The Definitive Guide to Kids Bike Sizes (Don’t Buy the Wrong Bike)


Kids love riding bikes.

Remember the sheer thrill of riding your first bike? More likely than not, it is one of the presents you will never forget.

As a bonus, it gets kids fit, gets them outside, offers them some independence, and most all of riding is fun. The great news is that kids can start properly riding bikes from about 3 years of age.

But kids don’t stay the same size for long. Everyone knows this. It’s a fact of life. That’s why choosing the right bike for your kid, can initially seem quite confusing, but is also crucial to their being able to ride their bike safely and with confidence.

When selecting a bike for a younger person, the most important things to ensure is that the child looks and feels comfortable on the bike, and that they think the bike is cool: Don’t get your kid a bike that they blatantly don’t like the look of, and hope they’ll change their minds once you get them back home.

They might, and they might not.

The last thing you want to do is scar your child emotionally for life by buying them a Destructor 4000 Extreme when what they wanted was the Princess bike with a basket and sparkles. Been there, done that.

Kids have never had so much choice of quality when it comes to bikes. From teenagers to toddlers, there’s a bike for your child.

But if you buy a bike that is too small your child may feel silly sitting on it, and also feel cramped. Conversely, buying a bike that is too large will be unwieldy, difficult to control, and undermine their fledgling confidence on the pedals.

Be under no illusion, the whole thing is a minefield, but a minefield you can cross.

See Kids Bikes divided into age groups:


Buying your kid a bike isn’t as simple as it was in the old days

At least not as simple as it was for me. When it came to my parents choosing the perfect bike for me it came down to which one of my brothers’ old bikes I wanted out of the garage. Having chosen, my father would lift the bike down off the peg, made sure it wouldn’t fall apart, and then said I had to be home before dark.

As adults, the proper way we choose our bikes is by reference to the frame size. If we can stand over the bike with our feet planted on either side of the upper tube, then we can say with some certainty the bike fits. This is not how you choose the right size bike for children.

Fear not though, because fortunately there are guides and guidelines for helping you choose a bike that is perfect for your child’s age and size.

Bike shop

What size bike does your child need?

When choosing a grown up bike, we use the size of the frame as our reference point. But when it comes to kids bikes we actually use the diameter of the wheel as the reference point. That’s because kids’ wheel sizes that determines the proportions for the rest of the bike. Kids’ wheel sizes are generally available in 12, 16, 20, and 24 inches. At 26 inches you’re into the standard sized adult mountain bike wheel size.

Roughly speaking, 12 inch wheels are designed for kids starting off biking and who on average are aged between 3-5 years of age, and by the time your child is 14 years old, you will mostly be looking at 24 inch wheel.

So how do you discover what size bike is perfect for your child?

The general rule of thumb is to use a sizing chart. Sizing charts are available from all good bike websites and stores. There are slight variations in some of them, especially when moving to adult sizing charts, but for children they do remain fairly consistent. Below is a good example of one that can be followed:

Wheel SizeAgeHeight
12″2-32’10”-3’4″85-100 cm
14″3-43’1″-3’7″95-110 cm
16″4-53’7″-4’0″110-120 cm
20″5-84’0″-4’5″120-135 cm
24″8-114’5″-4’9″135-145 cm
26″11+4’9″+145+ cm

Another useful form of chart for determining the right size of bike, and some might say more accurate, is the inside leg length approach.

Wheel SizeAgeInseamInseam
12″2-314-17′35-42 cm
14″3-416-20′40-50 cm
16″4-518-22′45-55 cm
20″5-822-25′55-63 cm
24″8-1124-28′60-72 cm
26″11+26+’70+ cm

Young boy biking

Height charts are not the definitive factor when choosing a kid’s bike

Height charts are not the be all and end all when it comes to picking your kid’s bike. Think of them more as a starting point to help give you an idea of what you after.

If the sales guy in the local bike store insists on only using a height chart when you visit, then turn round and walk away.

By far the most important thing to do is to get a test ride and observe how well your child is able to ride easily and in a controlled manner. There are other factors at work other than overall height. You must take into account the proportions of your kid’s body and personal riding disposition.

The importance of getting the right fit

Despite what some might say, choosing the right size bike in not a precision science. Guides and charts are useful but nowhere near as useful as watching your kid actually test out a bike. The bike should fit the child, not the other way round.

Safety is paramount. This is why you should never buy a bike that is too large for your child in the hope that ‘they will grow into it.’ Your child should be able to straddle the middle of the bike with their feet flat on the ground on either side of the bike with a good inch or two of clearance. They should not have to lean the bike one way or the other to get a foot flat down.

