What it means to convert a bike to electric

Alvin Carpenter, CEO Island City Bikes, LLC

When a bike arrives in our shop for conversion to an electric bike we view it far more than an exchange of services and goods for financial compensation. We view it as a responsibility and a trusted relationship. I do not say that as a matter of marketing babble but in sincerity. When you place your bicycle in our hands the unspoken message is, "I trust you to transform my bike into a safe, reliable method of transportation for years to come." Every build is personal. We never let any bike leave the workshop that cannot be defined as a "safe, reliable method of transportation for years to come." 

Our work does not end when we return your bike to you fully built into a powerful electric mode of transportation. The relationship of trust and responsibility that began at our first meeting will extend into the future. We stand behind our craftsmanship and our product and will always be here if you need us.

Isabella bike mechanic at Island City Bikes, Alameda CAlifornia

Meet Isabella one of bike mechanics and former pro racer.

The Process of Converting Your Bike to an eBike

Receiving the Bike

Receiving the bike

Without candor I say that every bike that arrives in our shop for conversion creates a sense of excitement. The reason is that we love bikes, working on bikes, transforming bikes into electric bikes and most importantly...taking a bike and reconditioning it back into its original condition. To us, it is very rewarding work. Many times we have taken bikes to convert to electric knowing from the very start we would lose money but we cannot resist the challenge. The experience we gain by these difficult projects is what makes us the best in the business. 

Our CPA informed us that we lose money on 8%-10% of our builds. It cannot be helped as it is the nature of this business. Once we receive a bike it is our pledge to convert it into a safe, reliable, electric powered mode of transportation. 

Cleaning the Bike

cleaning the biker

Cleaning a bike is imperative for a thorough inspection of the bike. When we inspect a bike we are looking for anything that would make it unsafe to convert to electric.  electric bikes are powerful and therefore the bike to be converted has to have no cracks in the frame, poor welds, or anything else that might comprise the safety of the rider. If after cleaning and inspection we find anything that renders the bike unsafe for conversion we return the bike to its owner and there is no charge.

Many things on a bike can be repaired or replaced  prior to conversion. For example; chains, cracked stems, rim tape, spokes, tires, shifters, derailleur, cables and cable housing, cassette and bent hangers. Derailleurs, chains and cassettes usually just need cleaning which is part of our service.

Disassembly of the Bike

Disassembly of the bike

While we do not disassemble all bikes there are times where it is necessary in order to correct apparent build problems and service areas of the bike that are unreachable. For example, the bike pictured above is a cargo bike that had all the tubes for the child carrier on backwards. In fact, every tube was on backward. We have converted many cargo bikes to electric and it is not rare to see these bikes assembled incorrectly. It is not the fault of the cargo bike company as many add-on components are installed by the end user and sometimes the instructions are confusing and difficult to follow.

We have done so many cargo bikes a simple glance can tell if the components are installed correctly, or if there are any missing components that are required. 

Ultrasonic Cleaning

ultra sonic cleaning of bike parts

This is a commercial grade ultrasonic cleaner. Ultrasonic cleaners use high pressure sound waves to create minute cavitation bubbles that force contaminates from objects placed in the tank. We use a biodegradable cleaner in conjunction with the ultrasonic cleaning tank. Nothing can clean a chain, derailleur or cassette better than ultrasound cleaning. It is through the use of ultrasonic cleaning that we were able to find the cracks in the pulley wheel mentioned earlier. 

There is nothing that will clean a rear derailleur as well as ultrasonic cleaning. This is vital to our work. If a rear derailleur will not function as intended it is pointless to use it on a new electric bike. Most derailleurs shift poorly due to grime and other contaminates impinging the pivot points or that might be hindering the pulley wheels. 

Every now and then we see a derailleur that is simply worn out. After cleaning in the ultrasonic tank it is much easier to evaluate the wear on a derailleur.

Evaluating Derailleurs for eBikes

Island City Bikes, Bafang installation

Please Note: When I refer to a "worn out" derailleur I do not mean an abused derailleur. All bikes that have been cared for and ridden for years at some point will have a worn out derailleur. A worn out derailleur means that the bike has been used as it was intended when initially purchased. 

