Basic construction principles and some projects (French 1940s)

[Intrepid Wheelwoman]

These chapters outline basic construction methods as well as illustrating some ideas for building simple vehicles based on standard bicycle parts.

Check out the suggestions on what to do if you can't buy any bicycle tyres

 

[Intrepid Wheelwoman]

Rest of chapter.

 

[silverbear]

Wish I could read the French. The tri car is an interesting concept. If I'm understanding what I see, the propulsion is from a fixed front axle and the rear wheel is made from the fork and frontish parts of a bicycle so that the steering is done with the rear wheel. Is that right? How clever. I wonder how that would steer going at a motored speed of say 15mph.? I need to stare at the photos some more. Thanks!
SB

 

[Intrepid Wheelwoman]

Yes SB that tricar fascinates me too. I'm wondering if I could put together a basic test chassis just to see how that drive and steering system would work out.
I found a plywood specialist in our region who delivers so I must check the budget for the next couple of weeks and see if I can afford to place an order.

 

[caduceus]

Single rear wheel steering worked fine when I was driving forklifts in a factory setting. However, those were short-wheelbase vehicles designed for getting around in very tight quarters, and as I remember, were very twitchy and imprecise at higher speed.

Today's crop of zero-turn mowers utilize rear wheel steering, and sometimes steer by braking differential at the front wheels with only a castering rear wheel mounted on a swivel. As on forklifts, the wheel track is as wide as the wheelbase is long. In all the preceding examples, the operator sits atop the front drive wheels to be able to see exactly where the vehicle is.

I imagine that steering a vehicle that is considerably longer than it is wide from the rear wheel would be similar to using a tiller on a boat. If you decide to do a proof of concept project I'll be interested.

 

[msrfan]

Yes, caduceus is exactly right. I operate forks lifts also and you have to be very careful as the rear of the vehicle swings way out the opposite direction you steer. So a longer than wide chassis would amplify this effect. I have no doubt it would take a person a very short time to master. I see no problem in proceeding with the project, but as intrepid says, a test prototype would be very beneficial, especially if it could be used for the finished product, saving a ton of money. I love this build thread and will be monitoring it all the way. Thanks for posting the articles. Lots of good info and construction methods some of us have never imagined.

 

[Intrepid Wheelwoman]

Thanks for pointing that out about rear castor steering. Having never driven a forklift or anything else with that kind of steering I hadn't realised just how different that would be to a conventional front steered vehicle. Rear castor steering is a feature of several of the vehicle plans Systeme D magazine published during the post-war years so I imagine it must've been practical and not just 'kite flying' on the part of the designer. The advantage with it is that unmodified bicycle parts can be used with minimal engineering which would make building one of these vehicles a lot easier for folk who only owned a basic set of handtools.

 

[Intrepid Wheelwoman]

Not my scans unfortunately, but still clear enough to get the general idea.

 

[atombikes]

You'll kill yourself with a rear-steer trike.

There's a reason why the Sidewinder trike never caught on and the company went out of business.

Check out this video around the 40 second mark, then imagine doing that at 30mph.

http://www.recumbentblog.com/2009/08/28/sidewinder-rear-wheel-steering-trike/

 

[Intrepid Wheelwoman]

I suppose the short answer Atom is that these old French designs were never intended to travel at 30mph. In the video the rider is deliberately making those tight spin about turns, but you would have to be insane to attempt anything like that at any kind of speed.

 

[2door]

I have quite a few hours in aircraft with a tail gear (taildraggers) and yes they can be a handful to control. With a trike style bike you wouldn't have the aerodynamic problems associated with an airplane but the weird steering and inherent instability would still be an issue you'd need some time to master.

If you plan to test the theory might I suggest you do it with a simple unpowered design and use hills or a friend to push it instead of investing the time in a powered platform. That might save you a lot of time and money if you find the rear steer not to your liking.

Tom

 

[Intrepid Wheelwoman]

I have quite a few hours in aircraft with a tail gear (taildraggers) and yes they can be a handful to control. With a trike style bike you wouldn't have the aerodynamic problems associated with an airplane but the weird steering and inherent instability would still be an issue you'd need some time to master.

If you plan to test the theory might I suggest you do it with a simple unpowered design and use hills or a friend to push it instead of investing the time in a powered platform. That might save you a lot of time and money if you find the rear steer not to your liking.

