FWD with Rear Wheel-Steering??

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Date: 14 May 2006 12:51:33
From: NYC XYZ
Subject: FWD with Rear Wheel-Steering??

Just wondering if there's such a creature. Whatever is the advantage
of a FWD design? And why not couple that somehow with rear
wheel-steering eliminate the steering issues of FWD designs?

Just curious.

Date: 07 Jul 2006 19:33:28
From: aorange
Subject: Re: FWD with Rear Wheel-Steering??

can anyone tell me why the steering on bent trikes is below as opposed
to the traditonal upright format?

Date: 03 Jun 2006 06:50:00
From: Qui si parla Campagnolo-www.vecchios.com
Subject: Re: FWD with Rear Wheel-Steering??

Date: 02 Jun 2006 13:53:37
From: john
Subject: Re: FWD with Rear Wheel-Steering??

NYC XYZ wrote:
> Just wondering if there's such a creature. Whatever is the advantage
> of a FWD design? And why not couple that somehow with rear
> wheel-steering eliminate the steering issues of FWD designs?
>
> Just curious.

I am sure that you have never driven a forklift w/ rear steering. Even
w/ 4 wheels they are damn unstable.

Regards, John

Date: 29 Jun 2006 20:57:46
From: Taunto
Subject: Re: FWD with Rear Wheel-Steering??

john wrote:
> NYC XYZ wrote:
>
>>Just wondering if there's such a creature. Whatever is the advantage
>>of a FWD design? And why not couple that somehow with rear
>>wheel-steering eliminate the steering issues of FWD designs?
>>
>>Just curious.
>
>
> I am sure that you have never driven a forklift w/ rear steering. Even
> w/ 4 wheels they are damn unstable.
>
> Regards, John
>

Is that because the wheels tend to keep turned from friction and swing
out more and longer than expected.

Date: 04 Jul 2006 16:39:18
From: NedTexTri
Subject: Re: FWD with Rear Wheel-Steering??

Stop cross-posting the recumbent chat in the ketplace forum.

"Taunto" <nope@notme.com > wrote in message
news:44a4a1b4$0$12693$742ec2ed@news.sonic.net...
> john wrote:
>> NYC XYZ wrote:
>>
>>>Just wondering if there's such a creature. Whatever is the advantage
>>>of a FWD design? And why not couple that somehow with rear
>>>wheel-steering eliminate the steering issues of FWD designs?
>>>
>>>Just curious.
>>
>>
>> I am sure that you have never driven a forklift w/ rear steering. Even
>> w/ 4 wheels they are damn unstable.
>>
>> Regards, John
>>
>
> Is that because the wheels tend to keep turned from friction and swing out
> more and longer than expected.

Date: 30 Jun 2006 12:02:32
From: Steve Kirkendall
Subject: Re: FWD with Rear Wheel-Steering??

Taunto wrote:
> john wrote:
>> NYC XYZ wrote:
>>
>>>Just wondering if there's such a creature. Whatever is the advantage
>>>of a FWD design? And why not couple that somehow with rear
>>>wheel-steering eliminate the steering issues of FWD designs?
>>>
>>>Just curious.
>>
>>
>> I am sure that you have never driven a forklift w/ rear steering. Even
>> w/ 4 wheels they are damn unstable.
>>
>> Regards, John
>>
>
> Is that because the wheels tend to keep turned from friction and swing
> out more and longer than expected.

I alsways figured it was mostly because of gyroscopic precession.

With front steering, if you start to lean to the left then the front
wheel precesses counterclockwise, causing the bike to turn left so it's
still under you. This is why it's possible to ride no-handed.

With rear steering, leaning to the left also causes the steered wheel
to precess counterclockwise, but since it's a rear wheel this will
cause the bike to turn right, throwing you down to the street HARD!

Date: 01 Jul 2006 00:21:25
From:
Subject: Re: FWD with Rear Wheel-Steering??

