Choosing The Right Flywheel Weight For Your Indoor Bike

When buying an indoor cycling bike to exercise from the comfort of your home, you must look at all its specifications and get the one that most suits your requirements.

Among all the specs, the one that matters the most is the flywheel weight.

As a beginner, you may face difficulties in choosing the right flywheel weight for your spin bike.

So, in this article, I’ll help you to find out what a flywheel is and how it can be the most crucial factor to consider when purchasing a spin bike.

So, let’s get started!

What is a Flywheel of an Indoor Cycling Bike?


A flywheel is the heart of an exercise bike. It’s the big round disc-shaped mechanical device located at the front of an exercise bike that is used to store rotational energy and ensures smooth operation.

A flywheel is connected to the pedals through a chain or a belt drive. As you pedal, this creates momentum and the flywheel rotates.

Interested in what I use for my indoor cycling? Check out my recommended gear page.

My Recommended Gear

Why Is a Flywheel Important On An Indoor Cycling Bike?

The absence of a flywheel in an indoor cycling bike leads to an ineffective and uncomfortable ride and may cause severe injuries. The flywheel helps to maintain a smooth and safe operation during your workout.

The weight of the flywheel limits the rotation. The flywheel weight also plays a vital role in controlling the resistance and inertia of the bike.

Hence, when purchasing a spin bike, anything that matters the most is the flywheel weight. So, let’s find out how flywheel weight matters, and what factors must be kept in mind while choosing the weight of the flywheel of a spin bike.

The Working Principle of a Flywheel  

For a flywheel to perform efficiently, it must store a certain amount of kinetic energy. Kinetic energy is a function of mass and speed. This kinetic energy is needed to simulate the smooth pedalling operation and give the feeling of a road-like sensation while riding.

The flywheel physics states that a flywheel will store twice as much as energy if you double the weight of a heavy flywheel keeping the speed the same.

Which Flywheel is Good?

For a flywheel to be called ‘good’, it must take some force to set it spinning. It also requires a certain amount of energy to get it stopped.

Heavy flywheels with large diameters store more energy as compared to smaller ones. Similarly, the wheels that spin faster store much more energy compared to the ones that turn slower.

Heavy Weight Flywheel VS Low Weight Flywheel

Flywheel weight is the most crucial factor to be considered when buying an indoor cycling bike.

Let’s discuss all the information that you must know regarding heavy and light flywheel weights.

Heavy Weight Flywheel Indoor Cycling Bikes

When it comes to choosing the flywheel weight, it is recommended that heavier flywheels are better as compared to lighter ones. Higher the flywheel weight the smoother the operation.

A heavy flywheel ensures safe movement by producing more power at a steady rate.

A heavier flywheel makes the movement controlled and less jerky. 

The heavier the flywheel the higher the combination of resistance and momentum that you can generate during your workout.

That’s how you can enjoy a more realistic feeling of travelling uphill.

However, there are a few drawbacks of a heavier flywheel:

  • The bike becomes more burdensome, which makes its movement difficult.
  • Another problem associated with a heavier flywheel is that it requires more momentum and energy to get it started and into motion.
  • Furthermore, as the wheel gets heavier, the bike becomes expensive.

Now, the recommended flywheel weight for indoor bikes is about 18-20kgs, whereas for commercial bikes the weight can be around 20-22kg. A flywheel in these weight classes generates a perfect amount of inertia and promotes a smooth, consistent and flawless cycle.

My Top Pick

The Sunny Health & Fitness SF-B1805 (Check it out over at Sunny)

The Sunny SF-B1805 has an incredible 44lbs (20kg) flywheel that is guaranteed for a smooth cycle.

It also features:

  • Magnetic Resistance
  • Belt Drive
  • Durable Steel Frame
  • 136kg (300lbs) Max User Weigh
  • Tablet or Phone Mount
Sunny Health & Fitness SF-B1805

This is a great, strong, and durable bike that offers a really smooth, quiet ride at an affordable price.

