Part One
As promised on another thread, here are some pointers to installing a Hub Motor on a C5.
I should first point out that any work done is done at you own risk and that I am only documenting what has successfully worked for me. Also that the preparation process should be done over time and not rushed!A quick google search will bring up a handful of (mainly Chinese) companies that will supply a 12 hub motor wheel that maybe suitable for installation on a C5, for example:
http://www.czbrushlessmotors.com/brushless-hub-motor-c-1.htmlhttp://www.leafbike.com/products/diy-bike-conversion-kit/12-inch-electric-hub-motor-kit/c-71/http://www.cloudelectric.com/product-p/ti-hubmotor-12.htmhttp://www.uumotor.com/blog/2013/01/36v-250w-12-inch-front-wheel-hub-motor/and countless others similar copies all trading via
http://www.alibaba.com/showroom/12-inch-hub-motor.htmlI went for the following leafbike kit (which included the controller etc)
http://www.leafbike.com/products/diy-bike-conversion-kit/12-inch-electric-hub-motor-kit/12-inch-24v-250w-electric-bike-kit-front-wheel-876.htmlI chose this mainly for the fact that the website looked more professional and had contact details etc and that the postage to my locale was the best. They also provided the best pdf schematics of the wheel size beforehand which helped me decide whether or not to attempt it:
As you may note or have previously seen when searching for hub motors before, there are some figures you need to keep in mind. The most important of which is the "dropout" or spacing. I recommend reading the following website for a great overview of what this is and how to measure:
http://sheldonbrown.com/frame-spacing.htmlThe C5 itself has a quoted front fork dropout of
85mm, where as most hub motors for front wheels have a dropout of
100mm.
In actual fact when I measured mine it was 90mm. "Only" 10mm/1cm away from the numbers quoted on the hub motor websites. This is where a process called "
cold setting" As you will read when researching, the process of cold setting should only be attempted on steel forks, which as luck would have it is what the C5 ones are made of.
A quick google will bring many website and forums with countless opinions on whether it is safe and recommended etc, all I can say is that there were more saying to do it, that not, so long no more that a 10% increase was the most being asked of the fork, which again is all that I was asking of my forks (90mm to 100mm ish
).
Preparation.
You will need the follow parts and 2 tools:
2 spanners
2x M10 bolt long - a least 8cm long
4x M10 nut
6x M10 washer
in order to make and then adjust 2 of these "spreaders":
These are the what we will use to slowly spread the forks aside.
Remove the existing wheel, and insert the 2 spreader sso that you end up with this - at this stage only loosely tightening so that the 2 bolts make contact with each other and the frame and not fall out - DO NOT over tighten anything at this stage:
middle outwards: bolt, nut, washer, washer, (washer), frame, gap, nut
Ensure that the 2 bolts are central aligned so that they are the same and have the same thread showing on both bolts.
The next step is easy, BUT the longest, and I really cannot point this out enough - the time you should take with it.
Twice a day I made a half turn each of the inside bolts, once on the way to work, once on the way back. This meant, over a period of a week the 2 bolts has increased the frame spacing behind the required 100mm to 116mm.
You maybe asking why to over 110mm when only 100mm is required. This
is process of cold setting and is forcing the steel to go beyond its "memory", so that when the bolts are removed it returns to 100mm:
That is basically it.
Some other pointers if you try it :
- I would suggest that 116mm is too much and that 110mm would have been enough to go to, but I had to reset the process due miss aligning bolts so over compensated, and ending up with 102mm
- Always ensure the bolts stay aligned
- If you need to check the spacing or another reason to start again, start from fresh and do not be tempted to rush the first few mm
- Don't rush - Have I said that enough times yet?
Once done you should end up with a fork frame that can accept your newly purchased hub motor:
Note, Large versions of these photos can be found here
http://photos.cm7.ch/C5/C5-Hub-Motor/Part 2 to follow soon,