Restoring and replacing derailleurs.

90% of all derailleurs function as designed after cleaning and lubricating. Some derailleurs are of such quality they should be restored, rather than replaced. Restoration means new pulley wheels, barrel adjusters, and cable clamp. These items are not very expensive and it is a shame to toss out a good derailleur because of a $20 part.

Note: Some of the finest derailleurs we see are Sram. Even their low end derailleurs are very well made and are worth restoring. While racing I always used Shimano groupsets and paid little attention to Sram groupsets. Now, because we work with derailleurs every day I have to concede...Sram makes fantastic derailleurs. 

Shift and Brake Cables

Bafang Installation

Shift cables and shift housing are integral to the proper shifting of any bike. The picture above is a brake cable on a very heavy cargo bike that needs replacing. All cables that show fraying or show corrosion need to be replace along with the housing. This is true for both shift cables and brake cables. It is not expensive to replace cables and housing and we do it routinely as part of our service. Brake cables we replace at our discretion as you have to be able to stop your bike.  

Shift housing and brake housing is often neglected but contaminated cables means contaminated housing. New cables and new housing will make the derailleur shift as if it were new. Electric bike motors need precise shifting and precise shifting cannot happen with old, contaminated shift housing.

Once, while lined up at the start of a road race at Sea Otter I saw a racer shift and the shift cable ruptured the housing. This can only result from never replacing old cable housing. An official also saw this and pulled him from the race. 

The Chain

Island City Bikes Bafang installation

Here we are measuring a chain to determine the amount of wear. What is known as "chain stretch," is actually the wearing out of the bushings and pins in a chain. A used chain grows longer, not from stretch, but from the bushings becoming smaller with wear. If a bike is a 7-9 speed and there is NO rust on the chain then the existing chain may be used. The exception to that rule is if the chain is of poor quality. Poor quality chains will break under power.

It is our experience that 10, 11, 12 speed bikes do not require special eBike chains if one is careful while shifting and a shift sensor is used (all of our conversions include a shift sensor). 

The Chainline

Island City Bikes Bafang installation

Chainline is the most difficult aspect of any eBike conversion. Chains are most efficient if running in a straight line but this is not possible with multi geared bikes. Typically, the only straight line between the cassette and the chainring is the cog in the middle of the cassette. Other than that one straight line, the chain deviates up into the low gear and down into the high gear. Under human power this system works. However, the power of an electric motor will exploit any deviation of the chain and can cause the chain to fall off (chain drop). It is the task of the builder to find the most efficient chainline. We do this through the use of a variety of spacers that are balanced between the motor axle and the chainring interface. It is not easy, and takes patience. However, dropped chains, that are the result of poor craftsmanship, is inexcusable.

The Chainring

Island City Bikes Bafang Insallation

This is a stock chainring for the Bafang BBS02 750 watt motor. It is made of stamped steel, comes with a plastic cover and has a very limited offset. Because if its limited offset it is, at times, inadequate for establishing a good chainline. Sometimes it works perfect and other times it will not work at all. The Bafang stock chainring for the 750 watt motor comes in three sizes, 44T, 46T and 48T, and all three have the same offset. The offset of a chainring is what moves the chain closer to the bike frame. If any bike requires more offset than a stock Bafang chainring supplies then a Lekkie chainring must be used. 

Again, it is pointless to build or convert a bike to electric knowing the chain will fall off on the first ride. The proper chainring must always be used.

Lekkie Chainrings

Island City Bikes Lekkie Chainring

This is a Lekkie 42T chainring. It has a 9mm offset that can put the chain right in the middle of the rear cassette. It is made of 7075 machined aluminum, lightweight, and most importantly it uses the narrow/wide tooth pattern. A narrow/wide chainring works so well at keeping the chain on a bike it has replaced the chain keeper. It works very well on any bike where chainline is an issue. Were it possible, we would include the Lekkie chainring on all of our builds as standard. 