You have to consider what happens if they suddenly need to hop off the bike quickly. This is especially true if your kid is a boy and you think you might like grandchildren one day. The bike should only have a slight lean when your kid puts their bottom onto the seat, puts one foot on a pedal and then scoots away.

When your child is riding away, they be seated in a mostly upright position, and their knees and legs should not be bouncing of the handlebars. On the other hand, their legs also should not be completely stretched out at the lowest vertical position of the pedals either. There should always be a slight bend in the leg.

Children should also be able to turn the handlebars in a sweeping motion to their full extent without being overstretched. Younger children tend to use the turning arc of the handlebars to steer more than older children and adults, who will also use balance to negotiate turns and corners.

Bicycle mechanic

Expert advice is invaluable

Never ever underestimate the power of good advice given by an expert. 5 minutes with an experienced and reputable bike expert can you save you hours spent scouting the internet for the answer.

As can often be the case with Google, you can find yourself with a 100 new questions and more confused than when you started.

Family biking together

Why do some kids bikes seem to weigh as much my own bike?

Fortunately, that’s no longer necessarily the case. The fact is that it used to be that kids’ bikes would be the only thing a Twister in Missouri would leave behind. The cheap ones still are.

But more commonly these days, most bike manufacturers now offer decent value lightweight bikes for your kid. This is an important fact to be aware of as proportionally speaking, kids’ bikes are harder to pedal than adult bikes anyway due to the smaller wheel base. So if you can, do try to buy as light as you can.

Father and son biking

Start them young, keep the keen!

  • Balance bikes, 2-5 years old: The younger you start your kid riding, the more confident they will be getting on a bike in later life. A great place for a young kid to begin their cycling odyssey is with a balance bike.Balance bikes are exactly what they say they are. They have no pedals, and tend to only have a have brake. They are brilliant for letting your kid develop their sense of inertia and balance and learning how to steer, and as they have no means of propulsion other than how fast they can push off the ground, they are relatively safe to use indoors, and are of course, a generally safe way to learn overall.
  • Basic Small Wheelers, 3-6 years old: These are your classic first ‘proper’ bike models. Typically they come with 12, 14, and 16 inch wheels at the outside. Some bikes in this range do come with simple gear sets and basic front fork suspension, but my advice to you is not to bother. They will more likely than not be cheap and add more weight than you child needs. The most important factor here is the fit, as discussed above. Make sure the kids’ feet can easily touch the ground, their hands can reach the brakes on the handlebars. This is where, in my experience, riders are born or broken. Unlike balance bikes, their feet will be on the pedals, not trailing along the ground for extra stability. They will also be going faster. What this means is they are now at the stage where they are more likely to have the occasional accident. Kids can deal with the occasional accident, but not if it becomes a familiar occurrence. So make sure you buy the right size.
  • The next level: 20 inchers, 6-9 years old: This is unfortunately where are most likely to come face to face with your first proper set of gears, and proper suspension. Geared versions of these bikes will come with between 5 and 10 gears, with hill climbing firmly in mind as opposed to speed. While not a necessity, it is handy for getting children used to how gears work. As a youngster, I rode BMXs up to the age of 16. As a result, despite owning a fully-fledged mountain bike, road bike, and folding bike, I still don’t fully trust or understand gears.Don’t bother with the bikes in this category that come with front fork suspension either. Yes they look cool, especially if you’re a kid, but the chances are the forks will be cheap, heavy and not actually be effective. The truth is that fully rigid bikes at this level will not only be lighter, but also be higher quality.If your kid is insisting on forks, then either buy the lightest frame possible, or upgrade to some 3rd party suspension forks. It will be money well spent.
  • Growing up too fast: 24 inches and bigger, 9-14 years old: Read the above bits about suspension and gears again, and just add it in here. The same is true for these semi adult bikes, as it is for 20 inchers. This is where you can start to find all the bells and whistles most normally associated with full adult bikes. Not only might you start to find bikes with up to 36 gears, but also things like triple chain sets.In my opinion these additions still just add extra weight and are more complicated, and are not worth the extra money at this level. If you can, let your kid be a kid just that little bit longer. If they insist on gears, then try to limit them to single or low digit gearing.

Children bike race

Mountain bike or Road bike?

Up to 24 inch wheel sizes, almost all kids’ bikes come in the mountain bike style with the wide, grippy tires and horizontal handlebars.

24 inch wheels start to give you the option to buy slick tired bikes with the racing bike drop handlebars. Really, it all comes down to what your kid wants to ride.

My best advice here is to stick with the mountain bike style until they fully progress to a grown up bike. That said, if all they do is ride on roads, and never go off road, then perhaps a road bike is the way forward. Whatever you do, make sure they try them out first. Your kid may either love the road bike or hate it, so it’s best to try it out first.

