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Mongoose

Mongoose Legion BMX Bike, 16, 18 or 20 Inch Bike for Kids and Adults, Hi-Ten Steel Frame, 25x9T, 36x16T or 40x16T Gearing, Black/Teal, Silver, Orange, Red, Green, Black or Light Blue

  • Based on 4,127 reviews
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Color: Silver/L18


Size: 18-Inch Wheels/L18


Features

  • Legion L18 is the perfect in-between option for our kids who wants the features of a standard 20 inch BMX bikes but require a slightly smaller frame, rider height recommendation is 3'8" to 4'8"
  • Durable Hi-Ten steel frame with 16.9 top tube length
  • Single speed drivetrain features a 140 mm one-piece crank with a 25T alloy chainring and American loose ball bottom bracket
  • Wheelset features 18 x 2.3 tires mounted on aluminum single wall 28H rims with 3/8 female axle front hub and 9T cog sealed bearing cassette rear hub
  • Aluminum U-brake provides precision speed control, while the Hi-Ten steel handlebar and fork are joined by a 40 mm stem and threadless sealed integrated headset for maximum steering performance

Description

Unleash the fun with the Mongoose Legion Mag, the perfect BMX bike for kids. With 16, 18 or 20-inch wheels, this kids bike is ideal for riders from less than 3'6"" - 6'0"" tall, offering a thrilling way to build confidence and skills. The hi-ten steel frame is tough enough to handle jumps and turns, while the 25x9T, 36x16T or 40x16T gearing keeps the ride nice and smooth. Aluminum mag wheels with sealed bearings ensure you’re on the coolest bike on the block. Alloy rear U-brakes offer reliable stopping power to help support your next trick or stunt. Young riders can feel like BMX pros. Assembly is easy with a few common household tools and the included instruction guide. At Mongoose, we know our roots – as pioneers in BMX and action sports for over 50 years, we're dedicated to delivering an epic ride every time. Get ready to push the limits.

Bike Type: BMX Bike


Age Range (Description): Little Kid


Brand: Mongoose


Number of Speeds: 1


Color: Silver/L18


Wheel Size: 18 Inches


Frame Material: High Tensile Steel


Suspension Type: Rigid


Special Feature: freestyle, Aluminum Frame, BMX


Included Components: Legion L18, Bicycle


Bike Type: ‎BMX Bike


Age Range (Description): ‎Little Kid


Brand: ‎Mongoose


Number of Speeds: ‎1


Color: ‎Silver/L18


Wheel Size: ‎18 Inches


Frame Material: ‎High Tensile Steel


Suspension Type: ‎Rigid


Special Feature: ‎freestyle, Aluminum Frame, BMX


Included Components: ‎Legion L18, Bicycle


Size: ‎18-Inch Wheels/L18


Brake Style: ‎U Brake


Specific Uses For Product: ‎Trail


Item Weight: ‎12 Kilograms


Style: ‎L18


Model Name: ‎Legion Novice


Power Source: ‎Pedal power (human energy transferred through a drivetrain)


Wheel Material: ‎Aluminum


Year: ‎2020


Seat Material Type: ‎Plastic


Warranty Type: ‎Limited


Assembly Required: ‎Yes


Is Autographed: ‎No


Number of Handles: ‎2


Global Trade Identification Number: ‎60


Minimum User Height: ‎38 Inches


UPC: ‎038675187160


Bicycle Drivetrain Type: ‎Single-speed


Manufacturer: ‎Pacific Cycle, Inc.


Item Package Dimensions L x W x H: ‎43.31 x 21.26 x 9.06 inches


Package Weight: ‎14.3 Kilograms


Item Dimensions LxWxH: ‎23.62 x 8.66 x 48.82 inches


Brand Name: ‎Mongoose


Warranty Description: ‎Limited lifetime warranty on frame and one year warranty on parts


Material: ‎steel


Suggested Users: ‎unisex-child


Number of Items: ‎1


Part Number: ‎M41700U10OS-PC


Date First Available: August 6, 2019


Frequently asked questions

This product is currently out of stock. Please check back later for shipping info.

