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The first portable electric motor drive for bike share programs (US, Canada, and the UK) that also works on your own bike or scooter. Read more

pledged of $100,000 goal
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Funding Unsuccessful

This project's funding goal was not reached on March 30, 2014.

The first portable electric motor drive for bike share programs (US, Canada, and the UK) that also works on your own bike or scooter.

About this project

UPDATE:   We have very exciting news! ShareRoller has received alternative financing in excess of the original Kickstarter target and as a result, we will be bringing our product to market on the same schedule as planned. We are now fully funded and production efforts are already underway. Please visit our main site for updates and to pre-order going forward:

Gothamist is "a ShareRoller convert" after one test ride!

Gizmodo test rides ShareRoller (and calls it "Awesome")!

Inhabitat takes ShareRoller for a test ride!


ShareRoller is the world's first portable, detachable electric drive system designed specifically for the major bike share programs in the US, Canada, and the UK. 

Plus, it can also be used on your personal bike or kick scooter, so it truly is a product that learned how to 'Share'.

ShareRoller weighs only 6-7lbs and is about the size of a 500-sheet pack of paper (8"x11"x2.7").  It can be carried easily on its own, or in a laptop bag, briefcase, or handbag.  And it can be installed or removed on a share bike in less than 10 seconds.  Seriously.

Once installed, ShareRoller's 750 Watts of power will propel you effortlessly at up to 18mph without pedaling (the speed of a strong CitiBike rider) for 12 to 20 miles of range, depending on battery size.  This is no puny 250 Watt 'assist' like many others on the market; ShareRoller packs a full 1.0 horsepower - as much power as a Tour de France cyclist in a sprint! 

With ShareRoller you can glide up hills, power through headwinds, and sail through a breeze on a hot day without breaking a sweat, and without pedaling if you so choose. ShareRoller transforms bike share by turning your share bike into an e-bike, and allowing you to go farther, faster, and with only as much effort as you desire. And since we love and encourage pedaling, with ShareRoller you can always pedal as much as you want - simply use ShareRoller's variable throttle button to choose exactly the amount of assist you desire.


Ever think you could use a CitiBike to cover 19 miles through 3 boroughs and over 3 bridges in a little over an hour?  Well, with ShareRoller you can.  Take a look at a recent ride below: Using the throttle heavily the entire time, and with some light pedaling, we averaged 15mph (including stopping for lights) and still had some range remaining when finished!

ShareRoller Extended Range ride w/ minimal pedaling
ShareRoller Extended Range ride w/ minimal pedaling


ShareRoller works on all eleven bike share programs above because they all use the exact same bike!  (UK & Canada kits will be power restricted to comply with local regulations).


ShareRoller can work on many bikes with the appropriate adapter mount.  We've already designed a few to prove the point (the Brompton folding bike was first in line), and we will continue to design as many adapter mounts as we can in the coming months (with our in-house CAD and 3D printing resources, it takes just a few days to custom-design each one).  We plan to poll all purchasers at the close of the Kickstarter to sort out the priority.  Plus, we're working on a universal mount that should accommodate many bike models.


ShareRoller works beautifully on the Xootr kick scooter (and we're going to design adapters for other scooters too).  We've been riding this around since the Fall and it's ridiculous fun.  Plus, there's no better way for commuters to get from their home to a train station (and then use ShareRoller on a share bike once they arrive in the city).  Or, if you encounter 'empty rack panic', you can always pull out your folding Xootr, clip on the ShareRoller, and motor on to your destination!

AND, ShareRoller + Xootr makes by far the lightest high-power scooter on the market.  It weighs only 17 lbs combined!  The nearest competing product weighs almost 40 lbs!  And costs $2,500!


With all the battery power tucked inside ShareRoller's highly engineered case, it would be a shame to not be able to charge your phone or iPad.  So you can, anytime, and anywhere.  In fact, you could charge 50 iPhones without depleting the battery.  Bring on the next blackout!


Visibility is paramount to safety when cycling.  We weren't impressed by the existing lights on share bikes, so we added two more.  20 Lumens of additional light will go a long way!


Let's just say it required thousands of hours of CAD design and prototyping.  It's a very complex system that has been designed with incredible precision - just take a look at our model:

ShareRoller uses friction drive to power the front wheel of your share bike, and attaches to the bike in a most ingenious manner (so much so that we've filed patents on it!).  The secret is that ShareRoller slides on and mounts to the triangular mounting bracket above the front wheel of the bike.  Simultaneously, the motor assembly swings out of the case and locks into position to securely and efficiently drive the front wheel (also Patent Pending!).

