Sunny SF-B1877 Indoor Cycling Bike | Perfect for Low-Impact Fitness

The Sunny SF-B1877 Indoor Cycling Bike is an excellent belt-driven system for low-impact fitness.  Adjustable magnetic resistance allows you to change your exercise cycling routine, making every home workout session feel different. Perfect for beginners and fitness enthusiasts or anyone needing to start an in-home calorie-burning workout routine.

The SF-B1877 comes equipped with a fitness console that tracks time, speed, distance, calories burned, odometer, RPM, and pulse. Monitor/maintain goal heart rate with the integrated pulse sensors in the handlebars. The steadier and more prolonged elevated heart rate is during a workout, the more weight loss occurs.

The Sunny SF-B1877 Indoor Bike features a 4-way adjustable seat. With a simple twist of a knob, you can move back and forth (and up / down), so your workout can remain comfortable. You’ll secure your feet in place with the caged pedal feature. Avoid foot slippage for increased intensity. This Sunny bike has a low 177.8mm Q-factor that provides better biomechanical and ergonomic efficiency.

Learn more in my complete review below!

Sunny SF-B1877 Indoor Bike
Sunny SF-B1877 Indoor Cycling Bike

Product: Sunny SF-B1877 Indoor Cycling Bike

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

Warranty: Frame 3 years / Parts 180 days

My rating: 8.75/10

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: 48.8L x 20.1W x 48H inches (124L x 51W x 122H cm)
  • Assembled weight: 83.7 lbs (38 kg)
  • Flywheel weight: 29 lbs (13 kg)
  • Weight capacity: 265 lbs (120 kg)
  • Seat: 4-way adjustable
  • Drive: Belt
  • Resistance: Manual magnetic
  • Fitness console: Time, distance, total distance, speed, RPM, calories, pulse, scan
  • Extras: Device holder, bottle holder
  • Warranty: Frame 3 years / Parts 180 days

SF-B1877 Frame construction

The Sunny SF-B1877 indoor cycling bike features a steel frame combining rectangular and oval tubes in its construction. The frame has a triangular design for improved sturdiness; the base longitudinal bar and the frame’s main tube are slightly curved.

Sunny SF-B1877 Indoor Cycling Bike

All the steel tubes in the bike’s construction come coated with a corrosion-resistant paint finish. The colors used are gray for most of the frame and black for the seat and handlebars’ posts. The flywheel is chrome-plated.

Of course, the bike also integrates several thermoplastic parts in its construction. For example, the brake cover and the drivetrain cover are durable plastic materials. The side panels of the flywheel are also plastic-made.

The fully assembled bike is a bit larger than the average spin bike made for home use. With all the parts built, it is approx 48.8″ (124 cm) long and 20.1″ (51 cm) wide. Therefore, it is advisable to leave at least two feet of clearance all around the bike for safe usage and ease of access.

The bike is not extremely heavy but does weigh approx. 83.7 lbs (38 kg). Thus, two persons should carry the packed unit. Nonetheless, once assembled, one person can transport this bike. Its front base stabilizer features a set of transport wheels—also, both base stabilizers of the bike feature adjustable levelers.

One last aspect to mention here regards the bike’s step-up bar. Not all spin bikes have this element, so it’s a plus. It is the small horizontal tube that connects the seat tube with the main oblique tube.

This can help a shorter user with mounting and dismounting and serve as a support point for stretching or various spin workouts requiring you to mount and dismount repeatedly.

Seat and handlebars

The Sunny SF-B1877 indoor cycling bike includes a pretty standard saddle. Its top is a hard plastic (probably nylon) shell with a high-density foam material top layer. It lacks the central cropping that more expensive bike seats have but does have contouring for breathability.

Sunny SF-B1877 Indoor Bike
Sunny SF-B1877 Indoor Cycling Bike

It has a standard collar-type attachment system, though, so not only can you easily remove it, replacement models compatible with the bike should be available in any bike shop.

