As an Amazon Associate, we earn from qualifying purchases. We also earn commissions from other affiliate programs through our links at no extra cost to you.
With the pandemic closing commercial gyms, people started shopping in a frenzy for fitness equipment for their home gyms. Those with large houses or separate spaces in their garage, basement, or attic are fortunate to have the space for any type of cardio or strengthening equipment needed, but what about those living in small apartments and houses without that extra space? That’s where our best foldable exercise bike reviews come in.
A stationary bike is a popular home gym addition because almost anyone can use it to keep fit or lose weight. Even those who are not confident riding a bike outdoors will find it quite easy to get on a stationary exercise bike and get going at a leisurely pace to start with. A fold up stationary bike is even better if you’re short on space because they’re designed to fold up into a compact package that you can store somewhere and pull out when you want to work out. They typically have quite a small footprint anyway, so you don’t need a lots of floor space for that.
A foldable exercise bike is also a good option if you don’t want to spend a lot on your fitness equipment, and it’s ideal for those who are looking for a low to moderate workout. Through some rigorous research, we’ve picked out the best among upright and recumbent workout bikes, so you’re sure to find one here to exactly fit your needs.
Before you buy, you may also want to learn about the different types of stationary bikes available and how to choose the right one for you.
Top Picks for Best Folding Exercise Bike
Best foldable stationary exercise bike
Exerpeutic Gold 500 XLS
Best foldable recumbent exercise bike
Sunny Health & Fitness SF-B2721
Best budget folding exercise bike
XTERRA Fitness FB150
Table of Contents
- 1 Top Picks for Best Folding Exercise Bike
- 2 Type of Resistance Offered
- 3 Upright, Spin or Recumbent Folding Bike?
- 4 Best Folding Upright Exercise Bike
- 5 Folding Exercise Bike with Resistance Bands
- 6 Best Folding Recumbent Exercise Bike
- 7 Folding Exercise Bike with Desk
- 8 FAQs
Type of Resistance Offered
If an exercise bike has to be constructed in such a way that it can be folded into a compact package, then certain types of resistance are automatically omitted. The components that make up an exercise bike have to be small, and the design of the frame and construction should lend itself to the machine being able to fold.
An air or fan resistance bike uses a large fan wheel on the front to create wind resistance as it spins. The harder you pedal, the more resistance is built to challenge you. In order to create enough resistance for a challenging workout, the fan size is quite large, which makes it unsuitable for a foldable bike.
There’s really only one kind of resistance that you’ll find in this category in the market, and that is magnetic. A magnetic resistance bike only needs a small flywheel and the resistance created is from a pair of magnets set on either side of the flywheel. You can increase the resistance by the turn of a knob or by using a digital control, and the magnets move closer to the flywheel. When the magnets move away, the resistance decreases. This simple and small mechanism keeps the overall bike compact and lightweight, and it can be designed in such a way that the frame is foldable.
Upright, Spin or Recumbent Folding Bike?
An upright style exercise bike lends itself well to a foldable frame because many non-folding upright bikes feature an X-frame with the seat positioned almost right above the pedals. Most upright bikes are not meant for pedaling while standing because they don’t tend to be stable enough when your weight is over the crank and pedals instead of the seat. However, if the construction of the frame is solid and the leg stabilizers work well, you can try and see for yourself.
Spin bikes use quite a large flywheel so that you get high torque and momentum in order to recreate a near road-feel experience. The construction of the crank and pedal system needs to be solid too so that you can pedal hard while standing. That’s why you won’t find any spin bikes that can be folded. There are just too many large and heavy components.
Although traditional recumbent exercise bikes feature a seat that can be moved forward and backward on a rail with the pedals in front of you, this design doesn’t allow for them to be folded up to save storage space. That’s why there are foldable semi-recumbent exercise bikes, which are actually built in the X crossbar way so that you can adjust the frame to make a broad X for a recumbent position or make a narrow X for an upright position. The seat is usually also adjustable for height. This type of folding workout bike also comes with a backrest for the seat so that you can recline while pedaling in the recumbent position. You also typically get two pairs of handgrips – one pair in the front for when you cycle upright and one pair on either side of the seat. This is the most versatile type of foldable bike for the home, as you can engage a different set of muscles with each position.
Best Folding Upright Exercise Bike
Marcy NS-652 Foldable Upright Exercise Bike
The Marcy NS-652 foldable upright exercise bike is a lightweight machine perfect for turning any space into an exercise area. The bike weighs 36 pounds, making it light enough for anyone to move around. The body is structurally sound and made from 14-gauge steel, ensuring that it will hold up under the most strenuous use.
