[anku94]

There's a category of vehicles that's quietly taking the world by storm, but hasn't yet found much traction in India.

(Two previous Team-BHP threads on e-bikes, one with no replies, and the other with 2 replies, are a good metaphor for the state of e-bike penetration in our country).

Having had some experience with these vehicles, I thought I'd write a small primer, followed by a documentation of converting my regular MTB into an electric one.

(The horse in the title refers to the 750W motor on my new e-bike, which is roughly 1hp )

Alright, so what are we talking about? I'm not talking about these:



(Tork T6X, a conventional motorbike with a 6KW battery, costs an arm and a leg)

These are boring. It's the same old vehicle minus the vroom vroom. Yawn...

The ones I'm talking about cost only an arm! And they look closer to this:



(Image credits: kalkhoff-bikes.com)

Yaar, itne me to purani Activa aa jati: everyone before riding one (Translation: dude, you could've gotten a second-hand Activa for the price)

Wonder how much will my firstborn fetch in the market: everyone after riding one

[anku94]

There are a couple of interesting terms that are cropping up in city planning nowadays: urban mobility and last-mile connectivity.

City planners hate cars. Cars are terrible. (There, I said it, please don't lynch me ) They occupy too much space on the road, and you have to build huge parking structures everywhere. And then there is pollution, and serious accidents because of 1000 kg vehicles moving through densely populated regions. You can't build a futuristic city with private cars as your backbone.

Scooters, mopeds, and motorbikes (which we so heavily use) fare better, but they are still too heavy. If you get rid of the ICE and replace it with a 5KW motor, you suddenly triple the price.

Enter bicycles. They are light and thin. You can load them on a bus or a local train (ok not in India, not yet), take them up an elevator, park them along a sidewalk without taking much space. They are never going to go beyond 20-30 km/h, and coupled with a weight of 15 kg as opposed to 120 kg, they have a fraction of the momentum. Birds are chirping, rainbows are cropping up, children are dancing, everybody is happy.

Except the guy who doesn't want to look like he walked through a waterfall as he pedals to office for 10 kilometers on a hot morning. The old uncle who had a bypass surgery last month, or the lady whose knees aren't what they used to be. The guy who doesn't want to go through a workout every time he goes out for an errand.

What makes e-bikes magical is PAS (Pedal Assist System).

An e-bike isn't an either/or between pedals and motors. It is a continuous, dynamic blend of the two. It's the closest thing to a mass-produced Iron Man suit we have.

A moderately fit guy can sustain producing 200W in power. This is more than enough to maintain 22-23 Km/h on a straight level road with a mid-range bike, if you're interested in a workout.

When you're starting from rest, you need a bit more. Say 300-350W until you get to speed. And then a pedestrian comes along and you have to brake. And then a traffic light. And then a flyover that requires you to produce 450W.

Pedal assist usually works in levels. A level 2/3 pedal assist (out of 5) will keep the motor normally inactive, but as soon as you come across a climb, it will kick in and start producing the extra 250W you need to go through it. If you start from stop, it'll produce the extra 150W you need until you're up to speed, at which point it will die down. At levels 4 and 5, it will continuously maintain 50-100W of power to supplement you, so if driving on a level road felt like a brisk jog to you earlier, it now feels like a leisurely walk.

It seamlessly steps in with a signature whine when you need it, and then it dies down. If you want a full workout, you can use a PAS of 1, or if you're out for a leisure ride, you can glide through the city at a PAS of 4. People who've ridden it with skepticism, in my experience, usually have idiotic grins plastered over their faces after a ride.



My first e-bike, Spero E60. Made the Sarjapur run in less than 12 parsecs.

Cost me ₹37,000, was rated for 60 kms per charge, but I routinely got 70-80 for the first year with power assist.

Reasons I loved it:

1. It was so much fun! Commuting in Bangalore is a chore, unless you have an e-bike. I completed 4000 kms in less than two years (all intra-city commutes, mostly 10km or less).
2. Routinely beat Google Maps ETA estimates. Did a Richmond Circle-Sarjapur Road in 45 minutes, in peak evening traffic (GMaps ETA was 1 hour)
3. Never worried about cops stopping me or towing me for any reason
4. Didn't have to pay 50% of the vehicle price in taxes for shitty roads
5. Never paid for parking in the two years I spent there. Except ₹10 once, I think. A lot of places have no policies about bicycles so the guards used to be flustered. Quickly learned that batting eyes works well even if you're a guy with a flashy bicycle.
6. It is with a close relative now. They crossed 50 and got a bypass surgery two years back. Routinely goes for 20-50 km morning rides now.

