Sunny Health & Fitness SF-RB4880 Recumbent Bike

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Sunny SF-RB4880

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300 lbsEddy
24 levels
6 workouts,
Frame: 3 years
Parts: 180 days

The SF-RB4880 is one of the new recumbent bikes from Sunny Health & Fitness released in 2019. Although it’s a heavy-duty exercise bike pretty close at least to light-commercial standards, it is only a bike for home use. It has a self-powered, motorized magnetic resistance system, with automatic resistance control. It also has offers several workout modes and other features to keep you motivated.

Key Features and Specifications

  • Assembled dimensions: 66L x 26W x 44.5H inches (168L x 66W x 113H cm)
  • Assembled weight: 112 lbs (50.8 kg)
  • Weight capacity: 300 lbs (136 kg)
  • Seat: Adjustable
  • Resistance: Eddy current, self-powered, 24 levels
  • Console: 6 training modes, 12 program presets, BMI, Recovery
  • Extras: Sound system, USB charging port, tablet holder,
  • Warranty: Frame 3 years / Parts 180 days

Frame construction

The Sunny SF-RB4880 features a heavy-duty frame construction, made of durable steel tubing. It has a one-piece chassis which considerably improves its overall sturdiness. It is also a pretty heavy bike; its net weight is approx. 112 lbs (50.8 kg), a weight which considerably improves its stability.

Speaking of stability, the bike has adjustable levelers on both its base bars, plus an additional one at the middle of its longitudinal frame bar. These stabilizers have large rubberized pads which prevent the unit from sliding or moving, and also prevent floor damage.

Although this Sunny exercise bike is rather heavy, its relocation isn’t too difficult once it is fully assembled. Its front base has a set of rubberized wheels, while the rear base features a lifting handle. Therefore, you won’t have to handle more than 30% of its total weight when moving it.

Most of the bike’s frame is coated with a corrosion-resistant and chip-resistant paint finish. The only exception is the sliding rail of the seat which is made of aluminum alloy. The bike’s construction also integrates several ABS covers, such as the ones that conceal the drive system, or the ones over the base of the seat.

The fully assembled bike is fairly large. It is approx. 66″ (168 cm) long, and 26″ (66 cm) wide. This being said, you will need a usage area of at least 90″ x 60″ (228 x (152 cm) for it.

One last aspect to mention here is the step-through design. You can easily pass through the frame and take position on the seat; this can be quite a plus for users with certain disabilities.

Seat and handlebars

The bike’s seat is designed to provide superior comfort. It is pretty close to the comfort provided by an office seat. To begin with, its bottom cushion integrates approx. 3″ (8.5 cm) of foam padding. It’s pretty large as well, 16.5″ (41 cm) wide and 12.5″ (36 cm) deep, providing plenty of contact surface.

The backrest features a flexible yet highly durable mesh structure. This being said, it will easily adapt to the shape of your body while also providing excellent breathability.

The whole seat assembly is adjustable. It is attached to an aluminum rail and has a lever-based adjustment system. This means you can easily unlock and re-lock it into the desired position without having to stand up. The seat adjustment span is designed to accommodate users with an inseam between 28″ and 34″ (71 – 86 cm), in other words, users between 5’0″ and 6’2″ (153 – 188 cm). It’s also durable enough to support users up to 300 lbs (136 kg).

It’s important to mention here that the unit’s backrest does not adjust independently from the rest of the seat. It doesn’t recline, nor it can be set to a higher or lower position as it is possible for the backrest of the Tunturi Endurance E80-R. It is directly attached to the steel backbone of the seat frame and will move along with the rest of the seat on its rail.

The Sunny SF-RB4880 features two sets of handlebars, one attached to the front mast, under the console, the other connected to the seat assembly. The front handlebars are adjustable. You can adjust their angle from the knob that keeps them in place. The seat handlebars are non-adjustable; they are directly welded to the frame of the seat. However, their grips include pulse sensors.

Resistance and drive

The Sunny Health & Fitness SF-RB4880 features a self-powered, eddy current resistance system. Therefore, the bike doesn’t need an external power source and its console doesn’t need any batteries. All the energy necessary to activate the resistance, power up the console, and even charge your smartphone or tablet, is generated when you pedal. It is important to mention, though, that when you use the bike for the first time, you will have to pedal for several minutes to generate enough power for the console.

The internal resistance elements are a small servo motor and a magnetic brake integrated into the flywheel assembly. Thus, when you adjust the resistance, the motor adjusts the intensity of the magnetic field which results in more or less pedal tension. Also, if one of the preset programs is in use, the console will auto-adjust the resistance.

This Sunny exercise bike makes available 24 resistance levels. The first one is fairly light, great for anyone who requires recovery training. Conversely, the 24th tension level provides considerably more resistance, recommended for anyone who wants to boost their cardiovascular rate and lose weight.