What about a BMX?

Why not give your kid something they might want to ride for years and years? As I have already stated, I rode mine solely all the way up the age of 16 before I finally managed to break it. That was a solid 8 years of almost constant daily use!

BMX style bikes have an awful lot going for them. They are tough, single geared, extremely durable, and their resale value is quite high.

The best thing about BMX style bikes though is their inherent ability to go anywhere and deal with any biking situation life can throw at them. By their nature they are small wheeled bikes, which means, as I’ve already stated, kids can start using them at a very young age, and many kids’ versions will come with a 12 inch wheel.

Even when moving to a fully sized 20 inch wheel BMX base, the bike is exactly the same, just slightly bigger. One of the big plusses of a BMX is that for the same money as a kids’ mountain bike, you’ll probably end up with a lighter and better bike overall.

Kid biking with parents

Final thoughts

Get the right size at the right time. Make sure the bike fits. Use the size guides, but remember they are only guides. Make sure they look comfortable on the bike. Make sure your kid wants the bike you’re buying. Buy the best you can afford, but don’t be stupid with your cash either.

Don’t bother with all the bells, whistles and heavy fancy gadgets bolted on to appeal to easily influenced minds. Do get expert advice, but do some research first so you can at least understand what the expert is talking about.

Really final thoughts

Be responsible and teach your kid how to be safe when they ride, wherever they ride.


Kids bike helmet

79 replies on “The Definitive Guide to Kids Bike Sizes (Don’t Buy the Wrong Bike)

  • Paul Nelson

    This was SUCH a helpful article. After read your article, I can get the right size for my 3 year old little boy. But I think if your child is less than 5, wearing the helmet will affect their head, I mean is cervical spine so be careful. Thanks so much for this article.

    • Tony Byergo

      If you think the helmet can reshape his head, what do you the concrete will do? Everyone, of every age, should wear a helmet when bicycling. Saved my neighbor’s life.

    • James

      Helmets are interfering with their vestibular development. I trained my boy like I was trained, like my father was trained; like his father before him and his father before him; like, in fact, every human since the invention of bikes, when it wasn’t considered a life-threatening, permanent-brain-damage-imminent-defcon-1-lethal activity. Once he was fluent in riding the bike (a few days), and if we’re in sight of cops or finger-wagging busybodies (we live in Southern California so this is basically everybody), and because it’s the law (naturally), we don the least offensive helmet we could find. Yes, helmets give bikers a false sense of safety, and make drivers less cautious around them, but a stupid, reactionary, illogical law-which-wasn’t-invoked-due-to-any-particular-uptick-in-brain-injuries is still the law. Considering that brain injuries just from falling down while walking, and from driving, are vastly more common than from falling off a bike, I’m surprised we’re not all forced to wear helmets while walking around and driving. Wait, nevermind. Forget I mentioned it. P.S. My kid has, miraculously, managed to cheat death despite sometimes riding without a helmet. We’re reckless devil-may-care types that way. We’ve preemptively made funeral arrangements and his headstone will read “THEY TOLD US SO.” So, relax.

      • Catherine

        A really helpful, well written article. Loved James’ response to Paul Nelson’s- hilarious. I sincerely doubt that Mr Nelson’s concern that wearing a bike helmet is going to affect the shape of his kid’s head is warranted – unless children’s helmets are made of cast iron in the US? In the UK we just shove any old flimsy polystyrene lid on and hope for the best..

      • Audrey H.

        You’re an idiot, sorry to say. Yea, we all did all of the devilish stunts when we were kids BEFORE people knew better. Same as why we were not vaccinated back then either. Now science, and more common sense has caught on. If you have ever seen a TBI child (traumatic brain injury) you will invest in the safest helmet that you can find. Sure it’s easier to not have one on, but if they learn WITH a helmet and develop the mindset that this is just what you do when you ride a bike, it will be the same as when you ride in a car—when I was a child many cars did not even come with seat belts—that’s how uninformed we were. Now we wouldn’t think of placing a baby on the front seat of the car, or let a toddler hang his head out of the window–because we know better. Get with the times, and keep your children safe.

