Alans BMX Bike Sizing Guide - BMX Sizing Explained

Tom dives into the world of BMX bike sizing, giving you the guidelines on sizing for BMX bikes from 12 inch all the way up to 20 inch. He touches on proper sizing for kids and what top tube lengths mean for you riding.
Check out our range of BMX Bikes over on AlansBMX.com - we have everything from little 12 inch bikes up to 29 inch cruisers and everything in between!
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Alans BMX - the longest established UK BMX shop since 1981.

[@simplespeed84]

Trying to find a new bike for my 7yr old 4ft son. This helped a ton. Hes moving from kids bikes to real bmx bikes. 🤘

[@lenBrill1971]

I'm 6'3 235 lbs. I stay with a chromoly frame and a top 21" + top tube length. 6061 aluminum isn't strong enough for big riders. 7000 series aluminum is strong BUT is incredibly sensitive to dents, nicks, scratches and similar damage. Where these frames are damaged is where they usually fail. 7000 series aluminum gives you very little warning before they fail. I've seen 7000 series aluminum head tubes/stear tubes snap off. Because there are usually no warning signs, you find yourself crashing having no clue wtf happend. One minute your riding and the next you eat it huge while having the handlebars still in your hand. It's like blowing a chain. It catches you completely off guard. I don't trust 7000 series aluminum to give me the heads up something is up. Chromoly frames have always been very strong, and if you've overstressed your frame and compromised its limits, almost always a crack develops somewhere. Let's say you come up short on a big set of doubles. You taco your rear wheel. Or even worse, you're endo into the inside of the double jump. And you taco your front wheel. Take a hard look at your frame welds. If you have damaged your frame, it likely will show up in a weld at the head / stear tube and or at the top tube / seat tube weld. Check your bottom bracket welds also. Chromoly is your friend and it talks to you. 7000 series aluminum is a punisher. It will punish for your error later down the road with no warning. I raced BMX from 1984 until 2000. Today I build and repair helicopters and fixed wing aircraft. I'm a licensed transport Canada licensed structures AME. I understand these materials and I bet your life on it everyday. P.S. VANS and thin platforms rock!! Stay old-school. That's how I stay "Clipped in". I don't like being tied to my ride when it's time to hit the ejection seat button😊🇨🇦

[@nunyabusiness8254]

6-0 230 45y.0 here. Haven’t riden since 90s. Should I get a 21 inch or 20 inch frame? What brand BMX? I’m just using it for work downtown commuting and have some fun jumping On my way to my car

[@artdimino1626]

Nice vid and presentation. Very much appreciated.

[@keithwray9546]

Very informative. Thank you.

[@text.-4076]

Congratulations you have been selected among our shortlisted winners from our previous giveaway, contact the number above^^^^^^^^^^^^^^^^^^^^^^^^^^^^^🎁

[@Cocosprinkle]

I wish I had seen this earlier!! I should have got my son the 16!!

[@leewright3592]

Great detail, thank you

[@text.-4076]

Congratulations you have been selected among our shortlisted winners from our previous giveaway, contact the number above^^^^^^^^^^^^^^^^^^^^^^^^^^^^^🎁

[@15minoffreedom]

Explained Very Well. BMX 101. Thank you

[@christiantabangay3202]

Your shop is a paradise that 20 inch is awesome im drewling so much i can bare to watch this video i love bmx so mich but cant afford it i can only imagine it i love this video though 🇵🇭👍👌❤️

[@text.-4076]

Congratulations you have been selected among our shortlisted winners from our previous giveaway, contact the number above^^^^^^^^^^^^^^^^^^^^^^^^^^^^^🎁

[@Mr11151968]

Good information thank u

[@duellcollins7989]

Alans BMX do you remember two bikes from the late eighties early nineties called the Hammer and the Pacific Hammer? One was purple and the other was chrome and trimmed in purple chrome.

