Instructables

Tadpole style recumbant - with the rear single wheel doing the steering with the front two wheels fixed - plausible?

Now in a way you couldn't really call this a bike anymore, as it will not be pedal powered.  Instead I am gearing one of my wheelchair motors left over from one of my robots to power the rear wheel.  It will be kinda like driving a boat on land.  So... am I nuts for trying it this way.  Included a quick BASIC concept sketch.

orksecurity3 years ago
I'd be worried that trying to steer from behind would be unstable -- the farther off-axis you are, the more the motor will try to push you even farther off-axis. It might be drivable but I think you'd be fighting it continuously.

(As opposed to going the other direction, where the vehicle would tend to pull itself back into going straight. Or motorizing the forward wheels and letting the steering/rudder wheel's drag tend to pull it back into straight-line position.)

Possible, but maybe not plausible.

iminthebathroom (author)  orksecurity3 years ago
Yes, you are probably right. I do have the option of motorizing the front as well, just as easy with the supplies I have to work with, "I have several work type trykes that I could use". Just being a little too lazy I think. Was seeing if it possible to avoid setting up a traditional tadpole steering system is all. Thanks for the input, its good to have people to bounce ideas off of.
kalboon3 years ago
*Wide rear tire, sorry =)
kalboon3 years ago
One thing that might help, use a very large rear tire, it will limit how far off center the driving wheel could push you, but overall, its probably a better idea to motorize the front.
paqrat3 years ago
Buckminster Fuller designed and built three versions of a three wheeled car with single rear wheel steering. His car had drive going to the front wheels though. For many years I labored under the misconception that because the engine was mounted in the rear and it had rear steering that the engine drove the steerable third wheel. I was mistaken.
call me nuts but it could be done. instead of trying to steer with the rear wheel set it up like an old tail dragger aircraft.

allow the rear wheel to move freely and control it with a stand alone break system for each front wheel.
example to turn right apply break pressure to the right wheel to turn left apply brake pressure to the left

but if you do it this way you wouldnt want to put the engine on the back wheel
i once drove a car with rear wheel steering (it was someone with too much time and money being funny) and it was freaking impossible to get used to, everyone kept crashing it into stuff by turning for too long or too soon
rickharris3 years ago
You may find these designs inspirational

Recumbent.jpg
iminthebathroom (author) 3 years ago
Looked inot it a bit more, apparently this has been tried from time to time over and over again. No one really seems to have any success, back to the drawing board...
It's true, rear-steer trikes are never really very nice to ride because they are so difficult to steer. If you need inspiration, be sure to check out Atomic Zombie, where you'll find tons of trike designs, some motorized.
frollard3 years ago
I'm reminded of a powered ride on pallet jack.

They have the power going to the rear wheels with the steering constrained exactly to the vertical axis, and a long lever for the operator to adjust the steering - they do have ork's suggestion of instability at high speed when in 'pusher' mode, so you always have to drive 'forward' backwards dragging the load.
iminthebathroom (author)  frollard3 years ago
yup, I may just go for a ride on one of those right now... you know, for kicks at 1 in the morning... the night shift is very slow - what can I say
I too am on night shfit. yay! No pallet jack for me. There IS a forklift in the building, but if I was driving it, the police would show up.
iminthebathroom (author)  frollard3 years ago
Nice, I on the other hand am the only person present for quite some distance. Enough so that I have to be equipped with a gps spot unit... A large now defunct pulp and paper mill is more or less my playground, not as cool as it sounds, but sometimes...
Insecurity detail, hm?

That's essentially how the writer Spider Robinson got started -- as he puts it, he had a job "guarding a hole in the ground to keep anyone from stealing it" -- which left him with lots of time to work on his writing.
iminthebathroom (author)  orksecurity3 years ago
More or less, I used to work at the mill when it was running. Then i was called back a year later to work as a first aid attendant for various companies who bought the paper machines. They also need extra plant protection officers, so I put my hand up. Gives me lots of free time that's for sure, lets just say a flurry of new instructables has started