Then, you simply remove the throttle assembly from the case, clip it onto the handlebar (where it perfectly positions the variable throttle button for your thumb), and away you go.  It may sound complex, but the whole process literally takes less than 10 seconds.  And it's just as fast and easy to remove it when you've arrived at your destination (which you will do rather more quickly than before!).

Friction drive is one of oldest and simplest technologies for an e-bike, and with our proprietary patterned urethane drive belt and variable pressure system, we've maximized the efficiency and effectiveness of this beautifully simple mechanism.


ShareRoller's motor retraction system makes it incredibly compact when being transported, and keeps the motor safely concealed inside the case.

As a result, ShareRoller is less than half the size of any other portable, self-contained friction drive system.  And because we use the absolute state of the art in motors, batteries, and control systems, ShareRoller weighs less than half as much as well!

At 6-7lbs and with an easy carrying handle, you won't mind carrying ShareRoller to and from the share bike racks.  Particularly when you know ShareRoller will get you over the Brooklyn Bridge without pedaling!


Batteries:  Not all Lithium batteries are equal!  We use the very latest (and most expensive) Lithium battery chemistries (NMC & NCA) for the highest power density, lowest weight, and greatest safety.  In fact, our extended range cells come from the same supplier that Tesla uses for their Model S!  And all battery packs are controlled by a sophisticated Battery Management System to maximize performance, longevity, and stability.

Motor & Motor Controller:  We use the most advanced Brushless DC (BLDC) motors on the market, with the highest quality magnets, windings, and bearings.  This maximizes power, minimizes weight and size, and provides superior durability.  Our state-of-the-art software-linked motor controller maximizes energy efficiency and even recharges the batteries when you coast downhill.

Microprocessor Control:  Every aspect of the ShareRoller is controlled by a computer the size of your thumb.  Our proprietary software constantly monitors throttle position, RPM, speed, voltage, current, power, and temperature to guarantee safe, efficient, and seamless performance.  You wouldn't want to know how many decisions per second are being made by the electronic brain, but all you see is the absolutely perfect operation it gives ShareRoller.

Mounting mechanism:  So innovative it's Patent Pending.  The critical breakthrough that allows ShareRoller to be attached or removed from a share bike in under 10 seconds.  It's taken a lot of creativity and a ton of engineering resources to perfect it, but as a result it works perfectly and effortlessly!

Retractable motor assembly:  Makes ShareRoller unbelievably compact when in transport.  The motor assembly swings in and out of the case in an elegant dance.  Unheard of in the world of portable friction drive systems (ok, it's a pretty small world).  Don't ask how many CAD design hours this required.. which is why it's also Patent Pending.

Variable pressure system:  Spring-loaded expansion mechanism guarantees precise pressure on the bike tire, resulting in optimal performance, even in wet conditions.

Patterned urethane belt:  We've worked tirelessly with our urethane supplier to develop a proprietary motor belt that maximizes grip and efficiency in both wet and dry conditions.  Plus, it won't cause excess wear of the bicycle tire or scooter wheel.  That's pretty important.


Unlike many Kickstarters we've seen, ShareRoller is not a first prototype, or even an early prototype.  It is a fully-developed, late-stage pre-production product.  We've been riding and refining ShareRoller for over 8 months, have iterated through over two dozen functioning prototypes, and have now arrived at a product that works beautifully.  That's why we're able to offer 25 Beta kits immediately.  Now we just need your help to move into full-scale volume production.

Initial concept in June 2013:  One ride on a CitiBike was enough to inspire our creative application of electric power.

Over two dozen prototypes tested and refined since:  We purchased our own $20k 3D printer in order to hyper-drive the design-prototype-test-redesign loop.  With a new version almost every week, we're pretty sure we set records on prototype development for a complex electromechanical product.  We could have spent that $20k on a snazzy video instead, but we felt this was a much better use of our limited funds!

Leveraging our state-of-the-art 3D printer for continuous prototype development
Leveraging our state-of-the-art 3D printer for continuous prototype development

Software fully developed:  Unlike others, we're not still 'tweaking' our software.  It's been through full testing and verification via hundreds of test rides.  It works.  It's done.

Suppliers lined up:  We've been working with the best suppliers in the business for over six months for everything from motors to batteries to urethane.  Our specifications and prices are established, and delivery timelines are clear.  And with our business building background, we ensure we have two suppliers for every key component.


