rhunderhill

RWSB-page (rear wheel steered bicycles)
Schwab, Arend L. Schwab

I agree it's the recumbent holy grail and would allow belt drive and hub gears etc. if it could be shown to be stable at all speeds and situations. I imagine it would require a relearning of how to ride but would be entirely worth it.

JanMM

Zombie Thread Alert!
This thread had been asleep for 12 years...................

Understatement ---> Not a lot of interest in FWD/RWS bikes. The one in the video looks well done.

BlazingPedals

Yeah, notice the video was posted 4 years after this thread 'died.' In the ensuing 7 years, this concept bike has remained, as far as anybody knows, a one-of-a-kind.

indyfabz

This is the 4th or 5th zombie thread I have seen today that been resurrected in the last day or so.

79pmooney

My first thought - you start to lean right. On a conventional bike, you steer right and near instantly the front wheel and therefor the bike is back under you. Very small correction needed and you basically never stopped going straight ahead. Rear wheel steering - you still need that bike under you but to get it there yo need to steer left. As others have said above, a challenge for our brains. Maybe the way to make rear steerers ridable is to have the chain linking the rear fork and the handlebars run in a figure 8. Now balancing would take your old reflexes and ti wouldn't take too long to figure out that you steer in the opposite direction to take corners. (Like anyone who grew up sailing small sailboats with tillers and graduates to a larger boat with a steering wheel.

"But officer, I did signal my turn correctly. I just forgot what bike I was on."

Ben

fietsbob

Dyamaxion , Buckminster Fuller's super aero car had 2WD, front, and 1 rear steered wheel..

it was kind of high CofG, and flipped over

Doug5150

Yea, a bunch have probably been built over the last ~100+ years or so.... by home-builders.

The Cruzbike design evolved out of this concept, but it still uses conventional front-wheel-steering geometry.

The desirable state of steering geometry is that a vehicle exhibits "positive stability", which means that the steering wheels will tend to return to a straight line as well as hold a straight line on their own, at any speed--even though some minimum speed may be required for this stability to function.

The mathematics for analyzing steady states of mechanical systems is Eigenvalue charts. There is one present in the article below, about halfway down the page:
https://en.wikipedia.org/wiki/Bicycl...cycle_dynamics

The Eigenvalue charts for mechanical-only rear-wheel steering shows that none devised so far can maintain positive stability. Furthermore, it appears as though such a design is not possible.

The best that can be done is to locate the majority of the vehicles mass (the rider's center of gravity) very close to the steering axis, and then the steering becomes fairly neutral--it does not tend to deviate from a straight line on its own, but then, it does not return to a straight line on its own either. These bicycles may be ride-able at typical speeds but companies generally refuse to manufacture and sell them as performance or general-use bicycles. Some are sold as cargo or commercial vehicles with cart-axle-type steering (such as tadpole vending trikes) but these are only intended to be used at VERY low speeds, and on level ground.

Note the distinction here:
1) it is not impossible to build a rear-wheel-steer bicycle that is ride-able; there's several designs that work.
2) it is probably impossible to build a rear-wheel-steer bicycle that exhibits positive stability.
A number of people have done #1 and think they've solved some great cosmic mystery--when they simply didn't have a full understanding of the problem.

What technically defines "what kind of steering" a vehicle has is its Eigenvalue chart; the common variations of front, mid and rear-wheel steering show typical kinds of charts. A casual way (that usually is correct) is to observe what wheels pivot relative to where the vehicle's mass is located. For the Kalle bike--the frame is two sections, and the rider's mass is fixed to the front section--so the rear section + wheel pivots to steer, and it is a RWS bicycle. (with the rider's mass located almost centered on the steering axis)

The Eric Wannee RWS bicycle pages show some bicycles and trikes that tried to use steering systems other-than-front-wheel-steer. Most of these toys were taken off the market and recalled due to reports of sudden crashes and injuries.

A lot of home-builders seem to think that if they're building a trike, it doesn't need to have positive stability since "it's got three wheels"--and they are likely to learn the truth the hard way. Wear your helmet! The Wannee pages have a bunch of RWS trikes that were recalled because they tended to jack-knife and roll over at high speeds and/or rough ground. And note that many of these were children's riding toys, so "high speed" may have not been higher than 5 or 10 MPH....

You can build a negatively-stable bicycle or trike if you want; it may be fun and useful at low to moderate speeds. But it's never going to be safe at high speeds and/or rough terrain, and you should think really really hard before you sell it to anyone else.

The Python is not called a "low-racer" because even tho it should have very low aero drag, it's design is negatively stable: it is unsafe at high speeds. So it is called a "touring" recumbent, not a racing recumbent. It tends to jack-knife at high speeds. And even tho the frame design is rather simple, no company has ever built and sold this design.

BlazingPedals

As almost everyone knows, in the 12 years since the thread was started, Cruzbikes have gone from making FWD kits to whole bikes. They're still FW steering, though. For RWS, here's one last reference before the thread can be re-buried for another few years: Huffy Green Machine.

JanMM

G'night, thread............................

cambiker71

I'll wake it up again, my trike is FWD RWS, dead easy to ride, no idea on high speed cos there's no hills near here and i'm not a fast pedal twirler at all
I doubt a two wheel RWS would be very relaxing to ride though!

CliffordK

I've thought about trying a rear wheel steering recumbent,simply crossing the right/left steering arms.

As far as front pedalling, front steering, our local CO-OP, Center for Appropriate Transport puts that into their trikes. I'm not sure if they use hand steering, or foot steering only.

BlazingPedals

I'm sure that is fun to ride on a local path at pedestrian speeds, but I would definitely not want to take it down a screaming 50 mph downhill.

cambiker71

It is fun up to and around 10 to 12 mph, and no, nor would I! ha ha

Ironfish653

The Mobo Triton falls more in to the 'toy' category, due to the direct drive front wheel, but does use a rear-steer setup. The 16" wheel size (20" pictured) is popular as an adaptive bike for kids with autism and similar disabilties who lack the coordination for 2-wheelers. My son has one, and it's way easy to use.

It runs a noticable toe-out on the rear wheels, for self-centering. The center tie rod is threaded, but it specifically mentions the toe-out and not to adjust it in the manual.

cambiker71

I'll awaken the thread again

Been busy chopping my trike up...

Mbrgr1

No new or old RWS thread would be complete with out mentioning the mass produced "Sidewinder", I have one in the garage and it's a hoot to ride, just don't cut the steering loose over 5mph!

Front wheel drive with a differential!

rm -rf

Yeah, lots of zombie posts. I wondered if the BF search was showing them on purpose, to get more threads going.

But a BF search returns the most recent matches first. You'd have to go into the search settings and pick "most viewed" or similar, or search a very obscure phrase to find these old threads.