Sunny Health & Fitness Magnetic Recumbent Bike SF-RB4708

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Sunny SF-RB4708

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350 lbsManual
8 levels
Frame: 3 years
Parts: 90 days

The SF-RB4708 is one of the newest exercise bikes from Sunny Health & Fitness for 2017. It’s a model with mobile arms, similar to the Marcy Air 1 fan bike, but this is a recumbent bike, with a backrest, not an upright bike. Its resistance system is also magnetic, not air-based. Like many other similar Sunny products, this exercise bike won’t break the bank. And even though it’s a new product, so far it has received an impressive number of positive reviews from users.

Technical Details and Specifications

  • Assembled dimensions: 60L x 25.5W x 52H inches (153L x 65W x 132H cm)
  • Assembled weight: 91 lbs (41 kg)
  • Weight capacity: 350 lbs (159 kg)
  • Seat: Adjustable
  • Pedals: With adjustable straps
  • Resistance: Magnetic, 8 levels
  • Console: Time, distance, speed, calories, odometer, pulse, SCAN
  • Warranty: Frame 3 years / Parts 90 days

Frame construction

The Sunny Health & Fitness SF-RB4708 recumbent bike features a frame made of steel tubing. The base longitudinal bar is a single piece, not two as for the Marcy ME 709 or the Goplus recumbent bike. This results in a superior overall sturdiness. The front and rear base bars attach to the main frame, though, via bolts. The front base integrates transport wheels, while the rear base features adjustable stabilizers. The middle of the bottom frame bar also has a small stabilizer which improves the bike’s overall stability. Also, the assembled machine weighs approx. 91 lbs (41 kg), so when it comes to stability, there shouldn’t be any issue.

Although the Sunny SF-RB4708 recumbent bike isn’t a large fitness machine such as a commercial elliptical or a treadmill, it still takes quite a bit of floor space. With the frame fully assembled, it is 60″ (153 cm) long, and 25.5″ (65 cm) wide, and along with that, it requires at least two feet of clearance all around on the sides and at least one foot of clearance at the front and rear for unhindered operation. This being said, it may not fit well in a small room.

All the steel parts in the frame construction are coated with a corrosion resistant paint, grey in color, this being the only color available for this exercise bike. But even though its frame coating is corrosion-resistant, the bike is for indoor use only. If storing it and/or using it outside, moisture can eventually damage its internal parts, or the screws and bolts may catch rust.

Finally, the bike’s frame is well-constructed; it can withstand users up to 350 lbs (159 kg). The bars of the seat base are square, not cylindrical as the handlebars and the other front frame bars, an aspect which increases its overall sturdiness.

Seat and handlebars

The Sunny Health & Fitness SF-RB4708 is equipped with a comfortable, contoured seat, featuring a durable synthetic upholstery. Both the seat and the backrest integrate a fairly thick layer of padding. The seat whole seat assembly is adjustable, being attached to an oblique rail, which offers an adjustment span between 26.5″ and 34″ (67 – 86 cm). Also, the distance between the seat and the closest hand-grip to the seat varies between 12″ and 36″ (30.5 – 91.5 cm). So, these being said, the bike can accommodate users between 5’0″ and 6’5″ (153 – 195 cm) with no problem.

In case you’re wondering, the backrest does not recline, nor does it adjust in any way, independently from the seat, such as for the Body-Solid B5R. It is attached directly to the same seat bar and will move along with the seat on the adjustment rail.

As we’ve mentioned above, this exercise bike features moving handlebars only. They cannot be locked in place and will continue to move for as long as the pedals are moving. However, in case you want to exercise using only the arms, you can place your feet on the floor.

Drive and resistance

The Sunny SF-RB4708 features a manual magnetic resistance system. It consists of a magnetic pad connected via a steel wire, to the lever on the front frame bar. By moving the lever up and down, you increase or decrease resistance.

There are 8 resistance settings available. The highest resistance levels (7-8) are not too hard, though. Differently put, this exercise bike delivers a light to medium workout, being an adequate choice for users who require recovery training or elderly users.

When it comes to the bike’s drive system, just as most other models with a manual magnetic resistance system, this particular one features a belt drive. It uses a stretch-resistant, heavy-duty belt, designed to last for many years of use. Since it’s a belt drive, it doesn’t require any lubrication. The bike’s operation is also very smooth and quiet.

The integrated flywheel is not extremely heavy. Its weight is not specified, but for bikes in this range it usually weighs between 8 and 12 lbs. It’s perimeter weighted, though, which means it delivers a smooth motion.