Designed for superior cardio performance, the Marcy exercise bike has counterweighted pedals to keep your strokes even and a foam padded seat for comfort during your long rides. The pedals have adjustable straps so that your feet stay in place, regardless of how fast you are pedaling.
The bike has an LCD screen that displays valuable information such as distance, speed, time, and calories burned. The interface is straightforward to use and even easier to read.
The bike has a magnetic resistance that can be easily adjusted to 8 different levels. Higher resistance will increase the cardio performance of your workout.
The manufacturer states that the bike is designed for people up to 250 pounds and a height of 5 feet 1 to 6 foot 3. However, some users under 5 foot 4 will have to stretch to reach the pedal, so it’s better to take into account an inseam range of 28″ – 33″. Its maximum rider weight capacity is 250 lbs.
The bike runs very quietly and can be used in an apartment setting. When you are done with your workout routine, fold up the bike, and put it in its storage spot until your next workout.
- Lightweight construction makes it easy to move
- Runs quietly and can be used in an apartment setting
- Very easy to assemble
- Need to be taller than recommended height to use comfortably
- Not strong enough to stand and pedal
XTERRA Fitness FB150 and FB350 Folding Exercise Bikes
Probably the most affordable one on this list, the XTERRA Fitness FB150 folding exercise bike is also our pick for the best compact folding exercise bike. It measures 31.9″ x 18.1″ x 43.3″ when unfolded and half that size when placed into storage, which you can do by wheeling it on its own transport wheels. The bike is constructed using an “X” body design constructed from a strong steel pipe. To fold, you remove the pin at the center of the X, fold, and then insert the pin through the first holes that align to keep it folded.
Despite its solid design, the bike only weighs 32 pounds when it is assembled. The manufacturer has recommended that anyone using the bike should be between 4 foot 10 and 5 foot 10 and not exceed 225 pounds. However, if you have an inseam longer than 32 inches, you may have difficulty extending your legs out far enough for a good cardio workout. The seat height is adjustable and the average rider for this bike is under 5 foot 6. This is also a good folding exercise bike for seniors.
This folding exercise bike for home use has magnetic resistance that can be manually set to 8 different levels by turning a large knob. However, the highest level isn’t high enough for anyone that’s looking for an intense workout. What you can do to break a good sweat is to just pedal faster. A small battery-operated LCD screen reports speed, distance, time, and calories burned and can interact with the bike handles’ pulse monitors to also display heart rate. The seat is large and well-cushioned, so you don’t need an extra seat cover, unlike other typical workout bikes. The handlebars have grips in several locations so that you can change up your riding posture.
The XTERRA Fitness FB350 bike is almost identical to the FB150, except that instead of the upright type bike seat it has a recumbent type seat. This means that the seat has a backrest for you to lean back against while pedaling. It also has an extra pair of handlebars, which are fixed on either side of the seat. The handlebars, seat and seat back are all padded for extra comfort. There’s also an accessory holder in front of the seat where you can place a remote control or your phone.
What the FB350 offers you that other workout bikes don’t is the ability to choose between upright and recumbent style pedaling because you can either lean forward and use the front handlebars to hold on, or lean back and use the side handlebars. Two people in the household with different workout preferences may also find this versatility useful. The seat can be adjusted to allow you to be comfortable in each type of position.
- Lightweight enough so that anyone can assemble and move this bike
- No need for an electrical outlet to operate the LCD screen
- Great for short to average height people
- Assembly will take less than 30 minutes
- Pulse sensors only on the front handles and not on the side handles for the FB350
- Not good for taller people
- Not for people who want an intense workout
Exerpeutic Folding Magnetic Upright Exercise Bike with Pulse
If you want a few more features on your bike or a higher weight capacity, you’ll need to raise your budget a bit. The Exerpeutic folding upright exercise bike is a sturdy machine designed for beginners to moderate exercise levels. It’s also a good upright exercise bike for moderately heavy people, as it supports up to 300 lbs. It offers 8 resistance levels, with the highest level offering the most cardio and calorie-burning effects. The machine features a high torque 3 piece crank system, a precision balanced flywheel, and a V- belt drive for a smooth and silent experience.
The compact design makes it perfect to use in any size home or apartment. It measures 31 x 19 x 46 inches when folded and opens up to 20 x 22 x 55.5 inches. It is easy to store and has wheels on it that engage when folded, making it easy for anyone to move the bike when it is not in use. The overall weight of the machine is 39 pounds.
