| |
Main
Date: 25 Jan 2007 09:06:14
From: 32GO
Subject: Fear of Flying
|
Hey guys -
Jeff and I got a bit off the topic in the TdPS. His last
post there said:
> I have no problem piloting a trike in the mid to high
> 20's but when I go down a hill of any decent size,
> I'm very quickly in the 30's and the trike does not
> feel stable.
I'm glad we got some numbers into this discussion. As it
turns out, I'm actually in very close agreement with Jeff
on this issue. Although we've been talking about tadpole
trikes, I think the same concerns apply to all 'bents and
other bikes as well.
If you've ever been on one of those parachute drops at a
thrill ride park, you've probably felt that irrational
fear that comes as you suddenly approach weightlessness
and watch the ground begin accelerating up toward you.
I say 'irrational' fear, because you probably assessed
the risk before you got on that thing and decided the
real danger was pretty minimal.
When I first read Jeff's comment that he "had to ride
the brakes" on downhills, I thought he was talking about
keeping his speed below 15 to 20 MPH, and for most folks
with normal reflexes, eyesight, mental stability and
such, feeling any kind of serious terror at 20 MPH on a
contemporary middle-of-the-road tadpole is probably very
close to that same kind of 'irrational' fear as the
parachute drop.
However, as you get into that 30 to 50 MPH range, any
concern for personal safety you feel is more in the
nature of 'rational' fear. The actual number for any one
person will depend on his riding abilities and his own
priorities, the trail, the weather, and the trike. I
think most current model tadpoles are stable and safe
at 20 MPH, but at 40 MPH there are definite differences,
and issues like frame stiffness, tracking, weight bias,
track width, wheelbase, seat height and steering
sensitivity begin to become very important. At speed,
brakes play a major role for a rider's peace of mind -
some folks feel uncomfortable with the higher lever
pressures of drum brakes; some discs are 'grabby' or
hard to modulate; brake steering makes some riders
very uneasy.
As a cyclist who's spent rekably little time on any
kind of two-wheeled recumbent, I'm often intrigued at
the conversations of 'bent bikers comparing their
impressions of long wheel-base, short wheel-base and
lowracers, and who feels safest at what speed on which
machine. Trikes are probably a bit different in that
they require almost nothing in the way of operator skill
or training at speeds up to 'casual cruising', and some
riders seem to be lulled into forgetting that as they
push the limits, trikes begin to demand some of the same
skills and heightened attention that it takes to ride a
bike fast.
Tadpoles are very stable and simple to ride at low to
medium speeds, and their braking ability may be the best
available on any 'normal' road vehicle, but at some
point, a trikey is exposed to the same real risks as any
other cyclist. For me, that transition from carefree fun
(in lower case) to gunfighter-eyed, yellow-alert, battle
stations, play racer mentality usually comes somewhere
between about 30 and 40 MPH. But hey, sometimes even a
little rational fear is FUN! (upper case with exclamation
point)
Regards,
Wayne
|
|
| |
Date: 26 Jan 2007 19:23:32
From: 32GO
Subject: Re: Fear of Flying
|
Hey guys -
Curtis wrote:
> I rather doubt [Wayne's] premise about a diamond
> frame rider making constant adjustments... At speed
> a DF is rather forgiving...
As I said, most bikes have good short-term stability -
in both roll and yaw axes. However, they will not
maintain an upright posture for seconds without the
rider making minor, and most likely almost subconscious
corrections. It would be very easy to PROVE me wrong.
Just strap about 100 to 150 pounds of sandbags on a
(riderless) bike, secure the handlebar rotation however
you'd like, hook up a tow rope from another cycle, and
start off down a straight road with it. Have a friend
run alongside balancing it up to 5 or 10 MPH, then let
it go. Make a video if you're able to get one to stay up
for a mile or two, and I'll retract my unfounded opinion
after I've seen it. Towing a tadpole with a dead weight
is not a problem, even around the block...