Steve Kirkendall writes:

>>>> Just wondering if there's such a creature. Whatever is the
>>>> advantage of a FWD design? And why not couple that somehow with
>>>> rear wheel-steering eliminate the steering issues of FWD designs?

>>>> Just curious.

>>> I am sure that you have never driven a forklift w/ rear
>>> steering. Even w/ 4 wheels they are damn unstable.

>> Is that because the wheels tend to keep turned from friction and
>> swing out more and longer than expected.

> I always figured it was mostly because of gyroscopic precession.

You'll have to explain what you mean by that. Fork lifts have no
gyroscopic effect nor do cars that are driven backward at high speed,
something that works well with front steering but is unstable in
reverse. In fact I can't imagine a rear steering vehicle that is
stable. Even fire engine ladder trucks with rear steering avoid high
speed turns with the rear steering unlocked.

> With front steering, if you start to lean to the left then the front
> wheel precesses counterclockwise, causing the bike to turn left so it's
> still under you. This is why it's possible to ride no-handed.

Get off it! Rear steering is demonstrably unstable and has nothing to
do with leaning. Consider that the original VW was an unstable car
that spun out dangerously in spite of front steering, because it had a
degree of rear steering from its wheel suspension dynamics. You will
also notice that there are no rear steering cars, motorcycles or farm
tractors, much less semi-trailer-tractor trucks.

> With rear steering, leaning to the left also causes the steered
> wheel to precess counterclockwise, but since it's a rear wheel this
> will cause the bike to turn right, throwing you down to the street
> HARD!

I don't think you grasp the concept and that you are guessing, beside
not having tried any of this. If you tried to back up a car with
trailer you might get a notion of the concept. That you state these
things as fact with no supporting evidence in the face of all that is
known about steering stability, I think you would best take a
different approach.

Jobst Brandt

Date: 30 Jun 2006 18:16:13
From: LioNiNoiL_a t_Y a h 0 0_d 0 t_c 0 m
Subject: Re: FWD with Rear Wheel-Steering??

Jobst Brandt wrote:

> I can't imagine a rear steering vehicle that is stable.
> ...
> Rear steering is demonstrably unstable...
> ...
> I don't think you grasp the concept and that you are guessing...

Jobst, it is you who is guessing, and badly. Richard Noble's
"ThrustSSC", the first-ever supersonic land vehicle (763.035mph on 15
October 1997) had rear-wheel steering.

http://www.thrustssc.com

--
"Bicycling is a healthy and manly pursuit with much
to recommend it, and, unlike other foolish crazes,
it has not died out." -- The Daily Telegraph (1877)

Date: 04 Jul 2006 11:47:59
From: Dave Larrington
Subject: Re: FWD with Rear Wheel-Steering??

In article <w1kpg.36084$AB3.14736@fed1read02 >,
nobody@devnull.spamcop.net says...
> Jobst Brandt wrote:
>
> > I can't imagine a rear steering vehicle that is stable.
> > ...
> > Rear steering is demonstrably unstable...
> > ...
> > I don't think you grasp the concept and that you are guessing...
>
> Jobst, it is you who is guessing, and badly. Richard Noble's
> "ThrustSSC", the first-ever supersonic land vehicle (763.035mph on 15
> October 1997) had rear-wheel steering.
>
> http://www.thrustssc.com

After which S/L Green opined that in future RWS should be confined to
fork-lifts.

--
Dave Larrington - <http://www.legslarry.beerdrinkers.co.uk/ >
They came for Dani Behr; I said: "she's over there, behind the
wardrobe".

Date: 04 Jul 2006 12:57:49
From: Peter Clinch
Subject: Re: FWD with Rear Wheel-Steering??

Dave Larrington wrote:

> After which S/L Green opined that in future RWS should be confined to
> fork-lifts.

Despite, IIRC, a considerable level of "help" from the car's systems to
keep it going where the driver wanted it to.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/

Date: 29 May 2006 18:18:49
From: T Smith
Subject: Re: FWD with Rear Wheel-Steering??