      • PhilMac

        Questions for James: Did I read this right?? What F’n driver is going to be LESS concerned about a biker’s safety just because they’re wearing a helmet? What evidence do you have to support this ridiculous assertion? While I might agree with the spirit of your reply that we’re all a little too damn over-sensitive these days, why would you care enough about bike helmets to diatribe about it here, especially if it makes one kid even A LITTLE safer??
        If you’re that passionate about it, contact your local representative and help draw up a bill outlawing bike helmets and maybe YOU can be grandfathered out since you come from such a long line of bad-asses. I’m a kid of the 70’s and guarantee I did all of the reckless, devil-may-care, stupid ish you sarcastically reference here. Admittedly, I’d piss myself if my kids did half of the the stuff I and my brother did. But while my brother only had scratches and bruises that have long since healed, I’m left with the reminder of my daredevil days EVERY DAY of my adult life. To this day I have no memory of what happened but I was told that I got tangled with another kid and flipped over my handle bars and landed directly on my dome. I do remember slowly waking up on my back on the asphalt and seeing my brother’s face as the fog cleared. This is some 35 yrs ago and for my efforts I got a concussion, a night in the hospital and a quarter size plug in my head where hair has REFUSED to grow ever since. Maybe not a big deal to someone as hardcore as you…just battle scars, right, tough guy? Point is that it doesn’t always have to be a traumatic brain injury. The law of averages says your kid will fall off a bike at some point in their riding career…and you’re a fool to think falling off a moving bike can be compared to falling while walking (smh). That comparison is just dumb. I don’t care who says what or how it may interfere with their vestibular development, and I hope it never happens to you or yours, but mine will have helmets on at all times for that one time where someone else makes a mistake that may cause my kid to wreck. But hey, If you’re that badd-ass, be a rebel and simply refuse to make your kids wear a helmet. Just save the diatribe on the final line of a post that’s about sizing the right bike for your kid. I don’t think anyone here is interested.

      • Mike

        Thanks for your opinion about not wearing a helmet. You sound like a guy that hit his head one too many times on the pavement.
        Hugs and Kisses xoxo

    • cynical

      Seriously?? If your kid is only going to be riding the bike for 1-2 hours at a time, that’s going to screw up their head?

    • Audrey H.

      I hope you really don’t believe what you said. If you feel that a helmet will compromise your child’s head, think of what the cement on the sidewalk will do—get with the times and keep your child safe.

    • Rafael castañeda

      Been a cyclist for 40 years(since 3) a helmet has saved my life many times, the helmets of 40 years ago were very different, heavy and some of them made of leather and rubber, I can only tell you if you love your kid, procure he or she wears a helmet when riding a bicycle, you will thank god or who you believe to when he only gets a head ache and bruces. I really hope you never regret not making your child wear a helmet.

    • Jane

      My child wore a Doc band helmet as an infant to fix her head shape, she had to wear it 23 hours a day. Wearing a bike helmet for riding is not going to reshape a 3 year olds head. They will not even fit a Doc band after 18 months.

      • Audrey H.

        totally agree—then you read that the child “survived” the accident, but don’t know that a lot of them no longer can function normally, sometimes a hard impact can cause them to go blind, or have enough of a brain injury so severe that the never walk, talk or do anything “normal” again. It’s such a sad sight to see a child who was injured in a small enough accident that should’ve just given them a heache end of in a nursing home for the rest of their lives.

    • Kay

      Is your kid going to be wearing his helmet 24/7?
      Is he/she wearing a custom cranial helmet MEANT to re-shape the skull?
      So don’t worry about skull deformities.
      Make your kids wear helmets. Teach them good habits when they are young.

    • Dan

      … and their bone is very resilient. Having a helmet on their head for the short period of time is NOT going to reshape their head. I’d rather have my child be safe than pound their “soft bone” into the concrete and suffer a life changing event. Where is your thought process? Darn suspect I’d say.

  • Christy

    My son is almost 4 but very tall for his age. Buying his first bike for Christmas so I can’t exactly let him try them all out. On both the height and inseam, my son is on the lowest range number for the 16′. Just worried it will be too big. Any advice?

  • Supernan79

    Great information! Very helpful. I had to chuckle at the last section where in bold it reiterates that kid’s should ALWAYS wear helmets… yet one of the first pics of the family biking along a leaf covered trail- not one of them’s wearing a helmet.

    Finger pointing aside, since those pics were clearly promotional, I’m so glad to have this info as our kids are also getting bikes for christmas and won’t be able to get on them until Christmas day.

  • Tres

    Be careful when adding aftermarket suspension forks to a bike that didn’t come with them from the factory. Sometimes the head tube angle can become dangerously steep when the suspension is at full compression. This, in very extreme situations can cause a head tube to become compromised, leaving the rider in a bad spot!

      • Eric Keahey

        Adding a suspension fork slackens the head tube angle, usually a lot on a bike not meant for a suspension fork (as the frame is built for a shorter fork). When the fork compresses, you will likely not even get back to stock geo. That said, I can’t imagine a situation where I would recommend adding suspension to a bike not designed for it, which rules out virtually all consumer level bikes (as opposed to more boutique/higher end Brand’s and bikes).

