse via the included Bluetooth HR chest strap transmitter, but you can also use the EKG sensors within the handlebar for pulse reading.
The console makes available 4 user profiles; each profile records the workout results of the users to be reviewed later. Each user can set up their profile by inserting personal data such as height, weight, age, gender, and name. Thus, the unit will provide a more accurate estimation of the calories burned or the user’s current fitness level.
There are 12 pre-set workout programs built-in the console, including Rolling Hills, Ride in the Park, Easy Tour, Stream Crossing, Pike’s Peak, Mount Hood, Pyramids, Summit Pass, Uphill Finish, Cross-Training, Intervals, and Stairs. It gives you the possibility to setup goals for time, distance, and calories. There’s also a Fitness Program, a Recovery Program, and an HR control program with 4 levels of difficulty.
The console unit is Bluetooth enabled. This being said, you can sync it with your tablet, laptop or smartphone in order to benefit from a better interface and stats tracking via the online Nautilus Trainer app. Via Bluetooth, you can also instantly transfer your workout data into your Nautilus Connect or MyFitnessPal account. The console, however, has a USB port as well. So, in case you won’t be using the Bluetooth feature, you can still transfer your workout data into your account via USB. The USB port also works as a charging port for your smartphone or tablet.
The bike’s console unit is also equipped with a 3-speed workout fan, sound system, and media tray. The workout fan, although not too powerful, does generate a little cooling if it’s the case. The media tray is placed right under the large LCD display; it’s large and wide enough to accommodate any tablet or smartphone. The sound system is compatible with most MP3 players, smartphones, and tablets, consisting of two speakers at the lowest corners of the console.
Assembly and Maintenance
The body of the bike comes fully assembled. Therefore, you only need to attach the base tubes to the main body, the console mast, the seat tube, the seat, pedals and the console, connecting the wires. This shouldn’t take more than an hour. The manual delivered with the bike provides clear instructions for the assembly, while the required tools are included.
For maintenance, it is recommended to periodically inspect the bike for loose bolts and parts, and retighten them if necessary. Also, keep the bike dust and moisture free. The internal parts come pre-lubricated from the factory and shouldn’t require any further lubrication for a long period of time.
The Pros
- Solid construction, supporting even stand up pedaling workout routines;
- Elegant, motivating design;
- 4-way adjustable seat;
- 2-way adjustable handlebar;
- Resistance controls integrated into the handlebars;
- EKG pulse sensors integrated into the handlebars;
- Large seat with gel inserts for maximum comfort;
- Large elbow rests;
- Smooth and quiet drive;
- 25 levels of resistance;
- 29 workout programs;
- Goal tracking;
- Bluetooth console, compatible with the Nautilus Trainer online app, and wireless workout data transfer into your Nautilus Connect or MyFitnessPal account;
- The console is telemetry enabled;
- Wireless HR chest strap included;
- Several amenities, such as 3-speed fan, sound system, media tray, USB charging port, bottle holder;
- Easy to assemble;
- Basically maintenance free;
- Excellent warranty pack.
The Cons
- A tablet placed on the media tray will cover the top, larger display.
Bottom Line
The Nautilus U618 Performance upright bike is a fitness machine pretty close to the commercial standards. It offers 25 levels of eddy current resistance, superior micro-adjustability, 29 workout programs, a Bluetooth enabled console with numerous other features and an impressive combination of comfort factors. Although it’s an upright bike, it can support high-intensity training, being perfect for a wide array of cardio workouts, interval workouts, strength and endurance development, recovery training, and of course, weight loss. Finally, it costs several $100s less than a commercial upright bike, offering an excellent value for the price.