[@TauuStorm]

I have one Question, I am a little bit tall to mi bmx, I am 1,83 m and my frames bike is 20,6. I would need a 21 or 21,25 acording to mi height but my question is, Is really important the size? I mean, should I change the frame or It doesnt really matter because it is not a big diference? Thanks Alan

[@carltonbreezy]

Nice one 👍🏿

[@alansbmx]

Appreciated

[@XNick291X]

What would you recommend for Cruiser BMX bikes? I'm around 5''1'/157cm and I'm wondering if a 24 inch wheel or 26 inch would be better. I have a couple of bikes in mind also.

[@ThatResolves]

What model would you recommend as a first bmx racer for a (5”7) adult

[@qhalipureecuador1150]

Hello friends, I'm Chris from Quito Ecuador. How can I get one freestyle BMX for kids 14"? Good video and explanation. Best regards

[@ashleystyles6888]

Great video. I can use this info for my grandson. My 20" condor feels small and looks stupid. I'm 51 and 6 feet tall and ive been looking at 24inch bikes. My 20" feels totally different to the street beat I had when I was a teen. Is this due to modern geometry and I need to buy old school? Or.... would I feel mute at home on a 24"? They're called cruisers and I'm not sure if cruising is my intention. To thrash to work and back, without looking stupid, whilst having fun is what im looking for. Thanks and merry Christmas.

[@alansbmx]

Hi Ashley, For the first part of your question, yes your street beat will have entirely different geometry compared to a modern bike. If you are used to short top tubes and quite relaxed fork angle then the modern geometry of longer top tubes and steeper fork angles will feel odd. 24 inch cruisers allow for much more standover and length and verge on the edge of mountain bike sizing. You will feel more stretched out and more room on a 24 inch bike compared to a 20 inch and most people prefer them for commuting whilst still having a bit of fun

[@ashleystyles6888]

@@alansbmx thanks for getting back to me. I once bought a 27.5 mtb thinking that this would "feel" right but the top tube was way too high. Then I bought the 2012 condor anniversary frame set. It's rideable. But not to go to work on. And, as you said, totally different when jumping e.t.c compared to a street beat.

[@text.-4076]

Congratulations you have been selected among our shortlisted winners from our previous giveaway, contact the number above^^^^^^^^^^^^^^^^^^^^^^^^^^^^^🎁

[@Vlexthebarber]

I’m 5’7 thinking of buying a new frame. Looking at 20.75”

[@ivanchavarriajr8026]

@ Alans bmx I'm 6' ft tall. Just got a 20" mongoose. What parts can change make the bike usefully without feeling huge. Just trying to work with what I have. Thanks in advance

[@x88868]

Put 18" wheels on it and remove the seat post and grips.

[@vanioriley]

The redline John Purse signature series 4130 big block. What siZe it is?

[@claywiththefootage-Clayton]

Hi do you think a 20 inch wheel would fit someone who is around 130cm

[@daddyT-_-]

Hi I'm 14 and I'm 5'9. Which size tube would be suitable for me? (note I'm still growing lol)

[@scutesscales6557]

I found a bike that I really like but it only comes in 20.75. I’m 5’8” so it would fit me well but I’m still growing so I’m not sure how long it would fit me?

[@ericanddave4048]

Im 6ft with a 24 inch rn what do u thinks the best for my height? I was thinking go up to a 26 or 29 bc the 24 feels a little small but idk i dont wanna drop a few 100 on it and end up hating it

[@soupyruns9709]

What size did you end up getting? And was it the correct choice?

[@gabrielmartinez5919]

What about weight? What’s an ideal weight for a Bmx street bike

[@user-hi9jn4im8f]

How much I'm tryna buy one

[@EliasGGYT]

Im 5.9 feet big so its ok that i use 20 inch?

[@grmm6845]

I found a 20 inch GT BMX in a scrap pile last week, I'm 6ft. Can anyone let me know if the bike is too small for an entry bike?

