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Assembly of kid's bike, bicycle from dad blog
Well, that's it. Except for the seat. I forgot to take that shot, but they are easy. This one had a quick-release clamp, so it was: insert post, close the clamp.

Assembling Kid’s Bikes

Assembling the Mongoose Mutant 16″ Boys Freestyle Bike to be exact.

The kids went from swaddled little burritos to training wheels…awfully fast.

Today my son and daughter, fraternal twins, turned four.

I remember on the morning they were born—I was remembering bringing home my first born.

Got that?

You know, there’s no manual. You don’t really know what to do. You leave the hospital and are like…

Holy Crap There’s No Call Button Now.

Then you figure it all out. So it must be easier with your second child, right? Well not if you’re second child is actually your second and third.

So I was back to feeling the same as the first.

Holy Crap What are We Going to Do?

Well, we made it four years now. About 43,000 fights over position on the couch, toys, dinner portions, dessert portions, socks and who gets what tricycle. A few cuts, scrapes, fat lips and black eyes. One incident of stitches (from a tricycle).

Well here’s the golden nugget:

Two of everything.



That’s what we had to do.

At least until now.

Now we just need to do two of everything, but “similar.” We can get away with similar because gender now plays a huge factor in their decision-making. It blurs the threshold of identical back into the land of similar.

Enter the birthday presents. Big Boy/Girl bicycles. One boy’s bright-orange-loud-graphics-with-footpegs-so-you-can-freestyle and one girls’ pink-with-tassles-and-handlebar-purse-with-baby-seat-for-precious-dolly-to-ride-along bicycles.

Take away all that stuff and they are two 16” bikes with training wheels.

See? Similar.

Here’s how to assemble them. And I’ll only do one, the Mongoose Mutant 16″ Boy Freestyle Bike, cause the other is…well…similar.

Here’s what you’ll need:

  1. Leatherman tool (or equivalent) from your back pocket to cut open the carton, and other stuff
  2. Metric wrenches (10mm, 15mm)
  3. Philips Screwdriver for attaching flair
  4. Unfancy pliers
  5. Allen Wrench (I forgot to write the size, but it’s metric, maybe 5mm)
  6. A radio that only seems to tune in classic rock, a fan to take the edge off the stagnant 96-degree heat and a dirty shop floor to sit and assemble it

That list worked for both bikes, although they’re different brands. Probably both made next to each other on the same assembly line in China.

#6 seems to work for anything I’m working on.


Tools to assemble a kids bike

Here’s the tools. You only need these, but have my permission always to use more tools if you can. Don’t bother breaking out the SAE, ’cause China=Metric.

Before I go over assembly, just throw away the assembly instructions right now. Not because it’s a man-thing. Because it’s made in China. Both instruction booklets were “generic” with illustrations of a men’s 26” cruiser. Absolutely useless.

I think I’ll step by step this via photo captions. Go.

Or stop and wait for 20 photos to load.

Dad blogger unpacks child bike to assemble

Unpack the bike from the abused and torn carton since you refused to buy the assembled version from Wal-Mart. No offense, but by the looks of some of the associates at our Wal-Mart, I can only imagine the bicycle assembly department is where old carnies go to “retire”. I won’t let my kid ride the back o’ the truck ferris wheel, nor a bicycle I didn’t assemble myself…


Kids bike front wheel assembly

I chose to start with the front wheel. Tip the bike shiny side down and put the front wheel in the forks.


Front wheel washers and nuts for kids bicycle

There’s a washer for each side. This a) locks the front wheel within the fork due to the shoulder on the washer and; b) provides support for the front freestyle pegs.


Did I really have to show you how to use a wrench to tighten the nut? Well, I finger-tighten each side, then a few turns on the left, then the right, then left, right…so the hub spindle stays centered within the fork. It used to be you could tighten one side and see that the spindle was sticking out too far on that side. I guess it’s just habit.


Freestyle BMX Footpegs

Here’s the freestyle footpegs going on. Hand tight, then it has a hole you can run a screwdriver through to tighten it up. Not sure how many Dork Manuals a four-year-old will be doing on a bike with training wheels, but you never know.

Dork Manuals?

Training wheels on a kids bike

The training wheels are next, and they ride on a metal spacer that locks them in the rear wheel channel. Add the nuts finger-tight so you can turn the bike right-side up, and adjust the training wheel height later.


The handlebars came assembled in the gooseneck backwards. So use the allen wrench to pull the top off the gooseneck and flip them around.