I haven't built a RWS 2 wheeler (only 3) but saw on TV one that
actually worked. See it in action at
http://www.ihpva.org/people/tstrike/RWS bike.mpg

On 14 May 2006 12:51:33 -0700, "NYC XYZ" <jack_foreigner@yahoo.com >
wrote:

>Just wondering if there's such a creature. Whatever is the advantage
>of a FWD design? And why not couple that somehow with rear
>wheel-steering eliminate the steering issues of FWD designs?
>
>Just curious.

Date: 01 Jun 2006 17:33:46
From: Mark Leuck
Subject: Re: FWD with Rear Wheel-Steering??

This appears to be the correct link

http://www.ihpva.org/people/tstrike/rws.htm

"T Smith" <ciscokid@tasmail.com > wrote in message
news:om9l72l3sf5jodr90lghajo9kg2iuufn7m@4ax.com...
> I haven't built a RWS 2 wheeler (only 3) but saw on TV one that
> actually worked. See it in action at
> http://www.ihpva.org/people/tstrike/RWS bike.mpg
>
> On 14 May 2006 12:51:33 -0700, "NYC XYZ" <jack_foreigner@yahoo.com>
> wrote:
>
> >Just wondering if there's such a creature. Whatever is the advantage
> >of a FWD design? And why not couple that somehow with rear
> >wheel-steering eliminate the steering issues of FWD designs?
> >
> >Just curious.
>

Date: 11 Jun 2006 11:44:20
From: T Smith
Subject: Re: FWD with Rear Wheel-Steering??

Oh no it isn't. The full link just didn't show as clickable. Copy and
paste the whole path into a browser to see a short movie.
http://www.ihpva.org/people/tstrike/RWS bike.mpg

On Thu, 1 Jun 2006 17:33:46 -0500, "k Leuck" <m..leuck@comcast.net >
wrote:

>This appears to be the correct link
>
>http://www.ihpva.org/people/tstrike/rws.htm
>
>
>"T Smith" <ciscokid@tasmail.com> wrote in message
>news:om9l72l3sf5jodr90lghajo9kg2iuufn7m@4ax.com...
>> I haven't built a RWS 2 wheeler (only 3) but saw on TV one that
>> actually worked. See it in action at
>> http://www.ihpva.org/people/tstrike/RWS bike.mpg
>>
>> On 14 May 2006 12:51:33 -0700, "NYC XYZ" <jack_foreigner@yahoo.com>
>> wrote:
>>
>> >Just wondering if there's such a creature. Whatever is the advantage
>> >of a FWD design? And why not couple that somehow with rear
>> >wheel-steering eliminate the steering issues of FWD designs?
>> >
>> >Just curious.
>>
>

Date: 21 May 2006 03:00:02
From: Bill Patterson
Subject: Re: FWD with Rear Wheel-Steering??

NYC XYZ wrote:
> Just wondering if there's such a creature. Whatever is the advantage
> of a FWD design? And why not couple that somehow with rear
> wheel-steering eliminate the steering issues of FWD designs?
>
> Just curious.
>
Go here to see a CALPOLY student riding one.

http://home.earthlink.net/~wm.patterson/index.html

Click down to the 2nd and 3rd photos.

I think the high seat provides a time constant that allows him to ride
the unstable bike. Low seat bikes weren't rideable by us.

I had many students try. This is the only one that succeeded

--
See bikes at: http://home.earthlink.net/~wm.patterson/index.html

See bikes and the first human powered helicopter at:

http://www.calpoly.edu/~wpatters/

Reply to wm.patterson@earthlink.net
wpatters@calpoly.edu
william.patterson@1962.usna.com

Date: 02 Jun 2006 20:32:45
From: Bill Patterson
Subject: Re: FWD with Rear Wheel-Steering??

Bill Patterson wrote:

>>
> Go here to see a CALPOLY student riding one.
>
> http://home.earthlink.net/~wm.patterson/index.html
>
> Click down to the 2nd and 3rd photos.
>
Oops, I got sick of that old web site and deleted it. Hope you got to it
before it was gone. I'm into helicopter avionics now. sorry.

