ECOTRIC DOLPHIN 20" Electric Folding Fat Bike Review - Lightest Inexpensive Folding Fat Tire Ebike?
There aren't any other bikes like the ECOTRIC DOLPHIN. It's the lightest, folding, step through, electric, fat bike that I was able to find, and turns out to also be one of the least expensive.
The bike is for my aunt who wants to be able to ride faster to keep up with her friends in group rides. She also wants to be able to ride the bike on the beach. Living in Florida, there are a lot of sandy areas that benefit from fast tires. The bike needs to be as light as possible in order for her to be able to lift it into her car trunk hatch. She will be using and doing longer term reviews of this ebike. Updates will be posted every few months.
What's The Problem With 20in Folding Fat E-bikes?
The problem with most 20in fat tire e-bikes is that they are loaded down with unnecessary accessories and features and end up weighing up to 85 lbs.
Most have a front suspension fork, which are cheap quality and add very little benefit and will soon wear out and lock up. You don't need a suspension fork for Florida flatland and beach riding, especially with fat tires. It was incredibly difficult to find a fat tire, folding, step through, 20" ebike without a front suspension. In fact the ECOTRIC Dolphin was the only one I found that had a rigid fork.
Some have rear suspension, which is also unnecessary for the type of riding that my aunt will be doing. The fat tires will provide a lot of suspension. A suspension seatpost can also be added, which is lighter than a rear bike suspension.
Many fat tire E-bikes come with front and rear racks. These are great if you plan to carry cargo, but they add unnecessary weight to the bike if you don't use them, and the goal here is a bike that can be lifted easily into a car for transport, so we don't need racks. The racks also increase the folded size.
Electric (torque sensing preferable, but not available in this price range)
Folding (needs to fit in car trunk)
Step Through or low top bar
Fat Tires (for riding on beach)
As much as a step through, folding fat tire ebike can look good, this one does it with style. The fenders add some nice flair to the bike. The bike is available in black or white. I chose the white one for better visibility.
The red rimstrips used in the wheels stand out and don't match the white/blue color scheme.
Some don't like the appearance of the visible battery behind the seatpost. Personally I don't care about that. It's held in securely, easy to remove, and probably easier to replace in the future since it is a generic design.
Who is this bike ideal for? Any casual rider looking for an electric boost, a step through frame design, wide tires for ability to ride on the beach, folding design for portability, and a relatively lightweight ebike.
If you don't need the ease of the step through frame, look for a bike with a regular frame. Step through frames compromise strength and stiffness for ease of mounting and dismounting the bike.
This is the kind of bike that I see people riding at campgrounds, on the beach, and around town.
The frame has 2 unique aspects. It folds in half making the bike easy to transport, and it is a step through design. I selected this bike for both of those features. The bike had to fold to fit in the trunk of a car. Also my aunt has difficulty swinging her legs over the top tube of a regular bike, and so she needs a low clearance top tube like this step through design offers.
The build quality of the frame is quite good. The welds look nice, there are extra gussets welded in several areas at connections to strengthen the frame.
The motor is an internally geared hubmotor with 500W output. It is branded by Ecotric, but it must be made by another manufacturer like Bafang.
The battery is 36V, 12.5Ah (450Wh). I tested the capacity using a discharge test meter and measured 12.7Ah down to the 31V cut off. I was impressed that the measured capacity exceeded the rated capacity, as my experience with most low cost Li-ion batteries is that the manufacturer lies about the capacity, overrating them by up to 50%. Hopefully this honestly rated capacity is a good sign for the quality of the battery.
I then continued the test down to 27.5V to see where the BMS would cut off. It did not cut off, and I didn't feel comfortable discharging any lower than that, so I stopped the test there. Hopefully the BMS would cut off at 25V minimum, and maybe the cut off is that low to take into account voltage sag while the motor is working hard.
The battery has a key on it with several positions.
Unlocked Off to remove the battery
Locked Off (key is removable) - Battery is locked to frame, power is off.
Locked One (key cannot be removed) - Battery is locked to frame, power to motor controller is on.
The key does not come out in the locked ON (run) position, which makes me worried that it will get hit and break off. They do this so that the user will not lose the key and be unable to turn it off at the battery level. A lower profile key would be an improvement.
The battery weighs 7.42 lbs.
The battery measures 15in (381mm) long, 3in (76mm) wide (width of bike direction), and 4.5in (114mm) in depth (front to rear of bike direction)
The battery uses an XLR style charging plug, common amongst these inexpensive ebikes.
