I understand that all I am saying is that when I think about the forces in the link (as it bends) and one side conected the a servo and the other conected to a dinamic two wheeled bicycle going round a negative camber roundabout with 37.37kg in the back is a problem that is not simple.
The low linkage point feels like it would make it easier.
All I am saying is that this might be more complicated than it first seems. It might be easy it might not I don’t know?
Dangerous talk! If we accepted that truism we’d never start anything.
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True.
I am just ponting out the dynamics of this progect might be really nasty . Bicycles are known to be difficult
It’s not a simple spaceship or aroplane
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Well, there’s only one way to find out…
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I agree with joe i can’t see pushing on the link as a good idea. powering the back wheel on a separate electric bike makes more sense and a low crossbar model would make it rideable for a variety of different sized people.
Not a significant amount of power and only one degree of freadom in the link .
I count two…
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One inporant one it cannot exult a latral force on the back of the bicycle
It’s a much simpler system
And only one wheal on the back .
If you have two the front of the is stabilise by a completely different methods to the back
Computer model?
@andrew_d
I’m not suggesting pushing on the link. The load cell in the tow bar would ensure no net force is transmitted to the bike.
Having said that there are scores of powered bike trailers turned up by a Google search which seem to work.
I can see how it would work in a straight line , but can’t quite figure out how it would work in other conditions.
We need to get a regular bike trailer, pedal it round the park and have someone shove it from behind.
EDIT: South London Makerspace in no way endorses such a plan of action 
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4 load cells and two motors and continuous rebalancing of power between them?
http://www.bikecommuters.com/2012/10/30/review-ridekick-e-trailer/
So how does this feel when you ride it? It’s a blast! The Ridekick is very stable
Just spoke to a Brixton Cycles mate outside the space. He said one of his bike mechanic mates who does the local markets on weekends hauls his workshop on an electric powered bike trailer.
It’s perfectly feasible to push a bicycle with a powered trailer.
You can do this with the trailer connected to the seat post or to the rear wheel stays.
You can have the trailer powered by one wheel only. The weight of the batteries helps with traction of the powered trailer wheel.
If you want to share the trailer between different bikes the seat post connection may be easiest.
You also need to run a throttle to the handlebar but this is relatively easy to swap between bikes so 5-10 minutes work each time. Nothing else is needed to connect to the bike - just the trailer mount and the throttle cable.
This will then be a throttle only assist which may now be illegal in the UK as the law has changed recently. Making it pedal assist is easy enough but difficult if you want to swap between bikes.
You can build your own trailer or modify an existing one but build you own would provide better cargo carrying options and capacity. Most trailer have low load limits and volume capacity.
I have a motor (24V) that is bought for this purpose. You can use it with lead-acid batteries or something more expensive. It needs a wheel with a sprocket on it and a length of chain and works similar to the ridekick. BMX wheels are good for this if you can get a pair.
I have a controller and throttle somewhere as well I think. I may actually be able to find all this stuff. If I can find it and someone wants to build a powered trailer for the space you can have it all.
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