Bill

--
Some thoughts on Apache helicopter avionics
http://home.earthlink.net/~wm.patterson/helicopterthoughts/
http://home.earthlink.net/~wm.patterson/helicopterthoughts/id17.html
http://home.earthlink.net/~wm.patterson/helicopterthoughts/id16.html

See bikes and the first human powered helicopter at:
http://www.calpoly.edu/~wpatters/
Single Track controls at:
http://home.earthlink.net/~wm.patterson/

Reply to wm.patterson@earthlink.net
wpatters@calpoly.edu
william.patterson@1962.usna.com

Date: 17 May 2006 08:07:29
From: gotbent
Subject: Re: FWD with Rear Wheel-Steering??

My limited experience in warehouses is that in long high speed
(remember we're talking fork truck speed) runs, the drivers go in
reverse so that they are in effect front steer vehicles.

Date: 15 May 2006 09:15:30
From:
Subject: Re: FWD with Rear Wheel-Steering??

Werehatrack wrote:
> On 15 May 2006 00:21:45 -0700, joseph.santaniello@gmail.com wrote:
>
> >If you were completely insane you could build a rear-wheel steering
> >bike with a robotic drive-by-wire system with a lean/attitude sensor to
> >counter the instability. Solar powered of course.
>
> Please, do us all a favor and don't suggest this to anyone in the
> military or the Post Office. We really don't need to have the
> government spending billions to develop such a device. (Of course,
> they'd probably make it AWD with adaptive traction control as well.)

Some industrious hobbyists could sure pocket a chunk of change if they
got billions to make something like a drive-by-wire bike steering
system with about $500 worth of parts!

It would be basically the same as this unicycle, just sideways, sans
motor:

http://tlb.org/eunicycle.html

Joseph

Date: 15 May 2006 00:21:45
From:
Subject: Re: FWD with Rear Wheel-Steering??

NYC XYZ wrote:
> Just wondering if there's such a creature. Whatever is the advantage
> of a FWD design? And why not couple that somehow with rear
> wheel-steering eliminate the steering issues of FWD designs?
>
> Just curious.

If you were completely insane you could build a rear-wheel steering
bike with a robotic drive-by-wire system with a lean/attitude sensor to
counter the instability. Solar powered of course.

Joseph

Date: 15 May 2006 15:39:15
From: Werehatrack
Subject: Re: FWD with Rear Wheel-Steering??

On 15 May 2006 00:21:45 -0700, joseph.santaniello@gmail.com wrote:

>If you were completely insane you could build a rear-wheel steering
>bike with a robotic drive-by-wire system with a lean/attitude sensor to
>counter the instability. Solar powered of course.

Please, do us all a favor and don't suggest this to anyone in the
military or the Post Office. We really don't need to have the
government spending billions to develop such a device. (Of course,
they'd probably make it AWD with adaptive traction control as well.)
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

Date: 15 May 2006 01:14:21
From: Hank Wirtz
Subject: Re: FWD with Rear Wheel-Steering??

"NYC XYZ" <jack_foreigner@yahoo.com > wrote in news:1147636293.688908.91260
@v46g2000cwv.googlegroups.com:

> Just wondering if there's such a creature. Whatever is the advantage
> of a FWD design? And why not couple that somehow with rear
> wheel-steering eliminate the steering issues of FWD designs?
>
> Just curious.
>

As others have mentioned, the advantage would be a short chain. Aside from
steering problems, the major disadvantage I see is a HUGE loss in traction.
Nearly all practical bike designs weight the rear wheel. Climbing with
something like the Flevobike that has only the weight of the drivetrain and
your feet holding it to the ground strikes me as frustrating at best,
bordering on dangerous.

Date: 20 May 2006 12:01:05
From: wvantwiller
Subject: Re: FWD with Rear Wheel-Steering??

