RadMini 4 Electric Folding Fat Bike Review

Josh Ross
eBicycles score

It’s time to talk about the RadMini 4 Electric Folding Fat Bike. Every time I dive deep into a particular bike for one of these reviews it’s an opportunity to learn. I get to do the kind of research that lets me really know what a product is all about. When it’s a good product, as is normally the case if you are reading my thoughts about it, then I get really excited about it.

That was definitely the case with the recent Tern models. The Tern bikes are amazing but I know the pricing isn’t going to work for everyone. If you like the idea of what Tern is offering but you need something a bit less expensive the RadMini 4 Electric Folding Fat Bike might be a great idea.

Rad Power Bikes is a company born from necessity. When the Founder and CEO Mike Radenbaugh needed a way to take on his 16-mile commute to school, he found a solution.

That early innovation went on to evolve into the biggest ebike brand in North America. Given that story, it’s no surprise that Rad Power Bikes is a company all about solutions that work for everyone. Let’s take a look at the RadMini 4 Electric Folding Fat Bike and see what makes it the bike it is.

Geometry and Sizes

RadMini 4 Step-Thru

The RadMini 4 Step-Thru and the standard version are the same other than the variation in a frame shape.

Like all bikes, the place to start is with a solid and well-built frame. The RadMini 4 represents two different models. The two models are virtually identical other than a dropped top tube for the step through version. I’m not actually going to reference the models as different other than to say that the two options do exist.

If you want the extra versatility of an easy step-through design then that option is there for you. Other than that detail the two are the same. I would say in most cases the easier step-through design is the option that makes the most sense but everyone has different needs. Choose whatever is going to work for you without hesitation.

The frame material of choice for the RadMini 4 is 6061 aluminum.

I’ve talked about this material choice for other bikes but I can mention it again here. Aluminum is an excellent option that keeps the price in check. It’s cost-effective and easy to work with while giving up nothing when it comes to performance.

When it comes to the top-of-the-line race bike designs there’s some small amount of weight savings with a carbon fiber option. For a fat-tired folding bike, aluminum is the best option.

When it comes to sizing the frame for the RadMini 4 is 16 inches (40.64 cm). Rad Power Bikes lists the geometry measurements as 16.5″ Seat Tube Length, 18″ Reach, 28″ Stand Over Height, 32.5″ and Minimum Saddle Height of 27.5.”

The total length of the bike is 68″ with a wheelbase of 45″. Folded dimensions are 41″ x 22″ x 28″ (L x W x H). Like all folding bikes though the seat tube length has little to do with the usable fitment.

The Radmini 4 is a one-size bike. Rad Power Bikes handles fitting based on leg length and lists a large range of useability. The ideal leg length is 28″ to 32″ inches with a note that at these leg lengths “you will be able to pedal and stand over the frame comfortably”.

It’s not all lost if you are a bit shorter and have a leg length in the size range of 24″ to 28″. Rad Power Bikes says “you will be able to pedal comfortably but you may not be able to stand over the frame without it contacting your body.”

RadMini 4 Electric folding fat bike in front of a van on a beach

In order to measure properly, Rad Power Bikes has detailed instructions for what you are measuring and how to do it. Leg length is going to refer to what Rad Power Bikes calls “your real inseam.” They call this “the distance between your body where it sits on your bike saddle and the ground” and specify that it’s not the same as your pants inseam. To measure this detail, there is a process.

Direct from Rad Power Bikes, “Wearing your regular riding shoes and with your back to the wall, stand with your feet spread so there are about 7 inches between them. This is about the distance apart your feet would be when straddling a bike with your feet on the ground (standover height).

Place a hardcover book against the wall with the spine of the book facing upward. Slide the book upwards towards your groin until it is solidly against your body. This may be a bit awkward, but is way more comfortable — and safer! — than trying to ride a bike that is too big.” Then just measure from the top of the book to the ground.

RadMini 4 Motor and Battery

The electric-assist system on the RadMini 4 Electric Folding Fat Bike is sourced from Bafang. Bafang is a well-known electric motor company based in Suzhou, China. For many people in Europe and the US, the name isn’t the most well-known.

Despite a smaller name recognition in some markets, Bafang is still a serious contender in the world of electric bike motors. The name represents a history of innovation since 2003 as well as 700 people in 5 locations all over the world.

In this instance the motor system that Rad Power Bikes has employed is unique. They have partnered with Bafang to create something just for the RadMini 4.

It’s a 750watt system housed in the rear hub. Torque sits at 80Nm and delivery of that torque gets metered through a 12-position cadence sensor or a twist throttle with a max speed of 20mph. The motor specs are impressive and should provide plenty of power for whatever you need.

