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

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 feel different. Perfect for beginners, fitness enthusiasts, or anyone needing to start an in-home calorie-burning workout routine.

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

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, providing 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 Monitor: 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 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 and drivetrain cover is made of durable plastic. The side panels of the flywheel are also plastic-made.

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

The bike is not extremely heavy but weighs approximately 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. The small horizontal tube connects the seat tube with the main oblique tube.

Therefore, it 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, so you can 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). In addition, its vertical 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 accommodates 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 climbing, a parallel, a standard, and a close grip. It also has a long loop bar in the middle, allowing it 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, which leads to a consistent pedaling momentum and is excellent for spinning workouts.

The flywheel is also bi-directional. Thus, the bike offers the possibility to pedal in reverse. However, coasting is not possible, just like any other spin bike. 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 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 has 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, 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 replace them.

Resistance system

The Sunny SF-B1877 indoor cycling bike has 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.

The resistance system has a magnetic brake attached to the bike’s main tube frame above the flywheel. The magnetic brake connects to the tension knob on 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, it simulates a steep climb on the most significant difficulty.

SF-B1877 Fitness monitor

Sunny SF-B1877 Indoor Cycling Bike

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

For the pulse reading function, you must hold on to the sensors integrated into the handlebars; the monitor 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 monitor 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 has no pre-set programs, and you cannot set workout targets for distance, time, or calories.

The battery-powered fitness monitor requires two AAA batteries, which come with the bike. It starts up when you press the button or detect 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 monitor, and the pedals.

Therefore, it shouldn’t take more than 20-30 minutes of your time. Furthermore, 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 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 monitor 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 fitness monitor LCD does not have an LED backlight;
  • The pulse and calorie readings aren’t super accurate.

Sunny SF-B1877 Indoor Cycling Bike Summary

The Sunny Health & Fitness SF-B1877 indoor cycling bike supports any spin workout. It features a heavy-duty frame, a 29-lb flywheel, and a magnetic resistance system. It also includes a fitness monitor 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, 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.

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 to consult your physician to determine if you have any medical or physical conditions that could put your health and safety at risk 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.

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

  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

  3. I was looking into new exercising equipment, and I would love to add a bike to my collection. Doing cardio is my favorite. It also looks comfy to sin on and work out. The price is reasonable, and the color is excellent too. I would love to show you my favorite bible verse, “Be strong and courageous. Do not be afraid or terrified because of them, for the LORD your God goes with you; he will never leave you nor forsake you.” — Deuteronomy 31:6/

    • Hi there, thanks for stopping by and sharing the beautiful bible verse with us. Would you please let me know if I can ever be of assistance?

      Kind regards, Robert

  4. I have been reading a few of these indoor cycling bike articles lately since I want to replace my broken one, but they all seem the same to me. I mainly want one to be durable because mine broke too soon, and I don’t wish to go through all that again. So is there anything I should be looking for for an extra durable bike?

    • Hi, thanks for stopping by and sharing your thoughts with us. I suggest you look at the Schwinn IC3 indoor cycling bike. It’s a durable bike, but it’s not too fancy and affordably priced. If you want something with more features, just let me know.

      Would you 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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