The seat offers four-way adjustability (up, down, front, back). Its upright post offers an adjustment span of approx. 9″ (22.8 cm), for users with an inseam between 27.5″ and 36.5″ (70 – 93 cm).

The horizontal slider adds approx—5″ (12.7 cm) of front-to-back adjustment. Therefore, the bike should comfortable accommodate users up to 6’5″ (196 cm) with no problem. It has a maximum user weight capacity of 265 lbs (120 kg).

The bike comes equipped with a multi-grip handlebar. It allows a climbing grip, a parallel grip, a standard grip, and a close grip. It also has a long loop bar in the middle, offering the possibility to adopt an aero grip. In addition, its side grips integrate metallic pulse sensors, and the included fitness monitor has a pulse reading function.

The bike’s handlebar lacks the horizontal slider feature, so it’s adjustable only up-down. However, its post offers several inches of adjustment. In addition, the whole handlebar assembly has a layer of high-density foam material for an improved and comfortable grip. Also, the top plastic cover of the handlebar can serve as a phone holder or tablet holder.

SF-B1877 Drive system

The Sunny SF-B1877 indoor cycle comes equipped with a reasonably heavy flywheel. It weighs 29 lbs (13 kg) and has a perimeter-weighted structure. The perimeter-weighted design provides extra inertia, leading to a consistent pedaling momentum, excellent for spinning workouts.

The flywheel is also bi-directional. Thus, the bike offers the possibility to pedal in reverse. However, just as for any other spin bike, coasting is not possible. Therefore, when pedaling in reverse, you will get the same resistance as when pedaling forward.

Sunny SF-B1877 Indoor Cycling Bike

The bike uses a belt for its transmission. The belt drivetrain comes with several advantages. First, it generates less vibration than a chain, so the bike delivers a very smooth and quiet pedaling motion. And second of all, it does not require lubrication.

Since it’s a bike made for spinning workouts, the Sunny SF-B1877 comes equipped with a heavy-duty, 3-piece crankset. In addition, it features long arms and a relatively narrow (177.8 mm) Q-Factor. This narrow spacing between the pedals reduces the lateral stress on the knees and ankles during pedaling, leading to a more comfortable pedaling motion.

The included pedals are aluminum alloy with rubber inserts on the edges for an improved grip. Unfortunately, they do not have SPD elements for spin shoes, but they have adjustable toe cages if you want to secure your feet. They also have standard 9/16 threads, so you can find compatible pedals in any bike shop if you ever want to replace them.

Resistance system

The Sunny SF-B1877 indoor cycling bike comes equipped with a manual magnetic resistance system. Therefore, the cycle does not adjust the resistance automatically. However, you don’t need a power adapter or an external power source for it.

The resistance system consists of a magnetic brake attached to the bike’s main tube frame above the flywheel. The magnetic brake connects to the tension knob on top of the bike’s frame. Therefore, when you turn the knob, you adjust the brake pad’s distance and the flywheel, increasing or decreasing the pedaling difficulty.

The bike’s brake is stepless; there are no pre-determined tension levels on the resistance adjustment knob. But as a general idea, on the lowest difficulty setting, the bike provides a pedaling resistance similar to riding a bike on a straight road. In contrast, on the most significant difficulty, it simulates a steep climb.

Sunny SF-B1877 Indoor Bike
Sunny SF-B1877 Indoor Cycling Bike

SF-B1877 Console

The Sunny SF-B1877 exercise bike comes with a fitness console. It features an LCD that tracks time, distance, total distance, speed, RPM, calories, and pulse. The speed and distance display in MPH and miles; you cannot set them to metric units.

For the pulse reading function, you will have to hold on to the sensors integrated into the handlebars; the console is not telemetric, so it cannot track your pulse from an HR chest strap. In addition, the unit’s display does not have an LED backlight.

The bike’s fitness console has only one button (MODE). You can repeatedly press it to select the desired workout metric or choose the Scan Mode, which rotates all the metrics showing each one for approximately 6 seconds.