To support the impressive motor specs there’s an equally robust battery.

It’s a large 672Wh 48V, 14 Ah Lithium-Ion Battery with a quoted range of 25 miles (40 km) up to 45 miles (72 km) and a 6-hour charge time. To check how much battery life the bike has at any time check the grayscale 2.75″ LCD sourced from King Meter. Choosing one of the 5 assist options with less assist will extend how many miles you can cover.

RadMini 4 Components

Flip over to the traditional bike side of things and it’s a little more of a mixed bag. The Bafang system put to use for electric assist does provide some cost-saving but also carries impressive specs. The mechanical bike components are somewhat less impressive on the spec sheet.

Fortunately, in this use, they should do a great job even if the numbers don’t sound as impressive.

RadMini 4 electric folding bike rear cassette

At the rear hub is a 7-speed freewheel with 11-34 gearing. On most bikes since around the mid80’s the freehub with Shimano compatibility is the standard. A freehub uses splines and it slides onto the wheel hub. Alternatively, a freewheel uses threads on the hub. For an inexpensive 7-speed drivetrain, it’s unlikely that it’s going to make much difference.

One challenge that can arise with a freewheel instead of a freehub is max gearing. Rad Power Bikes has put Shimano mountain bike components to use and sidestepped this issue. The rear derailleur is a Shimano Altus unit that represents one step up from the entry-level Tourney lineup.

The steps between gears on a 7-speed drivetrain are going to be a little on the large side but the choice of a 34-tooth max cog is a good one. Combined with the 48-tooth front chainring and the Bafang system I would not anticipate hill-climbing issues.

The braking system of choice on the RadMini 4 Electric Folding Fat Bike is from Tektro. The lever is an aluminum alloy comfort grip with a motor cutoff switch and integrated bell. At each wheel, there’s a huge 180mm rotor that should provide plenty of stopping power.

The caliper grabbing those large rotors is a Tektro Aries (MD-M300) cable-actuated caliper.

Although I’d love to see a hydraulic brake system put to use here the MD-M300 is a quality system built from a single-piece aluminum body. The biggest challenge with cable pull disc brakes is always pad adjustment. To help with that the MD-M300 features Automatic Caliper Centering (A.C.C), Inside Pad Adjustment, and Automatic Pad Angle Adjustment.

When it comes to stopping the bike there’s nothing to worry about and these features should help the rest of the experience.

Other Components

Not all the features of the RadMini 4 electric folding fat bike fit neatly into other headers but they are worth mentioning. At the front of the bike, a stem is a folding unit that helps make the folded RadMini 4 compact. When it comes to the riding experience though it’s the telescoping nature of the stem that is worth mentioning.

It’s not unusual for folding bikes to use this design and it’s important that it’s there to make sure the bike will fit a range of riders.

Along with the telescoping stem, the front of the bike features a suspension fork. The unit Rad Power Bikes uses has 60mm of travel as well as preload adjustment and a lockout. The preload adjustment will, again, help set the bike up in a way that fits you and your body. Then if you need to save a bit of energy lost to the movement you can lock it out.

Being a fat bike the RadMini 4 sports massive tires. Low pressure will help keep the bike feeling supple even if you don’t want to use the suspension.

As far as accessories there are a few included and a bunch of great options available. On the included side of things, there’s an integrated rear light, front light, and fenders at both ends of the bikes. Not included, but available, are solid front and rear racks that should let you make use of that impressive cargo capacity.

Other Models:

Assembly of RadMini 4

Like most bikes the RadMini 4 Electric Folding Fat Bike comes in a box mostly assembled. Once you’ve got the bike unpacked the assembly needed is minimal. It includes the pedals, the handlebars, the fenders, the front light, and the front wheel. All of the tools needed come in the box and the instructions are clear. If you’d like more info check out the RadMini 4 Assembly Instructions below.


I tend to downplay how much people will actually get off the beaten path with the various electric fat bike options. People often surprise me but I’m going to downplay the possibility again. A folding electric fat bike seems even less likely to find use on sand or snow.

RadMini 4 Step-Thru

That’s okay though, the large tires mean a cushy ride no matter how broken the pavement might be. Don’t be afraid to buy a RadMini 4 and cruise around the city.

There are a ton of great things about a bike like the RadMini 4. Fat bikes take up a lot of space but because it folds it’s going to be much more usable with a small apartment. The large tires mean not only a cushy ride but also a stable ride. My favorite part about the RadMini 4 is the cargo capacity.

It’s an inexpensive option that lets you carry all the groceries you might need to then folds up when you get to your house. There’s a ton of utility and a great price.


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