Here's a shot of the gooseneck.

Here’s a shot of the gooseneck.


I inserted the gooseneck into the headset, then the handlebars go on, after you get the brake cables all untangled.


Aligning handlebars on a child bike

I’ve got to get the handlebars aligned with the front tire/forks now. I usually sit on the seat, squint and use one eye to size it up. Then tighten with allen wrench.


If you’ve never done this before, the only useful thing you’ll find in the assembly manual is that the pedals are marked L and R, for left and right, repectively. Duh. Nah, really, the left side has reverse threads so the pedal doesn’t come off as you ride it. (That’s called precession). So when you can’t get the pedal to thread, try rotating it the opposite way. Bam.


Adjusting training wheels on child's bike

Now time to adjust the training wheels. Place on flat ground, tires at proper pressure, and I tried to make the height of each training wheel, well…similar.


I left about 1/2″ off the ground on both sides so he wouldn’t get all jerky and wobbly while riding.


Adjusting the brake levers. They were rotated down for shipping, so I raised them up to provide easy access while allowing a good grip on the bars. Tighten with yer allen wrench, but not too tight, this is China plastic we are dealing with. And I don’t want the lead to leak out of the plastic if I break it.


Dad blog child bike brakes

Now I adjusted the brake calipers. See the gap from the pad to the rim? There was alot of play in the handbrakes to get some stopping power. So I wanted to shorten the throw.


Adjusting brakes on kids bike

Take yer 10mm and loosen the cable retainer. Grab yer Unfancy pliers. And get ready to wish you had three hands.


Dad blogger assembles kids bicycle and adjusts brakes

Here’s where you wish you had three hands—four if you are trying to take a photo at the same time. You have to pinch the calipers together so the brake pads are about 1/4″ from each side of the rim, then use the pliers to tension the cable through the retainer, then use the 10mm to tighten the reatiner nut, all while trying to keep the calipers pinched.

Assembly of kid's bike, bicycle from dad blog

Well, that’s it. Except for the seat. I forgot to take that shot, but they are easy. This one had a quick-release clamp, so it was: insert post, close the clamp.


Happy Birthday Frank and Stella!


  • David Hemmer

    Would you be willing to help me with one question regarding putting the front wheel on this exact bike. The ridiculous manual says if there is a washer on the front axle it shoudl go outside the fork, but there’s one really tight up against the center that seems like it belongs there, but I can’t quite get the fork on. I could send you apicture. Please help!


    • Pete Fazio

      Sure, send a pic to and We’ll try and hook you up somehow.


    • Marty

      Yeah, As I remember, the washer goes on the outside locking the front wheel into the fork so when your little one does a wheelie, the front wheel won’t fall off!

      The 4th picture down in the post illustrates this.

      The washer was packaged on the front axle and the diameter of the hole in the washer was a little dirty due to some excess metal when the hole was punched and flared to create the ridge, making it a little stubborn to actually remove from the axle.

      Hope this helps. Now go do some wheelies.


  • car hire malaga

    Thanks for finally writing about >Assembling Kid’s Bikes – <Liked it!


  • ky

    Just wanted to say thank you for this! I spent about an hour the other day trying to decipher the Mongoose instructions, totally frustrated and po’d at the stupid thing and the company. Your instructions were great, and we were able to put the bike together with no problems.


  • JerseyPunker

    I had to laugh at the line about not trusting the retired carnie/WalMarx assembler. For some reason, perhaps because Santa was exhausted, we didn’t think to check SHIT before letting the kid hop on to try sitting on it in the living room. What could happen? Well, when gravity laid down the law, as well as the bike and kid with the training wheel going sideways and the handlebars and front wheel following suit, I couldn’t help but laugh. She was fine of course. It’s now April and we’ve finally got her excited about hopping on again. Funny thing is I’ve worked at a couple big chain auto shops and big box retailers and knew how bad the assemblers could be, and would never trust anyone I didn’t know well working on my grill, my car, my skateboard, or my bike when I had one or when I get another soon. I dunno. I guess I put too much faith in Toys ‘Я’ Us.


  • Fred Mackey

    Wonderful information here. Great job. I do have a question though. Should the plastic piece on the quill stem be removed ? Seems like it won’t insert properly if left on.



  • Jeremy

    I’ve always tried to have my kids part of the bike assembling process. Though I found that when it comes time to adjust the caliper brakes they end up learning that their dad doesn’t have patience and mildly swears :)


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