Sunny SF-RB420031 SMART Recumbent Bike | Perfect Performance

The perfect balance of performance, value, comfort, technology, and convenience has arrived with the Sunny SF-RB420031 SMART Recumbent Bike. In addition, you’ll get more connected with your fitness with the SunnyFit app available on Amazon, Google Play, or the Apple App Store.

The SF-RB420031 features eight smooth and adjustable magnetic resistance levels, making it easy to modify the intensity or follow the Sunny trainer’s video lessons during your home workout sessions. The lowest level delivers a relatively light pedaling difficulty, great for recovery training, while the highest level simulates a hill climb, perfect for aerobics.

The all-new SunnyFit APP takes your Sunny workouts to the next level! First, view your live metrics displayed in real-time as you tour the world with accurate location maps. Then, get the results you want with customized workout plans. When not using the SunnyFit App, the monitor will display fitness metrics in real-time: Time, Speed, Distance, Calories, Odometer, and Pulse.

The Sunny SF-RB420031 SMART recumbent bike features a seat with over 2 inches of cushioning and is 16.7 inches wide and 12.6 inches long. Get the most comfortable and intense recumbent exercise biking experience. In addition, the bike has a multi-grip handlebar that can adopt a low grip, an oblique grip, and a climbing grip.

Learn more in my complete review below!

Sunny SF-RB420031 SMART Recumbent Bike
Sunny SF-RB420031 SMART Recumbent Bike

Product: Sunny SF-RB420031 SMART Recumbent Bike

Price: For a great deal on this bike, merely go here to Sunny Health &

Warranty: Frame 3 years / Parts 180 days

My rating: 9.5/10

Affiliate Disclosure: As a Sunny Health & Fitness Affiliate Program participant, I earn commissions on purchases made through links in the post. Full disclosure

Details and Specifications

  • Assembled dimensions: 57.1L x 26.6W x 42.9H inches (145L x 68W x 109H cm)
  • Assembled weight: 64.3 lbs (29.1 kg)
  • Weight capacity: 265 lbs (120 kg)
  • Inseam range: 26″ – 35″ (66 – 89 cm)
  • Resistance: Manual magnetic, eight levels
  • Fitness Monitor: Time, speed, distance, odometer, calories, pulse, goals, scan, goals
  • Extras: Bluetooth, compatible with the SunnyFit app, device holder, resistance cords
  • Warranty: Frame 3 years / Parts 180 days

SF-RB420031 Frame Construction

The Sunny SF-RB420031 SMART recumbent bike features a rectangular and cylindrical steel tube frame. In addition, all the tubes have a durable gray paint finish.

Sunny SF-RB420031 SMART Recumbent Bike

However, some parts in the bike’s construction are non-metallic, rigid thermoplastic materials. Some of the most notable ones are the covers of the drive system, the console casing, the tube end caps, and the pedals.

The bike is pretty significant. With all the parts assembled, it is approximately 57.1″ (145 cm) long and 26.6″ (68 cm) wide. Its highest point is the console’s top, which reaches approximately 42.9″ (109 cm) above the floor level. In addition, it is also advisable to allow at least two feet of clearance all around the bike for easy access.

The bike has a step-through design. There are several inches of space between the seat assembly and the front-drive assembly. Thus, it offers excellent entry and exit possibilities. Not all recumbent bikes have this type of construction. Consequently, this can be quite a plus, especially for users with specific disabilities.

The bike is not super heavy, weighing 64 lbs (29 kg). Therefore, one person can carry and assemble the bike. Once completed, it’s easy to move as its front base has transport wheels and a set of adjustable levelers.

Seat and other parts

The Sunny SF-RB420031 SMART recumbent bike seat provides superior comfort. Both its seat pad and the backrest pad integrate a thick layer of foam cushioning. On the outside, they feature a thick layer of vinyl that is easy to maintain and moisture-proof.

In addition, the bike’s seat is adjustable. It attaches to an oblique rail and has a lever adjustment system. Therefore, you can easily adjust it while seated by pulling up the lever on the right side. The seat is approximately 22.4″ (57 cm) above the floor at its highest point. Also, the applicable user inseam range for this bike is approx. 26″ – 35″ (66 – 89 cm).

The bike comes with two sets of handlebars. One attaches to the seat assembly, the other to the front upright bar of the bike. The seat handlebars have pulse sensors. Unfortunately, neither handlebar is adjustable. However, both handlebar sets have rubber foam grips for superior contact.