Hank Wirtz <hank@REMOVEME.wirtznet.net > wrote in
news:Xns97C3EC825337Dhankwirtznetnet@216.196.97.136:

> "NYC XYZ" <jack_foreigner@yahoo.com> wrote in
> news:1147636293.688908.91260 @v46g2000cwv.googlegroups.com:
>
>> Just wondering if there's such a creature. Whatever is the advantage
>> of a FWD design? And why not couple that somehow with rear
>> wheel-steering eliminate the steering issues of FWD designs?
>>
>> Just curious.
>>
>
> As others have mentioned, the advantage would be a short chain. Aside
> from steering problems, the major disadvantage I see is a HUGE loss in
> traction. Nearly all practical bike designs weight the rear wheel.
> Climbing with something like the Flevobike that has only the weight of
> the drivetrain and your feet holding it to the ground strikes me as
> frustrating at best, bordering on dangerous.

That's exactly what I've always understood to be the case in automotive
design.

When light-weight, compact cars came out, the advantage to front-wheel
drive was that most, actually almost the only, mass was over the front
wheels in the form of the engine and transmission. To maintain traction
with such a mass distribution, there were clear advantages to moving to
front-wheel drive. That basic fact overrode the normal considerations of
the physics/dynamics of the larger, better-balanced designs under
acceleration along with those caused by transient situations like
steering.

In the bicycles case, the very fact that the rear wheel loading usually
predominates except in braking, combined with the possiblity of losing
steering/balancing whenever you lose traction seems like the 'double-
casualty' that most emergency planners dread facing to the point of
decreeing that their plans assume only one problem at a time needs
addressing. And, those planners deal with an ice-age timelines compared
to the reflex-driven casualty situations on a bike.

Talk about a divergent system response!

Date: 20 May 2006 17:49:01
From: Ryan Cousineau
Subject: Re: FWD with Rear Wheel-Steering??

In article <2038c$446f3d41$18ec6aba$30830@KNOLOGY.NET >,
wvantwiller <wvantwiller@knickerbocker.com > wrote:

> Hank Wirtz <hank@REMOVEME.wirtznet.net> wrote in
> news:Xns97C3EC825337Dhankwirtznetnet@216.196.97.136:
>
> > "NYC XYZ" <jack_foreigner@yahoo.com> wrote in
> > news:1147636293.688908.91260 @v46g2000cwv.googlegroups.com:
> >
> >> Just wondering if there's such a creature. Whatever is the advantage
> >> of a FWD design? And why not couple that somehow with rear
> >> wheel-steering eliminate the steering issues of FWD designs?
> >>
> >> Just curious.
> >>
> >
> > As others have mentioned, the advantage would be a short chain. Aside
> > from steering problems, the major disadvantage I see is a HUGE loss in
> > traction. Nearly all practical bike designs weight the rear wheel.
> > Climbing with something like the Flevobike that has only the weight of
> > the drivetrain and your feet holding it to the ground strikes me as
> > frustrating at best, bordering on dangerous.
>
> That's exactly what I've always understood to be the case in automotive
> design.
>
> When light-weight, compact cars came out, the advantage to front-wheel
> drive was that most, actually almost the only, mass was over the front
> wheels in the form of the engine and transmission. To maintain traction
> with such a mass distribution, there were clear advantages to moving to
> front-wheel drive. That basic fact overrode the normal considerations of
> the physics/dynamics of the larger, better-balanced designs under
> acceleration along with those caused by transient situations like
> steering.

Front wheel drive in cars has almost entirely been about packaging: no
long heavy driveshaft, no drivetrain hump in the passenger compartment.
It was really a matter of making more space for people and living with
the (in most cases, quite acceptable) dynamics you got. The fact that
FWD has some advantages in low-traction situations has been a selling
point, but I think it was almost always a side-effect rather than a
priy reason for going to FWD.