Ideal for someone who wants the best from their spin session whilst keeping noise to a minimum.

A bike with a flywheel weight of less than 16kg is not recommended.

Hence, I always prefer to choose a bike with a heavier flywheel weight so that you can avoid a choppy pedal stroke.

Low Weight Flywheel Indoor Cycling Bikes

A lighter-weight flywheel requires minimal effort to get started. These flywheels are not capable of creating enough inertia needed for smooth pedalling.

This can result in the riders experiencing stress on the joints which may lead to injury.

However, lighter flywheels help promote hamstring and glute recruitment during pedalling which makes your legs pedal faster enabling you to work harder.

Flywheel Positioning

Bikes with heavy flywheels usually have flywheels positioned underneath the sweat zone of the rider.

This is done to ensure smooth movement of the bike.

However, placing the flywheel in the sweat zone isn’t considered ideal because it increases the risk of wear and tear, which ultimately means that the bike would require more maintenance.

Many indoor cycling bikes nowadays tend to position their flywheel at the rear of the bike, i.e. away from the sweat zone so that the risk of wear and tear gets eliminated.

Bad Pedalling Technique and Bike Setup

There is no doubt in the fact that the flywheel weight plays a vital role in your successful workout session.

However, some other precautions must be observed to ensure a smooth riding operation.

For example, bad pedalling technique, proper form, and poor bike setup (despite the flywheel being heavy or light) may cause injury.

To avoid any harmful situations, you must ensure that you have set up the bike correctly and ensure that the pedalling operation is smooth.

You can do this by watching online video tutorials.


So, after looking at all this we can conclude that the bikes with heavier flywheel weights are comparatively better when compared with the ones with lighter ones.

Heavier weight flywheels ensure:

  • Faster Cycling
  • Smooth Riding Operation
  • Enough Inertia
  • Comfortable Ride 

Moreover, to fulfill the optimal design considerations for an indoor cycling bike, its wheel must be positioned at the rear of the bike away from the sweat zone. That’s how wear and tear can be reduced, and the bike is transported easily.

However, flywheels that are positioned at the front of the bike also perform an excellent job  – it’s just a matter of taking extra care to keep it clean and tidy.

Although this complete information was regarding choosing the bike based on the flywheel, be very clear that flywheels should not be the only factor to be kept in mind while buying a spin bike.

You must also keep an eye on other vital elements, such as pedalling technique, material durability and ease of riding operation.

If you have any questions, drop me a comment and I’ll be sure to get back to you.

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  1. Hi there, would you recommend a 18kg flywheel even for light weight women? I weight 49kg, my partner even less, I am athletic and want to build my leg muscles but not tire them out straight away. I was looking at spin bikes with a 12kg flywheel but I am now wondering if this would be too light? Yet surely not the same rules apply to a bodybuilder guy that apply to a deinty woman (within reason).

    1. Hi Julia,

      A great question!
      Yes, the 12kg will be lighter to move and won’t put too much strain on your leg muscles
      As it is lighter it may require greater effort to help tone your leg muscles though.
      To tone and improve muscle definition you need a certain amount of progressive overload. This will make your body ‘tear down’ your muscle fibres helping them to regenerate stronger which will ultimately lead to greater muscle tone.
      Now, the problems with a lighter flywheel compared to a heavier one is the smoothness of the cycle.
      With a heavier flywheel – yes it can be more difficult to move however once the cadence kicks in it will offer a much more smoother cycle just like a real road bike.
      I would recommend a weight of around 15kg minimum – this will give you great workout whilst offering that smoother ride!

      1. All other things being equal price etc.. If you could choose between Magenetic resistance with 37lb flywheel versus pad resistance with 49 lb flywheel where would you go.. Both have belt drive etc and similar other features price same. Thanks in advance

        1. Hi Jim,

          If it was me I would choose the 49lb flywheel with the pad resistance as it will provide a smoother ride.
          Both type of resistances are very good – it’s just with the magnetic there is less cleaning and maintenance.
          Overtime, with friction resistance on the pads, they will start to wear down however replacements can be bought very cheaply at a couple of dollars.