Sunny SF-RB420031 SMART Recumbent Bike
Sunny SF-RB420031 SMART Recumbent Bike

This Sunny recumbent bike has a set of resistance cords. The seat handlebars have three attachment rings for the cords, and the rear base bar features a collection of small pulleys. The cords have simple D-handles with thick foam grips.

SF-RB420031 Resistance system

The Sunny SF-RB420031 SMART recumbent bike has a magnetic resistance system. It is not motorized, so you don’t need an adapter or power cord. On the other hand, the fitness monitor cannot adjust the resistance automatically and does not have pre-set programs.

The bike features a tension knob that connects to the internal magnetic brake via a steel wire. For instance, when you turn the knob clockwise, the magnets move closer to the internal flywheel increasing the internal magnetic drag and the pedaling difficulty.

Conversely, if you turn the knob to the left, the magnets move further away from the flywheel, lowering the pedaling difficulty.

The main advantage of the magnetic brake is that the magnets do not touch the flywheel. Thus, the pedaling motion is very smooth and quiet. In addition, the magnets don’t wear out like a felt pad brake, and you don’t need to worry about their replacement or lubrication.

The bike provides eight levels of resistance. The lowest level delivers a relatively light pedaling difficulty, which is great for recovery training. Consequently, the 8th tension level provides considerably more pedaling difficulty, simulating a hill climb.

Drive system

This Sunny SF-RB420031 SMART recumbent bike comes with a belt drive system. It integrates a poly-v belt highly resistant to stretching and abrasion. Furthermore, the main advantage of a belt drive is that it does not require lubrication, and it generates less vibration than a chain.

Sunny SF-RB420031 SMART Recumbent Bike

The bike features a pretty sturdy crankset. However, since it’s not a spin bike, it’s not for standing on the pedals. The internal pulley is a strong thermoplastic material, while the crank arms are metallic alloy, cylindrical, and chrome plated.

The pedals are plastic-made, but they’re pretty durable. In addition, they have a textured surface and adjustable straps. They are also weighted, so they always self-level when you remove your feet from them.

The weight of the internal flywheel is not specified. However, as a general idea, it’s probably around 10 lbs (4.5 kg), and it is perimeter-weighted for improved inertia and motion stability.

The bike’s flywheel is bi-directional, which means that it allows reverse pedaling. However, coasting is not possible on the bike. Therefore, when you stop pedaling, the flywheel stops as well. In addition, when pedaling in reverse, the resistance remains constant, depending on the selected tension level.

SF-RB420031 Fitness monitor

The Sunny SF-RB420031 SMART recumbent bike has a reasonably simple fitness monitor. Unfortunately, it does not have pre-set programs or play any role in the bike’s resistance adjustment. It features an LCD without a backlight and also integrates a device holder. It is battery-operated and runs on two AAA batteries.

The monitor tracks time, distance, total distance, speed, calories, and pulse. The speed and distance are in Imperial units. However, there is no metric function. In addition, the pulse reading function is hand grip-only. Therefore, the monitor can only track your pulse if you hold on to the HR pulse sensors integrated into the seat handlebars.

The fitness monitor offers the possibility to set goals for your workouts. For example, you can set a distance goal of 5 miles. After setting this goal, the monitor counts down from it until it reaches zero. You can also select goals for time and calories burned.

The monitor is pretty straightforward to use. It has three buttons – Set, Mode, and Reset. The Set button covers the goal-setting function. The Mode button allows you to select the desired function, and the reset button clears all the data on the monitor to zero.

Sunny SF-RB420031 SMART Recumbent Bike
Sunny SF-RB420031 SMART Recumbent Bike

Like most other Sunny Health & Fitness Interactive series machines, the Sunny SF-RB420031 has Bluetooth connectivity and is compatible with the all-new SunnyFit app. In addition, there is a QR code that you can scan with your phone to install the SunnyFit app. This app is available for both iOS and Android devices.

Ride along with Sunny Health & Fitness expert trainers on the SunnyFit app. Connect your preferred mobile device through Bluetooth and view your real-time performance metrics. Then, take your Sunny workouts to the next level as you tour the world with accurate location maps.

Get the results you want with customized workout plans. First, explore 100+ workout videos that fit your schedule and goals. Then, compare your results on the exercise bike leaderboard, share your fitness experiences, get workout tips, and much more!