The charging port is covered by a simple rotating dust cover flap. Don't expect this to be watertight. Also looks like it will be easy to break the cover off by accident.
The top of the battery has an LED indicator with push button for checking the battery capacity (note that this only works with the key in the ON position.
The bottom of the battery has 2 electrical contacts that are recessed fairly deep to avoid shorts. There's also a fuse access covered by a rubber cap.
Removing the rubber ebike batter fuse cap reveals a 40A fuse (it would take 1440W of power to blow this fuse). Under normal operating conditions, this fuse shouldn't blow. If this fuse ever blows, it's an indication that something is wrong downstream of the battery, like a short in the wiring or motor controller. Simply replacing the fuse isn't likely to help without addressing why so much current was being drawn.
These are the specs written on the battery.
The charger is a 42V, 2A (84W) charger. This means that it will take about (450Wh/84W)=5.36 hours to charge a fully depleted battery.
The charger weighs
The charger measures 6.5in (165mm) by 2.81in (72mm) by 1.94in (49mm).
The input AC cable measures 58in (1.473m)
The output DC cable measures 44.5in (1.131m)
The controller has a basic LCD readout, which is actually nice because it's small, unlike some of the ridiculously huge displays on some E-bikes. The controller is mounted on the left side of the handlebar with the buttons on the left.
It has 3 buttons. The center turns the power on and off by holding it for a few seconds.
The top button increases the pedal assist level. Pressing and holding it for a few seconds will turn on and off the headlight.
The bottom button decreases the pedal assist level. Pressing and holding it will turn on walk mode. Walk mode is too fast on the flats and you'll be quickly jogging to keep up with the bike, and so they should have called it drag mode. However you probably wouldn't need walk mode for the flats, and therefore it's intended for walking the bike up hills, where it slows down enough to keep up with it.
READOUTS: PAS (5 Levels), Speed, Distance, Battery Level, Time
DRIVE MODE: Pedal Assist, Throttle, Walk Mode
The throttle is a twist style throttle mounted on the right side of the handlebar. It offers a smooth range of power level adjustment.
There are 7 speeds on the rear hub and 1 chainring in the front (7x1) for a total of 7 speeds. If you need to change the gear range, you can buy a new freewheel with a different range.
Shimano SIS Index Thumb Shifter (Right)
The rear derailleur has a cage around it. This is nice for protecting it when the bike falls over. It also protects the motor cable.
The Crank Arms
I find the crank arms to be too short, but that may be personal preference because I'm so tall. The crank arms are only 150mm long, while I'm used to 170mm cranks on mountain bikes. Someone shorter may find the crank arms to be the perfect length. I feel like I'm riding a kids bike.
The Q factor of the crank arms is unnecessarily wide. It appears that the crank arms were designed to clear the frame chain stays on a 26in fat bike. But the chainstays on this 20in fat bike are far away from the cranks because the wheel is smaller and the battery between the seat tube and wheel extends the distance from the bottom bracket to rear wheel. Narrower cranks could be used.
The pedals are nothing to write home about. They are generic folding pedals and the platform surface area is small. I would like to see a pedal with more surface area, which will be more comfortable under foot. I dislike the generic folding pedals because they don't fold down very much at all, maybe only half the original pedal length.
Replacing the pedals with some nice wide and long platform pedals for BMX or MTB will really improve the comfort.
The seat is nothing to write home about, nor is it terrible. It's a wide, decent seat for a casual rider. The seatpost is aluminum. The seat and seatpost combo weigh 2.06lbs.
It would be nice if the seat had a quick folding mechanism that allowed it to fold up and forward to clear the way for removing the battery. With the stock seatpost, the quick release seat post collar must be loosened and the seat/seatpost removed before the battery can be removed.
Here's an example of a folding seatpost.
The stock tires are Chao Yang 20” x 4” which can be inflated to 20PSI (1.4 Bar) and the tubes have a schrader valve. The tires are OK if you need the grip provided by the knobby tread, which is like a mountain bike tire tread. However they are loud on the pavement, and inefficient, so your range will be reduced.
Replacing the tires with smoother ones will make the ebike quieter and extend the range of the battery. The 4in wide fat tires offer a lot of grip without the need for a knobby offroad style tread.
