If you've been riding for a while, you know that picking out a 20 bmx rear wheel is a much bigger deal than just finding something that spins. The rear wheel is basically the heart of the bike. It takes the brunt of every landing, handles all the torque when you're cranking hard toward a jump, and is the first thing to get hammered when a trick goes sideways. I've lost count of how many times I've looked down after a rough session only to realize my rim looks more like a potato chip than a circle.
When you're shopping for a replacement or an upgrade, the options can get a little overwhelming. Between different hub types, rim widths, and spoke counts, it's easy to get lost in the specs. But honestly, it mostly comes down to how you ride and how much abuse you plan on putting your bike through. Let's break down what actually matters so you don't end up wasting money on something that's going to fold the first time you case a ledge.
Why the Rear Wheel Takes All the Heat
In the world of BMX, the front wheel has it pretty easy. Sure, it handles some impact, but the 20 bmx rear wheel is where the real action happens. Think about it—every time you hop, you're pulling up on the front and slamming the back. When you're grinding, your rear hub and spokes are right there in the line of fire.
Because of this, you generally want your rear wheel to be a lot beefier than your front one. While you might be able to get away with a lighter, thinner rim up front to save some weight, the back needs to be solid. If you're riding street, you're looking at constant side-loads from spins and hard impacts on concrete. If you're a park rider, you might want something a bit lighter for airs, but it still needs to be able to handle the G-forces of a deep bowl.
Cassette vs. Freecoaster: The Big Debate
This is probably the first choice you'll have to make when looking at a new 20 bmx rear wheel. It's not just a technical difference; it completely changes how the bike feels and how you ride.
Going with a Cassette
Most of us started on a cassette hub. It's the classic choice. When you pedal forward, it engages instantly. When you roll backward (doing a fakie), your pedals move backward too. People love cassettes because they're usually lighter, they're easier to maintain, and they give you that "pedal pressure" which helps with balance during certain tricks. Plus, let's be real—that loud clicking sound of a high-quality cassette hub is one of the most satisfying sounds in all of cycling.
The Magic of the Freecoaster
On the flip side, freecoasters have become insanely popular over the last decade. A freecoaster allows you to roll backward without your pedals moving. This is huge for street riding because it makes fakie tricks look much smoother. You don't have to worry about your feet being in the right position to "backpedal" while rolling out of a 180.
The downside? They're heavier, they have "slack" (a delay before the pedals engage when you try to go forward), and they can be a bit finicky to keep running perfectly. If you're more into technical street stuff, a freecoaster is awesome. If you like going fast and having instant power, the cassette is likely your best bet.
Understanding Rims: Single Wall vs. Double Wall
If you're looking at a budget 20 bmx rear wheel, you'll probably see "single wall" in the description. My advice? Stay away from them unless you're just cruising to the grocery store.
A single-wall rim is exactly what it sounds like—one layer of aluminum. They're cheap and light, but they're incredibly weak. For any kind of actual freestyle riding, you want a double-wall rim. These have an internal bridge that adds a massive amount of structural integrity.
You'll also want to look at the material. Most decent rims are made from 6061-T6 aluminum. Some higher-end ones use 7005 aluminum, which is even stiffer and stronger, though usually a bit more expensive. Also, pay attention to the width. Wider rims (around 36mm to 40mm) are the trend right now because they support modern, wider tires (2.4") much better and prevent the tire from "squirming" on heavy landings.
Axles, Bolts, and Getting the Fit Right
Almost every 20 bmx rear wheel you find is going to have a 14mm axle. This is the industry standard for a reason. 3/8" axles (which you'll often find on front wheels) just can't handle the shearing forces of a rear wheel, especially if you're running pegs.
You have two main types of axles: male and female. A male axle has the threaded rod sticking out, and you use a nut to tighten it down. These are old-school, reliable, and generally preferred by people who use pegs because they're super tough. A female axle uses a hollow internal axle with bolts that screw into it. These look a lot cleaner and can sometimes be lighter, but some riders find them a bit more annoying to work with if they're constantly taking their wheels off.
Spoke Count and Why 36 Is the Magic Number
You might see some wheels with 48 spokes, but that's mostly a relic from the 90s when rims weren't as good as they are now. These days, 36 spokes is the standard for a 20 bmx rear wheel. It provides the perfect balance between weight and strength.
The way the spokes are laced matters too. Most wheels are "3-cross," meaning each spoke crosses three others. This creates a very strong, stable structure that can handle torque from pedaling and side-impacts from landings. If you see a wheel laced "radially" (where the spokes go straight from the hub to the rim), keep moving—that's definitely not meant for a rear wheel.
Maintaining Your Wheel Without Losing Your Mind
Once you get your new wheel, don't just "set it and forget it." New wheels often have a "break-in" period. As you ride, the spokes will stretch just a tiny bit and settle into the hub flange. After the first few sessions, it's a good idea to check the tension.
If you notice your wheel has a bit of a wobble, don't panic. Truing a wheel isn't as scary as it seems. You just need a spoke wrench and a bit of patience. Tightening the spokes on the side opposite of the wobble will pull the rim back toward the center. Just make sure you do it in small increments—like a quarter-turn at a time. If you over-tighten one side, you'll end up with a wheel that's perfectly straight but shaped like an oval, which is a whole different nightmare.
Also, keep an eye on your hub bearings. Most modern wheels use sealed bearings, which are great because they keep dirt out and require almost zero maintenance. If your wheel starts feeling "crunchy" or has side-to-side play, it's usually just a matter of popping out the old bearings and pressing in some new ones. It's way cheaper than buying a whole new hub.
Final Thoughts on Picking a New Wheel
At the end of the day, your 20 bmx rear wheel is an investment in your riding. If you buy a cheap, unbranded wheel, you'll probably be looking for another one in six months. If you spend a little more on a solid double-wall rim laced to a reputable hub, it could last you years.
Think about your style. Are you doing big gaps to flat? Go for the beefiest rim you can find. Are you doing technical lines and lots of fakie variations? A freecoaster is going to be your best friend. Whatever you choose, just make sure you keep those spokes tight and your chain tensioned. There's nothing worse than having a great session cut short because your back wheel decided it had enough. Happy riding!