For a while now we have been thinking about electric bikes. Don’t get us wrong, we love the hair raising joy of blasting down a hill and the integrity of connecting directly to our pedal powered freedom machine. However we have also noted that the keenness can wear thin riding home in the dark drizzle in the middle of winter facing hill after hill. Plus, we’ve got a little baby now and are anticipating carrying her (and stuff) around.
Enter the electric pushbike. These have evolved a fair bit over the last five years, firstly motors have become more efficient/powerful and most importantly battery technology has leaped forward thanks largely to mobile phones.
A few of our E-bike considerations
Buying a new E-bike Vs Converting existing?
There are lots of new E-bikes out there ranging in price from $1000-$5000 dollars. Unsurprisingly, at the cheaper end they’re pretty poor quality, at the top end, amazing. We chose to convert Hannah’s existing bike instead of buying a new one as her bike frame is super sturdy and has good components. All up, the quality conversion kit we got cost around $1000 which saved us some cash (yay).
Hub drive Vs Direct Drive?
Hub drives sit in the wheel and are a very clever bit of tech. They do however move a considerable chunk of weight to the front or the back. They also require extra strong forks to handle the force the motor exerts- hence why many e bikes look a bit overweight.
Direct drives have the advantage of powering through the existing gears of the bike, in effect increasing the power, especially at low speeds. Given the last part of a path to our place is a 30 degree slope, this is essential.
We tracked down a relatively new design that is very elegant. The motor is installed through the bottom bracket of the bike. In effect this delivers the weight and energy to the strongest part of the frame.
Legal Vs Illegal?
A 250 Watt motor is the largest you can use without registering the vehicle. This law is derived from this being the upper amount of energy a pedaling human can supply. As a useful vehicle, say for towing a load, a larger motor would be great. However given the legalities we opted for a road legal 250W motor
So what is it?
We purchased a Bafang 8 Fun 250W Middle Drive Motor. The Manufacture is Chinese and focus their work on electric bikes. They have been around for a while and have good reviews of their product build and specification. These kits are available from here and there.
First off, I took the opportunity to strip off many of the old components, give the bike a clean and a new paint job thanks to some spray paint I found in the shed.
The kit arrived in two box’s. One containing the motor and controller, the other the battery and charger . This photo shows all the components laid out on a table. Neat, clear and only one way to attach all the cables.
We went to the Hobart Bike Kitchen to do the conversion work. The bike Kitchen is great! If you want to know more check out this nice video about the bike kitchen from our friends at Sustainable Living Tasmania. The bike kitchen is open on Sundays, click here for more details
Attaching the Motor: Firstly I had to remove the pedals, crank and bottom bracket. Most folks will need to visit a bike shop or bike kitchen to access the tools to do this. Dan and Matt from the bike kitchen gave me a hand to remove the Bottom Bracket (thanks), which was seriously stuck.
Next the motor and sprocket where assembled.
The motor was then inserted in the bottom bracket, and two collar nuts attached to hold it in place.
Then I re-attached the cranks and pedals. The one tricky thing is that I now required two left hand pedals and cranks!
Then I reattached the chain. I actually bought a new chain and rear sprocket so the drive train is all strong and tight.
Setting up Your Handlebars. Here I have attached all of the components to the handlebars. It includes two new brake levers (the extra cable from them tell a sensor to turn off the motor when braking), there is also a controller (in the center) and the on-off and booster switch on the left hand side. I had to remove one gear changer because the front gear has changed from 3 cogs to 1 cog.
Next the battery pack is attached, this unit attaches to the lugs that hold on the water bottle. The speed sensor and magnet are then attached to the back wheel. A the last bit is to connect all the cables neatly. Viola, an electric bike!
So whats it like?
Awesome. This bike is great fun to ride. The weight is down low and it feels very similar to a normal push bike. It also hoons up and down hills. A standard 30 minute ride home (up decent hills) is down to 12 minutes – yay. Just can’t wait for Frida (our little babe) to grow a bit so we can get her out and about!
What an Energy Nerd Says (that’s me)
This bike has a 12 Ah, 36V Battery. This can supply a maximum of 432 Wh of energy. At an average speed of 25Km/h using 250W we can travel for 1.7 hours or around 43Km. This equals about 10Wh per km. This 43km is powered by around 30 minutes of our home solar power system, or the equivalent of a 100W light globe for 4 hours. I think this is pretty good value for energy, and on our solar and hydro powered Tasmanian home, 100% renewable.
When compared to a car that gets about 10km per litre of fuel, and petrol contains about 9.1 kWh per litre. This means a car is using 900 Wh per km. That is heaps more than 10Wh per km from the e-bike
Are you interested in Electric Bikes? Well Bike Tas is organising an E-bike rally in Hobart this weekend. A bike ride over the bridge and an expo of electric bikes at Bellerive Oval. AWESOME!
* Your blogger is Anton Vikstrom, co-director of Good Life, gardener, maker, father and all round good guy.