Friday, December 26, 2014

Electric conversion - part 4

In the last post I left finished up staring blankly at the strange (to me) bottom bracket fittings, like these.

So I had a look through my tools for anything that could possibly fit into a ~40mm disc with semi-circular notches.  I found the following, which I have no idea whether it is the right tool or not, but after using a screw-driver and hammer to tap them loose, I was able with some effort to use said mystery tool to get them the rest of the way off.

The information I had suggested putting the pedal sensor on the right-hand side.  However, that would involve heavy modification to the chain case.  I figured it would just be easier to install the sensor on the left-hand side, where there was nothing to obstruct it.  Installation of the sensor was pretty easy.

Then it was time to put the little wheel of magnets that the sensor uses, and refit the crank.  Again, all fairly painless.

Now that I had the pedal sensor and the electric motor fitted, it was time to turn to the spaghetti of wiring and hook everything up. This largely boils down to matching colours and sizes of connectors.  The only mystery was the purple and black connector, which turns out to be for a brake sensor if you want to immediately cut power when brakes are applied.  This isn't really necessary with a 250W motor and 180mm hydraulic disc brake on the front!

I then attached the controller onto the bottom of the rack where it goes, and fed all the cables through the appropriate feed-holes.

The controller slots in under two tabs, and then a tab is screwed on at the other end, as shown here (sorry for the fuzzy shot):

Then I attached the U-shaped thing that connects to the frame, and slots through a couple of adjustable holes in the rack. 

I already knew that these arms would be too long, so I measured up the length I needed, and cut the first one.  I also gave my rear fender a bit of a clean while it was easy to do with no rack on the back:

After cutting the 2nd arm, and a little fiddling, I had the rack installed on the back:

Here you can see the trimmed arm from the side:

And closer again:

Finally the back wheel could go back in, and the bike was starting to look more or less back together again:

Well, except for the mess of wiring that still had to be routed through:

So I installed the display and power control interfaces onto the handle bars:

Connected the wiring to the motor:

Put the battery into the rack:

Now the backend was looking pretty much right:

But I did notice a minor issue:  Like August Gorman in Superman 3, I realised I now have two keys in separate locations that both need to be in the on position.  Fortunately, I won't need to resort to the same convoluted method as him, but I might need to get one of those retractable key fob things to hang the battery pack key on so that I don't need two key rings.

With everything hooked up, I turned the power on, and was very happy to see that it all seemed to be working:

However, I soon discovered that the motor would only run when I pedalled backwards.  The solution was to flip the wheel of magnets around the other way, as the polarity of the magnets is used to detect the direction of rotation.  Now the motor kicks in when pedalling forwards, but not backwards.

So now it is all working, and a quick test ride confirmed that it is going to be very effective.  The result is that I have a factory-like electric assist install on the bakfiets, and confidence that it will all work well, and that it will be well supported.  Indeed, Dutch Cargo Bikes have been great answering all my questions as I have proceeded through installing this kit over the last couple of days, including emailing photos of bits and pieces of the factory-fitted electric bakfiets they have there to help me work out what goes where.

The only frustration now is that I need to wait before going on any serious rides with it while I wait for the charger to arrive (it was supposed to be in the box, but didn't make it for some reason), and also I need to get a new lower crown race for the new forks, which was never part of the kit.  Both are very minor things, and I hope to be all set by New Years Eve.

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