        As a cycling advocate, and apparently a grammar nut, contact me if you’d like some help with some typos in here.

        Thanks for a good article

  • Faron

    Very clearly communicated article, thanks for taking the time. So it’s Christmas eve and I just finshed assembling my 8 yr old daughters first full size bike. Its a 20″ Mongoose Byte Girls’ Bike and with an inseam of 24″ im beginning to think maybe i needed to get a bigger bike?
    My considerations though, are that:
    1. She’s still not learned to actually ride a bike without training wheels, so getting her something she could control and felt comfortable riding was top priority.

    2. Ideally i wanted to get a lightweight bike as she is pretty wiry (all legs), basically for the same reason as mentioned above. But my budget was really tight so here we are,

    I guess what im asking most is, would it be better to just return this bike for a more appropriate size since every chart i’ve seen says she’s borderline too long for this one, or just stick with the smaller bike as it might appear less intimidating, lighter and easier to handle, or go ahead and get the 24″ inch since apparently it’s the most appropriate size for her going forward? I’m torn

    • Mads Phikamphon

      Sounds like the 20″ might soon be too small for your daughter, so maybe it would be a good idea to exchange it for a 24″ so she can keep using the bike for as long as possible (as long as she can ride a 24″ safely, i.e. that a 24″ isn’t too big for her).

  • Jennifer

    How tall do you think is too tall for a 24″? I’m looking into bikes for my small 11 year old. He’s been riding a 20″ BMX (it’s a pretty long frame), but needs something different as we head into better weather. I’m just trying to figure out how long a 24″ might last him…

  • Aga

    Hi, Please help!

    My almost 5 years old son been avoiding riding bicycle until now, he have a new bike in the garage (been there over a year! unattached) now he have decided to have a go…
    His 12″ bike seams to small and he really have a problem when pedalling. Due to salesman advice the bike is right size for him , he have a good balance skills but if I insist on getting another bike I should get 14″ one.
    My question is is it necessary to go size by size on bikes or can we go straight to size 16″ BMX bike? My son is 109cm tall.

    Thank you.

  • Ben

    Good article. I went and test fit my almost 9 year old on some mountain bikes over the weekend. He is just about 4’8″ with a 25″ inseam. He seemed to be about to outgrow a number of the 24″ bikes. I’m afraid he would outgrow the 24″ bike too soon for it to be worth the money for a decent bike. He tried a 24″ fatbike that fit him really well but with the fat tires it essentially had 26″ diameter wheels and a longer top tube than most 24″ bikes. Any thoughts? Thanks.

  • Anthony Garza

    I wish there was more support for the 18 inch wheel size. Some manufacturers are really starting to support it. My 7 year old is too small for a 20 inch bike to be not scary for her but her 16 and larger extent her 12 are just too small.

    I wish I could find her an inexpensive cruiser at 18 inch wheels

  • jan

    Hi. My husband weighs around 110kgs and was advised to ride a bike. What are the types of bikes which cater to that weight and also durability? Is BMX good for that too? It’s mainly on the road. Thank you.

  • Tim Stocker

    The worst way to size a child’s bike is by frame size since the frame size will vary from bike to bike meaning the stand over height and distance from saddle to pedal can vary even with bikes of the same wheel size. since i own and run a bike shop i may seem a bit biased but finding a reputable independent bike shop in your area to buy your child’s bike can yield excellent results . Most shops will offer a good choice of models and sizes of bikes that are professionally assembled to offer a safe and easy riding experience and let me tell you most bikes these days more than ever need a a pros touch . not to mention you can usually test drive the bikes outside as they were intended and have the bike setup to your child’s needs especially in regards to saddle height,handlebar reach and brake lever reach .

  • Linda

    Thank you for the article. I’m purchasing a bicycle for my three-year old grandson and wanted to make sure I am getting the correct size. Is there any preference on helmets? Is a Target brand okay? What should I look for in a helmet?


  • BCruz75

    I have a very tall 8yr old daughter who, almost overnight, started riding her way-too small bike like a champ. I’m weighing the pros and cons of a mtn bike vs BMX and what wheel size if I go mtn bike. Based on being very tall 8 yr old, I think 24 inch is best except she’s very new to riding.

    I’m not considering her type of riding as a factor in which type of bike to get…..daddy has both a mtn bike and BMX-style bike (29’er) bike and I’m leaning toward a BMX for its simplicity, weight, lower stand over height and length of time she can ride it.

    Now that I’ve given all the details to help with a recommendation, my question is
    Mountain vs BMX and which wheel size for each bike.

    Thanks in advance for any advise and RIDE ON!

