You’ve probably seen them. Those chunky, small-wheeled contraptions zipping through beach towns or folded up in the back of a Subaru. Most people just call them "Rad Minis," though if you’re looking to buy a brand new one today, you’re going to run into a bit of a snag.
Rad Power Bikes, the Seattle-based giant that basically birthed the affordable e-bike movement, officially retired the Rad Mini e bike nameplate a while back. They replaced it with the RadExpand. But here’s the thing: the "Mini" legacy is so baked into the culture of electric biking that people refuse to let the name die. Honestly, the secondhand market for these things is still thriving. Why? Because the original design solved a problem that most modern, over-engineered bikes actually make worse. It was simple. It was tank-like.
If you're hunting for one on Craigslist or wondering if the new versions live up to the hype, you need to know what made the Rad Mini a cult classic in the first place. It wasn't just the fact that it folded. It was the specific way it balanced 20-inch tires with a 750W motor that made you feel like you were riding a moped disguised as a bicycle.
The Rad Mini e bike: A Frankenstein Success Story
Back when Mike Radenbaugh was first tinkering with bikes, the industry was split. You either had $5,000 specialized mountain bikes or cheap, dangerous kits from sketchy websites. The Rad Mini landed right in the middle around 2016. It looked weird. People laughed at the fat tires on such a small frame. But then they rode it.
The secret sauce was the torque. Because the wheels are smaller (20 inches compared to a standard 26 or 29), the motor doesn't have to work as hard to get you moving from a dead stop. It’s basic physics. This made the Rad Mini e bike the undisputed king of stop-and-go city traffic and steep gravel driveways.
Why the 4-inch tires changed everything
Most folding bikes feel twitchy. You hit a pebble and you think you’re going over the handlebars. Rad fixed this by slapping 4-inch wide tires on the Mini. Suddenly, you had a massive contact patch with the ground. It felt stable. It felt like a motorcycle. You could ride over sand, light snow, or those annoying trolley tracks in the city without fearing for your life.
Does the "Step-Thru" Version Actually Matter?
If you are looking at older models, you’ll see two distinct frames: the High-Step and the Step-Thru.
The High-Step was the "cool" one. It had a top tube that made it look like a rugged BMX bike. But man, it was a pain to get on if you had a rack loaded with groceries.
The Step-Thru changed the game for accessibility. Honestly, it’s the better bike. Period. It’s easier to mount, more comfortable for a wider range of heights, and surprisingly, it didn't lose much frame stiffness. If you find a used Rad Mini e bike in the Step-Thru configuration, grab it. The High-Step was eventually discontinued even before the Mini name was retired because everyone realized the Step-Thru was just more practical.
The "Foldable" Lie
Let’s get real for a second. Every marketing photo of a folding e-bike shows a smiling person effortlessly lifting it into a trunk.
That person is an actor.
The Rad Mini e bike weighs roughly 67 pounds. That is heavy. It is "lug it up a flight of stairs and regret your life choices" heavy. While it does fold, it’s more about storage than portability. It’s great for fitting in a closet or the corner of a garage. It is not something you want to fold and unfold every single morning for a train commute. If you’re buying one specifically because you have a bad back and think folding it will make it "light," you’ve been misled.
Maintenance and the "Rad" Ecosystem
One reason this specific bike stays relevant is the parts. Rad Power Bikes uses a lot of "off-the-shelf" components.
- The Brakes: They used Tektro mechanical disc brakes for years. They aren't fancy, but every bike shop in the world knows how to fix them.
- The Battery: The classic external "shark" battery pack is iconic. Even if your battery dies after five years, you can find replacements easily, whereas many new e-bikes hide the battery inside the frame, making them impossible to service.
- The Motor: Bafang hub motors are the workhorses of the e-bike world. They are loud, sure. They whine a bit. But they are incredibly hard to kill.
The Great Controller Debate
Some enthusiasts complain that Rad "tuned down" the power in later versions of the Rad Mini e bike to comply with stricter regulations or to save the battery. This led to a massive secondary market for "35 amp controllers." People would swap out the brains of the bike to unlock more torque.
Does it void the warranty? Totally.
Does it make the bike climb hills like a mountain goat? Absolutely.
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What Most People Get Wrong About Range
You’ll see "up to 45 miles" on the spec sheet.
