How we convert a standard bike to electric

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When a bike arrives at the shop it undergoes a general evaluation to ensure the bike is suitable for conversion. What we are looking for is the condition of the frame, forks, wheels, and any possible corrosion that may lead to failure. Rust on a bike is not necessarily a deal breaker because it depends on how deep the rust has penetrated the frame. Surface rust on a steel bike is common and presents no harm to the integrity of the frame. 

We also look at frame geometry. Frame geometry will determine what type of battery we will use and where the battery will be placed.

Then, we look at the area around the bottom bracket. We are looking for any obstructions that may come into contact with the motor. Most obstructions can be removed (bash guards, chain keepers, chain guards). Also, we measure the bottom bracket shell to determine length. Some shells will be 68mm, 73mm, 100mm, and 120mm.

Sometimes we can evaluate a bike with a glance because we have built the same bike many times over. Other bikes will take a deeper examination. For example, a carbon fiber full suspension bike. Carbon fiber can be shaped and molded whereas aluminum and steel is predictable. The Bafang motor will fit any bottom bracket shell of steel, aluminum, and titanium, but carbon fiber bikes may have a bottom bracket shell that is irregular in shape that may prevent the use of a mid drive motor. See our article on the Bafang motor and carbon fiber bikes.

NOTE: Do not be concerned if your bike is dirty! We will clean your bike thoroughly when it is in our possession. 

When someone brings a bike to our shop for conversion we want to know as much as we can about the rider of the bike as well as the bike itself. The bike is a static, non-living object whose value (other than its artistic value) comes into being when it becomes one with the rider. Therefore, it is rider first and bicycle second. 

The who question is a question of responsibility. I have been ask to build electric bikes for children as young as seven. The parent tried relentlessly to convince me the child could manage an electric bike that could travel  up to 30mph. Of course, I held my ground and refused and certainly hope other builder also refused. An electric bike is fast and requires focus every time a person is on the bike...even if it is not moving. 

Once, a man called me to ask if I could build him a bike that can go 40mph. I said that I could and then asked for what purpose would he need a 40mph bike? He replied, "I just got my forth DUI (Driving under the influence of alcohol/drugs) and lost my license and now need a fast bike to get to work. I informed him that I would be willing to build him a 20mph bike, but nothing more. He said he would find someone else who would build the bike for him. 

Sometimes, it is time to hang up the cycling shoes. A man with dementia came to our shop and said he wanted us to convert his bike to electric because he kept falling off the bike every time he stopped pedaling. He thought converting it to electric would solve his problem. Of course the problem was not the bike and converting it to electric would not be the solution. He was 97, loved cycling and had reached that stage where...well if you have cared for an aged parent then you know what I am talking about and I will leave it at that. 

Age is not always a limiting factor when someone comes to our shop requesting their bike be converted to electric. We have converted bikes to electric for at least a dozen riders over 90 years of age within the last two years. Albeit, all of these riders have a long history of cycling and are very experienced cyclists. Some have cycled around the globe and across the US several times. Others are former racers. This group of elders may have many decades behind them yet they are still athletes in body and soul. In addition, their collective knowledge of cycling throughout the years under diverse conditions is encyclopedic. Their bikes are always well maintained and may even be of a different era but they always make for great eBike conversions due to their fantastic condition. 

The point is, electric bikes will not pose a danger to a rider over 80 who is an experienced rider and in great shape both mentally and physically. And, as we all know, there are some who are 80 plus who are in better shape than some of us who are much younger.

Now...the other side of the coin. Sometimes age is a very limiting factor. Three times this year (2020), I had to meet with the families of men who requested we convert their bike to electric. Each time I said the same thing; "I am sorry, but your (insert relation) should not be on any bike, much less an electric bike." Those were difficult meetings but in each case the family members were in agreement. One time a spouse said to me, "Of course you are right but he would not accept the fact he should no longer be on a bike unless it came from a professional."

Yes, it is uncomfortable saying "no" to an adult. However, we are all responsible for one another's well being, as we should be. Profit stands far behind character, integrity, and human decency. 