> In the bicycles case, the very fact that the rear wheel loading usually
> predominates except in braking, combined with the possiblity of losing
> steering/balancing whenever you lose traction seems like the 'double-
> casualty' that most emergency planners dread facing to the point of
> decreeing that their plans assume only one problem at a time needs
> addressing. And, those planners deal with an ice-age timelines compared
> to the reflex-driven casualty situations on a bike.
>
> Talk about a divergent system response!

For off-road bicycles, FWD is a non-starter, but road bikes are hardly
ever drive-traction limited. Most of the bikes configured with FWD
(almost all recumbents) have weight distribution and cockpit designs
such that substantially unweighting the front wheel is nearly impossible.

I suppose it's possible a FWD recumbent with cranks high enough for the
rider to pedal in sharp corners could get the rider in trouble if they
poured in the power hard at mid-corner, but that would be stupid.

The problems with current FWD bikes, relative to similar RWD ones, seems
to be mostly a matter of packaging, not dynamics: it's hard to make the
design so it has a good range of motion for the front wheel, an
efficient drivetrain, and cranks that don't move with the front wheel.

--
Ryan Cousineau rcousine@sfu.ca http://www.wiredcola.com/
"I don't want kids who are thinking about going into mathematics
to think that they have to take drugs to succeed." -Paul Erdos

Date: 21 May 2006 22:40:47
From: Allan Butler
Subject: Re: FWD with Rear Wheel-Steering??

I have personally seen a front wheel drive, rear wheel steer recumbent in
the past.

The bicycle was a simple straight beam that had the front wheel mounted
under it along with the steerable rear wheel being mounted under the beam.
Both wheels looked as if they were either 27 inch or 700c series wheels. I
was too far away and not conversant enough at the time to determine wheel
size on this bicycle.

At the time that I saw this bicycle it appeared to be quite unstable. The
person riding it was given quite a wide area for his maneuvers to keep the
bike upright. Now, I did NOT see the bike out in the middle of the country
side at speed to know how well it was doing. The times that I saw it I was
supporting RAGBRAI at overnight towns. This was before I got back into
cycling myself.

I never saw the bike on the years that I drove sag or rode on RAGBRAI which
started around 1991. It would seem to be counter intuitive to try and
balance a vehicle of this type when the back wheel moves opposite of the
direction one wants to turn. I want to go right so the back of the bike
goes left doesn't seem like it would be something that would be instinctive
to anyone that I know.

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Date: 23 May 2006 01:41:55
From: Robert Haston
Subject: Re: FWD with Rear Wheel-Steering??

It may have been a Flevobike - which more or less pivots in the middle -
otherwise it sounds home made.

"Allan Butler" <ka0ies@hotmail.com > wrote in message
news:1148268884_44@64triton.net...
>I have personally seen a front wheel drive, rear wheel steer recumbent in
> the past.
>
> The bicycle was a simple straight beam that had the front wheel mounted
> under it along with the steerable rear wheel being mounted under the beam.
> Both wheels looked as if they were either 27 inch or 700c series wheels.
> I
> was too far away and not conversant enough at the time to determine wheel
> size on this bicycle.
>
> At the time that I saw this bicycle it appeared to be quite unstable. The
> person riding it was given quite a wide area for his maneuvers to keep the
> bike upright. Now, I did NOT see the bike out in the middle of the
> country
> side at speed to know how well it was doing. The times that I saw it I
> was
> supporting RAGBRAI at overnight towns. This was before I got back into
> cycling myself.
>
> I never saw the bike on the years that I drove sag or rode on RAGBRAI
> which
> started around 1991. It would seem to be counter intuitive to try and
> balance a vehicle of this type when the back wheel moves opposite of the
> direction one wants to turn. I want to go right so the back of the bike
> goes left doesn't seem like it would be something that would be
> instinctive
> to anyone that I know.
>
>
>
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Date: 15 May 2006 05:04:58
From: Werehatrack
Subject: Re: FWD with Rear Wheel-Steering??

On 14 May 2006 12:51:33 -0700, "NYC XYZ" <jack_foreigner@yahoo.com >
wrote:

>Just wondering if there's such a creature.