    1. Hi Hannah,

      Sorry for only getting back to you now

      The Bodytrain bike is a great spin bike that offers really everything you need.
      18kg flywheel with a belt transmission – perfect!

      The Sportstech spin bike is a much more multi functional bike that provides everything the Bodytrain does but with a greater flywheel weight – this helps provide a more smoother cycle.
      What’s great about it though is the ability to connect to KinoMap!
      An excellent app that helps provide that extra motivation when cycling!

      Now, the L9 Spin bike personally I feel blows the other two out of the water
      This is more of your home studio bike now that gives you the fully immersive spinning experience just like being in a spin class!
      The subscription comes with the bike which is going to have you pushing yourself well beyond your limits with the very enthusiastic online coaches!

      What it’s coming down to though is your budget.
      If you feel you can stretch the extra mile then I would go for the Spinning L9 bike
      It offers so much more and is a great overall sturdy and strong home studio bike

      I hope this helps

  2. Greetings Ronan.

    I hope you are well.

    Please could you give me some advice and guidance?

    I am looking to keep fit during lockdown. I wish to have a challenging workout, train for 30-45 minutes, four to five times a week ( famous last words). I would prefer a quiet bike if one that is not excessively noisey.

    I am looking to spend about £250 on a spin bike. I have short listed two bikes.

    The first is a newer model, is belt driven and has magnets but a 7kg flywheel. It says it is the equivalent of 18kg although not sure how they can say this. It is also just been launched.

    The second is friction, chain driven but 15kg flywheel. It is an older bike.

    Any thoughts?

    Thank you in advance.

    Stay safe.


    1. Hi Dominic,

      It’s great to hear you’re looking to smash out this lockdown with a good solid workout routine!

      It’s all about consistency my friend!

      Yes, so these are two very good home spin bikes for your money. I actually have the XS Sports Bike – it was my first spin bike, still have it and still works a treat!

      You can check out my post of it here:

      JLL are also one of the leading manufacturers in affordable home spin bikes and the IC200 they have launched is excellent for it’s price tag!

      The 7kg flywheel is what’s going to help you generate your cadence needed to create that smooth and ‘real road bike’ feel to it.

      It’s the magnets that push against the flywheel that causes the friction that can give it a feel of a heavier flywheel – in this case 18kgs.

      As much as I love the XS Sports bike, as you said yourself it is a chain driven bike with friction resistance and I much prefer a belt driven with magnetic resistance.

      If it was me – I’d go for the JLL IC200

      You’ll get a much quieter cycle!

      I hope this helps

      Stay safe


  3. Thank you very much for this.

    Yes funnily enough I read your review of the 500. So basically the 200 will give me a harder ride right and be more challenging right even with the lighter flywheel? I guess I dont want to purchase a bike that is not going to provide enough resistance.

    I am looking to purchase a bike that is for an intermediate and will last me for a couple if years or so.

    Would YOU find the 200 a harder ride?

    I think they both look good though.

    Thank you once again and DO stay safe

    1. Hi Dominic,

      No problem,

      Yes, the flywheel itself will be lighter but with the magnetic resistance equivalent of 18kgs it will make you activate your leg muscles with greater force to push through with each pedal you take.

      With the IC200 you can work you way up gradually and build upon your strength just by using the turn of the crank in front.

      If you keep at it though, you’ll be promoting some serious leg muscle gain and shedding fat in no time!

      Great hearing from you again!

  4. Thank you for taking time out to help me.
    I guess I have the choice between the one that you have and the one that you want. I cannot lose!
    Thank you once again for your kindness.

  5. Hi Dominic

    I live in Perth WA, im about 5 foot ( small build). Im looking for a spin bike for home so as to avoid going to do a gym to do a classes. I’ve done spinning for a few years now. It is for cardio fitness and to tone but ab, thighs, hip area.