The button also covers the monitor’s reset function. You can press and hold it for a few seconds to clear all its values to zero. Unfortunately, it does not have pre-set programs, and you cannot set workout targets for distance, time, or calories.

The fitness console is battery-powered, and it requires two AAA batteries, which come included with the bike. It starts up when you press the button or when it detects flywheel movement. It also has a sleep mode, which automatically initiates after approx. 4 minutes of inactivity on the bike.

Assembly and Maintenance

Most of the bike comes pre-assembled. You only have to attach the two base stabilizers, the seat post, the handlebar post, the handlebar, the device holder, the fitness console, and the pedals.

This shouldn’t take more than 20-30 minutes. The task is relatively simple, and the manual provides clear step-by-step assembly instructions. Also, all the necessary tools for the assembly come included with the bike.

Sunny SF-B1877 Indoor Cycling Bike

For maintenance, you only have to keep the bike clean, wipe any sweat that may fall on the frame with a piece of cloth at the end of the workout, and periodically inspect the bike to ensure that all the parts are still functioning correctly.

Since the brake is magnetic, there’s virtually no wear and tear for the brake pad, so you don’t have to worry about its replacement. The drivetrain also uses a belt, not a chain, so it does not require periodic lubrication.


  • Heavy-duty steel frame – 265 lbs weight capacity;
  • Aesthetic design;
  • Adjustable stabilizers on both bases;
  • Transport wheels on the front base;
  • 4-way adjustable seat;
  • Multi-grip handlebar with pulse sensors;
  • Smooth and silent belt drive;
  • Perimeter-weighted flywheel for enhanced inertia;
  • Magnetic resistance, with zero friction;
  • Fitness console included – it can track time, distance, total distance, speed, RPM, pulse, and calories burned;
  • Bottle holder included;
  • Device holder included;
  • Easy to assemble;
  • Little maintenance is required.


  • The LCD does not have an LED backlight;
  • The pulse and calories readings aren’t super accurate.

Sunny SF-B1877 Indoor Cycling Bike Summary

The Sunny Health & Fitness SF-B1877 is an indoor cycling bike that supports any spin workout. It features a heavy-duty frame, a 29-lb flywheel, and a magnetic resistance system. It also includes a fitness console that tracks time, distance, total distance, speed, RPM, pulse, and calories burned.

Moreover, it’s a pretty solid bike, great for users of all levels, for high-intensity cardio workouts, muscle toning, interval training, stamina development, and weight loss. It’s also considerably more affordable than a commercial-grade bike, offering excellent value for the price.

I hope you found this article helpful and informative. If you have anything you would like to share or any opinions about my website, please speak up. I look forward to your comments, questions, and the sharing of ideas.

4 thoughts on “Sunny SF-B1877 Indoor Cycling Bike | Perfect for Low-Impact Fitness”

  1. Hi there, I want to thank you for reviewing this fantastic exercise bike. The Sunny SF-B1877 Indoor Cycling Bike has a feature that attracted me the most. You had mentioned that you could adjust the seat back and forth along with up and down height. Most exercise bikes have the up and down height adjustment BUT NOT the back and forth adjustment. But actually, the back and forth adjustments are so much crucial for a comfortable workout position. So I am going to consider this one seriously. Thanks again!

    • Hi Augustine, thanks for stopping by. I am glad to hear that you are considering this Sunny bike. If I can answer any questions or offer any assistance, would you please let me know? I’d be happy to help.

      Kind regards, Robert

  2. I have a Sunny bike, and I’m absolutely in love with it. I believe that Sunny Health and Fitness makes high-quality exercise equipment without the hefty price tag you see with other brands. I highly recommend anyone looking for an indoor cycling bike to give Sunny a try. You won’t be disappointed!

    • Hi Alicia, thanks for stopping by. Which Sunny bike do you have? Do you have any other types of exercise equipment? If not, would you please let me know if I can provide some suggestions that might interest you? I will be happy to help.

      Kind regards, Robert


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