How to Electrify an Existing Road Bike — With Help From the Ebike Underground

By Stan Purdum

Ebikes are a booming growth field in the bicycling industry, and many companies, including both established bike brands and new startups, are now churning out an impressive array of these electric two-wheelers, some as low priced as $500, with some quite good ones starting around $1,500.

But the commonly available ebikes in that price range generally do not include road bikes, which typically cost $5,000 or more in the e-version. But even some of the most dedicated road bike riders reach a point where, for any number of reasons, they may want to consider an ebike.

Looking for options other than buying a new bike, some riders have purchased a wheel — either front or rear — with a motor in the hub and converted a road bike they already own. Most of these conversions work pretty well.

But suppose you want to convert an existing road bike using a mid-drive motor — one that assists you in turning the cranks and transferring the power to the rear wheel by means of the chain. Advocates of mid-drive motors say that they provide higher performance and torque than hub-drive motors, offer a lower center of gravity on the bike and work more synergistically with the bike’s gears. The latter means the mid-drive motor is more efficient, making a longer mileage range possible. What’s more, with a mid-drive, changing a flat tire is no more difficult than on any non-electric bike, whereas it’s more of a project with a wheel that has a hub motor, and can range from complicated to impossible to do on the road.

So this is my account of installing a mid-drive motor on my 1995 Trek 520 touring bike. Though the 520 has some age and plenty of miles on it, it’s been maintained and is in decent condition. What’s more, I like the steady and stable ride it provides. It’s a chromoly steel steed, making it a good candidate. People experienced with mid-drive installations say both steel and aluminum frames are generally okay for such conversions, but carbon-fiber frames need to be individually evaluated. See “Carbon Fiber bikes and Bafang mid drive conversion.”

There are mid-drive kits available, and I choose a 750-watt motor from the Chinese motor maker Bafang (model BBS02) along with the kit and a 48V 14.5Ah battery, all sold in the United States by Ebike Essentials. Actually, I would have purchased a more powerful battery, but with the current worldwide supply chain problems, the one I wanted was not available, and the company wasn’t taking back orders. Nonetheless, the battery I got performs well and offers a range of up-to-93 miles per charge.

I got all of that, including shipping, for under $1,150. And I was helped in deciding what to order by my friend Don, from the “ebike underground.” That’s not an organization. It’s my collective term for people who are not part of the ebike industry, but who have figured out how make these conversions work as they should and have shared that knowledge in YouTube videos, discussion boards, blogs and other websites, and in some cases, directly from person to person with hands-on assistance. “Directly from person to person” describes Don, and his advice and guidance proved valuable throughout the installation process. Before helping me with my bike, Don had completed successful conversions of three tandem road bikes, including his own.

Other undergrounders were to help me later.

The package from Ebike Essentials arrived in a few days, but in checking the parts over, I noticed that they had sent me the wrong display and the wrong charger. When I contacted the company, they immediately sent out the correct items and included a postage paid label for me to mail back the incorrect ones.

Since the drive shaft of the motor has to be installed in the bottom bracket, replacing the crank axle, I first removed the entire crank and chainrings assembly from the 520, including the front derailleur and the bottom bracket cartridge. (The kit contains a new chainring and crank arms, made to work with the motor.)

Ebike Essentials has a helpful video on its site showing the steps of the installation.

When it came to the actual installation, Don recommended adding some waterproofing to the point on the motor where the wires come out. He dabbed on a product called “Liquid Electrical Tape,” and we let that dry overnight. The first problem in doing a road bike conversion is that the kits are intended for use on bikes with flat handlebars. My 520 has drop bars, which I like and had no wish to change. But using the drop bars required some ingenuity. For one thing, the mounting bracket on both the control unit and the throttle are a fixed size, set to match the diameter of typical flat bars. My drop bars were larger and thus neither of those devices would have mounted on them even if there were an available location. Fortunately, the display fit on my bars fine, with its two brackets straddling the stem.

From his previous experience electrifying his own bike, Don had a solution for the control unit mounting: From a piece of scrap aluminum and a short section of flat-bar-sized tubing, Don fashioned an arm that he attached to the down-curve of my handlebar, below the brake lever, using a radiator clamp (shown in the photo before I wrapped the handlebars with new tape). The “sleeve” on the arm is a length of inner tube.

I didn’t intend to use the throttle, and didn’t install it initially, but later I needed to set it up temporarily to diagnose a problem with the assist levels of the motor (more on that in a moment), so I used a piece of plastic plumbing pipe in the correct diameter. I tapered one end using a sander, until it slipped into the left end of my handlebar. I secured it into the bar end with a thick adhesive, and mounted the throttle to that. It was as easy to use the throttle in that location as was the bar-end shifter that had been there before I removed the front derailleur.

The other issue with using the kit on drop bar bikes is that the kit’s brake levers are for flat-bar bikes and don’t fit my setup. They have wires that connect to the motor to stop it when the brakes are applied. Don advised me that I didn’t need to stop the brakes electrically as long as I simply stopped pedaling when braking with my existing road-bike levers. The electric braking could be more important if I were keeping the throttle, since there is a small possibility that it could stick in the “on” position. But since I wasn’t intending to use the throttle, I could simply not use the kit’s brake levers. See here for more on the matter of ebrakes on ebikes.