This shift cable would have broke in short order leaving the rider stranded. Can a snapped shift cable pose a danger? Yes it can. When a derailleur cable snaps, the chain immediately falls into the lowest cog on the cassette. If you are climbing a hill when this happens, you will most likely will fall off the bike. In addition, if the "limit screw" on the derailleur is not properly set, the chain will wedge itself between the frame and the wheel. If that happens it is very hard to correct.

If, your bike has a "Rapid Rise" rear derailleur then the chain will go to the largest cog on the cassette. That is fine except for the fact if the low limit set screw is improperly set, the derailleur will go into the spokes and a crash is imminent.

Some shift cables are made of galvanized steel and they cost a third of stainless steel cables. Whenever we see a bike with galvanized cables we remove them and replace with triple strand stainless steel cables. Galvanized cables quickly erode and contaminate the cable housing. 

We always check cables, cable housing, and limit set screws on every bike. Many times, we find bikes where the limit screws are not set and the derailleur is held in place by the tension of the cable. It is done in this manner because it is much faster than using the limit screws. Always...use the set screws on the derailleur, as it is the only thing that will prevent a chain from falling into the spokes, or wedging between the cassette and the frameset.

The slanted valve stem is a problem that needs to be addressed, not ignored. This Schrader valve stem is being pulled against the sharp edge of the rim and eventually it will cut the stem, resulting in a flat tire.

A flat tie is not just an inconvenience...it can also be hazardous. Tires rarely go flat while they are sitting at home. Tires can go flat while riding in the rain or in the summer heat, in a high traffic areas, in dangerous areas, or on a steep hill. Not everyone knows how to repair a flat. With that in mind, whenever you have a stem that is slanted, treat it as if you already have a flat and have it corrected. Otherwise, you may have a flat at the most inopportune time.

The slanted stem occurs when the rubber inner tube sticks to the inside of the tire. As the tire flexes and moves, the tube, being affixed to the tire, also moves.

To prevent this from occurring, we remove the tire, put the tube in a bag with baby powder and shake (not us...the bag). Now, the tube being covered with baby powder will not adhere to the inside of the tire and the stem should remain straight. Will this solve the problem? Sometimes yes and sometimes it only delays the inevitable. The best way to solve the problem is to use a tube that has the small nut on the valve stem.

There is nothing more important on any electric bike (or any bike for that matter) than the tires. Tires are the only part of a bicycle that comes into contact with the riding surface. Tires are more important than brakes. Tires are what stop a bike, not the brakes. Brakes hold the wheel while the tires stop the bike.

The RV dilemma. Many have purchased a used motorhome that had tires that looked new and had very low milage on them only to find out each of the tires had to be replaced. The usability of a tire is never based on appearance...it is based on age.

When we inspect a tire we look at the sidewall, as the sidewall is the first place that will show degradation due to age. Then we look at the surface of the tire. The surface of the tire is where obvious signs of wear are visible. If we see too many holes or imbedded material we recommend replacement. If the tire tread is worn, it needs replacement.

Please note: Never rotate tires. Sometimes, a rear tire that is worn will be rotated to the front and the front tire to the rear. This practice is not accepted by any school of bike mechanics.

Tires are a consumable, and it is to be expected they will need replacing as a matter of safety.

Bike frames are made of steel, aluminum, titanium, and carbon fiber. Each of these materials comes in different grades and thickness. With metal frames we pay close attention to the welds (brazing) of the frames to ensure there are no hairline cracks. We are also looking for any previous repairs that may not be up to snuff. We have a frame builder on call to evaluate any frame we think might be a problem. 

Bike frameset are incredibly well made. That is why most manufacturers provide a lifetime warranty on their frames. However, that does not exempt from close inspection as there are frame failures! We pay special attention to seat tube and chainstays as these are more prone to failure than any other part of the frame.

This inspection is part of our cleaning process, as it is not possible to inspect a frame for small hairline cracks when it is hidden by road grime.

The one component we see on recall lists more than any other is the front suspension fork. While cleaning the bike, we inspect the fork to ensure it is working properly then we check the recall lists to see if it is a recalled fork. Last year we found four front suspension forks that were on a recall list, one of which was an "imminent danger of failure" recall. In each case we helped our client file a claim for new forks.

When a factory recall occurs, all dealers are notified. The dealer is supposed to contact all those whom he/she sold the product and notify them of the recall. Sometimes that does not happen. Other times, the bike is sold to another party and they do not know there was a recall in effect.