Don't believe it. Not because they're lying, but because of how you'll actually ride this thing. Because the Rad Mini e bike is heavy and has high-rolling-resistance tires, you’re going to use the throttle. A lot.
If you’re 200 pounds and riding on hilly terrain with the pedal assist set to level 4 or 5, expect 25 miles. Maybe 30 if you’re being careful. If you’re planning a 40-mile trek, you better bring your charger or be prepared for a very strenuous workout on the way home. Once that battery dies, you are pedaling a 70-pound lead weight with fat tires. It is not fun.
Comparing the Mini to the New RadExpand 5
If you can't find a used Mini, you're looking at the RadExpand 5. It's the successor.
Is it better? Sorta.
It’s lighter by about five pounds because they removed the front suspension fork. Some people hate this. They miss the "squish" of the front shocks. Rad argues that the fat tires provide enough cushion on their own, and honestly, they’re mostly right. By removing the suspension, they made the bike simpler and less prone to breaking. But it definitely feels less "off-road" than the old Mini 4 did.
The handlebars on the Expand also have a different sweep. It’s a more upright, "beach cruiser" feel compared to the slightly more aggressive stance of the original Rad Mini e bike.
Real-World Reliability Issues
We have to talk about the "Rad Error 30."
If you spend any time in owner forums, you’ll see it. It’s a communication error. Usually, it’s just a loose plug or a bit of moisture in a connector, but it’s the bane of many owners' existence.
The bikes are water-resistant, not waterproof. If you leave your Rad Mini e bike out in a rainstorm without covering the LCD screen or the battery terminals, you’re asking for trouble. A little bit of dielectric grease on the connections goes a long way in preventing these headaches.
Is It Still a Good Buy?
If you find a used one for under $800 in good condition, it’s a steal. Even at $1,000, if the battery health is good (ask the seller how many charge cycles it has!), it’s a solid investment.
The e-bike world is moving toward "mid-drive" motors and integrated batteries that look like regular bikes. But there is a rugged, utilitarian charm to the Rad Mini e bike that those sleeker bikes lack. It’s a tool. It’s a cargo hauler. It’s a camping companion.
Actionable Steps for Potential Owners
- Check the Odometer: On the LCD screen, you can see the total mileage. Anything under 500 miles is practically brand new. Anything over 2,500 might mean the motor or battery is nearing the middle of its lifespan.
- Inspect the Fold Point: The hinge in the middle of the frame is the most critical safety component. Make sure it locks tightly and doesn't "wiggle" when you're riding. If that hinge fails, the bike folds while you're on it. Not good.
- Listen to the Motor: A healthy hub motor should hum. If it’s grinding or clicking, the planetary gears inside might be stripped. It's a $50 part, but a $150 labor job to fix.
- Upgrade the Seat: Honestly, the stock seat on the original Mini was like sitting on a brick. Do yourself a favor and buy a Cloud-9 saddle or something similar the day you get the bike.
- Tighten Your Spokes: Small wheels with high torque put a lot of stress on the spokes. Check them every 100 miles. If they get loose, the wheel will go out of true and you’ll feel a wobble.
The Rad Mini e bike isn't the most advanced piece of technology on the market anymore. It’s arguably outdated. But much like an old Jeep, its simplicity is its greatest strength. It’s a platform you can modify, beat up, and rely on for years after the "fancier" bikes have ended up in a landfill because their proprietary software stopped working.
If you want a bike that feels like a tank and fits in your trunk, the Mini legacy is still the benchmark. Just make sure you've been hitting the gym if you plan on carrying it up any stairs.
Next Steps for Maintenance and Longevity
To keep a Rad Mini running for a decade, focus on three specific areas: electrical contact cleaning, mechanical brake adjustment, and battery storage. Use a dedicated contact cleaner on the main wiring harness once a season to prevent "Error 30" codes. Since these bikes use mechanical brakes, you'll need to manually adjust the pads using a 5mm Allen key as they wear down—don't just tighten the cable at the lever, or you'll lose stopping power. Finally, if you aren't riding for the winter, keep the battery at 50% to 70% charge in a room-temperature environment. Never leave it at 0% or 100% for months at a time, or you'll significantly shorten its chemical lifespan.