[@Unknown_Climber]

What would be good for 13 yr old

[@Alyssabreanne7]

anyone recommend any for a kiddo ready for an 18"? They just started racing a different bike but want to also learn park tricks and have been riding since they were 3. Under 400? There are none used. oof.

[@LuisRojas-em8vw]

you can put 20in hoops in a 18in frame as it is, it is a lot of difference to a 20in frame

[@LuisRojas-em8vw]

Rims 20inc to one 18 inc

[@alansbmx]

Not all frames and forks support fitting 20 inch wheels to 18inch bikes these days. This is why some companies make an 18.5 TT 20 inch bike like the United Recruit Junior which is a great step up from an 18 inch bike.

[@LuisRojas-em8vw]

thanks, I bought an 18 frame by mistake and I can't return it, it's a hyper bikes 18 and I have some odyssey 20 rims but I already bought them I'll have to see what I can do but it's possible that it works or not

[@AdrianaBanauna]

Question: my nephews bmx 20inch bike has the bars on the front and back, now he’s still learning to ride without training wheels but grow out of his old one and isn’t used to the new one yet. Can those training wheels or any others still be used for those kind of bikes? Like is there a way to remove the rear bars to install them or can they install with the bars attached on the bike or no?

[@AdrianaBanauna]

@Alans BMX

[@x88868]

Rear bars?

[@DeathorGlory91r]

@@x88868I think they mean stunt pegs

[@SolarTitanSC]

The back of my foot hits the peg when riding. What would fix this? My back wheel is as far as it could possibly go. Do I buy another bike? I'm 5'11'' with 12 and 1/2 inch foot. I'm riding a 20 tt wish I would of went a little bigger

[@alansbmx]

Hello, The rear end length (Or chainstay length) would be why your hitting the peg. Some longer TT frames may actually ahve a shorter rear end depending on the frames geometry. Alot of BMX riders with larger feet make sure they have their pedal in the middle of the foot rather than on the ball.

[@text.-4076]

Congrats 🎈 🍾🎊🎉 .., please text the number ^^^^^^^above so that you can select your item once the second place ie winner chooses theirs👍🇺🇸

[@tribalart88]

Still confused on the geometry. I’m 5 10” height and was looking at the KHE Plasma for flatland or the Wethepeople Sinus. The KHE is 21.25 where as the Sinus is 19tt l think. In your honest opinion which would the better to run with for my height for flatland?

[@alansbmx]

Hello, Flatland bikes are always going to be very short in the top tube and usually have 0 offset forks. These are ment to be twitchy and easily handled at low speed. For flatland we would suggest the Sinus Thanks

[@zsinjus]

im 143cm i think and looking for bmx bc my old one got sold

[@Trek50000]

My son is 7 years old and 4’ 4” tall. Should I get him a 18”?

[@text.-4076]

Congratulations you have been selected among our shortlisted winners from our previous giveaway, contact the number above^^^^^^^^^^^^^^^^^^^^^^^^^^^^^🎁

[@nevioth]

i'm 177cm at 43y / almost 5'10, purchased a bmx for the heck of it. Adjusting to the standing riding position takes a whole long while. Any tips? Besides riding every day

[@P3tchy]

Same as me, all I would say is pump tracks and keep practising.

[@nevioth]

@@P3tchy thank you so much

[@esk8unity]

im 5’3. beginner adult. should i go for a 18” or 20”?

[@alansbmx]

Short top tube 20 we would say

[@bmac65]

Hey. I’m 6’4. Mostly looking for mobility in short distance. Don’t want a big bike. You think a 21 inch top tube, 20 inch wheel will work for me?

[@alansbmx]

Hey! 21 inch top tube will be a bit too short for you. 21.25 should be perfect with some 10 inch handlebars and top load stem. We have everything you need in stock on our website www.alansbmx.com 😉 Cheers!

