Nautilus U616 Upright Bike

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Nautilus U616

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300 lbs22 lbsEddy
25 levels
29 programs,


Trainer 2


The first Nautilus U616 upright bike model was released in 2013. However, at the end of 2017, a new version was released. Although this new model is very similar in specs and features as the first model, it has a slightly different console, a black paint finish, and is also compatible with the RideSocial and Nautilus 2 fitness apps. For reference, this is the Nautilus part number 100669. The older model was the Nautilus 100390.

Technical Details and Specifications

  • Assembled dimensions: 41.8L x 21.6W x 57.6H inches (104L x 55W x 146H cm)
  • Assembled weight: 68.6 lbs (31 kg)
  • Supported weight: 300 lbs (136 kg)
  • Handlebar: 2-way adjustable, with pulse sensors
  • Seat: 4-way adjustable
  • Pedals: Weighted, with straps
  • Resistance: Eddy current, 25 levels
  • Console: 29 workout programs, Bluetooth, USB port, RunSocial compatible
  • Amenities: Speakers, fan, media tray, bottle holder,
  • Warranty: Frame 10 years / Parts 2 years / Electronics 1 year / Labor 90 days

Frame construction

The Nautilus U616 100669 features a steel frame construction. However, the upright post of the seat with its slider is made of aluminum material. All the steel parts within the frame are coated with a corrosion-resistant paint finish. As we’ve mentioned above, the color used is black, as opposed to the older (2013) model which had light gray paint finish. The side base covers of the pulley, flywheel, and other resistance elements are made of ABS material.

The bike offers an excellent overall sturdiness and stability. It weighs approx. 68.6 lbs (31.1 kg) which is twice the weight of the average road bike. This weight, plus your own weight, adds to the overall stability of the unit. Plus, the rear base is equipped with large, adjustable stabilizers, while the front base rests on two other rubberized pads which improve the unit’s grip on the floor. The front base also has transport wheels which facilitate the relocation of the bike once you have finished your workout. By using these wheels, you won’t be handling more than 1/3 of the unit’s total weight.

The fully assembled bike isn’t extremely large. Its footprint is approx. 42″ x 22″ (106 x 55 cm), while its highest point is given by the top of the console which is situated at approx. 58″ (146 cm) above floor level. Nautilus does, however, recommend that you leave at least two feet of clearance on each side, at the front, and at the rear of the bike, for safe access and operation.

Seat and handlebars

The Nautilus U616 is equipped with a high-comfort seat. The saddle integrates a thick layer of foam cushioning which considerably improves its comfort. It is definitely a saddle made for seated workouts, unlike the saddles included with many spin bikes, which are considerably slimmer. But nonetheless, you can still improve its comfort by adding an extra gel seat cover.

The seat has a standard attachment system to its slider. This being said, compatible replacements for it are widely available. Thus, in the unlikely event that you would want to replace it, you should be able to find a compatible model in any bike shop.

The seat offers 4-way adjustability. Its upright post features more than 10 adjustment notches with approx. 1″ (2.5 cm) in-between. This being said, it should be able to accommodate users between 5’0″ and 6’5″ (153 – 196 cm) with no problem, promoting a complete and healthy leg extension during pedaling. Plus, the seat’s horizontal slider offers several inches of front to back adjustment. It’s also durable enough to support users up to 300 lbs (136 kg).

As opposed to other upright bikes, the Nautilus U616 also offers handlebar adjustability. The handlebar assembly is attached to the front mast into a metallic collar, which is tightened by a large knob. Therefore, you can untighten the knob, adjust the handlebar to the angle that you desire, and then retighten it back in its place.

The handlebar features a multi-grip design. It offers the possibility to adopt at least three grips, including parallel, standard, and race. Its side sections feature a layer of rubberized material to provide a secure grip. Its lower section integrates a set of metallic grip sensors which allow the console to monitor your pulse. Plus, the bottom corners of the handlebar are equipped with elbow pads, a set of accessories that many upright bikes, or exercise bikes in general, do not include.

Resistance and drive

This Nautilus exercise bike is equipped with an eddy current (motorized-magnetic) resistance system. This means it requires to be connected to a power source in order to allow resistance adjustments. Any resistance adjustments can only be done from the console. Also, most of the onboard programs of the bike will automatically adjust the resistance, if selected.

An AC adapter is included with the bike. Its specs are Input:120V 60Hz, and Output: 9VDC, 1.5A. Its connector is situated at the front base of the bike. The console cannot be powered by batteries.

The main resistance elements of the bike are a magnetic brake and a servo motor. As you adjust the resistance from the console, the servo motor will move the magnetic brake pad closer or farther from the flywheel, this way increasing or decreasing the intensity of the created magnetic field. This ultimately leads to a higher or lower pedaling difficulty.

The bike offers 25 distinct resistance levels. The first 5 deliver a very light resistance, great for users who need recovery training, or elderly users. Conversely, the 20-25 levels of resistance provide a pretty consistent pedal tension, simulating a steep climb, and allowing you to achieve a higher fat burn.

The Nautilus U616 is equipped with a 22 lbs (10 kg) internal flywheel which has a perimeter-weighted structure, made to generate a superior inertia during pedaling. It delivers a consistent momentum and a steady pedaling feel. It also allows pedaling in reverse; however, coasting is not possible on the bike.

The crankset features durable steel crank arms. However, it’s not made for spin workouts. So, even though it may be solid enough to support your full weight during a standing up pedaling routine, this type of exercises are not recommended. This is, after all, an upright bike, made only for seated workouts.