The exact weight of the internal flywheel is not specified, by it’s fairly heavy for a recumbent bike. It is perimeter-weighted and provides a pretty consistent momentum. It is also bi-directional; thus, you can pedal in reverse if you want.

Most exercise bikes with a magnetic resistance system have a belt drive system, and the Sunny SF-RB4880 does not make an exception. It integrates a durable, stretch-resistant belt which delivers superior traction. Since it doesn’t use a chain transmission, you don’t have to lubricate it. Also, the pedaling motion is extremely quiet and vibration-free.

Finally, the bike has a durable crankset, with large non-slip pedals which also have adjustable straps. The pedals feature a weighted design, so they always turn face-up when you remove your feet from them.


The bike is equipped with a mid-range console. It doesn’t have online connectivity, nor it is compatible with any online fitness apps. However, it has plenty of programs to keep you motivated.

To begin with, the console features a multi-panel LCD display with LED backlight. It shows multiple workout metrics, including time, distance, speed, RPM, calories, watts, and pulse. For the display of speed and distance values, you can either select metric or English units. Also, for the pulse reading you will have to use the integrated sensors; the console is not telemetric, so it cannot read your pulse through a wireless HR chest belt.

The console has several workout programs. The first one is the Manual program which you can use if you want to pedal freely, adjusting the resistance as you like throughout your session. The next three workout modes are Beginner, Advance, and Sporty. Each one has 4 preset modes which you can challenge yourself with. And finally, there is a Cardio program and a Watt program. The Cardio program has three preset values for 55%, 75%, 90%, and a custom setting. The Watt program is designed to help you measure your energy output.

The console also has a BMI function and a Recovery function. The BMI calculator offers you the possibility to calculate your body fat percentage based on your weight, height, and gender. The Recovery function requires the usage of the pulse sensors; it is to be used at the end of your workout. It measures how long it takes your pulse to return to normal after the workout and based on the result, it will give you a fitness rating between F1 (excellent) and F6 (poor).

The unit has a very simple interface. The large dial in the middle serves for resistance adjustment, entering setup mode, and program selection. The Reset button clears all the values on the console to zero. The Start/Stop button initiates a selected program and also gives you the possibility to put your workout on hold if you need a break, while the last two buttons offer direct access to the Body Fat calculator and Recovery function.

The console also has three other notable features. One is the tablet shelf placed above the keypad. The second is the sound system. This consists of two speakers and an AUX input to which you can connect your smartphone or tablet in order to improve the sound quality of your music. And finally, there is also a USB port to which you can connect your smartphone or tablet to recharge its battery.

Assembly and Maintenance

The main body of the bike comes pre-assembled. You only need to attach the base bars, the console mast, the front handlebars, the console, the seat frame, the seat cushion, the backrest, the pedals, and several other covers. This may take more than an hour. However, the task is fairly easy to carry out; the manual provides very clear assembly instructions and schematics. Also, a basic toolkit is included.

Maintenance doesn’t require much. Basically, you only have to keep the unit clean, keep liquids away from the console, and periodically check for loose or broken parts.

The Pros

  • Sturdy, steel frame – 300 lbs capacity;
  • Adjustable, rubberized stabilizers on both bases;
  • Transport wheels on the front base;
  • Lifting handle on the rear base;
  • Step-through frame design for easy access to the seat;
  • Seat handlebars with pulse sensors;
  • Adjustable front handlebars;
  • Thick cushioning on the seat pad for extra comfort;
  • Flexible and breathable mesh backrest;
  • Lever-based rail adjustment system for the seat;
  • Weighted pedals with adjustable straps;
  • Self-powered eddy current resistance system;
  • 24 resistance levels available;
  • Mid-range console with an LCD display which can track time, distance, speed, RPM, Watts, calories, and pulse;
  • 6 workout modes with 4 presets for the Beginner, Advanced, and Sporty modes;
  • Body Fat calculator;
  • Recovery function;
  • Tablet holder included;
  • Sound system included;
  • USB port included;
  • Fairly easy to assemble;
  • Little maintenance required;
  • Excellent warranty.

The Cons

  • No bottle holder;
  • A tablet placed on the tablet holder will cover the console display;
  • For the first use, you will have to pedal for a few minutes until the console gets enough power to display your workout data.


The Sunny Health & Fitness SF-RB4880 is a self-powered, magnetic recumbent bike offering 24 levels of eddy current resistance, and a console with multiple workout programs. It excels in comfort factors featuring a consistently cushioned seat with a flexible mesh backrest. Its console also has a sound system, a tablet holder, and a USB charging port. It’s a sturdy bike, great for light to mid-range cardio workouts, interval training, stamina develompent, recovery training, muscle toning, and weight loss.

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