Sunny Health & Fitness SF-B1712 Indoor Cycling Bike

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Sunny SF-B1712

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265 lbsFelt-padN/AFrame: 3 year
Mechanical: 90 days

The Sunny SF-B1712 is one of the newest indoor cycling trainers from Sunny Health & Fitness. It was released in the second part of 2017, so it comes with an improved, more solid frame. Its an exercise bike with a pretty classic design made for spin workouts. It’s actually pretty similar to the older SF-B1110 model, but this newer model has a belt drive, not a chain drive.

Technical Details and Specifications

  • Assembled dimensions: 46.5L x 20W x 45H inches (118L x 51W x 114H cm)
  • Assembled weight: 101 lbs (45.8 kg)
  • Flywheel weight: 44 lbs (20 kg)
  • Supported weight: 265 lbs (120 kg)
  • Handlebars: 4-way adjustable
  • Seat: 4-way adjustable
  • Drive mechanism: Belt
  • Resistance: Friction, felt-pad
  • Fitness meter: Not included
  • Warranty: Frame 3 years, Parts 90 days

Frame construction

The Sunny Health & Fitness SF-B1712 features a thick and durable steel frame with a V-design; it’s a bike made for spin workouts, and even though it doesn’t have a conventional stepping pad above the crank, such as the SF-B1509C model, you can still step on the frame, on the V-weld above the pedals.

The base of the bike is H-shaped, made of square tubing for extra stability. However, there are two other important stability factors that need to be mentioned here. One regards the four adjustable stabilizers with large rubber pads, which allow you to perfectly level the trainer on any type of flooring. The other one is the weight of the bike; with the frame fully assembled, it weighs approx. 101 lbs (45.8 kg), which is at least two times more than the average mountain bike. Despite this weight, though, the unit is easy to relocate as its front base has two large transport wheels.

The Sunny SF-B1712 is a mid-size trainer. With all the parts assembled, its length reaches approx. 46.5″ (118 cm), while its width is ~20″ (51 cm). This being said, it can fit pretty well in a small room or apartment. However, it’s recommended to leave a minimum of two feet of clearance on the sides, and at least one foot at the front and rear, for ease of access and for a safe exercise execution.

The bike’s frame features a durable, rust-resistant powder coating. The color used is dark gray for most of the frame, but the upright posts and horizontal sliders of the handlebar and seat are chrome-coated. There are several non-metallic parts in the bike’s construction, though. One of them is the belt guard, and the others are the two side covers of the flywheel.

Seat and handlebars

The Sunny Health & Fitness SF-B1712 is equipped with a standard spin seat. This type of saddle doesn’t excel in cushioning, as for at least 1/3 of your workout you should be pedaling while standing up. However, its top does integrate a layer of foam padding for optimal comfort. Also, since it’s a standard seat, compatible replacements for it are widely available; you can basically find a more cushioned seat in any bike shop. Or, you can improve the comfort of the existent one by a gel cover or sheepskin cover.

The seat is 10″ (25.4 cm) long, and 7.5″ (19 cm) wide. It’s 4-way adjustable, which means you can move it up, down, front, and back. Its adjustment span can accommodate users with an inseam between 29.5″ and 40″ (75 – 101 cm), in other words, users between 5’0″ and 6’6″ (153 – 198 cm). You can also slightly tilt the seat forward or backward, depending on your preference, but doing this requires tools.

The bike’s handlebar features 4-way adjustability just as the seat. It has a multi-grip design, with a loop aerobar which has approx. the same length and curvature as the sidebars. It’s fully covered by a layer of rubber foam material in order to provide a safe and comfortable grip.

Resistance system

The Sunny SF-B1712 is an indoor cycling trainer equipped with a standard friction resistance system. It features a felt brake pad attached to the main bar of the frame and connected to the resistance dial on the same bar. By turning the knob, you can set the pad to apply more or less contact and friction to the flywheel, and thus increase or decrease resistance.