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

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Similar Products

Top Amazon Reviews

    • Extremely Easy to Assemble. Bike Looks Amazing. M8x1.25 Tap May be Needed.
Color: Orange Size: 20-Inch Wheels/MAG
Review Image by Dave Dave
Review Image by Dave Dave
Review Image by Dave Dave
Review Image by Dave Dave
Review Image by Dave Dave
Review Image by Dave 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 Dave
    • Kiddo loves this bike!
NICE bike after training wheels! HEAVY DUTY!
Reviewed in the United States on June 17, 2025 by Shane Brock
    • Great Purchase!
Color: Black/Teal Size: 20-Inch Wheels/L10
I had no previous experience with this brand of bikes before this, but bought this and two others as Christmas gifts. Wow!! My kids love these bikes! Well made, easy to assemble, great value. The first day my kids were ready to ride several miles on these bikes. The thicker tires made it easy to go over multiple types of terrain. Everything is just really well made and put together. Super stoked about this purchase and the two others! ... show more
Reviewed in the United States on December 28, 2024 by E. S.
    • 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 for a 10 yr. old.
Color: Orange Size: 20-Inch Wheels/MAG
My 10 year old grandson loved this bike!
Reviewed in the United States on April 7, 2025 by SMartin
    • I Will NEVER buy another Mongoose
Color: Orange Size: 20-Inch Wheels/MAG
With all of the four and five star ratings, I must be the problem, right? The bike came partially dissembled for shipping purposes. I expected that. What I did not expect was: 1. Missing parts. One of the nuts and both of the washers were missing from the front wheel. Ok. A shipping problem. But what kind of washers do I need to go find? Should be simple. Just read the instructions. 2. Horrible Instructions: For example, to attach the front wheel, I need to follow the appropriate set of instructions depending if my bike's wheel is, "nutted with step retaining washer, nutted with clip retaining washer or quick release". But I don't know which one my bike is; the nut and both washers are missing. Every section is just like this; follow the set of instructions that pertain to your bike. But where does it say if the bike I purchased has a quill stem, a threadless stem, a front load stem or a top load stem? I have no idea. Mongoose has been around for a while. So there are plenty of videos on YouTube. But there are so many configurations for Mongoose bikes, good luck finding the right one. I watched a bunch of videos, went to Wal-Mart (twice) and got $30 worth of nuts, washers, hex drivers and, no I didn't go out and buy the lithium gel they recommended! Then I paid a bike shop $45 to put the thing together because I still couldn't figure it out. The bike shop wouldn't do the brakes because of liability purposes. But they showed me that I needed to loosen a nut and put the brake cable out some. Should be easy, except... 3. CHEAP parts!: I stripped a nut and two screws trying to tighten the brakes just enough to barely work. It's Christmas Eve and I'm soooo frustrated. Should I be worried? Every single step in the instruction book says that if I don't do this step correctly, someone could get seriously injured or killed. Here ya' go son. Have fun! Merry Christmas. I could call Mongoose Customer Support. They are open Monday through Friday 8 to 5; because that's when dads assemble bikes right? Sorry for all of the venting. I've had the bike for a week and I have to say, I have NEVER had this much trouble assembling something that came in a box. I've got $250 invested into a $170 bike and I don't feel safe letting my son ride it. I am not a happy customer. ... show more
Reviewed in the United States on December 25, 2020 by Jared D.
    • Great quality
Color: Silver/Mag Size: 20-Inch Wheels/MAG
Our 10 year old, very athletic, grandson loves his new bmx. Does all the tricks and track work he wants.
Reviewed in the United States on February 17, 2025 by CocoS
    • BMX bike
Color: Red Size: 20-Inch Wheels/LSX
grandson loves it
Reviewed in the United States on March 21, 2025 by Pom

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