Shift Sensor

Island City Bikes Shift Sensor

We install shift sensors on all of the bikes we build and all of the bikes we convert to electric.  All bikes over 500 watts need a method of interrupting the power between shifts. A shifts sensor cuts the power of the motor while the gears are changing. This relieves the pressure on the drivetrain. Most electric bikes sold in bike stores are between 250 and 500 watts. At that level of power a shift sensor is not necessary. Our motors are  750 watts with a peak wattage of 1,500 watts. These are very powerful motors and that is why they need a power interrupt while changing gears,

Our Battery

Island City Bikes Lithium ion eBike batteries

Nearly all lithium ion batteries and battery packs come from Asia. We purchase our batteries from this company because they spend hundred of thousands of dollars on testing equipment. Our battery failure rate is zero. We carry batteries of all sizes and shapes. We have batteries that are so small they fit behind the saddle. These small batteries use Samsung 30Q cells and are very powerful.

Every battery comes with a lock, and a charger as standard. When we convert your bike to electric our goal is to use a battery that provides the most power in a location on the bike that is reasonable.

Battery placement

Island City Bikes Trek Bafang conversion

Our first choice for the placement of a battery is on the downtube. A downtube battery is designed to interface with the downtube of the bicycle in such a manner that easy installation and removal is made possible. 

What are the options if there is no room to place the battery on the downtube? There are some bikes where there is no room on the downtube due to size of the frame or the battery is impeded by the shock absorber of the full suspension bike. 

We stock all types of batteries in order to find the right battery for any bike. We have side load batteries, odd shaped batteries, even batteries that look like a water bottle. One way or another we will find the right battery for your bike.

Battery placement continued

Island City Bikes Trek full suspension Bafang build

As you can see from the picture above there is no place on the downtube for a battery. At this point we have a few choices. We carry all sorts of batteries is a variety of sizes and shapes. This bike required a side load battery and it needed to be mounted on top of the top tube. It could not be placed on the bottom of the downtube as the wheel would come into connect with the battery once compressed. The building of any electric bike, conversion or otherwise, is a matter of compromise. Compromise is NOT exchanging better for good...it is finding a way to make the impossible happen and then refining it until it works as if that was its intent from the very beginning. 

Esthetics vs. Function


The picture above is from Arron Walter's "Hierarchy of user needs." Note that the line of progression begins with "functional." From there it goes to reliable, usable and then a pleasurable experience. Function is the foundation, esthetics comes last. Some prefer to invert this pyramid and choose how something looks over how well it functions. We all do that under certain circumstances. For example, a $50 electric quartz watch is more accurate timepiece than a $10,000 Rolex self winding watch. 

When it comes to electric bikes, function is paramount. It has to function to the degree all parts work harmoniously as a consistent whole. Yes, esthetics are important to us and that is why we spend so much time on cable routing, cable looms, the use of cable guides, and the constant cleaning of the bike. 

The Bafang Mid Drive Motor

Island City Bikes Bagang BBSHD

What motor will we install on your bike? We use the Bafang mid motor exclusively. The name Bafang may not be a familiar name here in the US but it is throughout Europe, Asia, South America and pretty much everywhere else. It is the most popular motor in the world selling over 1,000,000 units a year. This motor is chosen over other brands due to its reliability, availability of parts worldwide, lightweight, no maintenance required, allows end users to set their own speed, and is the most powerful mid drive motor on the market. 

All other electric bike motors combined sales do not add up to a fraction of the number Bafang sells each year. We purchase Bafang motors 200 units at a time. By purchasing in quantity it allows us to keep the price of our electric bikes and electric bike conversions to the lowest possible. We have built hundreds of electric bikes with this motor and there is nothing we do not know of its engineering quality. We will always choose this motor for our clients as it is...to quote Tina Turner, "Simply the best."

Cables, Cables, Cables....

Island City Bikes eBike cable management

A man called me last year and said, "Dr. Carpenter, your cabling looks like crap." I said, "I know it does and that is why I lose sleep every night trying to figure our a better way to route cable." 

