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๐ตโโ๏ธ Own the trail, donโt just ride it!
The Mongoose Flatrock is a versatile adult mountain bike featuring 29-inch wheels and a lightweight 6061 aluminum frame designed for riders 5'4" to 6'2". Equipped with a 21-speed drivetrain and mechanical disc brakes, it offers smooth gear shifting and reliable stopping power for diverse terrains. Its knobby tires and double wall alloy rims ensure durable traction, while the front suspension fork absorbs bumps for a controlled ride. Backed by Mongooseโs 50+ years of BMX and action sports expertise, the Flatrock is built to push limits and elevate your off-road adventures.

















| ASIN | B08PXN962L |
| Additional Features | Lightweight |
| Age Range (Description) | Adult |
| Age Range Description | Adult |
| Best Sellers Rank | #52,241 in Sports & Outdoors ( See Top 100 in Sports & Outdoors ) #29 in Mountain Bikes |
| Bicycle Drivetrain Type | Derailleur |
| Bicycle Gear Shifter Type | Twist Grip |
| Bike Type | Mountain Bike |
| Brake Style | Disc |
| Brand | Mongoose |
| Brand Name | Mongoose |
| Color | Red |
| Customer Reviews | 4.1 out of 5 stars 426 Reviews |
| Derailleur Configuration | Rear |
| Frame Material Type | Aluminum |
| Included Components | Flatrock Bike |
| Is Assembly Required | Yes |
| Is Autographed | No |
| Item Type Name | Mountain Bike |
| Item Weight | 16.8 Kilograms |
| Manufacturer | Pacific Cycle, Inc |
| Minimum User Height | 5 Feet |
| Model Name | Flatrock |
| Model Number | R5864 |
| Model Year | 2021 |
| Number Of Speeds | 21 |
| Number of Handles | 21 |
| Number of Speeds | 21 |
| Power Source | Pedal power |
| Seat Material | Plastic or synthetic material |
| Size | 18-Inch Frame/29-Inch Wheels |
| Style Name | Bike |
| Suspension Type | Front |
| UPC | 038675236325 |
| Warranty Description | Limited Lifetime |
| Warranty Type | Limited |
| Wheel Material | Aluminum |
| Wheel Size | 29 Inches |
R**.
The kiddo likes it.
I had a little bit of trouble getting the breaks set correctly but that was definitely my own incompetence. I watched a YouTube video & was eventually able figure it out. Overall it's a great kid's bike and very pretty!
A**Y
Great size for a 10yo
We just gave this to our 10yo son for his birthday and we are very happy with it. I was torn between purchasing a 24inch or 26th inch, but the 24inch is perfect. The frame size coupled with the 24inch wheels is the ideal size for him, the larger size would have been too big. For reference he stands at approximately 4ft 8in, and he still has lots of room to grow with it. I am 5ft 3in and can also ride it. Walmart advertises this size as being suitable for 10-14yo and I think that is pretty accurate. The bike is not the lightest compared to higher end mountain bikes, but this will be used for neighborhood riding and going on park trails. And for the price, I was expecting a solid feeling frame. First impressions tell us the quality is good, comparable to any other bike. It was very simple to assemble. We did take it to a local bike store to have the gears checked and brakes tightened, but it was ridable out of the box. Overall for the price, we are really happy with the size and quality of this bike, and our son loves it!
S**.
"You Get What You Pay For" Should be the Title for Every Bike Purchased in this Price Range
It's a really heavy Mongoose but .. I knew that when I pressed the "add to cart" button. The hardware on the bike is mediocre but .. knew that. The bike does everything you need it to do .. unless you're a "bike person". If you ride this too hard .. it breaks. If you use it for transportation, or if you need a good beater for your kid who will be throwing this at the ground repeatedly until they move out of your house chasing some dream job in cosmetology or whatever nightmare they're dreaming of .. this is the bike for you. Assembly was complicated by the fact that it's just an okay bike. The tools they include are enough to assemble the bike with but, you can cut your assembly time in half if you just have some basic tools lying around the house. The bike rides and feels fine. With some fine tuning on the brakes and shifter mechanism, the bike would stop and shift fine. Solid "bang for the buck" on this but, if you spend another couple hundred bucks, there are better choices that would be worth much more than the extra investment. All in all .. this is okay and it's fine unless you're really trying to do anything outside the realm of "commuting".