[@bmac65]

@@alansbmx you guys serve usa? Is there a store on this side of the pond?

[@alansbmx]

@@bmac65we don't have a store in the USA but we ship worldwide 🌎. We are from the UK.

[@kevinsgonnapee]

S&m atf frame with 22 inch tt and elenze bars is the perfect combo

[@text.-4076]

Congratulations you have been selected among our shortlisted winners from our previous giveaway, contact the number above^^^^^^^^^^^^^^^^^^^^^^^^^^^^^🎁

[@tyronewontlie]

What top tube size should i get for a 5’6 person?

[@alansbmx]

Hello, 20.5 should be perfect

[@text.-4076]

Congratulations you have been selected among our shortlisted winners from our previous giveaway, contact the number above^^^^^^^^^^^^^^^^^^^^^^^^^^^^^🎁

[@nannywhu7279]

I’m 12 and 5,3 but still growing What do you think

[@alansbmx]

Something like a 20.25 or 20.5TT would be good if you are still growing.

[@user-es9pz6ly5x]

I’m 5’6 what bmx size would you recommend?

[@alansbmx]

Hello, you should look for 20 inch wheels BMX bike with 20.5 top tube size. We have many bikes available in that size: alansbmx.com/collections/20-inch

[@khulgarulfsson8067]

I am pretty short at 171cm (5’7”?). Would I be okay or perhaps even better off with a 19” top tube you think? I am mostly interested in spins, wheelies and manuals. No ramps or flying. Maybe small jumps but definitely nothing extravagant.

[@alansbmx]

Hello, We would suggest something around 20.25 to 20.5 toptube for you Alans Team

[@khulgarulfsson8067]

@@alansbmx Cheers! Thanks so much for answering 🙏👍

[@dopamine-87]

​@khulgarulfsson8067 hey did you end up getting your bike dude? Im the same height as you. What length tube you got with in the end? Cheers

[@khulgarulfsson8067]

@@dopamine-87 Hey :) Unfortunately no. :-( Sorry I can't be of any help. I still dream of a BMX but I just don't have the time to ride, so I ended up not getting one. A tragic fate, I think I might end up getting an electric mountain bike that I can use for commuting instead of taking the car. I just have to find a store where I can actually try it out.

[@dominikm4235]

bro said hes short but hes 171 💀

[@chandlerbingbong]

I reckon old skool 80's BMX's blow these modern bikes out the water.

[@alansbmx]

We love them still! But short toptubes, headsets coming loose all the time & caliper brakes are no good for modern riding.

[@stebensbobby]

Is a 21 inch good for cruising around town or should i get a 24 or 26

[@x88868]

Yes it is. Get it

[@daddyT-_-]

Get it

[@TheLegendaryLP]

I am 5’6 would TT of 20.25 be ok?

[@alansbmx]

Hey Larry, for your height we recommend 20-20.5 TT size so 20.25 would be definitely okay! We have a few bikes in your size available here: alansbmx.com/collections/20-inch/top-tube_20-25

[@ermieducoyan5725]

Sir what is the longest frame size of bmx? Thanks

[@SonicsOfClubPenguin]

Pretty sure 29"

[@text.-4076]

Congratulations you have been selected among our shortlisted winners from our previous giveaway, contact the number above^^^^^^^^^^^^^^^^^^^^^^^^^^^^^🎁

[@logandiefenbaker5366]

I'm 5,3 and 13 what bike size would be good for me?

[@alansbmx]

Hey Logan, 20 inch BMX bike with 20 inch top tube will be good! Have a look at our range of BMX bikes in your size here: alansbmx.com/collections/20-inch

[@text.-4076]

Congratulations you have been selected among our shortlisted winners from our previous giveaway, contact the number above^^^^^^^^^^^^^^^^^^^^^^^^^^^^^🎁

[@RastaOnABike]

i want a bmx with 24 inch wheels.