There are three crisis moments in building electric bikes...battery placement, chainline, and cabling. After the battery and motor are installed comes the attaching of the display, display control, throttle, electric brake cut off brake levers, green button, main harness, motor cable, shift sensor, speed sensor and power to motor cable. That is a lot of cables. 

What makes cabling so difficult is every bike is different is size, make, model and year of manufacture. Folding bike, full suspension bikes, extra small frames, extra large framesets, cargo bikes and tandem bikes all require different techniques. The only way to become adapt at cable management and cable looms is to do a lot of them. We work with cables 7 days a week, we learn from one another and we critique the work of one anther. Because there is such a wide variety of types of bikes it is impossible to be able to teach a single method of cable management applicable to all bikes. 

Today I was watching a young woman in our Alameda shop route cables and she said "What should I do?" I said, "Do it in a manner that you think meets the goal of esthetics and function." She is a licensed beautician...I watched her slowly begin to braid the cables as if they were hair. I had never seen anyone braid the cables of an electric bike. This is the type of creativity that is valued by all companies, big or small.


Island City Bikes waterproof connections

This is a picture a the cable coming from the battery to the motor. The connection is an Anderson Powerpole connector with a locking pin. We then use heat shrink to seal this connection. The other connectors on the bike are Higo connectors. Higo connectors are waterproof connectors that are used in a marine environment. All of the connectors on any bike we build or convert to electric will have Higo connectors. However, we will heat shrink each Higo connector to double insure your bike will be as water resistant as possible.

We are always ask by those who are commuting on their bikes, "How waterproof are your bikes?" I think the best answer to that question is what happened to one my clients who had her folding bike converted into an electric bike so she could commute to work. The very next day after I delivered her bike to her home I received a frantic call.

I was in my office when the call came in and she said..."I am on a bus crossing the San Francisco Bay Bridge and my bike is on a rack on the front of the bus and it is pouring rain...will my bike be ok?" I said..."Do not worry, we will take care of you if anything happens but I am sure the bike will be fine." I hung up and thought: The bike I built is going 60MPH on the front of the bus in the pouring rain....ye gads.Twenty minutes she called back and said..."every thing is fine and the bike runs great." Yes, all the extra work we spend using heat shrink on all our connections paid off and we do have the most water resistant bike on the market.

Securing the motor

Island City Bikes installing a motor stabilizer for bafang motor

This is a picture of one our technicians preparing a bike for a motor brace. We get calls all the time from people who either installed the motor themselves or have had another company install their motor and the motor has come loose. Our motors do not come loose. In fact any time during the life of the bike if the motor does work its way loose we will repair it at no charge.

In the picture above we see a Rivnut being installed. This is one of the methods we use to secure a motor. Rivnuts and Rivnut tools are expensive, and can only be installed by experienced technicians. 

There are other methods we use to use that are proprietary. We have spent countless hours in machine shops, meetings with engineers, and outside consultants to perfect a method of securing a mid drive motor to the degree we can provide a lifetime warrantee our motor will never come loose. 

Tires...Often Overlooked

Island City Bikes building electric bikes, evaluating tires

During the cleaning and inspection phase we found this split in the tire. We called the owner, showed him the picture and said the tires need to be replaced as they pose an immediate danger to any rider of this bike once we have converted it to an electric powered bike. He agreed.

What do I do when an owner refuses to replace a damaged tire such as this? I replace it anyway. I pay for it out of pocket. Why do I do this? First, I think you would do the same. Second, I would never wish to contribute to the injury of another in the name of profit. In this business, if I cannot give away a tire, cable, tube, housing, or anything else to make a bike safe then it is time to retire. 

I suppose when I am no longer in charge  things will change. For now, I own the company, and I do whatever it takes to insure every bike we build or convert to electric meets the highest standard of safety.

