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  • commuter and LIGHT TRAIL RIDING

Inspired by San Francisco’s foggy hills, the 21 Flow is your favorite new commuting buddy. With a stylish step-through frame and enough power to zip through traffic and up hills with ease, Flow is our most crowd-pleasing e-bike to date.

Includes rear rack, fenders, integrated brake light, and LED front light.

Suggested for riders: 5’2” - 6’4” and up to 275 lbs

Classification: Class 2 e-bike (up to 20 mph)

Why you'll love it:

  • Perfect for casual riders and commuters
  • Designed for versatility
  • Supports good riding posture

Available on backorder.

Estimated delivery: 4 weeks


All Espin e-Bikes come with a comprehensive 12-month warranty so you can buy with confidence.


All Espin e-Bikes come 95% assembled. All you need to do is put on the finishing touches.


We offer free shipping to 48 states in the US (excluding Alaska and Hawaii), delivered directly to your door.


Need help? Contact us via phone, email, chat. Our team is here to help.

Gives you the freedom to explore.


Motor Brand     


Motor Type 

Rear Mounted Geared Hub

Motor Nominal Output

500 watt nominal/800 peak output

Motor Torque

65 Nm

Battery Brand

Samsung Cells

Battery Voltage

48 volts

Battery Amp Hours

13.6 ah

Battery Watt Hours


Battery Chemistry


Battery Charge Time

6 hours

Riding Range Estimated Min
30 miles

Riding Range Estimated Max
50 miles

Display Type     
Espin color LCD

Speed, Battery, Assist Level (1-5), Odometer

Drive Mode     
12 magnet sealed cadence sensing pedal assist

Top Speed     
Class 2


Attachment Points

Rear Rack bosses, Fender Bosses


Zoom Dual Piston Hydraulic Disc Brake, Front/Rear w/180mm Rotor; Zoom levers with Integrated Motor Cutoff


Alloy Cranks 170 mm, 45T Chainring with Plastic Bash Guard


100mm Travel Hydraulic Lockout

Frame Size


Frame Type



S-Ride 8 speed 13-32T

Hand Grips



Zoom Alloy Swept back Handlebar 25.4mm




Wellgo Aluminum Alloy Platform

Rack Capacity

55 lbs (25kg) 15" x 5"


Selle Royal Freeway


Zoom 30.4mm


S-Ride triggers


CST 27.5 x 2.10


55 lbs


Locking Removable Battery Pack & Fenders

Size Guide


+ What's the difference between Espin's Flow and Sport e-bikes?

The Flow is a European inspired design built for the urban commuters who wants to zip through traffic and ride comfortably. Elegant 17” step through frame that allows you to mount and dismount easily and safely anytime you want.

The Sport comes in a 17 inch diamond frame and is for riders looking for a more sporty and aggressive riding style.

+ How will the Flow's tire do in snow or a beach environment?

The Flow is meant for pavement and will not handle snow. For snow, try the Nesta or Nero.

+ What is an electric bike (e-bike) and what makes it different from a regular bike?

An electric bike is just like a regular bike, except for 4 main electrical components: the battery, motor, controller and display. Other than that, it will function and ride just like a normal bicycle. 

The Espin eBike is a pedal assist bike, which uses the motor to increase the power created when you pedal. So it rides and turns just like a regular bike, it just makes riding easier, especially uphill.

+ What is Espin made of?

Espin pedal-assist eBikes are made from 6061 aerospace grade aluminum alloy.

+ Can I ride my Espin pedal-assist eBike in the rain?

Yes, we have waterproofed all the wiring and electrical connections so it can withstand rain. Of course, one should not let the bike just completely soak in the rain if possible, but there is no need to worry about riding in rain.

+ Can I assemble it myself?

Yes! The assembly takes less than 15 minutes and we even provide all the tools you need. If you run into any issues, you can follow along in the assembly video.

+ What maintenance is required?

Maintenance is exactly the same as a regular bike other than the four main electrical components: battery, motor, controller, display. You should do basic tune-ups on your bike after the first 100 miles. Regular tire pressure checking is important as you want to keep your tires inflated for maximum riding comfort. 

