Install hitch for bike trailer on 12 mm axle

pajtaz

Pedelecer
Nov 8, 2019
70
7
Netherlands
I have a Q128C rear hub motor that has 12 mm axle (rounded on top and bottom and flat on sides which allow it to fit into the dropout). I have a bicycle trailer hitch (see attached picture) that is made for standard 10 mm axle. Specifically, the hitch comes with cogs that are used to prevent the hitch from moving when installed on the axle. See pictures I attached below. First picture is how the hitch looks installed, second picture shows the hitch with corresponding cogs that are used to prevent the hitch from moving, and third picture shows how the hitch is installed with the cog.

Diameter of the cogs is 10 mm. Therefore I cannot put the cogs on the axle in order to prevent the hitch from moving. My question to you is how can I then install this hitch on the axle? I only came up with 2 options since I am sure I can safely install the hitch without the cog (it will certainly move under the load) and there are no cogs of this type with 12 mm diameter.
  1. I can use another type of hitch plate that can install into 12 mm axle without moving, just like the lock washer that came with the hub motor. I can just remove the ball and install it on another plate. The ball is held in place with a nut and a washer. However, I cannot find this plate anywhere. Does anyone know if plates with this kind of hole exist and where I can purchase them?
  2. Drill out the cog to match the axle. I really don't want to do this since I don't have the tools and don't know who would do it for me for a reasonable price.
I have and do not want to use an alternative plate that attaches to the frame. That cannot fit because of all the wiring and motor cable being there and I do not want to put that much stress on the frame.

I appreciate any advice. Thank you in advance.
Kid Car Cocoon.jpgHitch.jpgHitch with cogs.jpgInstallation of hitch with cog.jpg
 

gw8izr

Pedelecer
Jan 1, 2020
224
240
Hi, from your description and drawings I'd say drilling the hole would be a mistake as it wouldn't locate on the axle flats however opening the hole to fit the axle should take no more than ten minutes with a round file.

I know you say you have no tools but if you google 'mens sheds' and try and find a local group. It wouldn't cost you more than a packet of biscuits at most of them.

Hope this helps.
 

Raboa

Esteemed Pedelecer
Aug 12, 2014
312
97
48
I was looking for a solution myself and found something that was discussed on another forum.
I think if a company brought out a ebike trailer hitch they would be able to sell them. Due to the popularity of ebikes companies should start to include them in the box or sell as an accessory.
 

pajtaz

Pedelecer
Nov 8, 2019
70
7
Netherlands
Seems like gw8izr's advice is the best option for now. The specialist hitch adapter is no good for me since there is not much space around the dropout any more and either way I do not want any other frame attachments.

Seriously, there are no ebike trailer hitches? Even generic ones that simply fit on the axle would be helpful. Well, thanks for the advice, I will get a round file and work away!
 

Raboa

Esteemed Pedelecer
Aug 12, 2014
312
97
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I am going to contact a fabrication company to see if they will make some, probably be too expensive though. I have an Irwin step drill bit if you wish to borrow it, let me know.
 

pajtaz

Pedelecer
Nov 8, 2019
70
7
Netherlands
That looks good so far. Question is how to "lock" the existing hitch bracket to the 10 mm hole on the left? This new bracket will let you lock the new bracket to the axle but then you have to lock the existing bracket to the new bracket.

To do this, the 10 mm hole should look like a dropout. Or is there another way to do this?
 

Raboa

Esteemed Pedelecer
Aug 12, 2014
312
97
48
Hi, I based this design on my trailer hitch (see picture), you could probably design a multitude of configurations.

I plan to.put a 10mm bolt through the new bracket and trailer bracket. This might or might not fail, the new bracket is 5mm thick (might be too thick) so should be strong enough. You could cut down the sides of the 10mm hole to make a dropout shape if need be.
 

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Raboa

Esteemed Pedelecer
Aug 12, 2014
312
97
48
I don't mind redrawing the design with a dropout shape at the 10,mm hole end and sending it to you. The lines would be straight vertically, if you want angled lines I need to know the exact angle. You could then contact a laser cutting company and ask them to make you a bracket. The companies I contacted said it would not be worth it their while making one but would make multiples.
 

pajtaz

Pedelecer
Nov 8, 2019
70
7
Netherlands
Please send me the updated drawing, if you do not mind (in PDF, with dimensions?). I would not order any now because I am not sure this would necessarily work for me. I would have to take the drawing and see how to modify it so it fits my needs. Then I would contact someone locally to see if they can machine something for cheap.
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
11,717
4,551
57
West Sx RH
Whether a hitch rotates once fitted to the axle is largely due to how the tow bar connects and in which plain.
The Carryfreedom I have utilises a right angle heavy gauge (5mm s/s) axle bracket with a centre pin that sits vertically, for my 12 x 10 hub axles I simply drilled out the 10mm axle hole to 12mm and then secure using the axle nut. The pull on the hitch doesn't rotate/twist .
th.jpg
 
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Raboa

Esteemed Pedelecer
Aug 12, 2014
312
97
48
What you could do is drill a hole / cut a v shape underneath the centre of the 10mm hole. This would have to be the same width as the tab, this way you just bolt the new bracket to the old one and put the tab in the new hole. If you pay the postage I will send you one for nothing, I will have spare. I might have a spare hacksaw, small file kicking about, if you want that as well let me know.
 
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pajtaz

Pedelecer
Nov 8, 2019
70
7
Netherlands
I have a hacksaw for metal and I will end up buying a file anyway. Yes, let me know when you get it and I will pay for postage. Thanks!
 

pajtaz

Pedelecer
Nov 8, 2019
70
7
Netherlands
It looks great. This could be useful for many other people with hub motors.
 
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Abee

Just Joined
Sep 5, 2020
2
0
Hello all! I've come across this thread whilst trying to find a solution for my own ebike.

Trying to follow the solutions but a little muddled, Raboa is that the product you ordered from the link above for the doggy ride? I couldn't get that link to work.

I don't have all the specs, but I have a wisper 705 se and need to find a way to hitch my bike trailer to it.
I have a clamp type hitch at the moment but it doesn't work at all.

Any help would be greatly appreciated!
 

Abee

Just Joined
Sep 5, 2020
2
0
Hello all! I've come across this thread whilst trying to find a solution for my own ebike.

Trying to follow the solutions but a little muddled, Raboa is that the product you ordered from the link above for the doggy ride? I couldn't get that link to work.

I don't have all the specs, but I have a wisper 705 se and need to find a way to hitch my bike trailer to it.
I have a clamp type hitch at the moment but it doesn't work at all.

Any help would be greatly appreciated!
 

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