Electric Bike Specific Tires

Island City Bikes and eBike specific tiries


On all bikes we convert to electric we talk to the owner about tires. Tires are the most important part of any bicycle. Tires are the only part of a bike that comes into contact with the surface the bike is transversing. The only part of the tire actually touching the road is called the contact patch. On a narrow tire the contact patch is very small which means the bike will go into a skid much sooner that a tire with a large contact patch. On an electric bike you want to have the widest tires possible, within reason, because that increases the contact patch that interfaces with the surface allowing much better braking control. Also, large tires will roll over obstacles, cracks, bumps, and potholes much easier than narrower tires. 

A second consideration is the thickness of the sidewall. On stock tires the sidewalls are notoriously thin. Thin sidewalls make a tire much lighter. On electric powered bikes weight of tires is not an issue so eBike rated tires triple the strength of the sidewall. Strong sidewalls are very important to any electric bike. I cannot say this with greater emphasis. When descending and cornering at high speed on a eBike it is essential the sidewalls of the tires are robust enough to keep them from rolling off the rims.

A third consideration is puncture protection. EBike rated tires are loaded with puncture protection material that would not be possible on a standard tire due to its added weight. Weight of the tire means nothing to a bike that has a powerful motor such as the Bafang. All electric bikes should have electric bike rated tires.

Special Builds

Island City Bikes Tandem build with Bafang BBS02 750 watt

We do a lot of special eBike conversions such as this tandem bike. We carry every part necessary for every build in stock. It is a cardinal rule that once a bike is placed on a workstand it will stay there until the build is complete. That means the technician must have every part he or she needs to complete the conversion.

I will always remember the time a tech was building a bike and called out to me for a special part and after searching for the part I said, "Sorry, I forgot to include more of those in my last order." He glared at me...then slowly, without a word, took the bike off the stand and rolled it into a corner and then folded his arms. I never let that happen a second time. That tech is a professional and views himself as a professional and as a minimum deserves every tool and every part needed in order to do his job. 

Tern Folding Bike

Island City Bikes, Tern foldong bike with Bafang BBS02 750 watt

This a beautiful example of a folding bike that we built using a side-load battery and a BBS02 750 watt motor.  A folding bikes is one of the most difficult bikes to convert to electric. Battery placement is always an issue as it has to find a place on the bike that can allow a rigid installation. Motor placement is difficult as it sometimes the shape of the frame will not allow a motor brace. Lastly, cabling is always a challenge because all cables must be routed on the bike in such manner that it will allow the bike to fold. Fortunately, we manufacture our own motor braces, stock all necessary extensions, and have an assortment of batteries to choose from. This week we converted three Giant Expressway folding bikes and all of them came out as powerful folding bikes ready for commuting.

Xtracycle Bafang Conversion

Island City Bikes Xtracycle Bafang conversion

We convert more cargo bikes into electric bikes than any other company in the US. One of the reason people bring their cargo bikes to us is we do not charge any more for a cargo bike conversion than we would for any other bike. 

We have special equipment for working on cargo bikes so their size and weight are not a problem. We use a special pneumatic bike lift, manufactured in Eugene Oregon, that allows us to lift the bike and rotate to any degree in order to inspect, calibrate, repair and perform the conversion to electric. Also, we keep in stock all the extension cables, displays, and XL chains necessary for these conversion. We also have eBike rated tires in sizes that fit all cargo bikes. Cargo bikes are one of our favorite bikes to convert.

In conclusion

Thanks for reading about our conversion of standard bikes to electric bikes

Of course, there is far more involved in converting your bike into an electric bike but I think this can give you a general idea. I hope you do not think I am boastful in some of the claims I make but as my Mother used to say, "It isn't bragging if it's true." A man called me today and said, "What eBike at the bike shop do you recommend I buy?" I said to him, "In all honesty, none." "The best electric bikes available anywhere are sitting here in the room where I am standing." In our shop I am surrounded by the bikes of our clients that are being converted into electric bikes. There are cargo bikes, mountain bikes, tandem bikes, and city bikes. All of which, I believe are the best electric bikes to be found anywhere. 

It is not by fortune or chance we are where we are today. We are the most successful company in our field because of hard work, diligence, customer satisfaction, and love of bikes. 

Alvin Carpenter, PhD

Alvin Carpenter, PhD