Sunny SF-B1805 Indoor Cycling Bike | Sizeable 44-Pound Flywheel

The Sunny SF-B1805 Indoor Cycling Bike is a functional and durable bike with a magnetic resistance belt drive and user-friendly features. It will help you become stronger and healthier with a very intense workout that supports multiple hand grips, micro-adjustable resistance, and high-interval training.

Sunny SF-B1805 has a sizeable 44-pound flywheel that ensures a proper intense workout that will help strengthen your lower body and core section with a high-weighted wheel. In addition, the flywheel is created for stability and speed and will generate more momentum for an extended period.

The metal disks generate magnetic resistance through a magnetic field for endless resistance levels, and you can easily and quickly change the resistance levels. The closer the magnet gets to the flywheel, the higher the workout resistance.

The handlebar and the seat can adjust in four directions (up and down, back and forth) to accommodate people with different body sizes. It has steel toe-caged pedals with adjustable straps for your comfort. The inseam on this bike is between a minimum of 28 inches and a maximum of 38 inches.

Learn more in my complete review below!

Sunny SF-B1805 Indoor Cycling Bike
Sunny SF-B1805 Indoor Cycling Bike

Product: Sunny SF-B1805 Indoor Cycling Bike with Magnetic Belt Drive

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

Warranty: Frame 3 years / Parts 180 days

My rating: 9.25/10

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

Details and Specifications

  • Assembled dimensions: 48L x 23W x 45H inches (122L x 58W x 114H cm)
  • Assembled weight: 125.7 lbs (57 kg)
  • Flywheel weight: 44 lbs (20 kg)
  • Supported weight: 300 lbs (136 kg)
  • Handlebars: 4-way adjustable
  • Seat: 4-way adjustable
  • Pedals: With toe cages
  • Drive: Belt
  • Resistance: Manual magnetic
  • Fitness Monitor: Not included
  • Accessories: Bottle holder, tablet holder
  • Warranty: Frame 3 years, Parts 180 days

SF-B1805 Frame

Sunny SF-B1805 Indoor Cycling Bike

The Sunny SF-B1805 indoor cycling bike features a heavy-duty frame to support any spin workout. Most of it has thick steel tubing, which results in an impressive overall weight. With the frame fully assembled, the bike weighs approximately —125 lbs (57 kg), more than three times the mountain bike’s weight.

Therefore, no matter what workouts you have in mind, the bike won’t wobble or rock when you execute them. Since it’s an exercise bike designed for spin workouts, it has a stepping pad element between the main bar of the frame and the seat’s tube.

This stepping pad allows you to perform spin workouts that require you to repeatedly dismount, step up, and step down the structure to engage more muscles. It’s also rubberized to prevent damage to the paint finish and provide a better grip for your shoe.

Speaking of the paint finish, the Sunny SF-B1805 features a durable powder coating resistant to rust and abrasion. The color used for the mainframe is black, with the Sunny logo painted red. However, the seat and handlebars’ adjustment posts, sliders, and flywheel feature chrome plating.

With the frame fully set up, it is approximately 48″ (122 cm) long and 23″ (58 cm) wide. Therefore, it is advisable to leave at least two feet of clearance all around it to perform all the spin workouts correctly and quickly access the bike.

Seat & handlebars

The Sunny SF-B1805 indoor cycling bike has a high-comfort seat. It’s 8″ wide and 10″ (25.4 cm) long, offering plenty of contact surface. In addition, it integrates approx—2″ (5 cm) foam cushioning and shock absorption springs at the rear.

It also has a longitudinal groove for superior airflow and healthy blood circulation under the user. In all, it’s ideal for the average slim spin bike seat, at least in terms of comfort.

Sunny SF-B1805 Indoor Cycling Bike
Sunny SF-B1805 Indoor Cycling Bike

The seat is 4-way adjustable. Its vertical post, along with its horizontal slider comfortability, accommodates users with an inseam between 28″ and 38″ (71 – 96 cm); in other words, users between 5’0″ and 6’5″ (153 – 196 cm).

Its upright bar offers multiple adjustment positions, while the seat slider also provides several inches of front-to-back adjustment.

The bike has a multi-grip handlebar. It has two long aero bars in the middle, which offer the possibility of a racing grip. A tablet holder or reading rack is attached to the aero bars, a feature many other bikes do not have.

The whole handlebar assembly is urethane-dipped to provide a secure and comfortable grip. Just like the seat, the handlebar is 4-way adjustable.

SF-B1805 Resistance system

The Sunny SF-B1805 indoor cycling bike has a manual magnetic resistance system. Its magnetic brake hugs the top section of the flywheel. It is attached to the tension knob on the top of the main bar of the frame.

As you turn the knob clockwise, the brake will cover a more substantial portion of the flywheel, resulting in higher magnetic field intensity. Thus, this ultimately leads to more incredible pedaling difficulty.

Since the resistance system is manual, the bike doesn’t require a connection to a power source. In addition, the brake and the flywheel do not make contact, so the pedaling remains smooth and whisper-quiet without friction or wear and tear.

Unlike other spin bikes with a magnetic resistance system, this one doesn’t have pre-determined resistance levels. Instead, you can turn the tension knob until the resistance feels adequate for the workout you want to execute.

The highest tension setting provides quite a severe difficulty, offering the possibility of training on a superior level and achieving a consistent muscle burn.