Since it’s a recumbent bike, the crankset is not made for spin workouts. Differently put, you will probably break it if you try to pedal while standing up on the pedals. However, it’s equipped with a sturdy crankset, featuring solid steel crank arms. The pedals supplied with the bike are made of durable nylon material; they feature a weighted design and integrate adjustable straps for maximum foot stability. They also have standard threads, so it’s easy to find replacements for them if needed.

This recumbent bike features a narrow Q-Factor, which means the foot positioning onto the pedals is comfortable, without any lateral stress on your knees.

Fitness meter

The Sunny Health and Fitness SF-RB4708 recumbent bike comes with a fitness meter that’s a bit above basic. That’s because it can track your pulse along with time, distance, speed, and calories. It has an odometer function and it allows you to set up targets for time, distance, calories, and pulse. However, it can only track your pulse via the EKG sensors integrated into the handlebars; it is not telemetric, therefore it does not work with Polar or other wireless HR chest strap transmitters.

The meter is easy to operate. To begin with, it has a SCAN function which rotates the workout metrics showing each one on the display for 6 seconds. You can toggle the SCAN function OFF, by pressing the MODE button, in order to keep only the metric that interests you to view at all time. The SET button allows you to set a value for time, calories, distance and pulse, while RESET clears all the values to zero.

The unit has a sleep mode function to which will enter after 4 minutes of inactivity. It will turn back on when you begin pedaling or press any of the buttons. It’s battery powered and requires 2 AA batteries which are included.

The console unit is attached to a bar that allows angle adjustment. It also integrates a tablet holder, which can accommodate any tablet.

Assembly and Maintenance

The core of the bike is already assembled and attached to the main frame. Therefore, you only have to attach the front and rear base bars, the seat’s adjustment rail, the seat, the pedals, the moving arms and the console. This may take up to an hour. However, the included manual provides all the necessary assembly instructions. Also, all the tools required for the assembly are included.

Since the bike features a magnetic resistance system, there isn’t any maintenance required for the internal parts. So, the only thing to do for this matter is to periodically check for loose bolts and parts.

The Pros

  • Solid frame for a light recumbent bike, with a max. user capacity of 350 lbs;
  • Adjustable stabilizers on the rear base;
  • Transport wheels on the front base;
  • Step-thru frame design;
  • Mobile handlebars;
  • EKG sensors in each hand-grip;
  • Adjustable seat – can accommodate users between 5’0″ – 6’5″;
  • Cushioned seat and backrest, for maximum comfort;
  • Quiet magnetic resistance system;
  • Adjustable resistance (8 levels);
  • Weighted pedals with adjustable straps and standard threads;
  • Fitness meter that can track time, distance, total distance, speed, calories, and pulse;
  • Target settings for time, distance, calories, and pulse;
  • Tablet holder included;
  • Console mast is angle-adjustable;
  • Easy to assemble and operate;
  • Transport wheels and rear stabilizers;
  • Little to no maintenance required.

The Cons

  • No bottle holder;
  • No recumbent handlebars (or armrests) at the seat;
  • Meter doesn’t have backlight.


The Sunny SF-RB4708 is a heavy-duty recumbent bike for home use. It features a solid steel frame which can support users up to 350 lbs, with moving handlebars, a comfortable seat and a console with target settings for pulse, calories, distance and time. It’s an exercise bike for users of all levels, great for light to medium intensity workouts, stamina development, recovery training and weight loss. You can actually burn up to 5-600 calories per hour on it, depending on the resistance levels used. And finally, it’s not an expensive exercise bike, offering excellent value for the price.

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7 thoughts on “Sunny Health & Fitness Magnetic Recumbent Bike SF-RB4708”



    MODEL # SF-RB4708

  2. I read about several exercise bikes before buying my Sunny SF-RB4708 exercise bike and within a year of using it, the grinding noise started. I told the “customer service” people that I thought it was the pedal wheel bearing was bad, so they directed me to take it apart and send several videos. Eventually they agreed and told me they saw a wheel wobbling (not) which caused the bearing to go bad. I said, if a wheel was wobbling, then it was from the manufacturer and they should send me the bearings. They didn’t see it that way, so I’m going to fix it myself. Has anybody else had to replace the wheel bearings and if so, where did you get them and how much did you have to spend? thank you, Morrie

    1. Same thing happened to me. I’m replacing the bearings right now. I ordered the parts from Sunny Fitness themselves via their customer service line. They were slow, but I got what I needed and it was inexpensive. I’m having trouble fixing it, though. I have the right bearing per the manual, but they don’t match what my bike actual has. I guess I’ll make do with the different bearings and see what happens.

      1. Francine Kitchen

        Please do not post my reply just above. I was using the manual for a VERY similar model. My comment does not apply.

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