Tooling for injection molding:  3D printing is a wonderful technology, however for reduced cost and increased durability, we need to move to injection molded plastic for many of ShareRoller's components.  Building the molds needed to make these parts is enormously expensive.

Volume orders of components:  We're not using off-the-shelf parts; the majority of components that go into ShareRoller are custom-engineered to our specifications, and Minimum Order Quantities (MOQ) needed to get us into volume production are high.  Plus, to keep ShareRoller's cost as low as possible, we need to order all components in bulk.

Assembly and customer service facility:  ShareRoller will be assembled both by us locally and by established Contract Manufacturers.  And to ensure top service to all our customers, we intend to have a fully outfitted service and development facility here in NYC.  All of these things require significant start-up capital.

Delivery timeline:  Putting everything together, we arrive at our schedule below.  We are fully committed to delivering Beta units in time for Spring, First Production units before Summer, and Second Production units before the unbearable heat of July and August.  And since ShareRoller isn't an early prototype but a finalized pre-production product, we have very good visibility on these targets.


The specs below are not pie-in-the-sky targets that will get scaled back and dumbed down as we move through production.  Our prototypes meet or exceed all of the specifications below, and our production ShareRollers will do the same.


Taking advantage of the precise accuracy of CAD, we utilized every last cubic millimeter of space inside ShareRoller's compact case.  Packing in 240-400 Watt-hours of battery life, a sophisticated Battery Management System PCB, a 1.0 hp retractable motor, a retractable throttle assembly, an expansion mechanism, USB power, LED headlights, and a microprocessor into a case the size of a pack of paper wasn't easy.  We probably should keep this under wraps, but we're going to show you how we did it anyways:


The idea for ShareRoller was initially conceived in June 2013, right after CitiBike launched in NYC. One ride on the 45-lb 3-speed bikes was enough to spur the search for motor assistance.

The Aha! moment occurred when we noticed that the metal docking triangle just above the front wheel made a perfect place to mount a motor for front-wheel friction drive.

So we abducted a CitiBike:

We poked and prodded it in all sorts of humiliating ways, and measured every part down to the last micrometer.  And immediately we began work on an embarrassingly simple CAD mock-up:

First Primitive CAD Model - June 2013
First Primitive CAD Model - June 2013

We ordered a bunch of off-the-shelf components, 3D printed the mount, and installed the motor on the bike:

We stuffed the batteries and electronics in a bag, strapped it in the front basket, and began motoring around NYC at speeds that should have gotten us arrested. It was brilliant fun.

But we needed a better way to transport the components, and we didn't want to occupy the precious limited space in the CitiBike basket. So we found an off-the-shelf case that fit underneath the basket and managed to fit all the components inside.

This was an improvement, but it was still too difficult to open the case, remove the components, attach the motor mount, connect the wires, etc, etc..

That's when we bit the bullet and concluded we needed to design a custom case with a pivoting swing arm motor assembly. So we bought a 3D printer and set to work creating prototype after prototype after prototype. You can see a sampling of different prototypes as they progressed from the case above all the way to the beautifully functioning ShareRoller we have today:

ShareRoller Prototypes - July 2013 thru February 2014
ShareRoller Prototypes - July 2013 thru February 2014

 And it wasn’t just the case that went through iteration after iteration. The critical motor mount assembly went through countless revisions. They may look almost identical, but each of these motor mounts below had a new improvement.

ShareRoller Motor Assembly Prototypes - July 2013 - February 2014
ShareRoller Motor Assembly Prototypes - July 2013 - February 2014

Risks and challenges

Design & Engineering Risks: Since ShareRoller is not an early prototype, the vast majority of design and engineering challenges have already been overcome. However, there is always the chance that we will uncover additional engineering needs as we move through volume production and assembly. If this occurs, we believe we have the resources to address these needs quickly and effectively, and we will do everything in our power to maintain forecast delivery schedules.

Supplier Risks: We have worked with our major suppliers now for over 6 months and have developed tremendous confidence in their capabilities. However, there always remains the risk that one or more suppliers fail to deliver as promised. This is the reason we have two suppliers for every key component - should one falter, we have a second to fill in. Thus, we believe that this is a manageable risk and not likely to materially impact delivery timeframes.