The Exerpeutic is designed to hold a person up to 300 pounds and has a height range of 5 foot 4 to 6 foot 1. Although it is classified as an upright bicycle, it sits midway between an upright and a recumbent bike, and your legs will be a little more outstretched in front of you than with a regular upright bike. The leg stabilizers can be adjusted to keep the bike stable as you pedal.
The bike has a large LCD screen, and you can track calories burned, miles, time, and speed. Pulse sensors are located on the grips so that you can monitor your heart rate. The seat is larger than on most bikes. The pedals do include rubber straps that keep your feet secured throughout the entire workout.
The machine has magnetic tension and is very easy to change between 8 levels before and during the workout routine. The bike runs very quietly in comparison to other similar machines.
- Easy to fold up and store. Has wheels to move it
- Very sturdy even for heavier people
- Runs very quietly
- Assembly is easy and the tools are labeled for each task
- No easy way to adjust the seat height so that people of significantly different heights can use it
ATIVAFIT Indoor Cycling Bike Folding Magnetic Upright Bike
The Activafit Indoor Cycling bikeis a lightweight and compact bike that offers a lot for its size. Many people would be afraid of such a lightweight construction – only 27 pounds fully assembled, but the frame is solid and sturdy. You can even stand and pedal without feeling like you will tip over.
This particular model has a large padded seat that is perfect for extended exercising sessions. The comfortable foam will allow you to work out for longer periods of time because you won’t experience the pressure point pain that some smaller seats can cause. It also has a large media holder that your iPad can fit into if you want to watch TV while you exercise.
The bike has a magnetic flywheel, which makes it a quiet ride. You can ride this in this same room as someone watching TV, and you won’t bother them. There are 8 levels of resistance to easily increase your workout as you become more experienced with the bike.
The manufacturer has a 5 -6 foot tall recommendation on the unit with 300 pounds—however, some material found on this bicycle states a 275-pound weight limit.
The pedals have foot straps to keep your feet securely fastened, and a battery-operated LCD screen tracks distance, time, speed, and calories burned. You can also monitor your heart rate which’s picked up by the handlebar pulse sensors.
- Very lightweight with sturdy construction
- Folds very easily
- Very quiet to use
- Conflicting information is available about weight and height restrictions
Exerpeutic Gold 500 XLS Heavy Duty Foldable Exercise Bike
It’s rare that you’ll find a folding upright bike that can be used by very overweight people, but the Exerpeutic Gold 500 XLS Foldable Exercise Bike is so well made, with more steel in the frame, that it can be used by anyone up to 400 lbs in weight. It would be too heavy to pick up to move, but it does have transportation wheels so that won’t be a problem.
The bike measures 26.4″ L X 24.8″ W X 57.5″ H when folded, which is half its fully opened size. It is designed to accommodate individuals between 5’1″ to 6’5″ user heights, so it’s a great option for tall users, and the large cushioned seat gives most people a comfortable ride.
The 500XLS runs exceptionally quiet. The design of the double drive crank system, flywheel, and V-belt allows the pedals to move consistently, even when changing speeds. Most users report that this bicycle provides one of the smoothest and quietest rides they have experienced on an exercise bike.
The magnetic resistance is available in 8 different difficulty settings on a dial knob and is easy to change while in use. While some users say that the resistance is too low even at the highest level, another rider says that it is probably because there’s a tension piece hidden in front of the tension knob that sometimes comes loose during transit, so you just have to fix it back and you’ll get quite a challenging experience.
The LCD screen right below that displays calories burned, speed, distance, time, scan, and odometer. It also has the ability to monitor your pulse via the handlebars’ sensors so that you can maintain your desired heart rate. The large pedals have straps to allow for faster speeds without feet slipping.
- Heavy duty construction for heavy people
- Clear assembly instructions
- Operates very quietly, even at high speeds
- The tension piece sometimes comes loose during transit but it can be put back easily
Folding Exercise Bike with Resistance Bands
Slim Cycle Folding Indoor Exercise Bike
The Slim Cycle folding exercise bike is a 2-for-1 fitness bike that offers riders a unique way to get a lower and upper body workout and with resistance training at the same time. The bike seat is designed in a slight recumbent position with a back rest and side handlebars to enable you to also use the arm resistance bands to do some strength training and tone your arm muscles while you are riding. If you don’t, then you can just hold on to the side handlebars and use it like a recumbent exercise bike for low impact cardio, or use the front handlebars and pedal in the upright position for normal impact cardio.