Tom

Thanks Tom, I'm very glad to have your input. Any testbed I make will be based around cheap chainstore bike parts found in the council tip, some angle iron and a few bolts. So if it doesn't work out it can all be dismantled and go back into my spare parts pile without me having to spend any real money.
I would only add a motor into the mix if I was completely sure that it was safe to do so.

Mind you the first time I piloted a sidecar outfit (a Jawa) I was convinced that they were the inventions of the devil, and yet after a week or two I could manage the outfit at speed without any problems. I'm not saying that I want to drive a rear steer velocar at speed, I'm just saying that there might be some learning in the 'white knuckle institute' and 'school of hard knocks' before I'm able to reach any real conclusions.

 

[msrfan]

Maybe a limited turning rear wheel with a steering damper would slow down the action. I've often thought of a caster rear wheel spring loaded back to straight and steering brakes on the front wheels. Brake the front right wheel to turn right, left brake to turn left and no brakes to straighten out. Talk about a learning curve. I would definitely think twice and practice a lot before motorizing. You're doing a great job of researching and I'm sure your prototype will be fun to operate no matter what configuration you end up with.

 

[Intrepid Wheelwoman]

Maybe a limited turning rear wheel with a steering damper would slow down the action. I've often thought of a caster rear wheel spring loaded back to straight and steering brakes on the front wheels. Brake the front right wheel to turn right, left brake to turn left and no brakes to straighten out. Talk about a learning curve. I would definitely think twice and practice a lot before motorizing. You're doing a great job of researching and I'm sure your prototype will be fun to operate no matter what configuration you end up with.

Those are really useful suggestions msrfan and all of them would relatively easy to setup on a test chassis. Certainly a steering damper and some self centering springs would be a good place to start.

 

[silverbear]

msrfan,
I was thinking along the lines of a dampener as well... something to slow down the steering.

I remember the first time I test road my American Flyer with the canoe sidecar... wasn't going fast at all and nearly ran into a tree. It was awful getting used to it and I did not think I liked it at all. My brain understood that I had to turn the handlebar in order to turn, but my body wanted to do it as I had without the sidecar... mostly leaning into a curve. With three wheels leaning doesn't work. It took awhile getting the hang of it. Sounds simple, but it involves the intelligence of the body unlearning one thing and learning another. It isn't that the sidecar rig is better than or worse than... more a matter of different than and has it's own set or "rules".

The setup you describe, Dale, sounds like it could be safe enough at moderate speed, but there would be a learning curve and a person who had never ridden a two or three wheeled bike before might get the hang of it quicker than you or me.

I hope someone pursues this so we can all find out how well or poorly it works. Not me; I have too many unfinished builds as it is.
SB

 

[caduceus]

Fork configuration has a lot to do with stability in vehicles which steer with a single wheel, as does caster angle. I could see getting the torch out and carefully bending in more curve to increase stability. Then your basic configuration would be stable and dampeners or springs would be to enhance stability rather than maintain it. Just a thought.

 

[msrfan]

msrfan,
I was thinking along the lines of a dampener as well... something to slow down the steering.

I remember the first time I test road my American Flyer with the canoe sidecar... wasn't going fast at all and nearly ran into a tree. It was awful getting used to it and I did not think I liked it at all. My brain understood that I had to turn the handlebar in order to turn, but my body wanted to do it as I had without the sidecar... mostly leaning into a curve. With three wheels leaning doesn't work. It took awhile getting the hang of it. Sounds simple, but it involves the intelligence of the body unlearning one thing and learning another. It isn't that the sidecar rig is better than or worse than... more a matter of different than and has it's own set or "rules".

The setup you describe, Dale, sounds like it could be safe enough at moderate speed, but there would be a learning curve and a person who had never ridden a two or three wheeled bike before might get the hang of it quicker than you or me.

I hope someone pursues this so we can all find out how well or poorly it works. Not me; I have too many unfinished builds as it is.
SB

Yessir, I remember my first ride on an ATC. With that live axle lean to the left and it turns to the right. Kids did great because when they turned, they were thrown the opposite way and it turned perfectly.

 

[Ludwig II]

I've driven many forklift trucks over the years. I cannot recommend rear wheel steering at any appreciable speed and/or on slippery road surfaces. Hanging the tail out round a corner is somewhat ... interesting.