Periodically, someone ignores the past results (or doesn't try to find
out about them) and takes yet another shot at this concept. They
swiftly rediscover why they shouldn't have bothered.

>Whatever is the advantage
>of a FWD design?

On a bike, the advantages are not as great as on an automobile; about
all that is achieved is a reduction in the length of the chain run,
and an increase in maneuverability in situations where small
obstructions must be easily climbed. The principal difficulty is in
coupling the power when the wheel is not close to straight with
respect to the frame, and in accurately steering when applying power
if the cranks are mounted on the steered member.

>And why not couple that somehow with rear
>wheel-steering eliminate the steering issues of FWD designs?

Rear-wheel steering on a bicycle is an abomination. But please, don't
take my word for it; by all means, build one and find out for
yourself.

Forklifts (and a handful of essentially similar types of vehicle) need
and profitably employ rear-wheel steering. I know of no other place
where it is justified or useful.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

Date: 15 May 2006 04:46:54
From: Werehatrack
Subject: Re: FWD with Rear Wheel-Steering??

Date: 14 May 2006 21:20:39
From: JeffWills
Subject: Re: FWD with Rear Wheel-Steering??

NYC XYZ wrote:
> Just wondering if there's such a creature. Whatever is the advantage
> of a FWD design? And why not couple that somehow with rear
> wheel-steering eliminate the steering issues of FWD designs?
>
> Just curious.

I've been around the HPV/recumbent world for about 25 years, and I've
seen this question pop up every couple years. Everyone who has actually
*built* a rear-wheel-steer vehicle has abandoned it after the first
high-speed ride.

It's easy to see why if you understand vehicle dynamics. With a vehicle
that steers with the front wheel(s), the force needed to steer climbs
as speed climbs. This leads to a naturally self-stabilizing and
self-damping system. (OK, OK... it's a gross over-simplification.)

On a RWS vehicle, the force needed to steer *falls* as speed climbs. If
you have manageable steering at slow speed, the force drops to the
point that the vehicle can't be adequately controlled. Above a certain
speed, the steering is so "light" that the rider/driver can't
adequately control it... the vehicle occillates until it turns
sideways.

There's been couple RWS vehicles- someone mentioned the Thrust SSC,
Buckminster Fuller's Dymaxion, the Sidewinder trike:
http://www.sidewindercycle.com/products/sidedet.asp . There's
peculiarities with each: the Thrust SSC was limited to a couple degrees
of steering, the third and final Dymaxion was converted to
front-wheel-steering, and every posting I've seen about the Sidewinder
has mentioned high-speed instability.

Front-wheel-drive does have some advantages, particularly with very low
and/or very reclined recumbents:
http://www.zoxbikes.com/
http://www.challengebikes.com/html/index.php?taal=en#nme
http://www.ohpv.org/albums/bm2004/velox/pages/velox5.htm
http://www.ohpv.org/albums/bm2004/varnas/pages/varnas16.htm
FWD works pretty well with front-wheel-steering.

Rear-wheel-steering has been tried by lots of people... none has been
successful outside of a narrow performance window. I'd love to be
proven wrong- but I'm not holding my breath.

Jeff

Date: 14 May 2006 18:05:21
From: NYC XYZ
Subject: Re: FWD with Rear Wheel-Steering??

Mike Causer wrote:
>
>
> <SNIP>
>
> You're already
> complaining that your Streetmachine is not as fast as your old upright
> (something is very wrong here ...)

What's very wrong? 'Bents are generally slower than uprights, and the
'bent I have is a tourer while the upright I have is a "comfort
racer"....

> Mike

Date: 14 May 2006 21:57:58
From: Mike Causer
Subject: Re: FWD with Rear Wheel-Steering??

On Sun, 14 May 2006 12:51:33 -0700, NYC XYZ wrote:

> Just wondering if there's such a creature. Whatever is the advantage of a
> FWD design? And why not couple that somehow with rear wheel-steering
> eliminate the steering issues of FWD designs?