  • Stephen Lord

    The major question on 20 inches and up is WHERE your kid is going to (mostly) ride.
    For us this has changed what is good general advice significantly.

    Where I live the roads are simply too dangerous and the ones that aren’t don’t link up.
    We have some cycle paths that suffer the same problems in linking up.

    However we are blessed with a local “trail centre”. No cars and in theory no pedestrians either.

    We really started when he was almost 6. (Before this his steel ‘bike like object’ was a hindrance to him enjoying whereas he was already doing tricks on a scooter) .. but one day (after seeing older kids at school he wanted a real bike.. so I cut the “ride without stabilisers deal”) – 2 minutes later my wallet felt the first pinch of many.

    We got a 6 speed. He barely got on the 20 but it was just safe enough.
    We started off on a 10 mile ride (on a flat canal towpath). He decided to cycle back so it became a 20 mile ride. (I’ll add he wasn’t particularly fit … he’s tall for his age)

    We then quickly ran out of “safe” …. and started offroad.
    For us our local conditions turns a lot on it’s head.

    Gears are a must … as soon as possible. Whereas he could have done the towpath on a fixed speed he wouldn’t have averaged the 15 mph he did on his way back but more importantly once we moved offroad he wouldn’t be able to ride 3/4’s of the trails.

    He was riding red confidently very quickly… but then suspension quickly became a game changer … as he rode more and more aggressively which drove the move over to a 24er

    By this time he was 6 1/2 and 1m22 (4′ and change) but the hire guys at the trail centre let him try out a 24 incher. About 9 months after just getting on a 20 he just got on a 24.

    As per the advice in the article…. we went for a bike with Air Forks. (As it happened I found a bike with a decent Frame and Air forks)

    This came with cranks that were WAY too long (152mm) …. so initially we used the cranks from his 20 incher.

    At this point my wallet started feeling the pinch.
    I shortened a set of adult cranks to 140mm (with the right cranks it’s a lot easier than you’d think) and got rid of the front mech.

    After this the bike transformed. Off came 3kg of heavy/weak components and due to me having spares forr my own bike and the magic of “used” on eBay and a bit of timing (people selling nearly new 10 speed because they are moving to 11 speed) on went 1kg of better quality components.

    Again WHERE we ride had a huge influence.
    The local trail centre is great but known for the mix of sticky mud and sand and has lots of roots and 1′ dropoffs… and this had proven a constant issue on his V-brakes.

    Adjusting them for hand size leaves a tiny gap that quickly shows up any lack of true in the wheel. Combine that with sand in a sticky mud and it’s a horrible sound.

    So not because of performance (the v brakes had all the stopping power needed) but because I was constantly re-truing his wheels to 1mm tolerance I switched to hydraulic disk brakes.

    This is another geographical thing… I mention it as it means the wheels and frame need to be ready for disc brakes. An alternative is to add weight and use 36 hole/spoke+ wheels… and/or bigger tires but again down to what you want to use the bike for.

    For those interested we ended up losing 2kg (4.4lbs) from the bike and a single 1×10 speed set-up. A 30T ring on the front and a 36/40 on the rear – the 40 being an expander that goes on for real mountains.

    Another 1kg +of weight loss would possible for more money…and that would take it to sub 19lbs with a 7lb fork and his 20 incher is still in use as he only rides the 24er on trails.

    But the main point here is look to where you expect to ride and the conditions.
    If they can safely get on a bigger frame then it might be better for offroad.

    For those who may follow on a similar path: For what it’s worth I’d start off with the frame/forks/wheels and upgrade everything in one go. Trail riding is hard on the cheaper components and in 9 months we got through 3 rear mechs and 2 shifters and it would have been cheaper to start off with the stronger (and lighter) components.

  • Andrew

    Hi Mads,

    Firstly, this is probably the best article I have found in regards to bicycles for young children. Very clear and concise information, so thank you very much for taking the time to write it!

    My 4 y.o. currently rides a 14″ wheel BMX. Based on his size and in-seam he could possibly ride a 16″ or 20″ bike (this one being slightly big). Three cycle shops I have been to have given three different opinions on the next step of his riding journey – one says get a 16″, another says get a 20″ and the last says if he still can ride his existing bike keep it as long as possible then get a 20″.

    I am considering holding off on getting a new bike but want to know if there could be any potential issues if he rides a bike that is starting to get too small for him?

    Thanks in advance for your advice.

  • Peter

    Hi, i have a concern around choosing the right bike… All articles talk about wheel size and very few on the frame sizes. U fortunately i have to buy a bike online (small city – no bike shops) and i don’t know if a Bmx bike pf 18.5 top tube lenght or 20 inches top tube lenght will be too big. Wheels on both are 20 inches. My son is 6 amd a half, 128 cm, and 56 cm inseam… As we’re buying online it’s difficult to know if it’ll be too big…. Help please ????