The metallic rod of the resistance dial is equipped with a spring, so it also acts as an emergency brake. You can press it down to immediately stop the flywheel if needed.

There are no resistance settings marked on the tension dial. You can basically tighten it until you can barely pedal. This being said, the bike can offer high-intensity and high-burn workouts. Also, due to the considerable weight of the flywheel, the lowest resistance setting (as in no friction applied onto the flywheel) isn’t exactly light.

Drive system

One of the most important elements in a spin bike’s drive system is the flywheel. The Sunny SF-B1712 is equipped with a 44 lbs (20 kg) flywheel, which is perimeter weighted in order to deliver an aggressive inertia. It also renders the pedaling motion very smooth and stable, and even the workouts with the lightest friction applied are pretty consistent.

The flywheel is bi-directional. In other words, you can pedal in reverse if you want. However, since the bike doesn’t have a derailleur like a road bike, you cannot coast on it. The pedals continue to move for as long as the flywheel is spinning. Therefore, when you want to change the way you pedal, it’s recommended to use the emergency brake and stop the flywheel from spinning to avoid injuries.

This Sunny bike features a belt drive system, using a heavy-duty poly-v belt. A belt drive has its advantages. To begin with, you won’t have to periodically lubricate it. It generates less vibration than a chain, and the pedaling motion is almost silent.

The bike is equipped with an extremely durable crankset, with steel crank arms. This piece can withstand users up to 265 lbs (120 kg) in a complete standing up pedaling posture. The pedals are also highly durable, made of metallic alloy. They don’t have clips for spin shoes, but they’re equipped with adjustable toe cages if you really need the extra thrust. Also, the pedals have standard threads, so in case you want clipless pedals, you can easily find replacements compatible with the bike.

One last important aspect to mention here regards the bike’s Q-Factor. The Sunny SF-B1712 has a rather wide Q-Factor of 228.6mm, while the average road bike has a 150mm Q-Factor. Due to this fact, this bike may add a bit of extra lateral stress on your knees. So, this being said, if you’re recovering from surgery, or simply have bad knees, this may not be the bike for you. In this case, you might want to have a look at the Sunny SF-B1714 which as a Q-Factor of 122mm.

Assembly and Maintenance

Most of the bike’s frame is pre-assembled. The flywheel, the belt, the brake, and crank are already attached to the main frame. You only have to add the base stabilizers, the seat post, the seat, the handlebar post, the handlebar, and the pedals. This shouldn’t take more than 30-40 min. All the tools needed for the assembly are included with the bike, and the manual provides very clear step-by-step assembly instructions.

The bike’s drive system doesn’t need any maintenance since it uses a belt. However, the brake pad may require a bit of lubrication, and for it, silicone lubricant is recommended. Other than this, it’s best to check for loose parts and bolts periodically.

The Pros

  • Solid construction – can support users up to 265 lbs;
  • Heavy frame, offering excellent stability for spin workouts;
  • Small footprint;
  • Adjustable stabilizers;
  • Transport wheels;
  • 4-way adjustable handlebars; 
  • 4-way adjustable seat;
  • Integrated aerobars, offering multiple grip positions;
  • Solid crankset, can support just about any spin workout;
  • Extra heavy, 44 lbs flywheel for an aggressive inertia;
  • Durable, metallic pedals with adjustable toe cages;
  • Friction resistance, offering virtually limitless levels;
  • Smooth and quiet belt drive;
  • Little maintenance required;
  • Extremely easy to put together.

The Cons

  • Fitness meter not included;
  • A rather wide Q-Factor.


The Sunny SF-B1712 is an indoor cycling trainer designed for spin workouts. It features an inertia-enhanced 44 lbs flywheel, a belt drive system, and standard friction resistance. It has a V-frame with precision-machined weld points and an overall durable construction; it can support users up to 265 lbs. It’s perfect for medium to high-intensity cardio workouts, interval training, muscle toning, weight loss, and stamina development. And finally, it’s not one of the most affordable trainers in this specs range but does offer excellent value for the price.

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