Handcycle steering

W

Wheelz50

I'm in the process of planning to build a handcycle. It's likely to be based on a tadpole design. I might be over thinking things, but, if the boom /mast is to rotate or lean for steering and the cranks at the top of it, would the chain be pulled off each time you steer or is there enough give to allow for this dual action?
 
But why a tadpole all commercial hand cycles I have seen are deltas , much easier to make and the chains are much shorter.

Oh and they are much easier to get onto if you have mobility problems

Paul
 
There are a couple tadpole handcycles out there - Mostly off-road oriented, and brutally expensive.
I was looking at this one : https://jpmpro.com/jeetrike, and trying to understand how they dealt with the chain.
It has some pretty elaborate looking chain control mechanisms, as well as multiple chains.
Why Paul said a delta would be easier, and why most commercial ones are.
 
In the UK the ones I have seen are all for racing :)

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Paul
 
I'd think that a handcycle tadpole might be best designed with some kind of shaft, or hybrid, drive.
With chain drive, you're fighting the physics and geometry of it, the whole way.
 
A two chain approach with a UJ will cope. If it can cope with a FWD short chain length then it'll easily do a longer pair of chains. The crank column is actually in a good place naturally to use it as a steering column too for a go-Kart type steering mechanism

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Such a column will make getting on and off very restricted unless a method of tilting it for access is used. I'd recommend plenty of effort in CAD before braking out the angle grinder to ensure you can get on and off. A taddy is going to be much more complex than a delta.
 
An alternative taddy. From under the seat bring two arms up and put a crank on each arm driving a jackshaft under the seat which then drives the wheel. The jackshaft keeps both cranks in sync. The arms need to pivot fore and aft to provide tank steering. There will be a tendency to crank steering until technique is honed. Having the cranks synced both forward at the same time will reduce crank steering over having the cranks 180 out like a bike. Easier access too and a straight set of chains. Steering will get a little odd as going fore and aft on the arms will alter the timing between the cranks. Whether that will be an issue only trying it will tell.
 
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