Legal and Regulatory risks: Electric bike legislation is in a state of flux nationwide, with many regions subject to somewhat unclear rules, and changing legislation. However, we believe ShareRoller currently complies with all Federal laws on e-bikes, and since ShareRoller powers share bikes only after the rider begins to pedal, it is designed to be exempt from NYC's electric bike ban. We also believe ShareRoller currently complies with Terms of Use of major bike share programs.

Learn about accountability on Kickstarter


  • ShareRoller can definitely work on a regular bike, with exactly the same quick attach/remove process. However, the bike has to be 'fittable' with an adapter bracket. Typically this means there has to be a front brake mounted above the front wheel, and the front fenders can't extend too far forward. There are two ways we will be enabling this for backers:

    - Bike-specific mounts: custom-engineered mounts designed to fit a specific bicycle. We have the resources in-house to design 2 of these per week, but again the bike has to 'fittable'. We will poll all backers at the close of the project to sort out priority. For an example of how a 'bike-specific' mount works, see:

    - Universal mount: we are in the process of developing a universal mount that will have adjustability that will allow it to fit many bicycle types. We will have this completed shortly after the end of the campaign, and hopefully sooner.

    We realize this doesn't clarify whether ShareRoller is guaranteed to be able to fit on YOUR bike, but if you send us the bike model/type or some photos of the front end, we can tell you whether it's likely to work. Send any pics to:

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  • Both the Brompton and Xootr Mounts will be available for purchase upon close of the Kickstarter, as well as the Universal Mount we are currently developing.

    The cost of the Brompton Mount (as well as the Xootr Mount) will depend upon how many orders we receive for it. At less than 50 units, we will be using direct digital manufacturing (ultra-high-end 3D printing) to produce the mounts, so they will be more expensive than we'd like - approx $95 each, with 25% discounts on additional mounts. However, should we reach 50+ units for either mount, we will be able to manufacture with injection molding and the cost will drop to $30-40 each.

    The cost of the Universal Mount will be $95 with volume production, as it is more complex due to its adjustability. Please note that the Universal Mount will not fit all bikes, only many bikes that possess the following characteristics:
    - Front brake mounted on fork above front wheel (bolt assembly is used to attach the Mount)
    - Sufficient space above the front wheel to position the ShareRoller
    - Front fenders that do not cover the area where the ShareRoller must contact the front tire (they can often be trimmed back if they do)

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  • YES. ShareRoller will of course be covered by a 1-year limited warranty. If anything breaks under normal use, rest assured that we will fix it at our expense.

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  • First and second production run really means timing of production and delivery. There won't be any real differences between the two products. We just intend to ramp up production slowly and in phases. And actually the first phase is the beta units - produced entirely with ultra-high-strength 3D printed plastic, and assembled by us.

    And then the second phase for everything else, which encompasses 'First Production' and 'Second Production,' will utilize injection molding and outsourced contract manufacturers for higher volume production. To maintain quality standards, the first 100 units for June delivery ('First Production') will be assembled at a much slower pace and with more intense QC testing, ensuring that even the early production ShareRollers will meet all standards. Any learning curve on assembly will be offset by lower production rate. Once the June delivery units are completed, we will ramp up production to a 200+/month rate from July-on, which constitutes the 'Second Production'.

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  • We've spent a lot of time perfecting the wet weather performance, which is always more challenging for friction drive systems. First, we've tested dozens of urethane compounds to find which best grips with wet rubber. Second, we've designed in tread patterns to the urethane belt to give the water somewhere to go (just like on car tires). And finally, we've designed the variable pressure mechanism to allow you to increase pressure of the motor on the tire when it's wet out, since reduced friction coefficient requires increased normal force to achieve the same frictional force. As a result, it works very well in wet conditions.

    The only negative is that the increased force does reduce efficiency, since the motor is pressing deeper into the tire, so range is somewhat reduced in the rain. But it's not a huge difference.

    The production versions of ShareRoller will of course be weatherproof, and will be fine riding in the rain. They will not be immersion proof however, so deep-water river fording is out of the question.

    The motor will be rustproofed and with sealed bearings, and the plastics used will certainly be water and salt-tolerant.

    After riding in wet conditions, you will want to wipe down the case and motor assembly, which will get dirty from road grime. The motor assembly can in fact be rinsed under a faucet to get it thoroughly clean.

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  • From the testing we've done to date, we have not seen visible increased wear on the tires. Some friction drives use metal rollers, or worse yet knurled metal rollers, and these can dramatically increase tire wear, especially if there's slippage.

    Our urethane belt and variable pressure system is designed not to slip and not to abnormally wear out the tire. And our observations confirm that it's working!