The bike has 8 levels of resistance that are easy to change during your workout routine. The bike also has a large LCD screen that operates on batteries that will track your speed, time, distance, and calories burned.
The manufacturer has stated that this bike is designed for someone 4’10” to 6’2″ with a weight capacity of 300 pounds. However, most people that have ridden the bike say that although the seat height is adjustable, a more realistic height range is 5′ to 6′. I also don’t recommend this for seniors with balance issues, as the seat is much higher than on most recumbent bikes and you have to step over the cross braces to get on.
The machine easily folds for storage but does not have wheels to help with moving. There is a free app available to go with the machine that you can use to access 10 different virtual rides.
- Upper body workout at the same time as a cardio workout
- Design places less stress on knee and hip joints
- Lightweight design makes it easy to move
- Manufacturers weight limits are too broad for the machine
- Not for seniors
MaxKare Folding Magnetic Upright Exercise Bike
The MaxCare folding magnetic exercise bikealso offers a whole body workout. The bike comes with resistance bands to use while riding to tone your arms. The bands are positioned perfectly to help tone shoulder and back muscles, making this a very effective workout. When pedaling, you get a maximum of 8 resistance levels.
The bike has a recumbent styled seat that can be used in 3 different positions – recumbent, semi-recumbent or upright, and standing. For the recumbent position, it is extended to its fully opened state and the seat will sit lower to the ground and farther away from the pedals. In the upright position, the machine is half-folded so that the front and back legs are fixed closer and the seat sits higher and closer to the pedals. In the same manner, the machine can be fully folded and wheeled on its own transport wheels for storage. All this is done by simply turning a knob.
The seat is extra wide for comfort and has sufficient padding. It is constructed from steel tubing and is very sturdy.
Its recommended user height range is 5 feet to 6 feet and with a max weight of 265.
The LCD screen tracks speed, distance, time, calories, and heart rate. You can scan through each number and also check the odometer reading. This bike also comes with an iPad holder so you can cue up your favorite workout routine or movie while you are riding.
- Whole body HIIT training capabilities
- Very comfortable seat
- Magnetic flywheel for quiet bicycling
- Display console is not backlit
- The handlebars tend to loosen over time
Best Folding Recumbent Exercise Bike
Lanos Folding Exercise Bike
The Lanos folding exercise bike can be used either as a regular bike or in a recumbent position. This allows anyone to use this bike based on their comfort preferences. This also helps you change up your exercise routine from one setting to the other.
The bike has magnetic resistance that can be set to 10 different fitness levels. Changing the settings is very easy, and you will achieve the right cardio workout based on your selection.
The pedals are slip-resistant and have rubber straps to keep your feet in place. The large comfortable seat also has slip-resistance qualities that come in handy when you pick up the pace and get heavy into your workout routine.
The LCD screen allows you to monitor speed, distance, calories burned, and pulse rate. There is also a phone/tablet holder that you can use to watch TV or listen to music on your device while you are riding. You have to make sure that the two wires at the back of the screen are plugged in for it to work.
The machine is designed for anyone between the height of 5″ and 6’5″ with a weight capacity of 330 pounds, which means it is a good recumbent bike for a tall person or a heavy person. Don’t believe the lower height limit stated by the manufacturer because some very short people find it hard to reach the pedals and to mount the bike, as the seat is rather high off the ground. The machine is very sturdy, and most users have only complimented the machine for being quiet and easy to use, regardless of their weight or height.
- Use as regular or recumbent cycle
- Easy to fold and move
- 10 levels of resistance as opposed to 8 with most other bikes
- Not good for short people or for seniors
Exerpeutic 400XL Folding Recumbent Bike with Performance Monitor
The Exerpeutic 400XL is a very sturdy recumbent bike that is designed for heavy-duty use. The machine measures 19 x 46 x 33 inches when in use and folds to about half that size. The bicycle weighs 39 pounds, making it a little heavier than similar bikes.
The recumbent style is perfect for those who want the cardio benefits of bicycle exercise but find an upright bike harder to use or difficult to get on. This bike has a large comfortable cushion and side hand grips, making it easier to get on and off. The handgrips also have built-in pulse sensors so that you can monitor your heart rate on the monitor.
The ultra-quiet magnetic resistance has 8 levels of resistance. You can change the settings effortlessly, even during your workout. The pedals are slip-resistant and have straps to keep your feet in place during your workout routine.
