Sunny Health & Fitness SF-T7878 Manual Treadmill

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Sunny SF-T7878

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300 lbsManual,
3 levels
16 levels

The Sunny SF-T7878 is one of the new non-motorized treadmills released by Sunny Health & Fitness in 2019. It is a lighter and more affordable version of the ASUNA 7700 model but does offer twice as many magnetic resistance levels. Also, as opposed to the ASUNA model, this one includes an exercise meter and has a pulse reading function.

Technical Details and Specifications

  • Assembled dimensions: 56L x 26.5W x 55.5H inches (142L x 67W x 141H cm)
  • Running surface dimensions: 47.5L x 17.5W inches (121L x 44W cm)
  • Assembled weight: 110 lbs (49.8 kg)
  • Flywheel weight: 11 lbs (4.9 kg) x2
  • Weight capacity: 300 lbs (136 kg)
  • Incline: Manual, 3 levels
  • Resistance: Magnetic, 16 levels
  • Exercise meter: Time, speed, distance, odometer, calories, pulse, scan, goals
  • Extras: Tablet holder
  • Warranty: Frame 3 years / Parts 180 days

Frame construction

The Sunny Health & Fitness SF-T7878 features a solid frame made of steel tubing. The only ABS parts in its construction are the side rail covers and the flywheel covers. The machine offers superior sturdiness, being designed to support users up to 300 lbs (136 kg). All the steel parts in its construction are coated with a corrosion-resistant black powder finish.

Considering that it is a non-motorized treadmill, the Sunny SF-T7878 is a bit smaller than the average regular treadmill. With the frame fully set up, it takes approx. 56″L x 26.5″W (142 x 67 cm) of floor space. However, it is recommended to leave at least two feet of clearance on each side of it, and at least three feet of clearance at the rear of the deck, for safe and unhindered usage.

On the other hand, the machine is foldable. Its deck can be folded and locked in an upright position. With the deck folded up, the unit’s depth is reduced from 56″ (142 cm), to 28″ (71 cm). The folding mechanism has a soft-drop design; it involves a hydraulic cylinder which slowly lowers the deck all the way down to the floor.

The unit’s front base bars are equipped with adjustable levelers and transport wheels. Therefore, you can perfectly level it on the floor for maximum stability. However, its 110 lbs (~50 kg) of weight also plays an important role in its overall stability. It’s also fairly easy to relocate the unit once you have finished your workout.

The front upright bars of the treadmill are curved; this not only improves the unit’s overall stability, but it is also an aesthetic touch. The handlebars are directly welded to the upright bars. This also stands for the transversal bar which integrates the pulse sensors. The handlebars have a multi-grip design, including front grips for a stretched-out workout and side grips for extra balance.

Deck and incline

The Sunny Health & Fitness SF-T7878 treadmill features a heavy-duty rubber belt which offers a running surface of 47.5″L x 17.5″W (121 x 44 cm). This being said, the unit should be able to accommodate users up to 6’0″ (183 cm) with no problem, promoting a complete range of motion.

The deck integrates two solid rollers equipped with industrial-grade ball bearings for a smooth belt motion. Their exact diameter is not specified, but the front one is slightly thicker than the rear one. Also, the two flywheels are directly attached to the front roller and spin along with it. There is no extra internal pulley system for them.

As we’ve mentioned above, the deck of this Sunny treadmill features quite a durable construction. It is designed to support users up to 300 lbs (136 kg), regardless of the intensity of the workout. The internal running board is quite rigid; it doesn’t have an extreme flex, providing a firm running surface. The side rails are steel made, covered by ABS sheets which feature a non-slip surface.

The deck integrates several cushioning elements, placed in pairs at the rear, at the middle and at the front of the deck. This being said, it reduces the vibration generated by each footstrike and the overall impact on your ankles, knees, hips, and spine during running.

The Sunny SF-T7878 features an inclined deck by default. In other words, the front of the deck will always remain higher than the rear of the deck regardless how you adjust the incline.

The front of the deck is situated at approx. 15″ (40 cm) above floor level. The rear of the deck is at approx. 5″ (13 cm) above floor level at the lowest incline level, while at the highest setting, it gains a few extra inches. These being said, it is recommended to use the machine in a room with a ceiling that is at least 20″-22″ (51-56 cm) higher than your own height.