[@franciscoortiz1652]

So my son rides an 18 generic bike but I saw a bike with 18.5 frame and 20” wheels ..

[@alansbmx]

With the short top tube but 20 inch wheels we would suggest getting then to sit on the bike and check how they feel on it. The larger wheels also have a gyro effect and when rotating can be harder to turn left and right.

[@sn-jdm]

Im 5'9 would 20" be algood for me

[@stacdough3659]

no

[@rotclan9310]

I’m 5,10 but only 14 and still growing idk what to get and really confused? What do you think?

[@alansbmx]

Hey, you will definitely need a 20" wheel. You could get a top tube size of 20.75-21" depending on your preference :)

[@text.-4076]

Congratulations you have been selected among our shortlisted winners from our previous giveaway, contact the number above^^^^^^^^^^^^^^^^^^^^^^^^^^^^^🎁

[@theshamanarchist5441]

That's not a bike.... THIS is a bike - Crocodile Dundee

[@EliasGGYT]

So im 182 cm and and 20 inch is ok? So it doesn't matter?

[@alansbmx]

Hello, 20 Inch wheels yes buy you would probably want a 21 inch toptube or longer at that height.

[@EliasGGYT]

@@alansbmx alright,thanks!

[@tribalart88]

@@alansbmxI’m 5 10” height and was looking at the KHE Plasma for flatland. Do you think this would be ideal at 21.25?

[@simonjandrell5897]

is the radio revo 20 Adult

[@alansbmx]

More for Kids the Revo bikes. Double check the top tube lengths on the spec of the bike

[@simonjandrell5897]

@@alansbmx thanks.. I bought a Mongoose Pro XL in the end a great deal as it was half price £150 and absolute bargain

[@simonjandrell5897]

@@alansbmx very technical frame size I never imagined it would be so complicated and confusing?? I was like WOW!

[@TheSgkerr123]

Half an inch makes a big difference

[@KenzoyOfficial-ud6xg]

hi im a new subscriber can i have some a one frame for my bike

[@SuperSkaterboy1990]

Bro I’m a really good racer and am I retarded for being 6ft maybe a bit over and thinking about getting a new 20.5 inch top tube high end race bmx?

[@hottap5346]

1st

[@text.-4076]

Congratulations you have been selected among our shortlisted winners from our previous giveaway, contact the number above^^^^^^^^^^^^^^^^^^^^^^^^^^^^^🎁

[@BMXBikerDude3]

Yo 🌈🌈🌈🌈 Bruhh, Mate… But Now Major BMX Bike Brands Like “Cult” Bikes Or SE Bikes Have BMX Bikes Or Wheelie Bikes Where The Top Tubes Are 24 “ 26 “ & 29 “ Respectively……… ✌🏾✌🏾✌🏾✌🏾✌🏾

[@text.-4076]

Congratulations you have been selected among our shortlisted winners from our previous giveaway, contact the number above^^^^^^^^^^^^^^^^^^^^^^^^^^^^^🎁

[@HominidWannabe]

Hi im 5'3 ish and im wondering if i should get a 20 in , and i dont wanna be doing like big air and what not just casual stuff mabey a few dmall jumps. Thx in advance

[@stevenrix7277]

Yes 20 inch is fine

[@jackwilkinson3074]

You should pay for your shirt....

[@simonjandrell5897]

i wanna change my dangerous chinese folding bike for a BMX as they are as cheap as a bag of chips and i can throw it in the car

[@yurilopez439]

What is a folding bike?

[@Flying-Fox19]

I'm looking for an adult BMX bike as well. I miss these as a kid, they were awesome. Now Mtn bikes are everywhere.

[@Ben23858]

Don’t watch this video it doesn’t help you find any sizes if you’re a beginner like me and I’m trying to find a bite with fit see you it’s just a whole bunch of garbage talking around. We just get you more confused don’t recommend.