Assembly and Maintenance

The bike’s drive and resistance parts come pre-assembled and connected to the base frame. However, the other parts do require user assembly. You will have to attach the two base bars, the seat frame, the backrest and bottom seat pad, the front mast, the handlebars, the fitness monitor, the elastic cords, and the pedals.

Consequently, this may take more than an hour of your time, but the task is pretty simple. Plus, the manual provides step-by-step assembly instructions and schematics and includes all the necessary tools.

The bike’s internal parts do not require any maintenance. Thus, you only have to keep it clean, periodically check for loose bolts and parts, and retighten or replace them as needed.


  • Sturdy construction – can support users up to 265 lbs;

    Sunny SF-RB420031 SMART Recumbent Bike

  • Transport wheels and adjustable levelers on the front base bar;
  • Two sets of handlebars;
  • Elastic resistance cords for arm exercises (3 positions each);
  • Seat handlebars integrate HR pulse sensors;
  • Smooth and quiet belt drive system;
  • Oversized pedals with straps;
  • Eight levels of manual magnetic resistance;
  • Multi-function fitness monitor – it tracks time, distance, total distance, calories, speed, and heart rate;
  • Goal setting functions for time, distance, and calories burned;
  • Bluetooth connectivity – compatible with the all-new SunnyFit app;
  • Device holder included;
  • Easy to assemble;
  • Tools for assembly included;
  • Little maintenance is required;
  • Excellent warranty.


  • The fitness monitor LCD doesn’t have a backlight;
  • The fitness monitor does not have an RPM reading function.

Sunny SF-RB420031 SMART Recumbent Bike Summary

The Sunny SF-RB420031 is a home-based recumbent bike. It features an 8-level manual magnetic resistance system, a comfortable seat with elastic resistance cords, and a fitness monitor that tracks the essential workout metrics. In addition, the monitor also has Bluetooth connectivity and is compatible with the SunnyFit app.

Whether you are a senior looking to maintain an active lifestyle, too busy to get to the gym, or enjoy working out in the comfort of your home, the Sunny Health and Fitness Performance Interactive series recumbent bike is perfect. Accordingly, it’s a bike for light to medium-intensity, low-impact cardio workouts, muscle toning, and weight loss.

I hope you found this article helpful and informative. Would you please speak up if you have anything you’d like to share on the topic or any opinions about my website? I look forward to your comments, questions, and the sharing of ideas.

Please remember that you should consult your physician to determine if you have any medical or physical conditions that could risk your health and safety or prevent you from using the equipment properly. In addition, your physician’s advice is essential if you are taking medication that affects your heart rate, blood pressure, or cholesterol level.

6 thoughts on “Sunny SF-RB420031 SMART Recumbent Bike | Perfect Performance”

  1. I am looking for a recumbent bike for home use that is sturdy, like the Sunny SF-RB420031 SMART bike, which is excellent. I have been looking for a suitable exercise bike for my elderly mother, who often finds it difficult to climb onto an upright bike. So with the space between the seat and front base, this recumbent bike will be far easier for her to use. 

    With Bluetooth connectivity, she can not only connect to fitness apps but also listen to ebooks while exercising. Thank you for sharing a great review. 

    • Hi there, thanks for stopping by and sharing your thoughts with us. Would you please let me know if I may further assist you with exercise equipment? I’m always happy to help.

      Kind regards, Robert

  2. The Sunny SF-RB420031 sounds like an exercise bike I could see having in my home. At 64 lbs, it is not too heavy that it would be cumbersome to move around if necessary. However, some of the parts made of plastic would reduce the bike’s weight. I like the attached resistance bands; few exercise bikes include that option. It looks like it would be easy to adjust the seat for people of different heights, and the step-through design is a must-have. Some bikes have plastic seats. I like that this one has a foam seat and back.  

    • Hi Carolyn, thanks for stopping by and sharing your thoughts with us. Would you please let me know if I may further assist you with exercise equipment? I’m always happy to help.

      Kind regards, Robert

  3. I have to say, with my rekindled love for the gym, I very much appreciate these in-depth reviews you have here. I love indoor cardio machines more than every other type of fitness machine. The Sunny SF-RB420031 SMART Recumbent Bike here can give me the exact workout I need. 

    I’ve also recently thought about building my home gym in my garage. I may have to get this machine to put in there!

    • Hi Steven, thanks for stopping by and sharing your thoughts with us. Please let me know if I may further assist you with exercise equipment. I’m always happy to help.

      Kind regards, Robert


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