ASUNA 4100 Commercial Indoor Cycling Bike

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ASUNA 4100
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285 lbsFelt-padNo
Frame: 5 years
Parts: 180 days

The ASUNA 4100 is actually one of the newest bikes from Sunny Health & Fitness, and one of the best indoor cycling bikes for 2016. It offers a commercial quality construction, and is definitely made to withstand spin workout routines. It’s a bit lighter than an authentic spin bike, such as the Spinner NXT, and doesn’t have the high, 350 lbs user capacity, but on the other hand, it costs half the price.

Technical Details and Specifications

  • Assembled dimensions: 41.3L x 25.5W x 51.2H inches (105L x 65W x 130H cm)
  • Assembled weight: 110 lbs (50 kg)
  • Flywheel weight 40 lbs (18 kg)
  • Supported weight: 285 lbs (129 kg)
  • Handlebars: 4-way adjustable
  • Seat: 4-way adjustable
  • Pedals: With toe cages, and cleats
  • Drive mechanism: Chain
  • Brakes: Direct-contact, top-to-down felt pad
  • Resistance: Adjustable
  • Bottle holder: Yes
  • Computer: No
  • Warranty: Frame 5 years / Parts 180 days


Like most indoor cycling bikes, the ASUNA 4100 features a steel frame, pretty heavy, with a weight of 110 lbs (50 kg), in order to supply the required stability for intense workout routines. Most joints of the frame are welded, not attached with screws, which enforces its overall sturdiness. Basically, the only two parts that are connected to the main frame with screws, are its bases. The frame is double coated with corrosion resistant paint, while the seat post, handlebar post, and flywheel have a chrome finish. Currently, the only available color for the frame is silver.

Compared with other fitness machines, such as the Sole E55 elliptical, or the Ironman X-Class 410 recumbent exercise bike, this ASUNA model features a rather small footprint, taking only 41.3″L x 25.5″W (105 x 65 cm) of floor space. Thus, we can safely say that it makes a great choice for a small apartment, or a small room. Despite its small footprint, its stability is still great since it’s a bit wider than other models of this caliber, which matters a lot. On top of that, the bike’s bases feature adjustable feet, with rubber caps, which supply an excellent grip to the floor. The front base also has caster wheels, which ease the bike’s handling and transport once it’s fully assembled.

The only major plastic part within the composition of the frame, is the chain guard. This part is fixed by several screws to the frame, and it’s easily removed, in case you want to grease the chain.

Seat and handlebars

Most bikes designed for spinning workouts don’t offer an extremely cushioned and wide seat. The ASUNA 4100 doesn’t make an exception. The seat supplied with the bike is slim, contoured and rather hard, similar to the seats of most race bikes. It features some padding, but not extreme. Therefore, in case you’re not used to cycling, you may experience some soreness after the first sessions. However, once you become accustomed to cycling, this problem should cease to occur. Nonetheless, the seat is pretty standard, and you can easily find a replacement, or find a gel cover to fit.

The seat offers 4-way adjustability: up, down, fore, aft. Both the vertical and horizontal posts are square, which makes it virtually impossible to turn sideways during a more intense workout. At the lowest setting, the distance between the seat and the lower pedal is 29.5″ (75 cm), while at the highest setting, the distance is 36″ (91.4 cm). These being said, the bike can accommodate users between 5′ – 6’5″ (152 – 195 cm) with no problem.

The handlebars are also 4-way adjustable, featuring a multi-grip design. It’s a plus that the middle aero bars are connected at the middle, as it makes it easier to attach a tablet holder to them. The whole handlebar assembly is covered by rubber foam material, to supply a more comfortable grip, preventing any damage to the hands, during prolonged workouts.

Drive system

This exercise bike features a chain drive, which offers a higher durability than a belt drive, also virtually impossible to stretch. It’s a really silent drive system, actually producing less noise than your average road bike, as it doesn’t have a derailleur. While riding this bike, you will barely hear the chain and flywheel whirring sound.

The flywheel is quite heavy, with a weight of 40 lbs (18 kg), pretty close to the maximum asuna 4100 - pedalflywheel weight specific to indoor cycling bikes. It’s perimeter-weighted, offering a really consistent momentum, and superior stability. It also eliminates the “stair master” effect which may arise in bikes with lighter flywheels, especially when higher resistance settings are used.

The crank assembly is similar to the ones you’ll find in mountain bikes. It’s an extremely solid part, using steel crank arms, which can hold the entire weight of the user with no problem. In other words, you’ll be able to undergo full stand-up climb workouts, without worrying that the crank will give up on you. On top of that, the pedals are aluminum-made, with a hybrid design, incorporating cleats for spin shoes, but also freaturing toe cages for normal, sports shoes.

One last aspect to mention regarding the bike’s drive system is the fact that you can pedal backwards. But when pedaling in reverse, the resistance persists. Also, keep in mind that the pedals will continue to spin while the flywheel is spinning. So, if you decide to pedal in reverse, it’s best to use the emergency brake before starting this routine, to avoid any injuries.

Resistance system

The ASUNA 4100 exercise bike from Sunny Health & Fitness features a friction resistance asuna 4100 - felt pad resistancesystem. It consists of a felt-pad, which comes in contact with the flywheel in a top-to-down manner. To adjust resistance, you simply turn the knob situated on the main tube of the frame, until you find the resistance satisfactory. The resistance knob can also be used as an emergency brake. In case you need to stop the flywheel quickly, you simply push it down.

There are no levels specified on the knob, as in magnetic resistance bikes. Basically, you can tighten the brake pad onto the flywheel up to the point you can barely pedal. Evidently, resistance can be adjusted as you pedal.


The only accessory included with this exercise bike that we can mention, is a bottle holder. It comes attached to the right side of the fork. As insignificant as it may seem, it’s still a plus, as having your water bottle at hand during your workout is quite convenient.

Assembly and Maintenance

The assembly of the bike is as easy as it gets. The chain, flywheel, crankset, and brake come already attached to the frame. All you need to do is place the frame onto its rear and front stabilizers, add the seat and handlebars, and finally the pedals. This shouldn’t take more than 30 minutes.

Since it’s a chain driven bike, for maintenance you may need to grease the chain from time to time, especially if the bike is used daily. Also, the brake pad may require some lubrication. Especially when it’s new, a brake pad may squeak a bit, and may not provide an even grip to the flywheel. That’s why it’s best to add a few drops of silicone lubricant on its surface, or directly onto the flywheel. Other than this, just make sure the bike remains clean.

The Pros

  • Solid frame, commercial quality construction;
  • Elegant design;
  • Small footprint, great choice for a cardio fitness machine if space is an issue;
  • Superior micro-adjustability;
  • Solid crank set, can support just about any spin workout;
  • Hybrid pedals, with cleats for spin shoes, and with toe cages;
  • Friction resistance, virtually limitless;
  • Quiet, chain drive;
  • Little maintenance required;
  • Extremely easy to put together;
  • Excellent value for the price.asuna 4100 indoor cycle

The Cons

  • No fitness meter. But you can always purchase one separately.


Although the ASUNA 4100 does indeed offer commercial quality in its construction, its overall user weight capacity is only 285 lbs., while the full commercial models typically have a maximum user capacity starting at 300 lbs. Thus, it would be fair to say it’s only a light commercial bike. But nonetheless, it costs about 50% less than a spin bike, which is actually great. Also, it can support any spin workout, does supply an excellent training setting for high-intensity cardio, strength and stamina training, and of course, it can definitely help you shed some pounds.

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