The included pedals are made of a durable nylon material with a metallic core. They’re weighted so that they always self-adjust turning up when you remove your feet from them. They are also equipped with adjustable straps.

Finally, this Nautilus exercise bike features a belt drive system. It uses a heavy-duty rubber belt, resistant to stretching. This being said, the internal drive system doesn’t need lubrication. Also, the belt generates considerably less vibration than a chain.


As we’ve mentioned above, the Nautilus U616 features a different console than the previous model. It’s actually similar to the one on the Schwinn 170 MY17. It has a sleeker interface and offers greater visibility for the workout metrics than the previous model.

The bike’s console features a dual-display. The top larger display shows the profiles of the selected workout program, the selected goal and your progress towards it, the name of the current workout program, the levels of incline and resistance, and the heart rate interval. The lower display shows time, speed, distance, RPM, resistance level, calories burned and heart rate.

For the speed and distance parameters, the console offers the possibility to select either metric or imperial units. Also, not only that it can track your pulse via the integrated sensors, it is also telemetric. This being said, it can communicate with various HR transmitters which operate in the 4.5 kHz – 5.5 kHz range.

The console integrates an impressive array of workout programs to keep you motivated. To begin with, it has a Manual mode which allows you select any tension level during pedaling. There are 12 preset programs designed for various workouts. There is a Custom program which basically allows you to create your own challenge and try to break your records with each workout. There are 4 Heart Rate programs settings for 50-60%, 60-70%, 70-80%, and 80-90%; when one of these HR programs is selected, the machine will monitor your heart rate and auto-adjust the resistance in order to keep you within the selected HR range.

Goal tracking is also available. You can select a goal track for a certain period of time, and the console will monitor your progress towards that goal. For example, you can select a calories goal for a period of 7 days, and the console will track how many calories you have burned towards that goal.

The console provides 4 user profiles. Therefore, you can save a goal tracking for each one of them. Or, 4 separate users can save their own program settings and quickly select their program and workout parameters when they begin their workout. Each user can also save their weight, height, age, gender, and name, for a more accurate calorie count and progress tracking.

Finally, in terms of programs, the console also has a Recovery function and a BMI function.

The console features do not end here, though. Just as the Nautilus R618, this one features Bluetooth connectivity and a USB port. Thus, you can sync it with your smartphone or tablet in order to stream your workout data into your online fitness tracking account. It is compatible with various fitness apps, such as Nautilus Trainer 2, MyFitnessPal and several others. In case you don’t want to use the Bluetooth feature, you can still transfer your data online via a USB device. Also, the USB port of the unit doubles as a charging port for your tablet or smartphone.

As opposed to the older model, the console of this Nautilus exercise bike is compatible with the RideSocial virtual app. This is an online application which allows you to view and ride on a virtual trail on your smart TV, tablet or phone, based on a GoogleMaps trail. You can create riding events, ride alongside your friends and benefit from many other interactive and fun features through it.

In terms of amenities, the console integrates a sound system, a media shelf, and a cooling fan. The sound system is compatible with most MP3 players, smartphones, and tablets, consisting of two speakers at the lowest corners of the console. The media shelf is placed between the two displays of the console; it’s large enough to accommodate any tablet. The workout fan, although it is not too powerful, it does provide some cooling for your workout, and you can actually change its angle by tilting the console.

Assemble and Maintenance

The base of the bike with all the drive and resistance elements comes pre-assembled. Therefore, you only need to add the base bars, the console mast, the handlebar, the console, the seat post, the seat, and the pedals. This may take up to an hour, but the whole process is far from being complicated. The included manual provides very clear assembly instructions and schematics. Also, a basic toolkit is included.

For maintenance, it is recommended to periodically check the integrity of the unit, look for loose bolts or broken parts, etc. Any sweat drops that may fall onto the frame or console should be removed. Internal maintenance is not required. All the internal parts come pre-lubricated from the factory.

The Pros

  • Solid construction – can hold users up to 300 lbs;
  • Professional-looking design;
  • Adjustable stabilizers on the rear base;
  • Transport wheels on the front base;
  • Cushioned, 4-way adjustable seat;
  • Angle-adjustable handlebar;
  • Elbow pads included;
  • Pulse sensors integrated into the handlebar;
  • Smooth and quiet drive;
  • 25 levels of resistance;
  • 29 workout programs;
  • 4 user profiles;
  • Goal tracking; 
  • Nautilus Trainer 2, MyFitnessPal, Google Play, Under Armour and other online apps compatibility;
  • Compatible with the RideSocial virtual app;
  • Telemetric console;
  • Several amenities, such as 3-speed fan, sound system, media tray, USB charging port, bottle holder;
  • AC adapter included;
  • Easy to assemble;
  • Basically maintenance free;
  • Excellent warranty.

The Cons

  • A tablet placed on the table holder will cover the top display;
  • An HR chest strap is not included;
  • The cooling fan is not too powerful.


The Nautilus U616 is an upright exercise bike offering 25 levels of eddy current resistance, 29 onboard workout programs, Bluetooth connectivity and compatibility with the Nautilus Trainer 2 and RideSocial. It’s a heavy-duty bike, pretty close to light-commercial quality. It also offers superior micro-adjustability and a wide array of amenities, such as a sound system, cooling fan, and tablet holder. It’s definitely one of the most complete upright bikes for home use, offering an outstanding value for the price.

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