The LCD screen displays distance, calorie, and time and also has a pulse monitor attachment. The screen is located low down and right in front of you and has readings large enough for anyone to read with ease. This design means that if you have a standing desk, you can place this bike in front of it and pedal away while working.
The manufacturer has designated a weight limit of 300 pounds and recommends a height of 5 foot 2 to 6 foot 2 for the best results. However, there are shorter customers that say that the lower limit can go even lower, making it a good recumbent bike for a short person, and many customers say that anyone over 5 feet 10 inches will find that their knees will hit the display. Some people just remove the display if they don’t really need it.
- Can work out on it while working at a standing desk
- Good for short people
- Large comfortable seat
- Easy to read LCD
- Not for anyone over 5 feet 10 inches
- Pedals are too small for big feet
Sunny Health & Fitness SF-B2721 Folding Exercise Bike
The Sunny Health and Fitness SF-B2721 Comfort exercise bike is designed for versatility. The recumbent positioning of the bike makes it easy for almost anyone to use, including short people. However, tall people will not have enough leg room to fully extend. You can also set it at an upright position and hold onto the front handebars while you pedal. Although not designed for pedaling while standing, some users do use it this way for an even more intense workout.
The bike measures 33 x 21 x 49 and folds to about half of that size. It has a very sturdy construction and weighs 38.5 pounds. It is easy to fold and just as easy to move when you are putting it away. The seat, although cushioned, will be uncomfortable for some, which can be remedied by fixing a gel seat cover over it.
This folding magnetic exercise bike operates very quietly. You will be amazed at how little you hear when you are in full exercise mode. There are 10 levels of resistance so that you can change up your routine. The pedals have straps to keep you in place, even when you are pedaling hard.
There is a tablet holder in front of the display monitor, which if used will block the display, and there’s a water bottle holder behind the seat.
The manufacturer recommends a minimum height of 5 foot 2 and a maximum of 6 foot 2 with a 300-pound capacity.
- Very sturdy construction even for standing
- 10 levels of resistance
- Uncomfortable seat
- Not for tall people
Folding Exercise Bike with Desk
Research shows that sitting down too much during your day leads to health risks. But with long working hours at a desk in the modern age, it’s not easy to get a lot of activity built in. Some people remedy this by using a treadmill under a desk, but you may find it easier to work and exercise while sitting down, as it’s less distracting. If you choose to go this route, you have a choice between an exercise bike with a small desk attached and a mini under desk exercise bike.
With the former, you don’t need anything more to exercise while working, as it comes with a seat, pedaling mechanism, and work desk. The exercise quality is quite good because the pedals are anchored and there’s a flywheel to provide torque. Some can be folded to reduce the footprint slightly when not in use.
The latter is just the pedaling mechanism is a small portable machine that you place in front of your seat and under your regular work desk. When you don’t want to exercise, you can take it away and store it. The advantage of this mini exercise bike is that you can use it even if you have a large work setup with a desktop computer and other accessories, while the attached desk on the former type is just a small surface that’s large enough for a tablet or small laptop and maybe a mouse. However, don’t expect to get a challenging workout, as it’s designed to only keep you moving without much resistance.
We review only foldable exercise bikes with attached work desks.
Exerpeutic Exerwork 2000i Bluetooth Folding Exercise Desk Bike
The Exerpeutic Exerwork 2000i Bluetooth Folding Exercise Desk Bike does a credible job in turning sedentary time into active time by adding a work desk to the frame of a stationary bike. It is designed for a user height of 5’1” to 6’3” and with a weight limit of 400 lbs. When it’s fully extended it measures 43 x 25 x 50.5 inches, and when it’s folded up it measures 30 x 25 x 61.5 inches. There’s a pair of transport wheels if you need to move it out of the way when you’re done, but it is quite heavy.
This is our pick for the most comfortable foldable exercise bike and desk. The desk is adjustable in every way. You can tilt it forward and back through 3 angle adjustments and can be moved up or down through 5 different height settings so that a user of any height can work on it. It will go high enough for it to be used as a standing desk when you need a break from sitting.
The desk is strong and can hold up to 44 lbs. There’s an arm rest at the front edge of the desk, a small storage drawer, two cup holders, and a small LCD display screen set in the middle of the arm rest. The screen is basic and displays distance, time, calories burned, speed, odometer, resistance levels and scan.
