Below I share my experience converting a regular lady bike to an electric trailer equipped bike.
This was intended to transport around 6 bottles of water (5 Liter/1.3 gallon each).
Step 1: The ideia
I wanted to adapt my mother's bike to allow her to ride her bike easier because her health was impaired. In the end of 2010 to buy an electric bike in Portugal was very expensive. The same applied to lithium batteries. So I started making some sketches using my Alibre CAD software; not well know in Portugal but more than enough for my skills at an affordable price.
Step 2: And some measures to manfacture
In these two drawings you can see some measures in milimetres based on the original bike. Actually the original bike was a slightly different one but around the same dimensions. As you can see my initial ideia was to have the lead batteries in the top of the rear wheel. The kit ordered was organized in a different way as you will see.
Step 3: The choice of the electric kit
Then surfing on Ebay, I selected an affordable (the most!) one, similar to the one in the picture but with batteries in the sides of rear wheel. I opted by the sealed lead batteries because of the lowest cost. They have a slight problem: are heavy like hell!
The specs are 24 V, 250 W. Because I ordered it from US, I paid a lot in Customs :-) I'll have the numbers in the end.
Step 4: The emotion is about to start!
I received my kit in the post and took it happily to my coutryside house where I installed it in the bike. As you can see the front wheel is totally from the supplier...the tire is a bit large so it was tight inside the front fork. It includes the engine.
Step 5: Installation of the batteries
The batteries supports were in the kit; only had to be installed in each side of the rear wheel. The most difficult was to arrange it with the fender and the rear support.
Step 6: The controller box
The controller box is placed under the left side battery and has a small ignition key. The wiring on the left of the key is used to charge the batteries; just have to disconnect it and connect to the charger. In my case, there was an issue with the connections; they were both male ou female, I can't precise. The I went to an electronics shop and asked them to help me, adapting correctly the connection.
Step 7: Now the trailer...
My main raw material was a lot of ideias I had from other Instructable folks and an old suitcase that I was given by a friend of mine. So according to the sketchs I presented before I started the trailer chassis; it was intended to be the simplest possible. I asked my cousin to use his metalworks shop and with the semi automatic welding machine and using old children bikes parts I made it.
It was not that perfect but then I painted it black and so the welding defects became discreet :-)
Step 8: And the most difficult...the trailer hitch!
To solve this point, I investigated lots and lots of proposals from the Instructables community. The one that impressed me most was one using a hose connection. But I had another ideia...a dutch type lock. It seemed very pratical, so I ordered it from England and installed it. To fix it in the rear mount was a mess but I managed to find a way...until I started riding the bike and trailer set...the noise and shaking was incredible...besides that, the fixation of the dutch type lock was becaming increasingly loosen...
Step 9: The solution for the hitch
So, I went back to the ideia of a guy named Saul and bought gas hose connections. I bolted the female under rear bike mount and the male fixed to the trailer with a small bolt using a small piece of hose. The result was so amazingly better than the previous one! Thanks Saul!
Step 10: Thank you!
Thanks for those who commented my first version of Instructable...only now I had the opportunity to improve it. Later I sold this set by 150 € with, of course, a huge loss :-)
EZGlide Electric Kit: 377,50 €
Customs (came from US): 225 €
Material and electricity: 50 € est.
Shop support: 30 €
Total: 682,5 €
Profit = 150 - 682,5 = -532,5 € :-)
It help us understand why it is so difficult to be an enterpreneur.
PS: the picture here was taken with the dutch type lock, not the final hose type hitch.