A critical look at the Copenhagen Wheel and the FlyKly Smart Wheel

What is the difference?

Both the The Copenhagen Wheel and the FlyKly Smart Wheel have been gaining a lot of media attention and seems to have gotten a lot of people excited. They appear so similar that at first even I thought it was the same product. Neither of them are on the market, both of them can already be pre-ordered. Time for a more critical look!

Both are wheels with a electrical motor and batteries integrated in the middle. It is intended to replace the rear wheel of an existing bicycle to make it electrically assisted.

Electric motor upgrade kits

Neither these products are the first to offer a kit to convert a regular bicycle into an electric assisted one. Many products are already on the market in a similar price range where you get an electric hub motor for the front or rear wheel, battery pack and control unit.

These products are different because they offer a single package with all the components integrated into the wheel and add some extra features. They both claim to be "smart", but this is not something I can assert from the information currently available.

Copenhagen wheel

The Copenhagen Wheel The original concept has been developed by MIT and is now being commercialized by a start-up company named Superpedestrian. It can currently be pre-ordered for 800 American dollars. Besides an electric motor it also features regenerative braking, wireless connectivity with a smartphone, a lock, GPS-tracking.

The battery is replaceable but seems to be rotating inside the wheel which adds more rotating mass. Aside from supporting your ride it also does a mind boggling amount of other things.

A description of some of the other features from Design to improve life:

Copenhagen Wheel comes in a distinguishable red color.

As you cycle, the wheel's sensing unit is also capturing your effort level and information about your surroundings, including road conditions, carbon monoxide, NOx, noise, ambient temperature and relative humidity. Access this data through your phone or the web and use it to plan healthier bike routes, to achieve your exercise goals or to meet up with friends on the go.

Another cool feature of the Copenhagen Wheel is that you can share your data with friends, or with your city - anonymously if you wish – thereby contributing to a fine-grained database of environmental information from which everybody will benefit.

FlyKly Smart Wheel

The FlyKly Smart Wheel has mostly similar features, and even adds some more, at a lower price. One of the benefits is that the motor and batteries are not rotating.

The battery is not easily replaceable but does not rotate with the wheel, which should allow for better handling of the bicycle. Having two parts does mean that there needs to be a tight seal between them to prevent water from coming in. This has often been a problem for internal gear hubs, and for the FlyKly Smart Wheel the opening is many times larger. It will be interesting to see if can withstand some bad weather.

It features a patented motor design which is supposed to be more efficient. It has a similar range as the Copenhagen Wheel but requires less batteries and is about 2 kilos lighter.

FlyKly Smart Wheel has a seam along the edge because the center does not rotate.

Not so smart light

The FlyKly also has an optional light, they call it a smart light, I will not. Let me start what the makers have to say about the FlyKly Smart Wheel:

There are no wires or other gadgets to install. You simply remove your rear wheel, replace it with the Smart Wheel and you're all set!

We just established that gadgets and wires are undesirable and simplicity and minimalism is the main selling point. Let's see what they have to say about their light:

A sticky pad on the Smart Light tightly holds your smartphone in place. Additional safety straps work as an extra measure for rockier terrains or faster bikers.

Smart Light is easily installed with a simple theft-proof clip-on mechanism. A thin cable connects it to a dynamo on the front fork of a bicycle frame. To turn on the Smart Light you simply start pedaling.

Now there is a light, dynamo, wire, USB-charging cable, smartphone and straps. These are exactly the wires and gadgets that are the opposite of simplicity and minimalism.

There is very little information on the dynamo, and it is missing in all pictures. I am very interested to know what they came up with. From the description it seems like an old fashioned bottle dynamo that rubs against the wheel. These traditionally require a special mount on the frame, a compatible tire, are terribly inefficient and do not last very long. Running a power cable along the frame to the battery in the rear wheel would be more efficient, lighter and less error prone.

A front light has to be tilted downward in order illuminate the road and not blind others. To see the screen of your phone it should be titled upward. Don't even think about adjusting it, the theft proof clamp will make sure that you don't!

Nocturnal cyclists can blind themselves with their phone and others with a light that is pointing upward.

Motor placement

Both products have the motor in the rear wheel. There are several places for an electric motor on a bicycle, they all have some trade offs:

  1. The best place is at the bottom bracket. At the beginning of the drive train the sensors can measure exactly how much force is applied and control the motor output appropriately. Also having the weight in between the wheels affects the handling the least. Since current solutions require a special frame it is not (yet) possible to upgrade a bicycle to a bottom bracket motor.

  2. The next best place is in the rear wheel. Having more weight in the rear wheel affects handling and it limits the options for gears in the rear wheel.