  • Kamy

    My Girl is 6 years old but they are very tall for their age and here are a couple of things which I am not sure so checking here:
    1. She needs a bike with training wheels as she is going to ride the bike after almost 2-3 years
    2. What size of bike that would suit her best, should I go to nearby store to find this or if you could help


  • helene greenberg


    great article. my daughter is 3, just thinking of getting her a first bike, she looks too big on the radio flyer she has now.

    when you say a child’s feet should should be able to straddle the middle of the bike, while feet are flat on the ground, do u mean with the child already on the seat, or off the seat in a stopped position?

    thank you

  • Brittany

    Hi, looking for sizing for a cruiser for my 16 year old daughter. She’s a bit tiny for her older sisters 26 inch Raleigh. She’s 4 ft 11 inches, 98 pounds with a 27 inch inseam. Wears only a size 3 shoe. Looks like they make the cruisers in a 20inch, 24 inch and the 26 inch. Which would be best for her? Her sisters Raleigh 26 inch has the large balloon tires so I’m not sure if that is making a difference in her being comfortable on it? Thanks for any help.

  • Darla88

    Hi Mads, I would like to thank you for providing this article, it’s given me a great start on what I need to look at to find a bike for my son who loves to ride. Due to my budget, I usually shop for his bike’s at the local pawn shop, which is isn’t always the best fit, but the best I can do because he’s always in need of a new bike.
    I’ve been considering a foldable bike for his next birthday, they’re lightweight which from what I’ve read and quite easily adjusted to suit the rider. I’m not certain which would fit him best, I’ve never seen one to know. I’m going with what I’ve been able to find online so far. My son is approx 5′ and continues to grow at a rate I can’t keep up with. He’s never quite managed to master the gears on any his mountain bike’s, which concerns me but he rides what is available and loves it. His safety is my number one priority, so I haven’t a clue where to begin… aside from wearing a helmet and ensuring he can touch the ground.
    Yes I’m adamant that everyone wear helmets, especially after being the recipient of head injuries. I grew up hearing ” It’s like riding a bike…” It took me 7 year’s of getting back on, falling more times than I thought possible before I could stay upright for longer than than ten seconds. It’s still hard to balance, hard being an understatement. Riding a bike wasn’t the only thing affected, I’m sure you can tell I’m mentally disabled by what I’ve written here. Writing this has been time consuming, exhausting beyond anything a person who hasn’t very literally lost their mind could begin to imagine. That said, please protect your children, don’t take their life before it begins. I’m astonished by the adults who are debating whether they should have their child wear a helmet while on a bike, scooter, skates, hoover board..! Seriously, where’s the confusion, it should be the law for everyone, even at a young age. It’s every adult’s responsibility to ensure that you set a good example for all children by always wearing a helmet.
    I believe helmets should be provided like car seats, so everyone has a helmet to wear while on any wheels. Sadly that’s not available where I live, not yet, but I do my best to provide helmets as well as bike’s which safely function to those who want to ride. In the meantime my son wants for game consoles, but not for time racing around outdoors with his friends who are given both bikes and helmets to enjoy their youth.
    I do apologize for the novel I’ve written, but maybe it can open the eye’s of anyone who begins to think twice about the importance of wearing protection. I’m sentenced to an existence, I don’t get live since I lay paralyzed in my mid twenties. I’ve seen the horrific results of a little one out for a quick ride… Extensive head trauma, numerous surgeries, strokes, covered in bandages and casts. Even celebrated his 4th birthday from the comfort of his hospital bed. No person is the exception, anyone is a candidate. I promise that the shape of a persons head is the last thing on their on their mind, after suffering from a traumatic brain injury is focused on why. I wish I could do so much, but I can’t anymore, I don’t know how and if I’m lucky enough to accomplish a task, I’ll most likely will forget within the hour. If that’s what you want for children, you should take a good look at yourself at the very least.
    If my personal opinion isn’t welcome here, I’ll understand if this disappears or is redacted to be acceptable.

    My question is what are the pros and cons of foldable bikes. Are there any area’s in shopping online for a bike which I should be concerned about. Should a foldable bike be on my list of possibilities, or should I cross those off. I might be able to swing $200 maybe a little more, so where would you recommend I begin.

  • Monia

    Thank you for this guide, it is very helpful. On the 5th picture, there is a little girl with pink shorts on a pink bike. This bike looks absolutely perfect for my daughter. Is it please possible to know the brand and the model?

  • Molly Mac

    What a great article!