A bit of research on our part helps our clients have a safer bike for a safer ride. 

First, we look at the rim tape. Does it cover all the holes, or the spoke ends? Is it poor grade that will eventually fail? Has it slidden out of place? Does it impede the valve stem? All of these factors will affect the life of the tube.

Second, we clean and inspect every spoke. We look at the point where the spoke enters the rim. It is here where we find cracks as the tension of the spoke tries to pull it through the rim. Then we move to the hub. It is at the hub where spokes tend to break. We hand squeeze each spoke to see if any or loose or even broken.

Third, we look at the bearings...does the wheel spin smoothly on the bearing? Do the wheels wobble? If a wheel wobbles we put it on a stand and correct the bearing tension. If a wheel spins in an irregular fashion (difficult to explain) then the bearings need to be loosened (if cone and cup) or replaced.

We have 4 heavy lift workstands to safely lift any bike. Each workstand grips the seat post and raises it to a height of up to 6 feet. This allows us to work on your bike at eye level. When the primary cleaning process is finished, the bike is assigned to a mechanic and a workstand. The bike will remain with that mechanic and work stand until the conversion is complete. At that time the work will be examined by a second mechanic prior to the test ride.

When the bike is on the stand we begin the process of disassembly. We will remove the pedals, crank arms, crankset, chain, cassette, derailleur, bottom bracket, front derailleur, front derailleur shift cable, front derailleur shifter, left grip, left brake lever, and front and rear wheelset. 

While the wheels are removed we inspect the brake pads on disc brake systems and brake shoes/inserts if rim brakes. 

In order to install the Bafang mid drive we will need to remove the crank arms, crankset, and the bottom bracket.

There are several different types of crank arms and each requires a special tool and technique for removal. The picture above is a self-extracting crank arm. These were made to make their removal simple and fast. Sometimes they are simple and fast to remove but around 70% of the time they are very difficult to remove.

Around 5-10% of the time we encounter frozen crank arms, or crank arms where the threads have been previously stripped or cross threaded. In such cases the crankset has to be removed by careful use of power cutting tools. 

The most common bottom bracket spindle is the square tapered spindle. The Bafang mid drive motor also uses a square tapered spindle but the crank arms are not interchangeable, with some exceptions.

The picture above is of a triple crankset with a square tapered spindle. When we remove the crankset we do so carefully as we do not to strop the threads. We start of with a special tool called a thread chaser. The thread chaser cleans and straightens any threads that might be damaged. The we carefully thread in our second tool, the crank puller. This tool we thread in a far as it will go. If this tool is not all the way in, it will strip the threads once the removal tool starts pulling. 

Removing a crankset can be accomplished in 10 minutes if the correct tools are used with the correct procedure. Failure means at least an hour of work cutting off a crankset because the threads were stripped in the process.

However, there will be those cranksets that are permanently frozen to the spindle and the only path to removal is through the use of powered cutting tools.

There are many types of bottom bracket removal tools because there are many types of bottom brackets. The above picture is perhaps one of the most common and works with most square tapered spindles. 

It is very easy to strip the threads in a bottom bracket. In order to prevent that from happening, we insert the socket into the bottom bracket splines, and then we use a tool to lock the socket tight against the splines. Then we can apply as much force as necessary to remove the bottom bracket.

Bottom brackets can be frozen into the bottom bracket shell.  We see this in both old bikes and new bikes and they are very difficult to remove. We use several methods including heat, chemical solutions, counter force, overnight soaking, and so far we have yet to be defeated. If a bottom bracket cannot be removed it cannot be converted, so one way or the other...it has to go.

Almost all bikes have a derailleur hanger. A derailleur hanger is a detachable hanger that holds the derailleur. It is made of softer metal than the frame. If the bike falls or crashes on the derailleur side of the bike, instead of damaging the frame, it bends or snaps off the hanger. A derailleur hanger costs $15-$20 whereas a damaged frame can thousands. This part is called a sacrificial hanger because it is sacrificed to protect the frame.

90% of all bikes that we see have a bent derailleur hanger. Anytime a bike is loaded into a vehicle and lays on the derailleur side it can bend the hanger. They bend easily, as they should, to protect the frame.