[anku94]

E-bike basics

The global e-bike market is in the early stages of an explosion (or atleast a very robust growth) right now. Roughly every third bike sold in Amsterdam (the bicycling capital of the world) is an e-bike. The sales numbers in China are about 15 million units annually. Even in markets like the US that love their cars, ebikes form about 2%-3% of all bicycles sold, and this category is witnessing a very healthy growth rate of ~50% per annum.

Manufacturers are excited. At the Interbike convention in Reno, half the booth were of e-bikes [Reddit]

There are hundreds of bike frames and configurations available worldwide. The cost effective way, however, is to get your own MTB (Mountain Bike) and convert it with a kit. There are two kinds of kits predominantly available.

Hub Drive (Like my Spero E60)

The motor is integrated into the rear wheel, around the axle. You usually get the rim with the motor integrated, but if you know how to build wheels, you can go the DIY route.



(Credits: electricbikereview.com)

Advantages:

1. It's a lot cheaper. If you want an e-bike under 70k, a hub motor is pretty much your only option, and you can get one for as low as 30k.
2. It doesn't wear out the drivetrain. Since the extra power is supplied via the motor axles directly to the wheel, there is less wear and tear of the drivetrain involved. This becomes more important if you have high-end shifters and stuff installed.
3. Since there's quite a bit of space within a rim, you can go insane. I'm talking 2-3KW motors. Of course, these are not street legal, but if you're into offroading and all, or a nutjob in general.

The second option you have is a mid-drive. As the name suggests, it integrates with your crank, which has a number of advantages. This is the what I'll be talking about building in the following posts.



(Credits: bosch-ebike.com)

1. Mid drive kits tend to be more expensive. With a suitable battery, the price ranges from $900 to $1500 in the US. They can be ordered off Aliexpress, and you'll have to pay duties on top of that in India.
2. You don't have to get rid of your gears with a mid-drive. With most hub-drives, you have to get rid of your rear gears. With mid-drives, you usually have to get rid of the front gears, but the rear gears (which usually have a higher range of ratios and number of gears) can be retained. Mid drives are capable of taking advantage of these gears to maintain an optimum RPM.
3. Tire removal and maintenance is a lot easier, since there is no wiring/motor obstructing them.
4. The weight balance of your bike is a lot better, since the bulky components are towards the center of the frame.
5. There is a lot more wear and tear on your drivetrain, because that's how the power is transmitted to the wheels.

Legality of e-bikes

Across most of the world, including India, e-bikes are legal if the motor power does not exceed 250W, and the motor cuts off at 25 km/h. The notable exception is Le 'Murricans. Laws in the US vary from state to state, but generally motors upto 750W are allowed, as long as they cut off at 20 mph. This allows room for a lot of creativity, because 750W motors are capable of quite a bit more than 20 mph.

Now you would expect the standard automotive companies like Bosch and Yamaha, with their decades of expertise expertise, to be the leaders in these drive systems. But this is probably one of the first markets to have been dominated by the Chinese, from R&D to manufacturing. Chinese manufacturers have proven to be more nimble, better able to respond to customer requirements, innovate rapidly, and deliver cost-effective products. They own the IP, manufacture great mid drives, and maintain worldwide networks of resellers.

The market leader in e-bikes is this company you've never heard of - Bafang. Bosch mid drives require custom frames, are limited to 250W, and make the bike cost more than $2500. Bafang mid drives can be retrofitted into a standard bike frame, have options in the 750W-1500W range, and you can have a finished bike for $1500. Also, Bafang firmware is programmable - talk about dead in the water. No one really knows how many units Bafang sells, but 10M-30M annually is a safe bet.

Bafang has two models in the retrofittable mid drive kit category: BBS02, and BBSHD. BBS02 is the well-engineered mainstream choice, while BBSHD is for hot rodders who tinker with the firmware, change MOSFETs and make their bikes go at 2x their design cap (which is around 1500W for the BBSHD). BBS02 is available in 250W, 500W, and 750W.



(Bafang BBS02, credits: california-ebike.com)



(Bafang BBSHD, credits: nomadcyclespdx.com)

Batteries

Allow me to segue to batteries for a moment. They are about the same price as the motor itself, and are what makes electric vehicles practical.