  3. The third option is in the front wheel. Having the weight there affects the handling of the bicycle even more and it can be prone to slipping. However, the rear wheel can keep all its gears and it is easy to upgrade an existing bicycle.


Both wheels claim to work on most bicycles. Flykly even states "practically any bicycle frame". This is technically true, as in that the wheel will turn and will allow the bicycle to go forward, however the bicycle also needs to come to a safe stop.

The FlyKly Smart Wheel only works with rim brakes. In Europe many city bicycles come with coaster, roller and drum-brakes. Some high-end bicycles have disc brakes. These frames do not have mounts for rim brakes, and these wheels should not be used on those bicycles. An electric assisted bicycles should have a good set rim brakes or disc brakes on both wheels, anything else is just reckless.

The Copenhagen Wheel seems to have a coaster brake option (unclear), but most coaster brakes are not very powerful and have such poor modulation that they easily block the wheel. I don't think this is a good idea for an electric assisted bicycle.


Both wheels have very limited options when it comes gears. The Copenhagen Wheel website says supports gears on frames that are 135 mm wide at the end, and some expanded views of the internals show an 3 speed internal gear hub. It is not clear how this is in the final product.

The FlyKly Smart Wheel does not seem to support any form of gears but instead depends on the motor to keep a comfortable cadence.


Having an integrated battery means that you cannot take off the battery to charge it inside. The consequence is that you need to store your bicycle somewhere where you have access to a power outlet. In some cases an extension cord can help, but it is not always viable.

The makers of the FlyKly Smart Wheel claim it can be recharged up to a 1000 times. I don't believe this until I see it confirmed by independent research. For as long as I can remember manufacturers have promised me this about all kinds of batteries, but in my experience you are lucky if your batteries have half their original capacity after 500 charges.

The FlyKly Smart Wheel adds over 4 kilos to your bicycle. The Copenhagen Wheel 6 kilos. Have fun taking your bicycle up the stairs to charge it!

Side by side comparison

Name Copenhagen Wheel FlyKly Smart Wheel
Colors Red, more later White, black, grey, blue, red, green, yellow, pink, glow in the dark
Price $799 pre-order $590 pre-order
Wheel sizes 26", 28", more later 20", 26", 28"
Battery placement Rotating Fixed position
Battery replacement Relatively easy Quite difficult
Light No Optional front light with smartphone mount and USB charger
Weight ~6 kilos ~4 kilos
Power output 350 watt 250 watt
Battery type 48V 36V Lithium
Battery life 1000 charge cycles (doubtful)
Charge time 2-3 hours
Allows gears On frames with 135 mm wide fork ends. No
Brake options Rim brake and coaster brake Rim brake
Range 50 kilometers
Top speed 25 km/h (legal maximum) 25 km/h (legal maximum)


Both products are interesting additions to the existing line up of conversion kits, and come at a competitive price. Hands on product reviews will reveal how the motor and battery pack will perform. The FlyKly's motor design is pretty clever (if it works as advertised) and because it requires less batteries for the same power output it can be both lighter and cheaper than its competitors.

The fact that the whole system is integrated in the wheel can be very desirable for some people, and completely impractical for others. Anybody considering converting their bicycle should weigh their options carefully before choosing. The lack of complete specifications and hands on experiences make it impossible at the moment to say which of these two wheels is the superior product.

My main concern with the products is the tension between simplicity and complexity. At first the premise seems to be that it is an easy drop-in replacement that adds electrical assistance to a bicycle, but the makers did not stop there they also added all kinds of other features that makes it so complex that I have trouble wrapping my head around everything that these wheels can do.

I have very mixed feelings about the smartphone connectivity. It seems like a feature that will help sell the products because it looks cool. I expect that the novelty will wear of pretty quick and most people will not put the smartphone on the handlebar most of the time.

Both products are be marketed for urban use. This means short rides in familiar territory, even when the weather is bad. Attaching an expensive smartphone sitting to your handle bars for every ride makes little sense. It is one more thing to worry about, it is exposed the elements, and highly visible and prone to being stolen. You don't need navigation assistance, watching your speed gets boring pretty quickly if you are trying to go somewhere. Using your bicycle as an emergency charger when you forgot to charge it might be useful once or twice a year, but it won't help you if you did not bring your charging cable.

Check out my expensive iPhone that anybody can just snatch from my electrified bicycle!

Although the product videos look slick I doubt the execution will be as smooth as they make it seem. Making a good wheel with motor and integrated batteries is already hard enough. Making a good phone charger, light, lock, cycling computer, software platform at the same time and having it all work seamlessly together is a tremendous task that is nearly impossible to get right the first time. The obvious design flaws in FlyKly's light are examples of things can be improved in future revisions.