A**R
Great quality ๐ would highly recommend
Really nice bike ๐ easy to put together ๐ will last a really long time ๐I highly recommend if you go biking a lot โฃ๏ธ it's expensive but worth it
J**S
Not well made, parts already braking, no customer support
My husband and I recently bought the above bike on Amazon for our son for his birthday. We studied reviews and felt good about this being a good bike for a big kid--he's almost 6' and a stout guy. He loved the look of the bike; however, after a couple weeks of use, we've been very disappointed in the quality and functions of the bike. Here are several items of note: 1) The handle bar--this bar, although sleek looking, does not offer much room for adjustment and it is very uncomfortable, even painful, to ride for our son, me (5'8") and my husband (6'1"). We all experienced pinched shoulders and neck even after riding it just around the block. A neighbor helped us put a different handlebar in to raise the grip a bit, and although it helps, it's not quite the right size for the bike, the overall grip is still pretty narrow. Which means we will have to keep shopping around to make adjustments. 2) The handle grips and gear shift--these are entirely too small and spaced too close together! My son's hand, if he grips with a standard 4 finger grip, overlaps with the gear shift, so gears are shifting when he's just holding on to the handlebars and not meaning to shift gears. 3) The pedal/crank set--there is a decent amount of wiggle room in this. As I understand, this should be a pretty sturdy feel, but it jiggles. It doesn't appear that this is anything we can adjust, it is as it came. We had the bike professionally put together, and the mechanic noted this right away. 4) The kickstand--it has already bent and bends forward with the weight of the bike and no longer works. Overall, we are extremely disappointed in this bike. We feel that for the money, we shouldn't be having all these issues right away with it. We reached out to the manufacturer, and have not heard any response back. I'd shop for a different bike!
L**A
Its okay
Took it to a bike shop and the real cog was tight so i couldn't pettle backwards and now the gear shifter is broken but other than that its okay. ๐
B**N
My Go-To for Fun and Adventure!
If you're looking for a bike that's ready for anything, whether it's cruising around the neighborhood or hitting some easy trails, the Mongoose Flatrock is an awesome choice. I've been riding mine, and it's just a fantastic, reliable bike that makes getting out and about a joy. First off, it's really comfortable to ride. The front suspension (that's the "hardtail" part, meaning suspension in the front fork) does a great job soaking up bumps and uneven paths, so your arms and body don't take a beating. This makes longer rides or slightly rougher terrain much more enjoyable. Changing gears is super easy with the 21-speed twist shifters. Whether you're going uphill and need a lower gear, or flying downhill and want to pick up speed, a simple twist of the wrist gets you where you need to be. It shifts smoothly, so you're never struggling to find the right gear. I also really appreciate how lightweight yet sturdy it feels. It's easy to maneuver, which is great for weaving through paths or even just getting it on and off a bike rack. And when you need to stop, the brakes are reliable and give you plenty of stopping power. Overall, the Mongoose Flatrock is a fantastic bike for anyone who wants to enjoy the outdoors. It's built tough, rides smoothly, and is just a lot of fun. Whether you're a casual rider or looking to explore a bit more, this bike is a great companion!
M**N
Worth it
Great fit for my 6 foot tall teen son. It's a nice sturdy bike that should last him quite a while. The seat gets a little uncomfortable when he takes long bike rides so we will change that out but that's the only complaint he's had.
Trustpilot
4 days ago
1 month ago