The e-vehicle movement is founded upon Lithion Ion batteries. While battery technology hasn't grown by leaps and bounds like computers and mobiles have, but Li-Ion batteries are really a miracle when compared to traditional lead-acid batteries.



(Credits: vruzend.com)

All Lithium Ion batteries (even the ones you find in a Tesla) are composed of these 18650 cells. These have roughly the same profile as AA batteries, half an inch longer, couple mm thicker. (Personal electronics like mobile phones and laptops don't use 18650 cells nowadayas). Depending on the brand and price, the price varies from $3 to $9/unit, capacity varies from 2500 mAh to 3500 mAh, and voltage is usually 3.7V.

Compared to Lead-Acid batteries:

1. They have 5x the specific energy (charge carried per unit weight)
2. They have double the number of recharge cycles at 25 degrees C.
3. In hotter climates, this increases to 4x or even more.
4. Even towards their end of life, Li-Ion batteries retain 80% of their charge, compared to 60% for Lead Acid batteries
5. If you discharge them too fast (1 hour), Lead Acid batteries will only output 60% of their capacity, while Li-Ion batteries will still output 90%+.
6. They're 5x as expensive (but this number is decreasing)

We bought our last Lead Acid inverter battery 7-8 years back. It was 200 Ah, had to be transported in a car and carried by two people. Last week I bought a 600 Ah li-ion battery, and it is roughly the size of a 1.5L frooti bottle, and light enough to be mounted on a bicycle frame.

[anku94]

Alright, let's move to the fun part.

I recently moved to the US for grad school, and the lack of my ebike was really affecting my ability to go around. I got myself an old Cannondale MTB, but my city is quite hilly and it's not very easy to go around (my lack of an Adonis-like physique doesn't help matters either).

So I got myself an e-bike kit. Ingredients:

1. Cannondale F9 (Old MTB, some components upgraded, $300)
2. Bafang BBS02 mid drive kit (48V, 750W, $400)
3. 13.5Ah 48V battery (52 Panasonic cells, $460)
4. Other sensors and accessories, shipping and taxes ($200)



My donor e-bike, in all its muggle glory.



The boxes arrived after a painfully long week of ground courier. Can't ship batteries via air



Neighbours probably thought I was building a bomb!



The items laid out. I'll go clockwise over each "bubble wrap zone".

Top left is the battery. Above the battery are the handlebar grips. The right one integrates a half-throttle. Pretty neat.

To the right of it is a piece of cable with Anderson connectors. The motor comes with bullet connectors but the battery has Andersons. This needs some figuring out.

To the right of that is the gear sensor (small package behind white sticker). It detects when you're shifting gears and cuts off the motor momentarily. Supposed to lead to smoother shifting, and longer drivetrain life.

Below that, are the brake cutoffs. It's basically a hall sensor with a magnet. You attach the sensor onto the brake body, and a small magnet onto the lever. When you pull the lever, the magnet goes away from the hall sensor and closes the circuit. This cuts off the motor when you apply brakes. There's a pair, one for each lever.

The cardboard box has rubber feet to mount the screen and the thumb control. To its left is the wiring harness that connects the motor to all the sensors.

On the right we have a chainring. The larger the front chainring, lesser the torque and more the top speed. This is 48T, which would be considered large for most bikes, but is okay for a 750W mid drive.

To its right is some mounting clips for the motor. There is also a speed sensor in there somewhere.

A wrench for the lockrings, and crank arms.

To the bottom, you have the battery and the charger in blue. This is an advanced charger with an option to cutoff the charging at 80% or 90% (supposed to prolong battery life). The rubber feet on its right are for mounting the battery to the downtube.

[anku94]

Alright, so the first order of business is to fix the connector mismatch.

I can either cut off the bullet connectors and solder the piece of wire with Anderson connectors included in the package, or I can buy an Anderson crimper and crimp connectors directly to the motor.

The latter is safer, since the wires are supposed to carry upto 20A of current. But that would mean buying a $30 Anderson crimper that I wasn't going to use ever again. Decided to go ahead and solder properly, with heat shrink tubing and all.



WIP at the college makerspace. Working in an OSHA compliant workspace is an experience in itself. I remember dad getting us a 100 rupee iron and telling me to "have at it" some 10 years back. This one had a proper station, air suction to remove solder fumes, safety glasses and all that jazz.



With the motor working, I went home and decided to attach the battery. It sits on the downtube where a bottle holder usually is. Removing the bottle holder.





