Mongoose 20-inch MTMX Mountain BMX bike

Alloy front caliper and steel rear V-brake

By Mongoose

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Description & Features+

Mongoose 7-speed Mountain BMX bike is great for the kid who wants the performance of a BMX bike and the durability of a mountain bike. This 7-speed twist shifters adds to the excitement of this performing bike.
• Expanded BMX rider fit with mountain bike functionality = MTMX
• Falcon 7-speed twist shifter
• Alloy 4 bolt stem
• Alloy front caliper and steel rear V-brake
• Multi-surface tires with alloy multi colored spokes
• Always wear a helmet when riding


Available for Shipping to Canada Post
Assembled Height
37 in
Assembled Length
55 in
Assembled Weight
29.5 lb
Assembled Width
24.8 in
Product Identifiers
Walmart Item #

From the Manufacturer +

Ratings & Reviews+

Mongoose 20-inch MTMX Mountain BMX bike is rated 3.7 out of 5 by 27.
Rated 5 out of 5 by from Great little bike! This 20" bike was easy to set up, less than an hour and the wheels hit the pavement! Of course, this is not the first bike that's had to assembled so maybe it was easier for us. It is a great little bike to ride or even to try some free styling moves! It has 7 gears for your riding pleasure, the tires are a little wider for better traction and handling and overall comfort. The seat is easily adjusted, no tools required, which makes it nice when the kids take turns trying stunts. Our 9 year old never rode a bike with gears and she came back so excited because it was so much easier to get up the little hills in our neighborhood. Our older one told us that the gears shift much smoother than the old bike that they have so we were glad to hear that too. Along with the features that come with this bike, it is also nice looking and in my opinion could easily be for a boy or a girl. Our girl is enjoying riding this bike around the neighborhood with her friends and she isn't a tomboy by any means. Our family is enjoying this bike and I had my 8 year old nephew come over to try it and now he wants one too! [This review was collected as part of a promotion.]
Date published: 2015-11-06
Rated 5 out of 5 by from super bike!!!! this bike is really awesome for going everywhere on bumpy roads ! The gears from 1-7 work really awesome. This bike is a great bike.
Date published: 2015-10-07
Rated 3 out of 5 by from I'd give 3.5, but it won't let me The bike seems pretty sturdy and it better last awhile! I ordered it and assembled it myself. I had no idea i was going to need a collection of tools, namely allen wrenches, in order to assemble it. If that sort of info was mentioned in the description, i could have made the necessary purchase when i bought the bike. Small detail, but it was annoying. The bike came partially assembled. Mine came with handlebars upside down and backwards. Fixable, but another annoyance. The instructions are better than most these days as they are more than just pictures. But as others have stated, they are for several different models and that can be confusing. I had an issue with the brakes and after watching every video on-line and reading all of the instructions, i still found no answer. So i took it apart and started over and was able to put the clip back in which had slipped out in the tightening process. If you hate assembly or feel like it may be too complicated, have it done at the store. I called to see about bringing it in when i hit the snag with the brakes and was told they were so backed up, they couldn't tell me when it could be looked at, let alone fixed. Try telling that to an 8 yr old boy. It's done, but not because the instructions were clear or helpful with the issue! The chain popped off on the maiden voyage, but i think that was operator error. We are having difficulty with the concept of gears. This is more mountain bike than bmx, so if you are dealing with a younger child and/or one who has only had the simple, gearless bikes, be prepared! You can not go 1-7!! Seemed like common sense to me, but not to my son. The reflectors came already on the bike, but they constantly are in the way and will probably need to be relocated. Once it's together, it seems solid and sturdy. I'd do it all again, but this wasn't my first experience and i actually enjoy it...usually. i wish they would provide instructions for your model only, but at least they were in english.
Date published: 2016-06-16
Rated 5 out of 5 by from Best purchase we could have made for our son! We purchased this bike for our 8 year old son who previously had a Mongoose Mode 100 Bmx bike that we had to return. We did a ton of research before deciding to purchase this Mongoose MTMX bike for him. The previous bicycle was wonderful as far as being structurally built well and smooth riding. However, the previous bicycle was a longer length than most typical bikes, making it harder for my son to turn sharp curves and then a mechanical issue with the brakes, most likely from my son taking several falls due to the length of the bike wasn't a correct fit for him. I included this extra information about the previous bicycle because this wasn't a main concern to begin with for us, but soon learned that the length of the bicycle needs to be a correct fit for the best maximizing ride without over correcting easily. When researching, we originally wanted to purchase a single speed bike, he was used to the bmx style and all his friends have that type style bike. However, after researching and looking at each one in the store, my son loved this Mongoose MTMX, it has the Bmx look and style but also has 7 speeds to shift through for biking up hills and trails. The person helping us at the store, recommended it as well. My son rode it around a bit and was able to go through sharp turns easily, swiftly and stop on a dime. The bike rides smooth, goes well on trails, it was easy for him to learn to shift gears and he still has a bicycle that is a lot like a BMX. His friends love the bike as well, they all ask to ride it from time to time. They comment how easily it stops and they love shifting gears going up the hill by our house. The best part, I now am not replacing bandaids constantly from wrecks and falls, like the previous bike, which I believe is because this one is the correct length for my son and when he turns it isn't easy to over correct like the previous bike. The bicycle itself is the perfect weight, easy for me to lift and put in our suv to go trail rides, light enough for my son to get the speed he needs but not flimsy made either. The tires of all Mongoose bikes seem to be the best constructed I've seen from department stores. The shifter