Sunny SF-B1805 Indoor Cycling Bike

Last but not least, the unit’s tension knob also has an emergency brake function. You can press it down to immediately stop the flywheel from spinning.

For instance, this is quite important if you pedal at a very high speed, as it’s hazardous to try to stop the wheel by abruptly ceasing your pedaling. Furthermore, it may lead to injuries as the flywheel is quite substantial.

Drive system

This Sunny SF-B1805 indoor cycling bike has a 44 lb flywheel perimeter-weighted. This type of construction leads to highly aggressive inertia and delivers a smooth and steady pedaling motion.

The flywheel and the bike’s transmission allow pedaling in reverse. However, when pedaling in reverse, you will usually benefit from the same resistance as pedaling. Also, coasting is not possible on this bike.

Since it’s a magnetic resistance exercise bike, it uses a belt for its transmission, not a chain. A belt drive comes with several advantages. For example, you don’t have to lubricate it. It generates less vibration than a chain. And the pedaling motion is very smooth and almost entirely silent.

It has a highly durable 3-piece crankset with solid steel crank arms. Therefore, as long as the user doesn’t exceed the maximum weight capacity of 300 lbs (136 kg), the bike can support any workout that requires standing up on the pedals.

The included pedals are metallic alloy. They don’t have SPD clips for spin shoes but have toe cages if you need extra foot stability. They also have standard threads, so you can easily find replacements for them if needed.

The bike’s Q-Factor (spacing between the pedals) is one last aspect to note here. The Sunny SF-B1805 indoor cycling bike has an average spacing of 177 mm (6.9″) Q-Factor.

Sunny SF-B1805 Indoor Cycling Bike
Sunny SF-B1805 Indoor Cycling Bike

Therefore, your feet are positioned on the pedals naturally, and the pedaling motion doesn’t generate extra lateral stress on the knees and ankles.

There are other exercise bikes with an even smaller Q-Factor. So, if 177 mm is too much for you, you can check out two different models: the Sunny ASUNA 6100 or the Spinner L7.

SF-B1805 Assembly & Maintenance

The bike’s primary drive and resistance elements come already attached to the core frame. So you only have to connect the two base bars, the seat post, the handlebar post, the seat, the handlebar, and the pedals when it comes to assembly.

Consequently, it shouldn’t take more than 30-40 minutes. The manual provides detailed assembly instructions and schematics. Also, all the tools needed for the assembly come with the bike.

Maintenance doesn’t require much. The bike’s transmission doesn’t require lubrication. So, you must do a periodic check for loose or damaged bolts and parts.


  • Sturdy steel construction – can support users up to 300 lbs;
  • Transport wheels included;
  • Adjustable levelers with rubber pads on all bases;
  • Rubberized stepping pad element;
  • Durable metallic pedals with toe cages;
  • Cushioned seat with suspension springs at the rear;

    Sunny SF-B1805 Indoor Cycling Bike
  • 4-way adjustable seat;
  • 4-way adjustable handlebars;
  • Smooth and quiet belt drive;
  • Hefty, 44 lbs inertia-enhanced flywheel;
  • Frictionless magnetic resistance;
  • The bottle holder included;
  • Tablet holder included;
  • Little maintenance is required;
  • Easy to assemble;
  • Decent warranty.


  • A fitness monitor does not come with the bike.

 Sunny SF-B1805 Indoor Cycling Bike Summary

The Sunny SF-B1805 is an indoor cycling bike designed for spin workouts. It has a magnetic resistance system, a heavy flywheel, and a quiet belt drive. In addition, it offers superior micro-adjustability; its seat and handlebars are 4-way adjustable.

Moreover, it’s a heavy-duty bike, perfect for high-intensity cardio workouts, interval training, muscle toning, strength and stamina development, and weight loss. And finally, this Sunny exercise bike offers excellent value even though it doesn’t come with a fitness monitor.

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-B1805 Indoor Cycling Bike | Sizeable 44-Pound Flywheel”

  1. I used to be an avid cyclist. I haven’t had the time to ride till recently. The thing that I dislike the most is that I can’t ride in inclement weather. Since I live in the US northeast, that is a good part of the year. I have been looking for an inexpensive exercise bike for those times that I can’t bike outdoors. This seems to be just that. The only problem is that I can’t tell just how inexpensive that this Sunny model is not available at this time, and no price is listed. And I’d have to agree with the con of no console. But if the price is low enough, then that would be an okay trade-off.

    • Hey Jim, due to COVID-19, home exercise equipment is selling out as I’ve never seen before. It will get better in time, and the availability will improve.

      Stay safe, and be well!

  2. I like this indoor exercise cycle because it supports somebody weighing up to 300 pounds. That is important because, sadly, many people out there are struggling with obesity and all the health problems that come with it. As you mentioned in this post, you can adjust the seat to accommodate someone regardless of their body size.

    • Hi Michael, thanks for stopping by. Are you interested in getting an exercise bike for your home? If so, I’d be happy to give you some suggestions based on your requirements.

      Kind regards, Robert

  3. I wanted to buy something similar during the lockdown as gyms closed, but stocks had run out. So I managed with a stepper instead. As long as I’m active, that’s all that matters to me.

    Reading about this now may get me tempted to look once again. I know the stock levels of these machines are better now.


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