Topic: Installing a front wheel Hub Motor

[baselpat]

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.html
http://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.htm
http://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.html

I 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.html

I 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.html

The 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,

[baselpat]

Part Two

As you may have noticed on that last picture in the previous post I have also installed something else when fitting the hub motor. This is called a torque arm.
Why these motor suppliers seem to want to add these to an order or why do you need a torque arm? Because as hard as your tire is straining to go forwards,  the axle is straining to go backward. A Torque arm provide increased strength at the axle and are used to help prevent the axle from spinning out inside the drop outs.
I ordered mine from the same people I ordered my motor from to ensure "compatibility":

http://www.leafbike.com/products/electric-bike-parts/torque-arm/torque-arm-854.html



The are very simple to mount and to be honest for the sake of a few dollars extra over the cost the motor, I only only can see advantages especially when I don't what to put the forks and dropout under any more strain after the stretching previously. 

Most of the hub motor kits come with the controller, switched break levers.  These are simple to mount, but do take away from any original fittings of the C5 handlebar.  This should be taken into consideration when thinking about these hub motor kits:



With the final "electronic layout" of my kit looking like this:

 

Some of the other hub motor kits available would be possibly better suited if one was trying to retain and reuse as much of the original  switches as possible  - this was not an issue for me, as much of my C5 electronics had been replaced anyway.

Hope is of some help to someone, feel free to ask questions if I've not been clear.  I will post another part, once I have fully finished stripping down, cleaned and resembled my C5.

Pat

[Lancealot]

Hi Pat,

Well done and good documentation and advise.
1) How is it driving from the front when you are also steering?
2) Is this your primary drive or do you also have the rear motor aswell?
3) What the tyre you used?

Nice one thanks Lance

[mhurt]

I'd be interested in any hill tests you did. If it can get up a hill that a standard C5cant on power alone then it looks cost effective to do.


Either way,  an interesting mod and post.

[Luke S]

You would probably need a second battery as both motors will need power, so you could only go half the distance than if you had 1 motor 

[radiomarty]

Great work bud and interesting reading - thanks for the 'how to' which is a good resource for people 

[baselpat]

1) How is it driving from the front when you are also steering?
2) Is this your primary drive or do you also have the rear motor aswell?
3) What the tyre you used?

Lance,
1) Heavy, but manageable. Only done small distance testing so far. All indoors in my underground lair  , sorry I meant car park...
2) I'm trying to get the C5 road legal, so this will be my only motor. (this  post shows I temporally had 2 motors, but that is no longer the case)  I have to admit it is a bit of a let down after the old motor....
3) A bargain bin find in a DIY German chain -cost me less than a pint of beer 

I'd be interested in any hill tests you did. If it can get up a hill that a standard C5cant on power alone then it looks cost effective to do.

Due to lack of legal road certification, I have only tested in a underground car park and access ramp.  This thread that I posted about my hill climbing twin, was only ever going to be a temporary solution.  However once I am road legal, I have a very large hill (200m) I plan to climb as part of testing/celebration  but I expect to have to pedal a fair bit.... again, will update once I have some "real world data/feedback" 

You would probably need a second battery as both motors will need power, so you could only go half the distance than if you had 1 motor 

Hi Luke,  My current setup was already a dual battery 24V system, so had this in mind when I ordered the 24V kit.  I plan to now save up for some LiFePO4 batteries which would greatly reduce the weigh requirements, but as you have likely seen cost a small fortune  and hence a little further down my shopping list. Also I will only have one motor from now on...

[mhurt]

When I say hill,  it's about a 6% incline for a mile )  nothing to most people,  but I just don't have the stamina or energy (yup,  I'm using the wrong vehicle type but my wheelchair isn't as much fun :p)
To be honest,  another C5 motor might be be sufficient,  but the hub motors are a touch less fragile.

[baselpat]

To be honest,  another C5 motor might be be sufficient,  but the hub motors are a touch less fragile.

The motors maybe a touch less fragile, but the original kit controller wasn't 

A small update.....

I found that the controller for the hub motor I had installed was very sensitive to voltage drops (ie when using the other motor or even just the lights  ...) and eventually gave up the ghost completely after one dropout too many.    It would appear the people I ordered the kit from also agreed (sort of) and had in the last month replaced the "kit" to include a new controller.  I found (with the Chinese "owners"/support of the company found that their new version of the controller was compatible with what I had already brought.  All that was required was some plug/socket changing on the sensors etc.  So I ordered this new controller at a reduced / replacement price.

So far the new controller is working well with the tests I'm making - BUT that said - I have decided to now keep the motor 24v circuit completely apart from horn/lights etc which now have their own 12V 4A battery in the boot.

So far all working well.  The "new" controller seems to give the motor a bit better pull off power, but the top speed etc remains unchanged.  I do like the new functions of a reverse gear  , Cruse Control  and even a regenerative brake system    that should give me a few extra KM's once fully on the road.