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  #11  
Old June 21st 04, 09:21 PM
Ian Smith
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On Mon, 21 Jun, Just zis Guy, you know? wrote:
David Martin wrote:

I was just thinking about this and considering what pushing a rear
steer trolley is like. There is only one word I can think of to
desribe the thought of rear wheel steering on a fast downhill and
that is SCARY (followed by lots of road rash and a stay in hospital).


ISTR that Thrust SSC was rear-steer.


It was, and when teh engineers proposed it as teh solution to various
problems it was mightily poo-pooed. It'll never work, inherently
unstable, blaah blaah. In fact, read on in the thread for the sort of
comments heaped on teh rear-steer proposal.

They built a steering prototype by taking a mini, locking teh front
wheels straight, detaching teh back axle and substituting a long pylon
with steering wheels on teh back, such that the geometry was a
scaled-down version of the Thrust proposal.

Apparently it steered beautifully, no problem at all, as long all teh
linkages were fully 100% ok and there was no slop in anything.

regards, Ian SMith
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  #12  
Old June 21st 04, 09:24 PM
Ian Smith
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On Mon, 21 Jun 2004 15:44:19 +0100, Doki wrote:
Does anyone make a FWD / rear steer recumbent? Seems to me you'd save a lot
of chain length. Perhaps they'd struggle for grip up hills?


There are FWD,FWS tadpole trikes - russian titanium ones turn up
occasionally.

There's also one that is FWD via a differential, and steered by
braking teh front wheels individually, like a tank. The back wheel is
just a castor. I quite like that as a scheme, but I don't think I'd
dice with rush-hour traffic on downhills with it - seems to me it has
teh potential to pirouette and dump you on teh road if you forget
yourself and tug on a brake inappropriately.

regards, Ian SMith
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  #13  
Old June 21st 04, 09:35 PM
Simon Brooke
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in message , Peter Clinch
') wrote:

Doki wrote:
Does anyone make a FWD / rear steer recumbent?


FWD, certainly. Zox and Flevo are the obvious examples, plus the Very
Serious Speed machinery used at the likes of Battle Mountain is
sometimes FWD (well, it's not like they have to go round hairpin
bends...).

Rear steer is a different matter. I think it was in C+ that someone
asked this and Mike Burrows answered it. IIRC he basically said that
what's fine in theory doesn't work quite so well in practice and rear
steer bikes tend to be patronised by people called Koko with large red
noses...

The Flevo is an interesting exception to the usual rules: it doesn't
steer at either wheel but has a hinge in the middle of the bike, and
can be ridden completely no hands as far as steering goes (though bars
are provided to mount brake and gear levers)


Can you post a URL: All I find on the Flevobike site
URL:http://www.flevobike.nl/indexmodellen.html is a very nicely
finished and interesting looking velomobile (come to think of it, it's
reviewed in the latest VeloVision). I can't find any reference to your
hinged in the middle bicycle (but being unable to read Dutch is a
drawback here).

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/

;; I'd rather live in sybar-space

  #14  
Old June 21st 04, 09:35 PM
Simon Brooke
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in message , Doki
') wrote:



Mark South wrote:

The problem is that to turn away from an obstacle you have to steer
towards it. This means that situations can arise where it is not
possible to avoid the obstacle with rear steering but it could have
been avoided with front steering.


I'm afraid I don't really *get* countersteering. I must do it, but
I've never noticed myself do it. Probably all bunged away in the brain
stem and never consciously thought about.


Countersteering is one of those things about cycling which people have
religious beliefs about. In practice you can steer a bike by starting
the turn by turning the handlebars the opposite way, in order to get
the wheels out from under the CoG, but it isn't necessary or even
common. If you had a radio controlled bike with a rigidly mounted crash
test dummy this would be the only way to steer it. But 90% of bike
steering at any normal speed is balance and body weight, and
countersteering is very rare in practice (I very rarely do it and
watching other people I very rarely see it.

Mind you, cycling theorists will tell you this is impossible. And that
wheels stand on spokes and that steering is a matter of gyroscopic
precession, and all sorts of other things which are indeed partly true
or true under some circumstances, but which True Believers recite as
mantras of universal truth.

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/

...but have you *seen* the size of the world wide spider?

  #15  
Old June 21st 04, 09:36 PM
Doki
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Ian Smith wrote:
On Mon, 21 Jun 2004 15:44:19 +0100, Doki
wrote:
Does anyone make a FWD / rear steer recumbent? Seems to me you'd
save a lot of chain length. Perhaps they'd struggle for grip up
hills?


There are FWD,FWS tadpole trikes - russian titanium ones turn up
occasionally.

There's also one that is FWD via a differential, and steered by
braking teh front wheels individually, like a tank. The back wheel is
just a castor. I quite like that as a scheme, but I don't think I'd
dice with rush-hour traffic on downhills with it - seems to me it has
teh potential to pirouette and dump you on teh road if you forget
yourself and tug on a brake inappropriately.


Get a little lug you flip over to lock both brakes together like you do in a
tractor then . Or two sets of brakes on each wheel - one for steering and
one for braking.


  #16  
Old June 21st 04, 09:38 PM
Ambrose Nankivell
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In ,
Simon Brooke typed:
in message , Peter Clinch
') wrote:

Doki wrote:
Does anyone make a FWD / rear steer recumbent?


FWD, certainly. Zox and Flevo are the obvious examples, plus the
Very Serious Speed machinery used at the likes of Battle Mountain is
sometimes FWD (well, it's not like they have to go round hairpin
bends...).