    I have shortlisted the following.

    Prices in Australian dollars:

    Sporttop s7 price 2k

    Keiser MP3 i 2.5K

    Matrix IC 5 2.5 K

    Im not sure of any others in Australia worth looking at.

    thanks in advance.

    1. Hi Gaby,

      It’s Ronan here – however Dominic is a cool guy though!

      These are all great spin bikes and offer the best features for your indoor cycling needs!

      All of these bikes are fully adjustable to different heights but in terms of the smaller bike – this would be the Sporttop S.7

      As you have a height of 5 foot – this bike may feel more comfortable to ride as it will give you a better reach on both the saddle and handlebars.

      All the bikes have resistance levers rather than turn dials or cranks which I personally feel is better to control resistance

      All the bikes have magnetic resistance with the Keiser & IC5 having a Poly-V belt for its drive – which is ideal for a quiet cycle!

      In terms of connectivity to Bluetooth, ANT+ and connecting to 3rd parties such as Strava, Zwift or Sufferfest – I think the Keiser & IC5 is the best.

      Personally, if budget wasn’t an issue – I would recommend the Keiser!

      I love the Keiser bike as it provides a ‘real road cycle’, it’s smooth to cycle and I really enjoy connecting up Zwift to it to compete

      I think it’s great!

      Hope this helps

  6. Hello!

    Thanks for your article I found it useful. I live on Thailand and have found it difficult choosing the right bike. I found one in a good price range that is a 15kg flywheel and seems of better quality compared to what else is available. I have never tried spinning before but I would like to start as I think this will be convenient for me to hop on my bike at home after work. I first ordered a foldable upright bike but found the resistance too little and I’d like to have a more serious ride. Do you think the 15kg flywheel bike will be enough for me as my options are limited? Thanks in advance!

    1. Hi Samantha,

      A 15kg will offer a good enough cycle and should store a certain amount of momentum or kinetic energy that will offer a good workout.
      I usually do advise a bike with a flywheel anywhere between 18kg-20kgs in weight as it’s smooth to cycle but stores that momentum for a really tough workout.
      At the end of the day, it really comes down to how you use the bike. By cranking up the resistance or interval training on it – you’re guaranteed to work up a sweat!

  7. Hi there,
    Thanks for all the useful info.
    I have done a lot of research and have narrowed it down to the L9 spin bike.
    My concern is the 42” handlebar height.
    I am 5’2” with a lower back issue and at the gym I adjust the Keiser bike’s handlebars to level 6 and the seat level at level 4. It’s one of the old models and the handlebars go up quite high.
    I would like to know if the L9 handlebars can be adjusted sufficiently higher than the seat level.
    Also I have never used magnetic resistance on a spin bike. Is it worth the extra money and home bike would you suggest that provides this and all the other features recommended by you?
    Thank you!

    1. Hi Vanita,

      Usually to make sure you have proper form the seat and handlebars should be at the same level.

      You can raise the handlebars higher and drop the seat lower though if that suits.

      Just make sure that when cycling that you’re back is straight from your hips to your shoulders – this should take any pressure off your back.

      The magnetic resistance is a great feature to have on a spin bike as it’s a lot quieter compared to a friction based resistance and also requires very little to no maintenance.

      It seems the L9 has a felt pad above the flywheel which is friction based resistance. You’ll still get a great workout from this though!

      1. Thanks for the reply Ronan… I have tried lowering the saddle height but that causes my knees to ache. Since adjusting the saddle height parallel to my hip and the handlebars higher works best for me, do you think that the L9 would still be a good fit?
        If not, I will seriously consider the Keiser M3i as the handlebars go up much higher and it offers so much more. Do let me know what you think.
        Thank you!

        1. Hi Vanita,

          The L9 can be adjusted to a height of up to around 6 inches.
          If you feel this still may put too much strain on your back, It may be best to go for the Keiser MSi

  8. Hi

    Do you know what the main difference is between the spinner L1 and L9? Or is their any other bikes you would recommend – £800 max.