An excellent tire choice is the VEE Tires Speedster 20” x 4”. This tires have a smoother profile for lower rolling resistance but still offer lots of grip. They are designed for electric bikes. Also available with a whitewall appearance, which will look cool on this white frame bike.
The first thing I noticed about the brakes was that they were backwards compared to any other bike I have ever ridden. The rear brake is on the left and the front is on the right (moto style). It takes some getting used to, but due to the weight of the bike it is a bit irrelevant. I did notice that my tendancy to use the right brake (rear) first makes the braking appear way stronger, because I'm actually braking the front which has much more traction.
The brakes are mechanical disc brakes (CSTAR Mechanical Brake Calipers) with 160mm discs. Pretty standard quality and stop really well. However they were not well adjusted out of the box. I could pull the brake levers all the way to the handlebars without getting full braking power. Using the barrel adjusters on the brake lever and calipers to tighten the cable was easy and sufficient to adjust the brakes for full brake power. However it really needs a full front and rear brake tuning to properly adjust the brakes and reduce squeeling. The brakes were a bit noisy, which is usually a sign of improper adjustment.
It would be nice if the brakes were properly adjusted out of the box, but most bikes I have unboxed rarely are. Even high end bikes sold at a bike shop usually need a tech to tune the brakes before it goes into the showroom floor. Most riders struggle with brake adjustment, but fortunately there are instructions and videos avaliable online. I'll be publishing some.
You are the suspension (there is none 😂). But seriously, the use case for a bike like this doesn't require a suspension. This bike will be used on roads, smooth gravel trails and sandy beaches. The 4in wide fat tires will be effective at providing a smooth ride and floating over uneven and soft ground. A suspension fork or rear suspension would add unnecessary weight to this ebike. If a rear suspension is desired, a suspension seatpost like Cane Creek Thudbuster can be added to the bike.
The Ecotric Dolphin is a low frills bike, so there aren't many extras, which is nice to keep the weight down. It does have nice fenders on the front and rear to prevent water, mud, sand from getting sprayed up on you as you ride.
There are mounting points for a rear rack should you choose to add one.
There is a cage that protects the derailleur and the motor cable that goes into the axle. This cage is a nice feature because it will prevent the derailleur and motor cable from getting damaged when the bike is inevitably dropped or falls on that side. It's easy to damage a derailleur or bend the derailleur hanger out of alignment. Once that happens it will cause the shifter to skip gears.
The Ecotric Dolphin frame folds in half, positioning the front and rear wheels next to each other. The handle bar folds down next to the frame. The seat can be lowered or removed.
There's no latch that holds the frame together when folded. A strap or bungee will be a great helpt to keep the frame folded while moving it.
The seatpost has a quick release to easily remove the seat and seatpost. Then the battery can be pulled out. This reduces the bikes weight by 10lbs, making it easier to lift in and out of vehicle.
So far, I've been super impressed by the quality and power of this bike. It's everything that I was looking for.
Neighborhood, Urban, Light Trails
ELECTRIC BIKE CLASS:
United States (With UL-Certification)
41.41lbs (Without Battery)
SHIPPING WEIGHT (WITH BOX AND PACKAGING):
Rear-Hub Geared Motor
MOTOR NOMINAL OUTPUT:
BATTERY AMP HOURS:
BATTERY WATT HOURS:
ESTIMATED MIN RANGE:
ESTIMATED MAX RANGE:
PAS (5 Levels), Speed, Distance, Battery Level, Time
Pedal Assist, Throttle, Walk Mode
6061 Aluminum Alloy
17" Reach, 15.5" Stand Over Height, 21.5" Minimum Saddle Height, 30.5" Maximum Saddle Height, 24" Width, 49" Wheel Base, 65" Length
Folded Dimensions 36"x28"x21"
Fender Bosses, Rear Rack Bosses
7 Speed 1x7 Shimano
Shimano SIS Index Thumb Shifter (Right)
Plastic Folding Pedals
24" Wide, Folding Front Stem
160mm Discs, CSTAR Mechanical Brake Calipers
Rubber Ergonomic Grips, Non-Locking
Unbranded Wide Plush
20” x 4”
20PSI (1.4 Bar)
Front and Rear Fenders, Front Reflector, Rear Reflector, Bell, Class 2 Sticker
Locking Removable Battery Pack, 1.7lb Standard Charger, Max Total Weight 265 lbs
Beach Cruiser Dolphin Class 2 Budget Folding Foldable Ebike Electric Bike 500w