The Flevo is an interesting exception to the usual rules: it doesn't
steer at either wheel but has a hinge in the middle of the bike, and
can be ridden completely no hands as far as steering goes (though
bars are provided to mount brake and gear levers)


Can you post a URL: All I find on the Flevobike site
URL:http://www.flevobike.nl/indexmodellen.html is a very nicely
finished and interesting looking velomobile (come to think of it, it's
reviewed in the latest VeloVision).


http://home.hccnet.nl/Mark.Maier/rec...evoracer99.jpg

There's one, it's a Flevoracer.

A



  #17  
Old June 21st 04, 10:04 PM
Danny Colyer
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Simon Brooke wrote:
Countersteering is one of those things about cycling which people have
religious beliefs about. In practice you can steer a bike by starting
the turn by turning the handlebars the opposite way, in order to get
the wheels out from under the CoG, but it isn't necessary or even
common. If you had a radio controlled bike with a rigidly mounted crash
test dummy this would be the only way to steer it.


I've got one of them [1], and that is indeed how it steers.

But 90% of bike
steering at any normal speed is balance and body weight, and
countersteering is very rare in practice (I very rarely do it and
watching other people I very rarely see it.


I never used to notice it, but now I often notice myself starting a turn
by countersteering. For some reason it's much more noticeable on the
Street Machine that it used to be on my ATB. Perhaps it's more
necessary on a bent than on a wedgie.


[1] It was my 30th birthday present from my Dad. I downloaded a 2.84MB
movie of it in action from URL:http://www.taiyoedge.com/, but it
appears to no longer be there. Instead, it should be temporarily
possible to get it from he
URL:http://www.speedy5.freeserve.co.uk/z-freestyle.mpg

--
Danny Colyer (the UK company has been laughed out of my reply address)
URL:http://www.speedy5.freeserve.co.uk/danny/
"He who dares not offend cannot be honest." - Thomas Paine
  #18  
Old June 21st 04, 10:15 PM
Mark South
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"Simon Brooke" wrote in message
...
in message , Doki
') wrote:

Mark South wrote:

The problem is that to turn away from an obstacle you have to steer
towards it. This means that situations can arise where it is not
possible to avoid the obstacle with rear steering but it could have
been avoided with front steering.


I'm afraid I don't really *get* countersteering. I must do it, but
I've never noticed myself do it. Probably all bunged away in the brain
stem and never consciously thought about.


It's not countersteering, with a rear-steer vehicle that is *steering*.

Countersteering is one of those things about cycling which people have
religious beliefs about.


But on a rear-steered vehicle you have to swing the rear towards the object you
are trying to avoid. Fact, not religion.

In practice you can steer a bike by starting
the turn by turning the handlebars the opposite way, in order to get
the wheels out from under the CoG, but it isn't necessary or even
common. If you had a radio controlled bike with a rigidly mounted crash
test dummy this would be the only way to steer it. But 90% of bike
steering at any normal speed is balance and body weight, and
countersteering is very rare in practice (I very rarely do it and
watching other people I very rarely see it.


Which probably tells you that humans are not well adapted to it as a balance
control mode.

Mind you, cycling theorists will tell you this is impossible. And that
wheels stand on spokes and that steering is a matter of gyroscopic
precession, and all sorts of other things which are indeed partly true
or true under some circumstances, but which True Believers recite as
mantras of universal truth.


This is all a bit uncalled-for. There is no myth about what I said relating to
rear-steering recumbents. Nor have I claimed that any of the false statements
above are true.
--
"You need to declare a jihad on your own ignorant ass."
- Ed Dolan in alt.rec.bicycles.recumbent


  #19  
Old June 21st 04, 11:05 PM
Simon Brooke
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in message , Ambrose Nankivell
') wrote:

In ,
Simon Brooke typed:
in message , Peter Clinch
') wrote:

Doki wrote:
Does anyone make a FWD / rear steer recumbent?

FWD, certainly. Zox and Flevo are the obvious examples, plus the
Very Serious Speed machinery used at the likes of Battle Mountain is
sometimes FWD (well, it's not like they have to go round hairpin
bends...).

The Flevo is an interesting exception to the usual rules: it doesn't
steer at either wheel but has a hinge in the middle of the bike, and
can be ridden completely no hands as far as steering goes (though
bars are provided to mount brake and gear levers)


Can you post a URL: All I find on the Flevobike site
URL:http://www.flevobike.nl/indexmodellen.html is a very nicely
finished and interesting looking velomobile (come to think of it,
it's reviewed in the latest VeloVision).


http://home.hccnet.nl/Mark.Maier/rec...evoracer99.jpg

There's one, it's a Flevoracer.


Ahh! Interesting.

Questions:

Are the handlebars attached to the forward chassis, or to the rear
chassis?

Are the handlebars rigidly attached, or is there a linkage?

What is the mechanism of the link - does it have bearings like
conventional headset bearings, or something more robust - and are there
mechanical problems at the link in practice?

Has anyone here ridden such a thing and if so how did it ride?

Front wheel drive without twisting the chain line has a lot to be said
for it.

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/

Tony Blair's epitaph, #1: Here lies Tony Blair.
Tony Blair's epitaph, #2: Trust me.
  #20  
Old June 21st 04, 11:19 PM
Mike Causer
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On Mon, 21 Jun 2004 23:15:13 +0200, Mark South wrote:

"You need to declare a jihad on your own ignorant ass."
- Ed Dolan in alt.rec.bicycles.recumbent


Has The Troll of arbr discovered a sense of humour? Maybe I should
rescue him from the killfile....

Mike

 




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