Search  for anything...
Mongoose

Mongoose Legion Kids Freestyle Sidewalk BMX Bike

Based on 4,033 reviews
Condition: New
Checking for the best price...
$249.99

Buy Now, Pay Later

As low as $41.67 / mo
  • – 6-month term
  • – No impact on credit to apply
  • – Instant approval decision
  • – Secure and straightforward checkout

Ready to go? Add this product to your cart and select a plan during checkout.

Payment plans are offered through our trusted finance partners Klarna, Affirm, Afterpay, Zip, Apple Pay, and Google Pay. No-credit-needed leasing options through Acima may also be available at checkout.

Learn more about financing & leasing here.

Selected Option

Free shipping on this product
This item's return window has been extended for the holiday season: FREE refund/replacement until Jan 31, 2027

To qualify for a full refund, items must be returned in their original, unused condition. If an item is returned in a used, damaged, or materially different state, you may be granted a partial refund.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

Availability: In Stock.
Fulfilled by Amazon
Arrives Monday, Nov 16
Order within 1 hour and 56 minutes

Available payment plans shown during checkout

Protect Your Purchase

Easy claims online, fast replacements, no fees

Checking for protection plans...

Recently Viewed

At a glance

Condition
New
Size
20-in Wheels/L10
Color
Grey
Model
M4136G27U2OS11
Weight
28.6 lb
Material
High Tensile Steel
Bike Type
BMX Bike, Kids Bike
In the box
ReflectorsUser Manual
Warranty
Limited lifetime warranty on frame. 1 year limited warranty on parts. 30 day limited warranty on wearable parts.

Features 5

  • FIRST REAL BMX: Designed for riders 5'3" to 6'0" tall, this freestyle bike combines full-size 20-inch wheels and authentic BMX geometry for progression on the street and at the skatepark.
  • CONFIDENT GRIP: Wide 2.3-inch tires provide confident traction on pavement, park surfaces, and packed dirt. Built to help riders stay planted while building skills and trying something new.
  • BUILT FOR PROGRESSION: A durable 1-piece crank helps keep pedaling smooth and reliable while developing strength, balance, and bike control through every stage of learning.
  • TRUE BMX FEEL: A 9T alloy rear hub pairs with BMX-specific gearing for responsive acceleration and a ride feel that's right at home on jumps, transitions, and neighborhood sessions. Alloy U-brakes provide dependable stopping power.

Specs 35

Bike Type BMX Bike, Kids Bike
Age Range (Description) Youth
Brand Mongoose
Number of Speeds 1
Color Grey
Wheel Size 20 inches
Frame Material High Tensile Steel
Suspension Type Rigid

Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Monday, Nov 16

Yes, absolutely! This item's return window has been extended for the holiday season: FREE refund/replacement until Jan 31, 2027.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

  • Klarna Financing
  • Affirm Pay in 4
  • Affirm Financing
  • Afterpay Financing
  • Zip Pay in 4
  • Financing through Apple Pay
  • Financing through Google Pay
Leasing options through Acima may also be available during checkout.

Learn more about financing & leasing here.