on the handle bar is sturdy and the chain grabs quickly without making jerky movements to change from one gear to the next. My son can stand while changing gears up a hill! For those parents who remember changing speeds from bicycles not long ago, that was impossible, with the jerky movements. The chain also stays tight, no matter who has rode my sons bicycle, through changing gears and others riding it, it holds up well. A favorite thing that everyone seems to notice is the spokes have 2 that are completely bright orange on the front and back. A nice little touch of color for one cool bike. The last thing I want to include is the seat is well constructed, it feels like memory foam, the seat is a bit wider than the previous Mongoose my son had, his comments were that the previous bike had a narrow seat that was longer and would hit his legs making it uncomfortable at times to ride. This bike for him, the seat feels comfortable, which means he wants to ride his bike pretty much non-stop. I like the design on the seat to match the rest of the bike with the orange and gray color scheme. I highly would recommend this bicycle for the above reasons and for these reasons: *Construction of bicycle A+ *Weight of bicycle A+ *Easy to shift and no jerky movements when shifting, chain stays put, gears are smooth changing and easy to learn A+++ *BMX style but a Mountain Bike, the color scheme all are appealing A+ *Brakes are excellent, stop on a dime A+ *Seat is well constructed, memory foam, wider than most and not uncomfortable after a long trail ride A++ *length of bicycle makes it easy to maneuver, not too long, makes it easy to do stunts and ride trails A+ *right under the $100 mark in price, well worth the money, the frame and style remind me of a much more expensive bicycle A+ *Tires of the bicycle are rugged, thick, but not huge making the ride smooth no matter what surface the bike is being rode on. A+++ *color scheme is cool, the spokes have 2 spokes that are painted orange, seat has some orange gears on it to go great with the gray and orange theme. A+ My only complaint which is minor, but still is something for a con, the frame has the Mongoose logo and cool orange accents, but we learned that it isn't painted onto the frame, they are all stickers. So in time that could peel off. I think since they went great lengths to paint the spokes with orange and the seat, the frame shouldn't have had stickers for the name and accents. But, for a bike at the $100 mark, that is minor! I give that grade a C- for the stickers. Hope this review helps, while rather long, I like to give a full opinion. I go by a lot of reviews when selecting items, I find it helps in deciding a product that will last. I believe this bicycle will be one that will get a lot of use until my son outgrows it. The purchase for us was a very positive experience and I would definitely recommend this bicycle 99.9% and give it two thumbs up!
Date published: 2015-06-06
Rated 4 out of 5 by from Premium look, nice performance The Mongoose MT mountain bike was a really smooth combination of mountain bike and 'street' bike. It is light enough to allow the rider to perform jumps and tricks, and can easily be carried if needed, which is perfect for moving from location to location or up or down stairs. The assembly went smoothly enough, and I found you can adjust the height of the handle bars and seat. The shifting of the gears isn't flawless, but does work nicely (7.5 out of 10 for now, though I expect it was become easier to slide with use). I really enjoy that there are 7 different gears as opposed to the common 5. The pedals come with traction nubs on them to help prevent slipping when riding. At one point, I went over a speed bump at the local park and thought I snapped the brake line, but it fed straight back through, so that was a relief. On the other hand, I found the seat to be small and VERY uncomfortable and should be redesigned especially since this bike is intended to be both mountain and street bike. The height of the seat was an issue as well. It was too short to sit down on comfortably, and there was no way to make it taller. Although I am bigger than the average rider might be, I am still a pretty short person, so again, I think the seat should be on a longer post. The colors (grey, black, and orange) were nice and very unisex. I would hope it can be bought in more varieties of colors, sizes and styles. All in all, the Mongoose MT is a bike to keep in mind if you're looking for a bike for a petite person or a kid between the ages of 8 and 18. It's a great value for what you get. [This review was collected as part of a promotion.]
Date published: 2015-11-10
Rated 5 out of 5 by from Adjustable as child grows So I received the 20" Mongoose MTMX Boys' Freestyle Bike in Gray.  It came in a box to be assembled. I am sure to most people this would not be an issue, but for a single lady with not a whole lot of arm strength this was more than an issue. Don't get me wrong, I do most everything for myself so a bike should be a breeze. And I have to say the pedals and attaching the front wheel was not hard at all, but the handlebars were another story. The bolts were on so tight it took me three days working on trying to loosen the bolts to finally get them off just to make a simple turn of the post and retighten. I think I stripped one or two of the bolts in the process. Needless to say I was more than a bit frustrated before it was even ready to be ridden. I have to say the bike itself is very nice looking and seems very solid. It, like most bikes I assume, has an adjustable seat height as well as handlebar height. When reading the directions it looks like there are a few upgrades you can do with the bike for those looking to use it for more than just leisurely riding. My grandson is an average size 6 year old, and it is the perfect size for him to ride comfortably at the lowest heights. So this bike should grow with him for several years. It has nice heavy duty tires and handlebar brakes with 7 gears. The gears are a little tight for the 6 year old to do by himself, but he still rides it with no problems.   Maybe the gears will loosen up a bit after a little use. I would give the mongoose mtmx bike a great review if only they could deliver it preassembled. It does state on a tag that Walmart will assemble for free, but since it was ordered online and delivered to my home, I didn't want to drag it to the store in pieces. I highly recommend having Walmart assemble it for you. [This review was collected as part of a promotion.]
Date published: 2015-11-01
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