Help needed for child's bike

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11/14/2017 11:40 PM


Complete newbie here. I've been taking my 3.5 year old to the BMX track in Santa Clara. He has been racing in the balance bike races for 6 months and doing very well. He also has his own pedal bike without training wheels and has quickly got the hang of riding as fast as he can. He's been watching the bigger boys on the BMX course and I can tell he is Keen to give it a go. Now, I've seen big guys on very small bikes and small kids on bigger bikes, normal size wheels and very, very thin wheels. What would be a good bike size wise for him to start on? I'll let him try out a rental first but I'm curious as to what size we would look for. He will be 4 in January, and 42 inches tall. Also, any recommendations for bike shops in the San Francisco/ Bay area?



11/15/2017 2:17 AM

Striders have 12in wheels there are 14in bikes if he is close to outgrow that size. Most people ride a 20in bike for bmx and for racing (older kids and adults) and tire size all depends on what you are doing racing seems to use a thinner tire bmx typically will use a larger tire.
Hope that helps


11/15/2017 4:04 AM

12inch at that age definitely. There are lot big companies that offer really good 12inch options, including 3 piece cranks etc.


If I could go a tenth as high as Larry Edgar goes, then I would still be blasting super high.

11/15/2017 5:38 AM

If he rides standing up all the time, get him the Cult 12" Juvi. If he's a sitter or awkward when standing, go with the spawn 16" Banshee.


11/15/2017 9:34 AM

My 5 year old son rode half track this year on a 16" Mirraco Wedge. It was not bad for the first half of the season but as the kids got better they moved up to 20" bikes and just smoked my kid. Try and get him the biggest wheel size he can comfortably ride. I don't know the sizes very well and who fits what but I know they make a micro mini race bike for kids that is 20" but has a small frame and very low bars(mountain bike looking bars).


11/15/2017 10:28 AM
Edited Date/Time: 11/15/2017 11:20 AM

I went through the same issue and now again that we are going to an 18" bike

My son is 5. He started on a strider balance bike which I bought early when he was 7 months old. Clearly he didn't use it for a year later or more..

At 4 years old We then moved to a 16" redline pitboss and skipped training wheels. He can ride that bike just fine but he is at the top of the seat post and his legs are crunched up in his chest when he pedals....for Xmas he is getting a 18" wethepeople curse, in hopes of spreading him out some and giving his legs some room to pedal and more seat height

Few things to think about

1-When he turned 4 he got his redline. I bought it because it was aluminum and 15lbs. He weighed around 32lbs at the time, so the bike was almost 50% of his body weight. A 16" specialized hi-ten bike was 25lbs.

my specialized plus tire mtb weighs 30lbs for comparison and I weigh 220

2- he's tried bmx racing and gets smoked by same age kids on 20" true race bikes. However he spends most his time riding down the steps at the track and playing. He doesn't have the mindset for a track only bike

3- the local mtb skills part is his main joy. He rides that and the pump track until he gets bored and then we are doing something else. As much as a race bike would help him be faster on the track. It would only work for 5% of the riding he does. I'm not buying a race bike to sit in the garage all the time until he is old enough to tell me he wants to race and practice...which may never happen and if so perfectly fine. Plenty of kids at the race had fit/haro/cult regular bmx bikes in 20" and they did mid pack results. But they still had fun and went to the trails after the race

So my final decision was a basic bmx bike will be his one bike to putz in the hood, take to the track and take to the bmx park

Hope this helps share my experience

My choices as a kid was much easier. Here's a 20" huffy with mag wheels. I started with a girls bike with banana seat, I had no other choice. Now go play.


11/15/2017 12:49 PM

baitdragger wrote:

I went through the same issue and now again that we are going to an 18" bike

My son is 5. He started on a strider balance ...more

18" from real brands are pretty big bikes. My smallish 11 year old just moved to one at 55" tall. I foresee him on it for a few years with tweaks. The Pitboss is actually a small "real" 16 in. Our Fit PRK16 is significantly bigger that the pitboss.
Hell our cult juvi 12 is closer in size to it.

Just double check all the measurements.


11/15/2017 1:23 PM

My son's on an 18" united. He's an average height 9 year old, and it's about right for him. He'll be on that for another couple of years. I've just pre ordered an fbm halafast 20" frame for him with the idea of building it up with him over the next couple of years (I've got some spare parts already, and it'll be perfect when he's outgrown the 18"). He's not even really that bothered about riding, but to be fair there's not much to ride anyway. This winter we're building trails, and they'll be a small pump line for the kids to play on and build confidence.

Racing is a bit different. The skinny tyre 20" wheels are 20 x 1 3/8ths and they're supposed to be like a kids version of a cruiser, so they often look a bit too big. But the general rule is a bmx is supposed to be small. My son could ride a full sized 20", but he wouldn't be able to mess around on it or learn tricks and stuff, on a bike that big.
Weight is a massive aspect to consider though. Kids bikes are generally made cheaper, because they'll be outgrown, and there's not enough call for great quality/price kids bikes. So they often weigh as much as a full sized 20".

My advice would be to get something light, it doesn't even have to be a bmx. But the lighter it is, the more he'll enjoy riding it, and getting kids stoked on riding is half the battle. A decent bike will hold value as other rad dad's will always be on the look out for a second hand bike for their kids. I know I'd rather buy a good second hand bike, than a crap new bike for my son.
I'm hoping the halafast will hold good value so I can sell it on to another cool kid in a few years time (or it'll go on the wall with the rest of my unintentional fbm collection)


11/15/2017 1:33 PM

Thanks for all the great posts and information.

He is very competitive but still young and growing.

I don't want him to outgrow a bike too quickly and I don't want to go too cheap incase he catches on quickly or too expensive in case he takes up basketball (seems like a new interest everyday)

Both the cult and the spawn look like good bikes and of course they have to come in blue!!

I'll give him a few trial rides at the track and see how it goes.

Thanks everyone


11/15/2017 2:42 PM

jmz313 wrote:

18" from real brands are pretty big bikes. My smallish 11 year old just moved to one at 55" tall. I foresee him on it for a ...more

I had looked at that since the 16" subrosa I looked at is huge compared to the pitboss but he is at the very end of the size guidelines from WTP and Sunday, etc. he's almost 47" tall

As much as I don't want him to get old....I don't want a bike that he'll outgrow in 6 months

The 16" WTP has the same crank length and BB height as his redline. I couldn't see that being any better

I figured I can start with the handle bar back a little to compensate for the longer top tube


11/21/2017 4:59 PM

BMX track -- are you looking for a RACE bike? I assume you want to be competitive? Don't look at these heavy-ass street/park bikes everyone is recommending. Look at an 18" or 20" wheel micro race bike.

Here's my daughter at 4-and-change on her GT micro. Best advice is hit up your track, look at the little kids, and ask parents if your kid can check out the bike and fit it for size. Turn3 Racing has some really small frames. I assume you want to buy complete though.



12/25/2018 8:28 AM
Edited Date/Time: 12/25/2018 8:28 AM

Aren't 20" bikes already kids bikes?

I'll let myself out....


I don't crash, I do random gravity checks...