Sunny Health & Fitness ASUNA Sprinter 6100 Indoor Cycling Bike

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ASUNA 6100

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350 lbs37 lbsManual
8 levels

If you’re looking for a more affordable alternative to the Keiser M3i exercise bike, the ASUNA Sprinter 6100 from Sunny Health & Fitness is definitely one of the best choices that you can make. Not only that it costs roughly $1,000(!) less, it offers a similar construction and quality. It’s also one of the newest exercise bikes from Sunny Health & Fitness for 2018, one of their best training bikes at the moment.

Technical Details and Specifications

  • Assembled dimensions: 59L x 22W x 48.4H inches (150L x 56W x 123H cm)
  • Assembled weight: 126.7 lbs (57.5 kg)
  • Flywheel weight: 37 lbs (16.7 kg)
  • Supported weight: 350 lbs (158.7 kg)
  • Handlebars: 4-way adjustable
  • Seat: 4-way adjustable
  • Pedals: Toe cages & SPD clips
  • Drive system: Belt
  • Resistance: Manual magnetic
  • Fitness meter: Time, distance, speed, RPM, calories, pulse, recovery, goals, SCAN
  • Accessories: Bottle holder, tablet holder
  • Warranty: Frame 5 years, Parts 180 days

Frame construction

The Sunny ASUNA 6100 Sprinter is a commercial-grade indoor cycling trainer, featuring a heavy-duty construction; it’s a bike made to support any type of spin workout also having an impressive weight capacity of 350 lbs (~159 kg). Most parts within the bike’s frame construction are made of steel tubing, the only plastic parts being the belt and crank covers. Also, the seat post and the handlebar post with their horizontal sliders are made of durable, high-grade aluminum.

The rear flywheel placement, the U-frame construction, and its impressive 126.7 (57.5 kg) weight deliver an exceptional stability. Plus, its stability is enhanced by the adjustable, rubberized stabilizers found on both its base bars. These being said, you can be sure that the bike won’t wobble or rock, even if you’re close to its maximum supported weight or if you engage in a highly intense sprinting workout.

The ASUNA 6100 is a fairly large exercise bike compared to other spin bikes. With the frame fully assembled, its length is 59″ (150 cm) and its width is 22″ (56 cm). The bike’s highest point is given by the tablet holder; its top part reaches a height of approx 48″ (123 cm) above floor level. It’s recommended, though, the leave at least two feet of clearance all around the unit, to be able to perform any spin workout safely, without any hindrance.

Although this indoor cycling trainer is pretty heavy, its transport isn’t too difficult once it is assembled. Its front base integrates two large silicone wheels which facilitate its relocation.

Last but not least, the frame features a durable, rust-resistant and chip-resistant double coating finish. The color used is black for the base frame; however, the seat and handlebar posts have their natural aluminum polish.

Seat and handlebars

The saddle included with the Sunny Health & Fitness ASUNA 6100 Sprinter is a pretty standard spin bike seat. It’s 6.5″ (16.5 cm) wide, and 10.5″ (26.6 cm) long. Its rear part integrates approx. 2.5″ (6.3 cm) of foam padding to improve comfort. It has a longitudinal groove for an improved airflow under the user. In all, it has all the necessary ergonomic factors. But as a general idea, just as any other spin seat, it is not made for comfort. Especially if you’re new to spinning, it will take some time to get used to it.

The seat offers 4-way adjustability. Its upright post offers 22 adjustment positions the distance between them being approx. 1/2″ (1 cm). The horizontal slider also provides several inches of front to back adjustment. This being said, the bike can accommodate users with an inseam between 28″ and 42″ (71 – 106 cm).

The bike’s handlebar also offers 4-way adjustability. Its upright post has 15 adjustment positions, while the horizontal slider also offers several inches of fore-aft adjustment. The handlebar assembly offers multiple grips, including bull-horn, drop-down, aero, cross, and a few more. The main grip section is covered by a layer of rubber foam for a secure grip, perspiration absorption, and an overall superior comfort.

The handlebar assembly integrates a dual bottle holder and a tablet holder. The bottle holder compartments are large enough to accommodate most types of hydration bottles. The tablet holder is placed behind and above the fitness meter so it won’t block the view of your workout statistics.

Both handlebars and seat are very easy to adjust. They’re equipped with large knobs, easy to grip and turn. Therefore, even if multiple persons use the bike, it will take less than a minute to adjust it to your own size.

Drive system

The Sunny ASUNA 6100 Sprinter features a rear-drive, similar to the BodyCraft SPR. It integrates a 37 lbs (16.7 kg) precision flywheel which delivers a consistent momentum and a smooth pedaling motion. Although it doesn’t have the thick perimeter-weighted design as other spin bikes, it still provides quite an aggressive inertia, great for high-intensity training.

The flywheel is bi-directional. It allows reverse pedaling and when pedaling in reverse the fitness meter will continue to count the calories burned, RPMs etc. However, due to the simple drive system, coasting is not possible; the pedals continue to spin for as long as the flywheel is spinning.

The bike features a smooth and silent belt drive. It’s powered by a heavy-duty belt which is resistant to stretching, designed to maintain the same performance for many years of use. As opposed to a chain drive, a belt drive doesn’t require lubrication; also, it generates less vibration.

As we’ve mentioned above, this Sunny exercise bike is rated for a maximum weight capacity of 350 lbs (~159 kg). Evidently, this also stands for its crank system and pedals. It is equipped with a heavy-duty crankset featuring solid steel crank arms and metallic alloy pedals.