Other than that, the electrical components should require minimal maintenance and if any issues arise, please follow the instructions to diagnose the issue, which will be included in the user manual. If you are still unable to fix the problem, please submit a warranty claim and we will process your claim as soon as we can as we understand you want to get back on the road as quickly as possible.

Customer Reviews

Customer Reviews

Based on 121 reviews
Maggie Lynch

These bikes are overbuilt for fun bike riding. They are commuter bikes that take all the exercise out of actually riding a bike.

Timothy Stambaugh
Espin electric bike

I had a small problem with electric power, but the company was very helpful and the problem was solved quickly. Great company support.

Queen Anne
Good Bike . . . Figuring it All Out

The 21 Flow is a FUN bike to ride.
On my first ride, I was trying to figure out the gears and the pedal assist when crack/clackety . . . the chain loosened and the pedal assist stepped in, and the derailleur broke. ;-( I took it to a local shop and they replaced it, along with the gear shifter which was way better because it showed which gear I was in. For some, this may not matter; to me, it meant a LOT. Since then, it's just been a matter of practicing for awhile NOT using any pedal assist, and then on the flat, just experimenting with how the gears and assist work together. It is quickly becoming intuitive, but was not at first. On my first longer ride, about 10 miles, I had to think more about how to get a bit of a workout, through lower assist and higher gearing; it can be more like a motorcycle than a bicycle. (The company reimbursed for the derailluer/gear shift replacement though getting through to them on the phone takes a day or so and if you miss a call back it can take another day; that was frustrating).
It would be VERY helpful if the company were to suggest a rack. We have a truck camper and sometimes go on dirt roads. NOT a good idea; at one big road dip, the bike swung out too far, came back to the camper and the brake lever rammed a small hole in the camper door ;-() We bought the Thule EasyFold XT which provides a ramp to push the bike up and down, to avoid lifting 55 pounds. It all works fine on paved and not bumpy roads, and we've added a strap, as there is a bit of play. I'm not seeing a better rack option . . . nothing perfect yet.
There's a learning curve to all of it, and we are working out the bugs. The bike is easy and way powerful enough for me. At first the seat was NOT comfortable, but after just three rides, it was just fine.

Jim Wachsman

hi we loved your bike but I had to give it to my son
I got it for my wife bust she is not that mechanical she fell once trying to figure the buttons while riding other wise very nice maybe a simpler control panel would be better jim

Dan Chichester
An amazing — truly electrifying - purchase/experience

As I looked again at my perfectly serviceable off the rack mountain bike that had served me many seasons… I debated once again, "Do I *need* an electric bike?" But how many times had I ridden that in recent years? Not many. Not for lack of interest, but honestly… some hills are a bit tougher than they used to be. Maybe I didn't want to be *that* guy pushing it up an incline instead of riding it, or struggling a bit too much to get it going out of a full stop.

Whatever the reason, I finally hit "buy." And wow. This is everything I love about bike riding — freedom, fun, in motion, distance doesn't matter. The build is terrific, it's an extremely solid piece of machinery. And, in blue, very striking. The "almost fully assembled" is spot on. The couple of steps you need to go through aren't much — wheels, pedals, handlebar — but they might seem a bit of a puzzle, especially as the espin instructions and videos could use a step up: I found some better ones on YouTube and was together in under half an hour. The first half turn when the motor kicks in brought a grin to my face and will make ANYONE a convert. My wife got on, took it to the end of the road and back, and was immediately, "Where's mine?" (We ordered her the flow.)

Couple of dings in the box: the display bracket was cracked on arrival: espin immediately sent a new one. And the deraileur had bent inward, which meant I could not shift into the 2 topmost gears. espin diagnosed the issue with a couple of photos, sent a replacement hanger, and covered the adjustment at my local bike shop. In both cases, very personal and impressive customer service!

My one true criticism is the display: it washes out easily in mild sunlight, in bright sunlight — forget reading it without a fair bit of squinting and concentration. I get that the color display is fancier, but for practical purposes an LCD one would probably have been better to stick with.

Any ebike is an expensive purchase, but this one has already delivered on its value. I am looking forward to putting many more miles on this as often as I can.

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