    My son is 8 years old and almost 5 ft tall and is a stocky kid. He loves riding bikes but it’s been a challenge because he shot up 2 1/2 inches this year and according to your chart, we’re gonna need a bigger bike! Lol. Sounds like a trip to the bike store is necessary if only to get an idea what wheel size he’s ready for! BMX seems like the way to go for him..we really need something sturdy but that is not too complicated since he is still young. Any suggestions?


  • Dee

    Hi I have an 11 year old son who cannot cycle a bike. I want to get one for him that I could take the pedals off of and try to get his balance. He’s 5ft 1″ tall. What would be the best size bike for him in this regard. He wouldn’t cycle up to this point and has now decided he wants to but he’s too big and heavy for me to hold him up until he gets his balance. Any help would be appreciated. I don’t know the measurement of his inside leg.

  • Natalie

    Read your article, which has lots of helpful info and thanks for that. My almost 5 year old has been using a glide bike for the past 3 years and is doing very well at the balance and steering part. Time to progress to a pedal bike. Went to our local bike store and I was absolutely shocked at the weight of the bikes she tried. Tried a Trek, Cannondale, and a BMX of some sort and they were all much heavier than my own bike. With the training wheels, she did alright but has some learning to do in the pedalling department. I worry that the training wheels will make her focus less on balance and steering but trying to learn to pedal those tanks requires them I think at least at first. Can you recommend any brands that are the lightest weight? I was hoping to just go straight to pedal bike without training wheels.

  • Hatake Yuen

    Absolutely agree about the BMX! At first, I didn’t think this could be the best bike for kids, but the Mongoose BMX totally change my mind.
    I purchased it for my 9 year old brother and are very pleased. I would definitely recommend the purchase of this bike

  • Jeff

    This information was quite useful when I bought my children’s bikes recently. Thank you. (A small request though; proofread and edit. Grammar issues are distracting)

  • scruffy1

    i have a complete noob 14 yo son who of course knows everything – for a first bike i expect 24″ is the go, and from the article, a bmx would be appropriate

    any sage advice on this plan ? noting that he will have his own very strong ideas on the subject

  • Vaani

    Hi ,
    My son is going to be 7 years old this month and he has just begun to ride his bike which was kept unattended from a long time now .He is riding the bike pretty well however since he is tall and the bike is not appropriate for him anymore i am planning to gift him a new one on his birthday but i am little scared if it would be a good idea to give him a big bike all of a sudden as he has just started to ride the bike.

    Please suggest.

  • I. W.

    I am looking for bikes for my two 8 yr old boys and this was the most helpful article so far. Wow, great info to take into the store with. Thanks.

  • Renee

    Hi, trying to but a bike for my toddler who is 3. This will be his first bike so I’m not sure which one to get. He is 3’2″ and 37lbs. Im thinking 14″, 16″ or balance bike. I showed him pictures of the balance bike and he didn’t like it but when I showed him his favorite characters bike like spiderman, captain America he was super excited. I put that in bc u said they should like the bike. Do u think a regular bike is the best choice to start with or the balance bike? Thanks for any advice.

    • Lloyd

      In my opinion,you should get a balance bike first,then move onto a small bike,had my daughter on the balance bike for a year,and she’s nearly on a small pedal bike at 3 without stabilisers,taught my first daughter without stabilizors too.I don’t really see the point of stabilizors,I think they make learning to ride a bike take much longer.Hope this helps.

  • Daniel

    Thanks for your best article I must say that you got very interesting content here ,
    it useful and helpful before people make decision on that purchase ,
    really appreciate thanks for your sharing !!!!!

  • Kelli DeAnn Crofton

    Awww, man!! I just “purchased” my sons first bike for his 3rd birthday through a rewards program at my work. I cannot return it. I think i bought it too big!!! He is 38″ tall and it is a 16″ bike with training wheels. Im soooo sad! Any ideas or suggestions??

  • Arlene

    What type a bike would be good for an eight year old boy first time rider? Looking for something light weight and not too big since we live in an apartment. Please help need some guidance on how to choose a bike? Should the bike have training wheels?

  • yara

    Hello, I want to buy a bicycle for my sister. She’s 12 years old. I don’t know which bicycles that I should buy for her. please recommend me to buy it thanks

  • Freddy

    Regarding the helmet debate; as a swimming coach and PE instructor I teach all my students how to tuck and roll, plus lifesaving skills for in and around water. SO all you who are wagging your fingers in the face of those who enjoy the freedom of cycling and prefer not to use helmets, have you taught your kids how tro fall without hurting themselves? Whether running, walking, skateboarding, cycling etc. the technique is the same. If you haven’t then please get off your high-horses and leave us lesser mortals alone….


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