The mount is attached but it is too close to the frame and the battery doesn't slide all the way in.



Decided to mount the battery cradle further up on a single screw, as a temporary measure. Later, I'll buy a Velcro strap to secure it further, or drill a hole on the lower part of the mount for the other screw.

[anku94]

The allen key was pretty much all the tools I had. Carried everything else to the friendly bike shop nearby.



Removed the crank arms and the bottom bracket. This had probably never been done in the bike's life. Took every ounce of my non-Adonis physique and then some.



Alright, let's get rid of more old stuff. The front derailleur's gone. Apologies for the lack of proper zoom, I had a stupid mid-end phone, and was in a hurry since the shop closed in two hours.



Slid the motor in the bottom bracket. Now have to flip it around and attach the locknuts.



Locknuts and left hand crank attached. Flip again. This was becoming harder as the frame gained weight from new components.





Attached the chainring. But houston, we have a problem. The chainring touches the y-fork thing when the screws are all the way in. More jugaad



Got a bunch of washers from Rocky the shop guy, barely clears the y-fork thing but seems to work alright.

[anku94]

Attached the speed sensor to the y-fork. It has two parts, one part sticks to the frame (with zip ties for added support). The other part's a small magnet that is screwed to the rim on one of the spokes.

Could only find ugly green zipties that evening. Rest assured, they've been replaced with black ones now



The screen and the thumb controls on the front are on.



It was 6pm and Rocky kicked me out. A bunch of the sensors are missing, the wires are all over the bike, but it works and I won't have to climb that damned hill again.



Next day I come in at 11. We start with the gear sensor. This is somewhat annoying since you have to remove the entire gear cable, cut the bowden sleeve into two at the right spot, jam the gear sensor between the sleeves, run the wire through the entire thing, and readjust the derailleur again.

While removing the wire, we realized that the screw on the brake + shifter assembly had rusted and stripped. We got a drill to try to remove it, but unfortunately meant drilling a permanent hole in the brake/shifter housing.





Almost done now, attaching the brake sensors. I thought it'd be neat if I could install it under the brake. The black chicklet sized thing to the left of the red double tape is the hall sensor. The double tape is where we want to install our magnet.

The organization is clearer in the next picture. Unfortunately I did not have enough double tape, so had to make do with electrical tape for the other side magnet. I then taped all around it for good measure, so that the magnet doesn't fall away.

With all that done, we tucked in the wires, zip tied everything, changed the brake pads, added a new, longer chain (because of the larger chainring), and that was it. The bike's as ready as it'll ever be.

[anku94]

Final pics!





How does it feel?

Absolutely amazing. With a 250W motor, you have to be a bit careful about how much wattage you're pumping through it on climbs. They can go upto 500W in bursts, which is helpful but risky to the motor's health if you do it on a sustained climb. This is anyway not a problem in most Indian cities, which tend to be flat.

There's absolutely no such problem here. This 750W mid drive will happily accelerate from 12 to 20 mph on a 10% incline. The first day I was grinning like an idiot going 20 mph on hills I had struggled to do 8 mph on, without breaking a sweat. I could not care less about where I was going - took the wrong turns and weird detours on the way home.

It has only become smoother with the addition of the extra sensors since then. There are some problems with the rear cassette and I might have to end up changing it, but nothing major.

With such a large chainring, I find myself needing only the first 3 (out of 8) gears to hit the 20 mph cap. Both the gearing and the motor have plenty of room to go further, if I decided to make firmware tweaks. These motors like to spin fast so it's a good idea to stick to lower gears as much as possible.

What happens if something goes wrong?

The support system is somewhat ad-hoc. I could ship back the equipment to the reseller on the opposite coast, and they'd probably repair it. The relatively failure prone components are the integrated controller and a nylon reduction gear. Replacement parts are easily available and you can make the repairs with simple tools.

The good thing about electric vehicles is that they are so simple. Batteries usually function very well until they die, especially if you have good quality cells like Sony/Samsung/Panasonic. Sensors can be replaced. The only thing left is the motor core, which can be rewounded by local guys AFAIK unless it is seriously trashed.

So should we all sell our Activas and kids and get one of these?

E-bikes are fun, and while they're becoming ubiquitous in China, biking is harder in India. You may be able to use one for better part of the year in Bangalore or Mumbai, but are not really an option in 45 degree afternoons of June, pedal assist or not. Bicycles work better as a part of a larger transport infrastructure, where you're able to carry them on buses/metros for larger distances.

