Planning a recumbent trike built from scratch

I posted a few days ago about this proposed new project:

• Staying with SolveSpace for new trike project — February 17, 2025

My current custom trike started out as a standard trike that I modified, with front suspension, solar panel, etc. Great, but having got hands-on experience with that, have learnt so much, and now contemplating a new project incorporating everything learnt.

Why not build the trike entirely from scratch? let the imagination run wild! That might seem very ambitious, but I reckon it is doable with basic handyman tools. There are DIY trike plans on the Internet, and YouTube videos of guys showing how they made their trike, but I want a complete rethink.

In the previous post, I put a link to YouTube video playlist "Graham Makes Stuff", parts 1 to 4. Just about everybody who builds something like this, finds that it doesn't  end, they keep thinking of improvements, and they make many changes. Graham is no exception. The year following building the trike, he made a series of modifications, including adding front suspension. See his later videos:

"DIY Trike build part 5. Riding, testing, things I've changed"
https://www.youtube.com/watch?v=Mm20VcANAkw

"DIY no weld trike part 6. More changes, tweaks and improvements"
https://www.youtube.com/watch?v=OhFYDE0yG8M

While I think of it, Ben, the owner of Trisled, an Australian trike manufacturer, the only Australian trike manufacturer, built this for his dad, a one-off:

https://trisled.com.au/solar-mobility-quad/

...very simple mounting of the solar panel. A curved frame and attached with cable-ties. Something to consider.

Designing a trike from scratch, no legacy constraints; this is such great fun! Here is a proposed side view:

There are various objectives, one of which is to get the centre-of-gravity very low. The seat is low, also angled so that the pedals will be quite high -- even high enough that there could be a floor-plate to prevent the feet from falling onto the ground.

The yellow colour is the frame, which will be 50x50x3 square aluminium. The reason for it extending high at the back is for attaching the solar-panel frame. Solar-panel, motor, they will be optional; Plan to build the initial trike human-powered only, so as to keep it simple.

The back wheel will have two shock absorbers, each side of the wheel, to keep the length of the trike as small as possible. Though, the forks will be a bit longer than shown in the above diagram, to allow for greater upward deflection of the wheel.

The front wheels have been moved back, a lot more than my current trike, to avoid the wheels hitting the feet when doing a sharp turn. I still want the trike to be narrow, at most 730mm, so as to easily go through doors. The narrow width is another reason why want to get the centre-of-gravity very low; though, it is not so urgent due to optional tilting.

The green-filled construction is a round rod, at the right end a swivel to which the steering arms will be attached. Now this is very interesting; the steering arms will allow turning left or right, but also control tilt. The two functions are independent; swivel the steering arms to turn left or right, like any normal recumbent trike, move the steering arms to the side for tilt either way.

There will be a simple mechanism to disable tilt, but if it is enabled, you can go around a corner with as much tilt as you want. This is much better than some other tilting trike designs that have tilt directly linked to the turning.

I'm waiting for an eye operation, in the public system here, as I don't have private health insurance. The public health services here in Australia are very good. There is a date set for the operation, but there is the possibility of being called in earlier. So not going on any trike tour or train adventure for awhile. While here at home for the next couple of months, great opportunity to have fun with this next trike project.

The wheel-knuckle, looking forward to building that. It is arguably the most difficult part of the project, but I have it worked out, and can even see how to build it without any welding. Waiting on some aluminium to arrive.    

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