Similar Products

Top Amazon Reviews

GREAT BIKE! HIGHLY RECOMMEND.
Size: 20-Inch Wheels/MAG Color: Orange
Review Image by Big Daddy
I assembled it today and it took 20 minutes tops. If you have ever assembled anything before then it should be fairly easy. I didn't open the manual for instructions besides confirming my suspicion of which direction the large washers with the raised ridge were orientated. The raised edge goes inwards towards the forks FYI. The brakes were very easy to adjust, I seen reviews stating how difficult they were to adjust or setup. Not sure why but they couldn't be a more basic setup. I also recommend making sure the bearings in the fork tube are not to tight. The ones on the bike I received were WAY to tight and you could physically feel individual bearings moving when you turned the handlebars. After adjusting accordingly it moves nice and smooth. I saw a review that their stalk broke and this could be why it broke. If they are to tight you can damage them and eventually the stalk as well. I definitely recommend this kids freestyle bike. Brings back memories of my bmx bikes back in the 80's. The orange color is awesome as well. Especially since my grandson is a big Oregon State beavers fan. ... show more
Reviewed in the United States on September 1, 2026 by Big Daddy
Extremely Easy to Assemble. Bike Looks Amazing. M8x1.25 Tap May be Needed.
Size: 20-Inch Wheels/MAG Color: Orange
Review Image by Dave
Review Image by Dave
Review Image by Dave
Review Image by Dave
Review Image by Dave
Review Image by Dave
The bike from the pictures looked pretty cool. I didn't realize how beautiful this bike would be until it came in the mail. I purchased the Legion Mag in orange for my 8 year old. It was great to see his reaction on Christmas when receiving this bike. He was so excited. I read some other reviews from reviewers who had complaints on the difficulty of assembling the bike and in my opinion the people having trouble assembling the bike must be blatantly ignorant or illiterate. The instructions for assembly are written so a teenager could assemble this bike, with clearly labeled diagrams and more in depth explanations than what is necessary for assembly. The instructions on assembly are excellent and I had almost no trouble assembling the bike without them until it came to adjusting the brakes. I assembled the entire bike without instructions except for the brakes because it is just self explanatory. I was also able to assemble the brakes without any trouble or needing the instructions although I did refer to them for proper adjustment and alignment protocols. The only issue I had when assembling the bike is when I got to the point of attaching the handlebars to the handlebar binder assembly attached to the stem. The four socket cap screws that tighten down on the handlebar binder bracket would not thread easily. I felt as though I would break the screws or destroy the threads if I attempted to tighten them down far enough to grip the handlebars. There was too much paint in the threaded holes and also the tolerances on the machining of the threads was not great. I have included some pictures showing just how much paint was removed from tapping and also chips from burs in the threaded holes from poor tolerance drilling and tapping at the factory. In order to fix this problem I grabbed a tap handle and a M8x1.25 normal thread tap and tapped the holes. I would give this bike a 4.9 out of 5 if I could just because I needed to tap these holes and a tap was not listed as a required tool. I don't think many people will have problems assembling the bike even if they have this issue and need to tap the four holes as these are the only holes that need anything to be screwed into. Honestly if you don't at the very least know how to use a tap and die set you probably shouldn't be assembling a bike as it's not safe to do so if you're not familiar with basic tools. You could wind up hurting your child from pure negligence if you don't know how to use basic hand tools to assemble this bike properly. My suggestion is that you take it to a local bike shop and pay $30-$40 to have them assemble the bike and adjust the brakes if you don't know what you are doing. I assume some people who buy this bike will do just that with the majority of people knowing how basic hand tools work and them being able to assemble it themselves. Overall the bike is amazing, my son loves it, it was extremely easy to assemble, and I recommend you tap the holes on the handlebar binder even if it doesn't need it as it will allow you to make a more secure connection. Please don't listen to people complaining about difficult assembly as it was extremely easy even the detangler brakes something of which I've never seen or dealt with on a bike before. The instructions are very clear on how to hook the brakes up and how to adjust them properly and I was actually surprised how easy it was to assemble the brakes because I was expecting something very difficult based on the reviews but it turns out these brakes are easier to assemble than normal brakes. ... show more
Reviewed in the United States on December 30, 2020 by Dave
Amazing Color!!!
Size: 20-Inch Wheels/MAG Color: Orange
Review Image by BILLY FLORES
Review Image by BILLY FLORES
Great product, my son is happy. It just remains to try it on the street.
Reviewed in the United States on September 1, 2026 by BILLY FLORES
It's nice...
My 5 ½ year old boy is a little bit taller & thicker than most of his peers & the bike is almost too big for him but that was kind of the goal when deciding to upgrade his BMX. He was way to big for his first peddle BMX bicycle, so it's nice he'll grow into this one & he really seems to be enjoying it. I did throw a front brake on there just because I had one laying around that fit perfectly but tbh I adjust that to where it barely grabs because we're not too keen on him doing an indo & knocking his teeth out. There's no peddle brake on this bike, so if you're going from a bigginner bike, that almost always have the rear peddle brake, just be aware this has a hand brake, it does require large enough hands to reach it, & a bit of strength to get the brake to engage. All in all, so far, it's a nice BMX for a 5 ½ to say up to about 7 or 8 years old depending on how big a kid. I wouldn't consider this a beginner bicycle, it's more of a 2nd or 3rd bicycle not a 1st IMO. ... show more
Reviewed in the United States on October 17, 2024 by JJ47
Great bike
Size: 18-Inch Wheels/L18 Color: Silver/L18
My son, absolutely loved this bike when he received it, and it was put together, the bike was perfect for his size. It rode very smooth and I feel like I got what I paid for unfortunately after moving into our new place, the bike was stolen from our backyard
Reviewed in the United States on May 29, 2026 by Latisha
Good quality Bike
Size: 20-Inch Wheels/MAG Color: Orange
Great Bike for a beginner and a leap above Huffy and Walmart bikes. I remember Mongoose being a Good recognizable brand decades ago. This bike was easy to assemble. I think it took an hour to unbox and put together. Box was damaged heavily, but bike was packed so well with foam and wrapping that there wasn't a single scratch. The most important part is the kid is happily surprised and liked the color. ... show more
Reviewed in the United States on March 2, 2026 by The Real Hughleys
Reason they sell Mongoose at Walmart..
Size: 20-Inch Wheels/MAG Color: Orange
Update: dropping this from 2 to 1 star, complete junk. Front tire doesn't take air, needing to go buy new tube. Once rear tire has air, it rubs on the brake controller that cannot be moved.. Will need lower profile tires on top of the seat post already replaced. BE PREPARED TO PUT ANOTHER $50 into this bike just to use it!!! I wanted better model than walmart was selling, doesnt seem any better. Seat post is 7 inches long, all the way up its 1ft from crank shaft in up position!! Really, my normal sized 11 year old has his legs almost 40 degrees higher than parallel when pedaling.. This isnt a 16 inch bike, 350mm post on way. Bottom of 360 rotor was bent on 1 end from transit damage, bent back enough to attach brake cable. The so called foot pegs are a joke, they are smooth!! If a kid actually used them, they would slip off and break their foot. Rear brake setup is as lame as most reviewers state, cant even put old school pad on frame.. ... show more
Reviewed in the United States on September 4, 2019 by vtwin
A very happy kid!!
Size: 20-Inch Wheels/MAG Color: Orange
Mya nephew was very happy......
Reviewed in the United States on May 3, 2026 by Imanuel Hodges
How it works
Checking for best price...