    As much as I would like to purchase a peloton the price tag is ?.

    Thank you. Claudia

    Thank you.

    1. Hi Claudia,

      Spinning’s series of the L bikes are more or less very similar but with a few added details over the years.
      The main difference between the L1 & L9 is that the L9 has SPD clips allowing for a more secure cycle with the use of SPD shoes.
      The L9 also has a heavier flywheel at 16kgs compared to the L1 which weighs 14kgs.
      This is ideal for offering a smooth and real road like cycle!
      A bike I do recommend however is the BodyPower SP.IC20 – 20kg flywheel and belt driven!
      Also at a fraction of the cost!
      Check it out on the link above within the article

  9. Hi Ronan,

    When you say a flywheel is 20 kgs, does it weigh 20 kgs or is it 20 kgs generated with magnetic resistance.


    1. Hi Praveen,

      The flywheel has an actual weight of 20kgs.
      The weight of the flywheel doesn’t necessarily come down to how much force you need to move it
      It comes down to how smooth the cycle can be.
      For example a spin bike with a flywheel weight of 20kgs will have a much smoother and consistent cycle than a bike with a 15kg flywheel weight.
      Yes, the heavier flywheel will require additional energy to get it moving but once it generates momentum it should be easy to cycle.
      It’s the resistance that’s going to deliver your workout.
      Increasing the resistance is going to try and slow down this momentum of the flywheel as you push through and try keep the same RPM.

  10. Hi, I am totally new to the indoor bike craze but i figure that i will not be going to the gym any time soon. Do you have any thoughts on the SunnySF-B1877

    Endurance Belt Drive Magnetic Indoor Exercise Cycle Bike. The flywheel is 29 lbs and I would really like this for cardio and getting myself into shape overall. Not sure if age means anything, but I am over 55…

    1. Hi Annette,

      Sunny do make incredible spin bikes.

      This seems like a very good bike. The flywheel is slightly less than what I usually recommend (40lbs or 18kgs).
      It will still provide a good cycle and will be easy to get the momentum building on it but may not be as smooth as a bike with a heavier flywheel weight to it.
      And your age doesn’t need to be factored into the equation at all…as long as your willing to burn fat but know when to take a break if it becomes too difficult.
      Age after all is just a number!

    1. Hi Ruthie,

      Yes, BH Fitness design awesome bikes.
      Yes, the flywheel has slightly less weight than what I would recommend but not by much.
      You would still get a great and smooth cycle from this!

  11. This was a great article, thank you! I live in the US and I was wondering if you had any bike recommendations that I can find here. I noticed that some of the bikes you mentioned in this article were in the UK. I looking to spend around $500 USD. I did come across a Sunny sf-B1879. If possible I would appreciate your thoughts. Thank you

    1. Hi Tom,

      The Sunny SF-B1879 is actually a great spine bike.

      Sunny are one the leading manufacturers that design great bikes so you know it’s a well-made bike.

      Key features I like with this bike is it has magnetic resistance – great for an effective yet silent workout.

      It’s belt driven – also helps keep noise level at a minimum and requires very little to no maintenance.

      Dumbbell holder where you can work out your arms the same time as you cycle – great at promoting upper body muscle!

      For the price at just under $500 I think it’s a great spin bike!

      1. Thanks for all this information, Ronan. With the Sunny SF-B1879, do you think it’s still okay given it’s 30lb flywheel? Is that too low? I’m drawn given the price and the other features (magnetic resistance, belt). I’m a recreational spin class taker for workout/cardio purposes (and don’t ride outside on a real bike) but considering a bike for the home. Thanks!

        1. Hi Rebecca,

          A 30lb flywheel isn’t too bad at all. I do generally recommend somewhere between 18kg – 20kgs (39lbs – 44lbs). It will still offer a great cycle though and Sunny are a great bike manufacturer so you can’t really go wrong

  12. Question, I’m looking at a spin bike with a 7kg flywheel and magnetic resistance. Is this equal to getting a heavy flywheel I’d say 18kg?