Rear wheel steering is highly unstable. With computer help it can be made
to work, as on the motorised land speed record holder Thrust SSC. But if
you read the pilot's (Andy Green) comments about it it's not ready for
prime time yet.

OTOH, for very low speed use most fork-lift trucks use it. You're already
complaining that your Streetmachine is not as fast as your old upright
(something is very wrong here ...) but maybe if you're going slowly
enough you could use rear-steer.

[original cross-posting trimmed]

Mike

Date: 14 May 2006 21:45:32
From: Peter Clinch
Subject: Re: FWD with Rear Wheel-Steering??

NYC XYZ wrote:
> Just wondering if there's such a creature.

Some have been attempted. The general problem is the successful
rider generally goes by a name like Koko and has a red nose and big
feet...

> Whatever is the advantage of a FWD design?

Much shorter chain lebgth and no re-routing around the rider necessary.

> And why not couple that somehow with rear
> wheel-steering eliminate the steering issues of FWD designs?

People have tended to fall off the models to date with alarming
regularity!

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net p.j.clinch@dundee.ac.uk http://www.dundee.ac.uk/~pjclinch/

Date: 14 May 2006 15:29:09
From: DougC
Subject: Re: FWD with Rear Wheel-Steering??

NYC XYZ wrote:
> Just wondering if there's such a creature. Whatever is the advantage
> of a FWD design? And why not couple that somehow with rear
> wheel-steering eliminate the steering issues of FWD designs?
>
> Just curious.
>

Flevobike used to build a 2-wheel bike with FWD and a central steering
pivot, the drive system was lighter (less chain!) that way. A lot of
people do homebuilt copies of it:
http://images.google.com/images?hl=en&q=flevobike&btnG=Google+Search&sa=N&tab=wi

The flevobike is not a rear-wheel steer however.
------
It is generally held (and so far, proven) that one cannot build a
dynamically-stable vehicle that uses rear-wheel steering; the best you
can achieve is neutral steering, which does not "self-correct" to keep
the vehicle in a straight line if it is upset. Such vehicles have a
nasty tendency to understeer and/or experience sudden
spin-outs/rollovers at higher speeds and on loose surfaces. No modern
car or motorcycle company has ever built a rear-wheel-steer vehicle
(intended for higher-speed travel) that I have heard of.

Erik Wannee has a page up:
http://www.wannee.nl/hpv/abt/e-index.htm
The Kalle bike is a front-wheel-drive + rear-wheel-steer example that
(as far as we know) is rideable. So far it seems to be the ONLY example.
Has anyone [reading this] ever rode one???
~

Date: 14 May 2006 22:07:10
From: Mike Causer
Subject: Re: FWD with Rear Wheel-Steering??

On Sun, 14 May 2006 15:29:09 -0500, DougC wrote:

> No modern car or motorcycle company has ever built a rear-wheel-steer
> vehicle (intended for higher-speed travel) that I have heard of.

The current land speed record holding vehicle, Thrust SSC, used rear wheel
steering, but with dedicated computer assistance. The driver (pilot),
even with the computer, rating it 8 on a scale of 10 on instability.

[rec.bicyles.ketplace and rec.bicycles.misc trimmed]

Mike

Date: 15 May 2006 03:33:33
From: DougC
Subject: Re: FWD with Rear Wheel-Steering??

Mike Causer wrote:
> On Sun, 14 May 2006 15:29:09 -0500, DougC wrote:
>
>
>
>> No modern car or motorcycle company has ever built a rear-wheel-steer
>>vehicle (intended for higher-speed travel) that I have heard of.
>
>
> The current land speed record holding vehicle, Thrust SSC, used rear wheel
> steering, but with dedicated computer assistance. The driver (pilot),
> even with the computer, rating it 8 on a scale of 10 on instability.
>
>
> [rec.bicyles.ketplace and rec.bicycles.misc trimmed]
>
>
> Mike

Yea but they "cheated", twice: first they confined the range of steering
to a very-small amount, and then by computer-controlling it.