The bike provides 24 levels of magnetic resistance that you can increase or decrease with a turn of the dial. It is Bluetooth enabled so that you can connect to the MyCloudFitness app for tracking your progress. You can choose from 24 workout programs and 3 goal settings (time, distance and calories burned) via the app. It is also compatible with the MyCloudFitness Chest heart rate monitor if you want to get one to monitor your heart rate.
The seat with backrest is very thickly cushioned comfortable and upholstered in a breathable fabric to keep you cool for hours. The seat is adjustable 4 ways – up, down, forward and back, but you can’t make micro-adjustments for your height. There are just two settings for each direction. The backrest can be set in one of two angles as well, so this is a semi-recumbent bike. Of course, you can choose to stand at the desk with one leg on either side of the cross bar.
- Very sturdy construction and ultra comfortable
- 24 levels of resistance
- Lots of features
- Smart/connected features
- Digital display is small
- Not for short people
FitDesk 3.0 Standing Adjustable Desk Bike
The FitDesk 3.0 Standing Adjustable Desk Bike is another very good option with a heavy duty steel frame that can support up to 300 lbs of weight. It comes with arm resistance bands attached below the semi-recumbent style seat, so that you can exercise your arms as well when you’re not using them for work. If you need to rest your arms, the desk has adjustable armrests with massage rollers that you can pull down and out of the way when working.
There’s a digital display screen that is mounted behind the desk and it displays time, speed, current distance, lifetime distance, calories burned, and scan. The desk surface is anti-slip and if you want to watch your favorite shows on a device, there’s a built-in tilt top phone or tablet holder. It hides a small storage space for your earphones, tablet, or any other small accessories. The optional desk extender has a cup holder on the left side and a wide area to use a mouse or keep anything else you might need.
The bike offers 8 levels of magnetic resistance and it is possible to work up a sweat on it. There’s a knob to adjust the resistance. The pedals are large and have foot straps.
The seat is cushioned and has a stated height range of 4’10” to 6’6″. However, some people shorter than 5’2″ have said that it’s not meant for very short people. You also need the included seat extender if you’re over 5’9″. The seatback is also padded but can’t be moved forward and back. The seat saddle is not very comfortable to use as-is for long hours. We suggest that you buy the optional saddle adaptor so that you can add your own seat like the Sun Bicycles Western Trike Saddle to it.
The machine has a footprint of 16” x 28” and weighs 47 lbs. It will fold into quite a compact and movable unit that can be wheeled away on its transport wheels.
- Good resistance levels
- Lots of features
- Easy to assemble
- Good display monitor but will be hidden behind a laptop screen
- Desk height can’t be adjusted
- Not for very short people
- Seat is not comfortable
A folding exercise bike is a great choice if you live in an apartment or any place where you don’t have a dedicated workout space. You can pull it out from a closet, set it up anywhere for a workout, and then fold it up again and move it back to storage. They’re also good if you don’t have the budget for a full-featured non-folding workout bike, as a folding one typically costs less.
Keep in mind that while all good folding bikes will allow you to work up a sweat, if you’re already in a pretty advanced level of workouts, a folding bike may not be challenging enough for you.
Losing fat overall requires a two-fold approach. You can choose a cardio routine like riding an indoor stationary bike while also cutting calories. However, this does not mean that you will specifically target belly fat, as you can only lose overall body fat. If you want a flatter tummy, you should also add tummy toning exercises, like squats or stomach crunches to your workout routine.
If you are just starting on a fitness program, wanting to only stay active for a few minutes each day, or you have to exercise at a low intensity after surgery or illness, then 20 minutes is likely enough for you. However, you will likely need to slowly increase the amount of time you spend on an exercise bike if you want to lose weight. You will also need to increase the intensity of your workouts by increasing resistance on the bike.
In order to create an exercise bike that you can fold and wheel away to a corner or under a bed for storage, the frame has to be designed for it and the total weight of the bike has to be as low as possible.
A full-fledged non-folding exercise bike typically comes with a heavier frame and larger and heavier components that will stand in the way of being folded. A large display screen or flywheel, seat rail for recumbent bikes, etc are all features that are great to have but cannot go on a foldable bike. The construction will also be more heavy-duty, and a spin bike will even allow you to stand and pedal furiously.
All these features are more basic and lightweight on a foldable bike, therefore it will usually be less expensive than an equivalent non-folding bike.
References: Owen, Neville1,2; Healy, Geneviève N.1,2; Matthews, Charles E.3; Dunstan, David W.2 Too Much Sitting: The Population Health Science of Sedentary Behavior, Exercise and Sport Sciences Reviews: July 2010 – Volume 38 – Issue 3 – p 105-113