When the assembly was complete, both Don and I test rode the bike, and it seemed to us that no electric assist could be felt or discerned in PAS (Pedal Assist System) levels 1 and 2 (out of nine assist levels total). From 3-9, the assist was ample, evident and increased with each successive level.

I contacted the support team at Ebike Essentials — they deal only by email, but they responded within a few hours. They requested that I install the throttle, even if only temporarily, to determine if the motor was driving the chain in levels 1 and 2. To make the test, I set the bike up in a trainer, hooked up the throttle and ran it in both levels. The throttle caused motor to move the chain, turning the back wheel in both settings, without turning the pedals (which is what it is supposed to do). That convinced the support team that the motor was operating properly.

One support tech wrote “PAS levels 1 and 2 on our most current & up to date motors have been detuned so that the motor would not be as fast in lower PAS levels and so our customers would have more incremental power resolution as PAS levels are increased from 0 through 9.”

I was unpersuaded, however, and wrote back, asking, “Did your ‘detuning’ of the motor go too low? If technically the motor is assisting at levels 1 and 2 but I as the rider feel no assist, then in reality, there is no effective assist at those levels.”

The reply came from a different tech, who contradicted the first one and said, “Our motors are not detuned and are programmed to operate at full power.” He also said, “Believe it or not, you are the only and first customer to ever have this critique as our customers seem to enjoy having access to more incremental levels of power.”

He did go on to say, however, that if I sent the motor back at my expense, they would reprogram it so that levels 1-3 all ran at 40% power. That made no sense to me. What was the value of having three settings that performed exactly the same?

And I’d already been looking around the internet and found several YouTube videos from Bafang motor purchasers who weren’t satisfied with the PAS settings (so I may have been the “only and first customer” to complain about the settings to the Ebike Essentials team, but I wasn’t the only and first to be dissatisfied with the settings.)

The people making these videos were part of the ebike underground, showing how they hacked the motor settings themselves and got things operating as they wished. Here’s a good video on YouTube. As I continued to search, I found where undergrounders had recommended what was needed to do the job oneself. So I thanked the Ebike Essential team for their offer and moved on.

The first thing needed to reprogram the motor is ebike conversion software, available as a free download from Penoff’s Hobby Page. Apparently, at some previous time, there was a configuration app from Bafang, which was laden with bugs and didn’t work very well. But Stefan Penov (his name is spelled differently from the page title) started with that and made it better, and then released it as an open-source app.

On his hobby page, Penov says, “Basically I took the original software which also included all required source files and made it look better, fixed many bugs, improved its operation and added a small help file. Now you don’t need administrative rights under windows 8 and 10 to be able to see the available COM ports. The interface looks more tidy and well aligned and also uses better English. Numerous bugs were fixed, regarding error messages and error checking, communication, parameter limits and so on. I found this program as an open source (including all source files). I am providing it the same way.”

Armed with Penov’s app, I then ordered a programming cable that connects the USB on one’s computer to the BBS02 controller cable. I found this on Amazon, where there are several on offer. (Search on “bafang motor programming cable.”) Look for one that includes the driver. I didn’t think of that and then had to search the web for the driver separately. I found the driver free here.

The step-by-step help file that Penov included with his app guided me in looking at every setting.

I also found some good advice here, including info about a setting when not using the ebrakes.

As the motor came from Ebike Essentials, every PAS level, 1 through 9, supposedly provides 10% more motor power from the previous PAS level, as follows, though I can’t verify that levels 1 and 2 were actually performing as marked:

PAS 0 – 0 % Speed & Current

PAS 1 – 20 % Speed & Current

PAS 2 – 30 % Speed & Current

PAS 3 – 40 % Speed & Current

PAS 4 – 50 % Speed & Current

PAS 5 – 60 % Speed & Current

PAS 6 – 70 % Speed & Current

PAS 7 – 80 % Speed & Current

PAS 8 – 90 % Speed & Current

PAS 9 – 100 % Speed & Current

In any case, once in the app, I tried a few different changes, and I found that it didn’t require major increases to feel the assist in levels 1 and 2 — just a few percentage points in both speed and current, but it was enough to make each assist level useful.

So far, the only other thing I reprogrammed via the app was the wheel size, which had a default of 26 inches. With the 520 being a road bike, I reset it for 700c, which was an option on the pulldown list.

I’m by no means an expert in all of this, but the help from Don and others from the ebike underground, plus a computer-savvy cycling friend, enabled me to complete the conversion so that I’m on the road again on my surefooted Trek 520 — or maybe I should say E520 — and loving it.

I’m not happy with that the handlebar connections look homemade and inelegant (though they work fine), but I’m hoping that as the ebike world continues to grow, better options for adapting to drop bars will become available.

It’s not the only road bike I own, just the only e-road-bike. I expect to still be riding the others for some time to come. But there are some monster hills in my area where a bit of e-push will be welcome as I age.

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Stan Purdum has ridden several long-distance bike trips, including an across-America ride recounted in his book Roll Around Heaven All Day, and a trek on U.S. 62, from Niagara Falls, New York, to El Paso, Texas, the subject of his book Playing in Traffic. Stan, a freelance writer and editor, lives in Ohio. See more at www.StanPurdum.com.