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  • There are strict airline regulations that govern transport of Lithium batteries. We're not finished all our work here, but preliminary research indicates that batteries of up to 300 Wh are permitted under the "Larger lithium ion batteries" category. Therefore, the Standard Range ShareRoller, at 240 Wh, would qualify for air travel (US FAA).

    The extended range ShareRoller would only qualify if the pack were split into two 200 Wh packs that can be separated for air travel. Fortunately, the ShareRoller already has a split battery pack due to the required dimensions to fit on the CitiBike. So in order to make the extended version FAA compliant, we'd just have to put in a connector that could be manually unplugged for air travel to qualify. If there is sufficient interest for this feature after the Kickstarter closes, we will endeavor to build it in to production versions.

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  • Electric bike regulations differ by country, state, and even city. However, the quick answer is that we believe ShareRoller is legal in all of the bike share markets we outline above, keeping in mind that ShareRoller will be power and speed limited via software in Canada and the UK.

    More specifically, in the US, e-bike laws primarily regulate speed and power. The Federal e-bike requirements are no more than 750 Watts power, and a maximum of 20mph on flat ground with a 170lb rider _not pedaling_. This law primarily regulates manufacturers, however. States and cities have their own laws governing use. Interestingly, some states are more tolerant of speed and power.

    Here are the requirements for the major states with bike shares:

    Washington, DC: 1,125 Watt max, 35 mph max, although must be registered, and not allowed in bike lanes (under proposed redefinition)
    Massachusetts: n/a 25 mph max
    Illinois: n/a 20 mph max
    Minnesota: 1,000 Watt max, 20 mph max
    California: 1,000 Watt max, 20 mph max
    Ohio: 750 Watt max, 20 mph max
    Tennessee: no state law
    New York: effectively no state law

    And, importantly, in NYC:

    Recently passed legislation in NYC (Local Law 40) outlaws "motorized scooters", defined as:

    "motorized scooter" shall mean any wheeled device that has handlebars that is designed to be stood or sat upon by the operator, is powered by an electric motor or by a gasoline motor that is capable of propelling the device without human power and is not capable of being registered with the New York State Department of Motor Vehicles."

    So since the ShareRoller requires one to be going 1-2mph before the motor will kick in (~one pedal stroke), it's not technically capable of propelling the device without human power, and is therefore designed to be exempt from Local Law 40.

    In Canada, e-bikes (PABs) are limited to 500W and 32 km/h at a Federal level. Two provinces matter to share bikes:

    Montreal - Quebec: same limits as Federal.
    Toronto - Ontario: same limits as Federal

    Thus, the ShareRoller will be software-limited to 500W and 18mph and will be perfectly compliant in Canada.

    In the UK (London Barclays Bike Share), electric bikes are limited to 200W average power output, with a maximum speed of 15mph. Thus, ShareRollers delivered to UK customers will be software limited to comply with these regulations. Keep in mind that 200W average power warrants 350W+ peak power, which is what we will program as a limit into the software.

    ShareRoller will technically require 'type approval' due to application of motor power without use of pedals, however there are no known cases of enforcement of the requirement for type approval.

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    Thanks for helping bring this product to reality. Your name will appear under our 'Benefactors' list on our website

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    FOUNDING BACKER - One ShareRoller from the first production run. Save over $350 off the summer production price.

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    EARLY BACKER - One ShareRoller from the second production run. Save over $250 off the summer production price.

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    FOUNDING BACKER, EXTENDED RANGE - Increase your range from 12 miles to 20 miles, with only a 1/2 lb weight increase. One ShareRoller with Extended Range battery from the first production run. Save over $350 off the summer production price.

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    EARLY BACKER, EXTENDED RANGE - Increase your range from 12 miles to 20 miles, with only a 1/2 lb weight increase. One ShareRoller with Extended Range battery from the second production run. Save over $250 off the summer production price.

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    SHAREROLLER, EXTENDED RANGE - Increase your range from 12 miles to 20 miles, with only a 1/2 lb weight increase. One ShareRoller with Extended Range battery from the second production run. Save over $350 off the summer production price.

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    I WANT IT NOW!! SHAREROLLER BETA _PLUS_ PRODUCTION, EXTENDED RANGE - NYC Residents only. Start ShareRolling immediately! Get a fully-functioning Beta version of ShareRoller to use right away, and then we'll update it with a brand new, fully-polished production version in July 2014. Both kits will be Extended Range.

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Funding period

- (30 days)