The machine’s incline system is manual. It consists of an adjustable rear bar which offers three positions. The incline increments are 7%, 8%, and 9%. This being said, you cannot adjust it during your workout.

Resistance system

The Sunny Health & Fitness SF-T7878 is a non-motorized (manual) treadmill. It doesn’t require an external power source while the belt is completely self-powered. The speed range doesn’t have any limit; you can basically run as fast as you can on it.

On the other hand, this Sunny treadmill features a magnetic resistance system. The front roller is equipped with a dual flywheel system which is connected to the tension dial on the left upright bar via a steel cable. By turning the dial clockwise, the internal magnetic brake moves closer to the flywheel which results in a higher belt movement difficulty.

The two flywheels attached to the front roller weigh 11 lbs (~5 kg) each. They not only add difficulty to the movement of the belt, they also improve the overall stability of the motion.

The machine makes available 16 levels of resistance. The lowest level basically offers only the resistance generated by the weight of the two flywheels. But as you adjust the dial and increase the resistance, the belt becomes more and more difficult to move. Thus, the machine promotes high-intensity training and great possibilities to develop your stamina and strength.


Since this Sunny treadmill is not motorized, the included console doesn’t play any role in the resistance or belt speed adjustment. It is basically a fitness meter that tracks your workout stats. It features an LCD display which tracks time, distance, total distance, speed, calories, and pulse. Speed and distance are only shown in imperial units (MPH and miles); there is no option for metric units. Also, the unit can only track your pulse via the two sensors integrated into the front bar. It is not telemetric and does not work with any wireless HR chest straps.

The meter unit is battery powered. It requires two AA batteries. It features three buttons; these are Mode, Set, and Reset. The Mode button allows you to select which one of the aforementioned workout metrics you view on the display, or select the Scan mode which rotates all the metrics, showing each one for a few seconds. The Set button gives you the possibility to set goals for time, distance, and calories. And finally, the Reset button clears all the values on the unit to zero.

To start up the console, you can either press Mode, or begin walking on the treadmill. It also has a sleep mode to which it will enter after a few minutes of inactivity on the machine.

There are two extra notable features with regards to the Sunny SF-T7878 console. One is the tablet holder; this accessory is placed above the LCD display, so in case you place your tablet or phone on it, it won’t cover your workout stats. The other one is a heart rate zone diagram placed above the tablet holder. This shows the heart rate zones that you should aim for depending on your age, in order to benefit from a better aerobic output, fat burn, etc.

Assembly and Maintenance

The Sunny SF-T7878 come fully assembled. You only need to unbox it and unfold it. The belt may require a bit of adjustment and must be lubricated before the first use. The manual provides all the necessary instructions, and the box includes lubricants and an Allen wrench for adjusting the belt.

For maintenance, the machine requires periodic lubrication (not just before the first use). Also, the belt should be kept clean to prevent any dirt or textile fibers to be caught into the rollers. Other than this, it is recommended to periodically inspect the machine for loose bolts and/or broken parts.

The Pros

  • Heavy-duty frame and deck – can support users up to 300 lbs
  • Small footprint;
  • Folding design with a soft-drop hydraulic system;
  • Adjustable stabilizers on the front base;
  • Transport wheels included;
  • Multi-grip, one-piece handlebars;
  • Non-slip side rail covers;
  • Self-powered belt action offering the possibility to run as fast as you can;
  • Manual incline with three positions for 7%, 8%, and 9%;
  • Shock absorption elements integrated into the deck;
  • Dual flywheel system for a smooth and steady belt movement;
  • Manual magnetic resistance with 16 distinct levels;
  • Quiet operation; 
  • No power consumption;
  • Exercise meter included – it can track time, distance, speed, total distance, calories, and pulse;
  • Goal settings for time, distance, and calories;
  • Tablet holder included;
  • Comes completely assembled;
  • Little maintenance required;
  • Excellent warranty.

The Cons

  • No horizontal position for the deck;
  • No LED backlight on the console display.


The Sunny Health & Fitness SF-T7878 is a heavy-duty manual treadmill designed for home use. It features a dual flywheel system for a smooth belt motion, a magnetic resistance system with 16 tension levels, and a console which tracks the most important workout metrics. It’s also foldable and has a manual incline system. It’s an excellent machine for high-intensity cardio training, weight loss, muscle toning, and stamina development.

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