    1. Hi Wes,

      Unfortunately not, a 7kg flywheel will be less stable and wont offer the ‘smoothness’ that an 18kg flywheel will

  13. Hi Ronan,
    I am in Australia and looking at buying a spin bike. My partner is 6’2 and 120kg and fairly strong and I am 5’7 and 80kg so there is a difference in both of us using it. What would you recommend as a good bike that would suit both of us. With our height differences we would need something that would have a lot of height and seat adjusting options.

    1. Hi Tanya,

      Height differences on a spin bike can be an issue. You want to make sure it’s not too small where your legs can’t get full movement but also not too tall where you can’t provide full effort at the bottom of the pedal rotation.

      Have a look at the BH H916 SB2 –

      The saddle can be adjusted up and down by 19″ and handlebars by 14″

      This should provide full range of movement for you and your partner

  14. Hi Ronan,

    Recently I wanted to purchase an indoor exercise bike to lose some weights! Your article had certainly helped! But I am struggling whether which bike should I buy ? Below are the links of bikes that I am considering, would you mind checking them out and decide for me ☺️





    Thanks a lot!!

    1. Hi Jing Wen Soh,

      I think the 140 Exercise Bike is the better bike- yes it’s more expensive than the other ones but it has a heavier flywheel weight of 6kg compared to the others at only 4kgs.

      It also offers more functions and programs you can take advantage to really aid your weight loss.

      Hope this helps

    1. Hi Shane,

      Honestly, I prefer the DOMYOS 500.

      18kg flywheel
      Belt driven
      & has a leather resistance (rather than felt pad)

      And for £60 extra I think it’s definitely the better buy!

      Plus it looks much more awesome!

      Great bike

  15. Hi Ronan, I have recently discovered spinning. I am currently using a standard home fitness bike which is about 6 years old and not particularly suitable. I use the Peloton app on my iPhone /watch and am starting to get addicted!
    Can you recommend a spinning bike which would provide a great workout using the app without having to buy the Peloton bike? Budget is up to £1000.

    1. Hi Paul,

      Peloton is seriously addictive – it’s a great way to get into cycling too!

      The only issue with Peloton is that it can be quite expensive when you factor in the bike plus the subscription costs.

      I’ve actually wrote an article about 3 other alternatives to Peloton – check them out here!

  16. Hi Ronan,

    I’m looking to get a spin bike for home and have narrowed it down to 3 (although I keep changing my mind!!)

    One was actually the one you recommend in the article, but there are 2 others which seem interesting:


    So I guess my question is the more expensive version of the body power bike worth the extra £130ish?

    Or would you say I should go for something more like this one instead –

    Of course there is also the XS one you spoke about earlier…. OMG I’m sooo confused!

    My biggest priority is keeping the noise down, but also want to have something which is durable and has decent resistance.

    Any help you can provide would be very much appreciated!

    Thank you 🙂

    1. Hi Rachael,

      Sorry for only getting back to you now.

      When it comes to choosing the right spin bike – one of the 1st things I look for is flywheel weight. Between the 3 of these the JLL has the heavier flywheel at 20kgs.
      However, both Schwinn and BodyPower make really good durable bikes.
      The more affordable option is the BodyPower with the Schwinn being the most expensive.
      But the JLL offers both affordability and greater flywheel weight – so I would recommend the JLL in this case.
      Hope this helped

    1. Hi Chamila

      Out of the 2 bikes I would purchase the Energitics bike due to the heavier flywheel on it.

      The lifespan bike looks great but I feel you’ll get a better cycle from the Energitics



    1. Hi Lyn,

      It looks like a great durable bike! Chain-driven indoor bikes offer an incredible cycling experience.
      It may not be as silent as a belt-driven bike but you’ll still get an awesome workout in with this.
      Good luck!

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