Workcycles Bakfiets build

Ok, this will be a bit different than your normally scheduled programming.

A year ago, my Bakfiets came in two huge boxes from the Netherlands. What's a Bakfiets?

Basically, a bicycle with a long box up front, with a steering linkage running underneath. I got it to transport kids and groceries because I found I wasn't getting outside enough. It worked great for me until recently, when I moved to a much hillier city a month ago. While I'm able to struggle up the 3 mile long hill separating downtown from my home with great effort - the bike is well over 100 pounds alone, then add me and a couple kids on and you get the idea - I do arrive everywhere a sweaty hot mess.

So I did what any GRMer would do, and added power. Lots of power!

Luna Cycle was (is as of this writing) running a great sale on their Bafang mid-drive kits, with a motor, battery and everything required to electrify a bike included for about $750. I ordered one, so we shall see how it goes!

Spoiler: if you're interested in an e-bike, get one. The mid-drive kit is amazing. 

So basically, adding an electric motor to a bike can be done three ways. 

First, you can add a rear hub motor inside the rear wheel. This didn't seem like a good option for me because my rear wheel has internal hub gearing, so I'd lose the multiple speeds. Also, this bike has Roller Brakes, a kind of drum brake built into the rear hub, so you would lose those.

Second, you can use a front hub motor inside the front wheel. Not a great option here either, because this bike has lights driven off the front hub's dynamo and also has a front hub brake, so I would have to find another braking solution. There are also downsides to hub motors that I won't get into here, but basically I was left with 

option 3: a Mid-Drive. Basically a mid-drive replaces the bottom bracket of a bike and adds an electric motor assist to the front sprocket. These bikes work well with mid-drives because they have plenty of space to mount the motor, and they come pre-equipped with a single front chainring. 

A mid-drive can be set up to assist only as you pedal, and also on a throttle. They can be set to respond to cycling cadence or also torque, though the torque-based units seem to require an odd oval-shaped custom bottom bracket shell, as seen here: 

Obviously can't just add that to any bike, so I am stuck with the cadence-based systems, which are more powerful but perhaps feel less natural in use. Of those, the Chinese maker Bafang seems to have pretty much cornered the market, and have two models, the 750 watt BBS-02 and the 1000 watt BBS-HD. I chose the BBS-02 since I doubt I need the extra wattage, and it was half the price on sale at Luna Cycle.

As you can see, the motor unit hangs off a normal bike's downtube and drives a sprocket that connects to a freewheeling front chainring. It's a pretty simple system and seems to work well as long as you don't ask too much of it. 

This is cool. I hadn't seen the mid drive retrofit kits before. I know there's a civil war brewing in the MTB community over eBikes, but they make a ton of sense for commuters. 

Have you been running it long enough to get a feel for range/assist level/recharge times? What's it weigh?

I have not, just ran it to daycare and back. I think I have 16 miles on it so far. 

The bike itself weighs a lot. 100+ pounds. The BBS-02 weight about 8 pounds and battery kit probably weighs 10-20?

I'm guessing you're not in Berkley *snicker* any more since you said you moved to a hillier area and Berkley is as flat as they come.

I've wanted a bakfiets for a few years now, but I can't justify the steep price tag. https://humofthecity.com/ is good website that has pretty exhaustive reviews of many of these kinds of bikes. She lives in San Francisco, so the electric assist gets quite a workout. 

I'm interested in your experience with the cadence-based assist system. It's the main thing keeping me from pulling the trigger on one of Luna's kits. Once you've ridden a torque-based system, it's hard to imagine going back. 

What are the differences in riding between the two systems?

Torque sensing systems respond to pressure of the rider, basically calling up more energy the harder you push on the pedals. They are generally much smoother and more responsive, and give a more natural cycling impression. Unfortunately from my research most if not all kits require a custom frame design.

Cadence systems like mine generally act like an on/off switch controlled by pedal motion - when you begin to pedal the motor assists you at a level you choose- generally 0 through 9. They can also usually be controlled by a throttle without pedaling. They tend to be more powerful and less expensive, and fit more bike types.

I've seen a few of those bikes around Minneapolis, both with parents hauling kids and couriers delivering goods.  They do look pretty heavy so the electric drive seems like a good idea.

Why not leave the kids at home, buy a backpack and trade the hearse in on a bicycle that weighs less and can be pedaled uphill?

In reply to Trans_Maro :

apparently that's child neglect

I've never seen one of these and now want one for trips from the cabin to the beach, three miles and one small hill.  

I have a Wike Super Cargo Trike that is very heavy. It is flat where I live, but I am interesting in an e-bike conversion for it. Sounds like a fun project. Subscribed to this thread.

The whole system is a pretty simple install if you have worked on bikes in the past. Basically, if you can remove and install a bottom bracket, you can install a Bafang mid-drive yourself. 

Unfortunately for me, my drive-side crank arm extraction threads were slightly crossthreaded, and became worse by the minute at my ham-fisted attempts to thread the extractor onto the junked threads. Once the extraction threads are ruined your crankset is basically garbage, but unfortunately garbage that's taking up valuable real estate where your nice shiny new motor drive wants to live. Oops. 

There are several ways to get a crank arm off a square taper bottom bracket if you ruin the extractor threads. First, you can ride it around without a bolt holding it on and eventually it will surprise the hell out of you and fall off the bike while you're riding it. Not my idea of fun, but certainly cheap. You can use some sort of tool - hammer, chisel, flathead screwdriver, pry bar - and try to pry it off the bike and risk damaging the bicycle frame. Or you could try cutting it off with a saw.

I decided to go with the brute-force route of using a three-jaw puller, which you see my son helping me find the best example of at Harbor Freight above. Some may be able to do this procedure in a manner which leaves the crankset usable in the future. I, alas, was not. 

The offending part removed, we can now proceed with assembly. 

You're going to love having the assist on there! I've got a cargo bike with a rear-wheel assist, and it's been the nicest thing being able to get out with the kids for rides, errands, or to get to the park. They quickly got to the point that they prefer the bike to the car most days. Ours is a LvH bullitt with a BionX D500 e-bike kit, and while I love the natural feel of pedaling it, I wish the assist didn't top out at 20 mph (for when I'm riding solo). Bakfiets rule.

I'm a bike mechanic - you need this:

http://www.parktool.com/product/universal-crank-puller-for-square-taper-and-splined-cranks-cwp-7

No more wrecked cranks!

Another option that won't be for everyone is to strip the frame, mark, cut, jig and then weld in this: https://framebuildersupply.com/products/motor-cabinet-for-shimano-e6000-series-steps-system

In the US you could use someone like Bilenkey, here in the UK I'd use Winston Vaz in London, or maybe Rourke if you are further up the country.

In reply to Sanchinguy :

I'm a bike mechanic too. I have that tool. Doesn't help on threads that are already stripped. 

Yeah, that makes it pretty useless - didn't catch the stripped threads thing.  Sorry...  Very cool bike!