We check every hanger with the Park Tool Dag 2.2 Alignment tool. A bike with a bent hanger will never shift smoothly regardless of how much you adjust the cable. 

I have written a great deal about the necessity of tires on an electric bike. The wider the tire, the greater contact patch is with the surface, thus better stopping power! Larger tires make for a much more comfortable ride. Also, larger tires act as suspension on bikes. Suspension is important when riding a bike that can travel at sustained speeds of 25mph. Bumps, potholes, and obstructions in the road can come up fast and sometimes the only protection you have against a crash is large tires to absorb the shock.

Tire have to be in good condition. Stock tires, that came with the bike, are often found wanting and should be replaced with better tires. Old tires may appear in great shape with lots of tread but once we remove the tire from the wheel and look at the sidewalls we ofter (always) find age cracks throughout the tire! Tires have to be stored in a dark place, on a bike that is suspended, with the tire not sitting on the ground.

The answer to this question lay within as to what type of riding do you plan to use the bike. If you intend to use your bike off road, then you can use either the Bafang BBSHD 1000w or the BBS02 750w. If you plan to use your electric bike on public roads and bike paths, then we strongly suggest the BBS02 750, as that is your only legal option. However, it is your bike and your choice...we can only inform and advise as to the laws that regulate the use of electric bikes.

We have found the 750 watt motor meets the needs of 90% of all riders. We base that on the input we receive from all of our clients that are on bikes we built with the 750w motor.

We have installed the Bafang 750 on many heavy cargo bikes and yet to have a single motor fail. These are heavy bikes, often are used to carry children and yet the Bafang 750 is up to the task.

It simply is not true that the Bafang BBSHD is a better motor than the BBS02. The only people I know who make such a claim are those who sell the BBSHD. Yes, power comes from the motor but a mid drive motor climbs not with just brute force, but through the combination of front chainring and rear cogset. For example a 750w motor with a  36T chainring and a 11x36 rear cassette will out climb any BBSHD.

The other day I was talking with a Bafang reseller and I ask, "Selling many HD'S?" He looked at me and replied, "The HD is my number one seller." Think about that for a moment...The Bafang BBSHD is illegal in all 50 states for road use, is used by no eBike manufacturer, is heavier, slower and is more expensive than the BBS02 750, but it is still his number one seller. The reason for this is it is promoted by all resellers of Bafang motors as a better motor. It isn't. We have built hundreds of bikes...we know what is the best motor from hard data of actual bikes on the roads....no marketing, no opinions, no guessing...we know what works and what does not work.

All electric bikes are regulated by Federal and State law. There are three classes of electric bikes and when we convert your bike to electric, we give you the opportunity to choose which class of bike you would like.

Class I: This is a bike that does not have a throttle and the motor assist cuts off when it reaches 20mph.

Class II: This is a bike that has a throttle and the motor assist cuts off at 20mph.

Class III: This is a bike that does not have a throttle and the motor assist cuts off when it reaches 28mph.

It is your bike and it is your choice what type of electric bike you would like us to build. You can change your bike at any time, as the process of converting from one class to another is as simple as reprogramming the controller of the motor.

We have a number of batteries to choose from. The standard battery that comes with our electric bike conversion is a 48v 13 downtube battery. This can be upgraded to a 48v 17.5Ah or a 52v 17.5Ah battery. The larger the battery the greater the range. Most of the bikes we convert use the 48v 13Ah battery and it seems to provide sufficient range. We know this because only two people have returned and requested a larger battery.

Note: Sometimes a client does not get to choose  the battery if the frame geometry dictates the shape/size of the battery. When we work with full suspension bikes often (not always) the only battery that will fit is our 48v 10.5 side release battery. 

This is the side release battery and it is our favorite battery. The cell group is Samsung 35E and it makes for a great long range, light weight battery. It weighs significantly less than most downtube batteries and yet still is very powerful because of the Samsung 35e cells.

The design of this  battery allows it to fit in tight places. Most downtube batteries slide from the top down and this requires a distance on the top tube to be greater than the battery base plate. Whereas on a side release battery, if the base plate fits the battery will fit. We also like to use the side release battery when we are placing the battery on top of the top tube because it is much lighter than the 48v 13Ah battery.