The pedals are dual-sided. They’re equipped with toe cages and adjustable straps on one side, and with SPD clips for spin shoes on the other. They also have a standard 9/16″ configuration, so compatible replacements (if needed) are widely available.

One last aspect to mention here regards the bike’s Q-Factor (spacing between the pedals). The ASUNA 6100 features a comfortable, narrow Q-Factor of 152.4 mm (6 inches) similar to road speed bikes. This is quite a plus, as the positioning of your feet on the pedals is natural and the pedaling motion doesn’t generate any extra lateral stress on the knees. Thus, you can perform longer workouts, with a lesser impact on the joints.

Resistance system

The Sunny Health & Fitness ASUNA Sprinter 6100 features a manual magnetic resistance system. It consists of a magnetic brake connected to the tension dial on the main tube of the bike’s frame. As you turn the knob, the magnets rotate, increasing or decreasing the intensity of the magnetic field around the flywheel, and this way, generating more or less resistance.

Since the bike’s resistance system is exclusively manual, the unit doesn’t require being connected to a power source. Also, the console doesn’t play any role within the resistance adjustment.

The tension knob has 8 “clicks” or differently put, the bike offers 8 distinct levels of resistance. As the flywheel is fairly heavy, the lowest resistance level isn’t too light. So, this isn’t exactly a bike for recovery training. On the other hand, the top resistance settings deliver quite a high level of difficulty simulating a steep climb. Thus, the bike offers leg muscle strength development possibilities.

Last but not least, the tension knob also fulfills the function of an emergency brake. As we’ve mentioned above, the pedals continue to spin for as long as the flywheel is spinning. So, in order to avoid injuries, before dismounting, or before changing the way you pedal (to reverse pedaling), it’s recommended to press the knob down in order to instantly stop the flywheel.

Exercise meter

The included fitness meter is similar to the one of the Horizon Fitness Elite IC7 bike. It features an LCD display divided into 6 main sections. It indicates time, distance, speed, RPM, calories, and pulse. There’s a SCAN function which applies to the top panel of the display. When enabled, the readings on the top display will appear in this order: Time-Distance-Calories-Pulse-RPM-Speed, each one being displayed for 6 seconds.

The unit has a goal-setting function for time, distance, calories, and pulse. If you select a target goal for each one of these metrics, the console will countdown from the selected value until it reaches zero.

Distance and speed can be shown in either metric or standard units. The console is also telemetric; it can read pulse via the included wireless HR chest strap. The handlebars do not integrate grip sensors, though.

The meter unit also has a Recovery function which can be run at the end of the workout. The console will monitor the amount of time that your heart rate takes to return to normal after the workout. At the end of the test, the console will provide you with a fitness rating between F1 and F6, F1 being “excellent”, while F6 being “very poor”.

The unit features four buttons: SET, MODE, RESET, and RECOVERY. The MODE button covers the selection function, the SET button allows you to increase or decrease the target values for the unit’s metrics, the RESET key clears all the data to zero, and the RECOVERY button initiates the Recovery test function. The unit does not have pre-set workout programs.

The batteries for the fitness meter are included. It requires two 1.5V AAA-type batteries. To start it up you can simply push one of the buttons or begin pedaling. It also has a sleep mode to which it will enter automatically after four minutes of inactivity on the bike.

Assembly and Maintenance

The main body of the bike with the drive and resistance elements, and the seat, comes pre-assembled. All you have to do for assembly is attach the base bars, the handlebar post, the handlebar, the console, the tablet holder, and the pedals. This shouldn’t take more than 30 minutes. All the necessary tools are included and the manual provides very clear assembly instructions and schematics.

Maintenance doesn’t require much. All you have to do is wipe the perspiration from the frame at the end of the workout, periodically check for loose bolts and parts, and for the proper alignment of the flywheel. The internal parts do not require lubrication.

The Pros

  • Commercial-grade, sturdy construction – can support users up to 350 lbs;
  • Bases with adjustable, rubberized levelers;
  • Transport wheels on the front base;
  • 4-way adjustable seat;
  • 4-way adjustable handlebar, with a multi-grip design;
  • 37 lbs precision flywheel for a smooth pedaling motion and solid momentum;
  • Heavy-duty crank made for standing up spin workouts; 
  • Dual-sided pedals with SPD elements and toe cages;
  • Narrow (152.4 mm) Q-Factor, minimizing the lateral stress on the joints;
  • Frictionless, wear-free, magnetic resistance with 8 level settings;
  • Smooth and quiet belt drive, great for apartment use;
  • Fitness meter that tracks time, speed, distance, RPM, calories, and pulse;
  • Goal settings for time and distance;
  • Recovery function;
  • Wireless HR chest strap included;
  • Dual bottle holder included;
  • Tablet holder included;
  • Little assembly required;
  • Little maintenance required;
  • Excellent warranty.

The Cons

  • The fitness meter doesn’t have backlight.


The Sunny Health & Fitness ASUNA 6100 Sprinter is an indoor cycling bike built for all types of spin workouts. It features manual magnetic resistance system, a belt drive system, and a telemetric exercise meter that can track time, distance, speed, RPM, calories, and pulse. It offers superior micro-adjustability. It’s an excellent cycle for interval training, strength and stamina development, muscle toning and weight loss. Finally, it’s quite an affordable trainer considering its quality and versatility, offering an outstanding value for the price.

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