You might be able to install a kids seat somewhere, but you can't transport two adults on one unlike a full-fledged two-wheeler.

Price is a big factor. While it's an easy choice when the alternative is $500 per month in car payments, insurance and parking, most people are not used to spending 30,000 rupees on a bicycle and have it be called low-end.

But, if you're in a city with benign weather, or are looking for an excuse to not take the car out 8 months of the year for daily commute, or want to replace 5 km morning walks in the neighbourhood park with 25 km rides through nearby villages, or your primary means of transport is Ola/Uber, then there is nothing quite like one of these.

Alright, I want to learn more

The only EV forum in India is PluginIndia - they post electric vehicle reviews on youtube, including e-bikes.

There are a couple of small-time assemblers selling 250W hub drives for 30k-50k. Spero, Hero Electric, that Salman Khan ebike, Hulikkal, Lightspeed, Smartron Trox. (I've just read the names on different forums, haven't ridden any of these except my Spero). They should be perfectly fine for the most part.

Or you can buy a super-slick looking Giant with a 250W Bosch mid-drive for around 1.5L, I think. I've seen them in some high-end bike shops in Bangalore.

Or you can buy stuff from Aliexpress and build your own.

http://reddit.com/r/ebikes is a good starting forum, and http://endless-sphere.com is for when you really want to get crazy with hotrodding, custom firmware, recumbent bikes, and all sorts of crazy builds. (I'm not affiliated with any of these, but the folks at r/ebikes were super helpful in helping me plan a build).

[GTO]

Thread moved from the Assembly Line to the 2-wheeler section. Thanks for sharing & rating thread 5 stars!

[superbad]

Superb thread, very informative. This has definitely got me interested in dabbling with e-bikes. Do you think this can work with our desi brands - Hero, BSA etc? Also what about charging the battery? Pedal power or electrical outlet?
The only thing you missed is the one thing which is most prevalent in India & the main reason people still don't prefer bicycles/e-bikes - theft. Parking this bike on the roads mean that the owner will constantly fret about its safety. As is well known, locks/chains are no big deals for the inventive thieves. Plus a few hundred watt motor, a juicy battery & all that metal is prime target for the unscrupulous elements in the black market. So unless one has a safe & secured private parking space in home/office/gym/wherever you go, this bike is really not recommended.

[gauravanekar]

I have two questions:
1. Is it possible to retrofit this into a gearless 'basicest' btwin, I am worried about front and rear sprocket alignment. Reason being gearless sprockets are closer to wheel bearing compared geared setup.
2. How much time it would take for a 25 km 4 lane highway ride without traffic. What's your estimate? Temperature is expected to be benign here in Bangalore early morning

[arunphilip]

Beautiful thread!

It takes passion, and a flair for writing, to draw in petrolheads into reading a thread about bicycles. And you've achieved it marvellously.

I'm sure anyone reading this thread will immediately start thinking of getting one, so infectious is your enthusiasm.

Then, I look down at my waistline and think "Hmm, I'm sure there's a few thousand kilowatts in those inches". Maybe I ought to skip the 'E' in e-bike!

[Shreyans_Jain]

As much as I'd like to join the bandwagon, fact is that Delhi NCR is just too polluted during winter months. Any kind of outdoor physical activity cannot be good when PM levels are consistently over 300.

[RGK]

Thank you Anku for your timely thread. I had a chance to look into Hero Lectro EZephyr brought by my friend.

His observations are

1. Tyre width is very small and the jerk is felt.
2. The handlebar is not comfortable for long rides.

He had contacted Hero cycles for replacement of tires with wider ones and a comfortable handlebar. I took a small test ride and felt a cushioning saddle is a must.

In India, E-bikes will be a success if prices come down and a good infrastructure is built. (separate lanes, no car zone etc).

Having said that, climate plays a vital role in e-bike success. Unfortunately, tropical climate is not ideal for day to day usage.

[Thermodynamics]

Informative. Thanks.

Sometime back I was searching DIY stuff to covert a normal bicycle into an e-bike and there are oodles of them in the internet. Products like these are available online from 3000/- excluding battery. Also YouTube DIYs are plenty and many of them claim a budget of 8000/- for a basic e-bike conversion.

I understand from your post, a quality conversion would easily cost 35000/-. In which case this is still an enthusiast hobby and cost would be a main deterrent for mass adoption. Bajaj CT-100B is just about the same price.