We build a fair number of electric bikes with 52 volt batteries but that is because it is what our clients request. However, if you wish for your motor to provide years of trouble years service then we always recommend 48v batteries.

It is true that a 52v volt battery will make an electric bike faster and will increase range but the downside is that it can prematurely wear our the  motor and the drivetrain of the bike.

Every Bafang mid drive motor is rated as a 48v system. That is the way it was designed by the engineers at Bafang . To stay within the design parameters set by the engineers of Bafang will provide you with years of trouble free riding.

Here you can see the crankset has been removed. It looks very simple to slide the motor in and tighten it up and off you go. There are many things  that can make this job very difficult. First, the bottom bracket might have an occlusion that will block the axle of the motor from being inserted. Any occlusions need to be removed by hand filing, or the use of a Dremel. Second, cables might need to be rerouted. The shift cable  and the brake cable (or hydraulic hose)  must not be impeded by the motor. Many bikes have internal routing of the cables and lines and these exit right into the path of the motor. The motor cannot be allowed to sit on these cables and lines therefore we will reroute them. Rerouting shift cable requires experience, if done incorrectly the shifting of the bike will be compromised.

It is incorrect that there certain bottom bracket sizes that prevent the use of the Bafang mid drive motor. There is no bottom bracket size that we cannot make an adapter. We do not sell our adaptors and are solely for use of our clients. It has taken years to reach the point where we can install a Bafang on any bike with any bottom bracket standard. We have invested thousands in lathes, mills, cutting and drilling tools. 

There a few adaptors available on the internet but the problem is they are for the most common sized bottom bracket shell. There are 22 different bottom bracket sizes. We are the only manufacturers that can accommodate any bottom bracket standard through our use of custom adaptors.

Once the motor is in place we install the fixing plate. The fixing plate has raised ribs on one side. These ribs face the bb shell. Two M6 bolts are installed but not tightened. This fixing plate has to be tightened to the degree those small ribs are forced into the bottom bracket shell. Sounds easy? No...

Every week people call us about their motors coming loose...not our motors, but those built by themselves or other builders. When we install a motor it has a lifetime guarantee of never coming loose. We use different techniques for each type of frame material. For example, if the frame is of steel or titanium we use a different method than we use on a softer material such as aluminum or carbon. 

This is a M33 locknut and locking cap. Some believe this M33 locknut and cap plus 60Nm of torque is all it takes to secure a motor to a frame. Sometimes that is the case but other times not even close. There are many factors involved in securing a Bafang motor to a bicycle frame in a way that it will not come loose for the life of the bike or motor. For example, frame material, location of the bottom bracket shell, circumance and length of the shell, the facing of the shell (is it perpendicular to the motor mousing), obstructions on the downtube where motor rests, all of these play a role in proper motor installation. The black locking cap is more for aesthetics than locking. If the motor is not correctly set, the cap will have no effect. We do not use Loctight on the locking cap as it is more decorative than functional. 

Some say, "Bafang motors come loose...avoid them." Time for some clarification. First, a poorly installed Bafang mid drive will work itself loose. A properly install Bafang mid drive will never come loose. These motors are the most powerful motors of their class. It is no secret ( well...may it is a secret)  that some bike manufacturers reduce the amps of their motor in order to keep them in place. Bikes are commonly sold with 250 and 500 watt motors that behave in a civilized fashion but the problem is that there is not enough power for the hills, large riders, or heavy loads.

What good is an electric motor if it can only be ridden on flat surfaces? There are thousands of miles of beautiful hills to enjoy so have a motor that can exploit every foot of available terrain.

We have a number of methods we use to secure a motor and they all depend on the type of bike, frame material, size of the motor, geometry of the bike, and type of use. There is no "one size fits all." It was an imperative for us to develop a dependable method of securing the motor as we need to warrant the motor against movement for the life of the bike. By developing these methods we are able to make use of the full 750 watts, or 1000 watts of the Bafang mid drive.  However, there are some instances where we may be working w/exotic frame material or custom frame geometry that will require de-tuning of the motor in order to decrease the torque. 

Out of all the motors we have installed, they are still exactly where we placed them.