Jeff said:
> I forgot to stick up for the Tricruiser... Sid was a
> pleasure to deal with and the Tricruiser was fun to
> ride.
SHAMELESS PLUG - Link to the TriCruiser website:
http://www.americruiser.com/
I hope most folks understand that I wasn't 'attacking'
either the trike, its maker or snubbing it because of
its price. I was highlighting the clear distinction
between that tadpole - comfort oriented, with a very
high seat, fairly flexible frame and a lot of both brake
and bump steering effect - to a lower, stiffer, more
performance oriented design with more yaw stability at
high speed and much better roll stability at any speed,
and with virtually no brake or bump steer.
My impression of the TriCruiser is that it was designed
as a sort of 'neighborhood cruiser', especially for
folks who lack the flexibility or strength to cope with
a laidback trike seat less than a foot off the ground.
IMHO, it was simply (and I would hope very obviously)
not designed for the downhill speeds that most cyclists
reach on day trips - especially with a big dog flopping
around on its sky-high rear rack. ;-)
Regards,
Wayne
|
| |
Date: 26 Jan 2007 10:11:20
From:
Subject: Re: Fear of Flying
|
On one downhill run I got my Linear LWB up to 82 kph (50 mph). It felt
solid as a rock, and it was only my nerves that gave out. I started
having brief thoughts like "hope the front wheel's QR skewer is done up
tight enough", and then "what would happen if a tire blew out?". Well,
potential road rash at that speed didn't sound like any fun, and I was
already over the posted 60kph (40 mph) speed lilmit, so I was happy to
stop pedaling and just coast until the road levelled out more.
The next time I went down that hill I was happy to stay at only 70 kph.
;)
k
|
| | |
Date: 26 Jan 2007 13:24:37
From: Edward Dolan
Subject: Re: Fear of Flying
|
<k@drumbent.com > wrote in message
news:1169835080.901551.169150@q2g2000cwa.googlegroups.com...
> On one downhill run I got my Linear LWB up to 82 kph (50 mph). It felt
> solid as a rock, and it was only my nerves that gave out. I started
> having brief thoughts like "hope the front wheel's QR skewer is done up
> tight enough", and then "what would happen if a tire blew out?". Well,
> potential road rash at that speed didn't sound like any fun, and I was
> already over the posted 60kph (40 mph) speed lilmit, so I was happy to
> stop pedaling and just coast until the road levelled out more.
>
> The next time I went down that hill I was happy to stay at only 70 kph.
> ;)
It is possible to go much faster safely on a 2-wheeler than on a 3-wheeler.
But I do not feel comfortable on any bike at a speed much above 35 mph. Like
you, I start to think about all the things that could go wrong. Nope, it is
just not worth it! Speed kills; it always has and it always will. I can even
get into trouble if I walk too fast.
Regards,
Ed Dolan the Great - Minnesota
aka
Saint Edward the Great - Order of the Perpetual Sorrows - Minnesota
|
| |
Date: 26 Jan 2007 11:32:08
From: Edward Dolan
Subject: Re: Fear of Flying
|
"32GO" <wayne@32go.us > wrote in message
news:1169744774.208908.127910@s48g2000cws.googlegroups.com...
[...]
> Tadpoles are very stable and simple to ride at low to
> medium speeds, and their braking ability may be the best
> available on any 'normal' road vehicle, but at some
> point, a trikey is exposed to the same real risks as any
> other cyclist. For me, that transition from carefree fun
> (in lower case) to gunfighter-eyed, yellow-alert, battle
> stations, play racer mentality usually comes somewhere
> between about 30 and 40 MPH. But hey, sometimes even a
> little rational fear is FUN! (upper case with exclamation
> point)
Wayne is comfortable at those speeds on his tadpole because he rides such a
bike exclusively. However, for the rest of us, a top speed of around 20 mph
is more reasonable before the handling gets tricky. That is fast enough for
any recumbent trike, even a well designed delta like the Kettwiesel. The
truth is that tadpoles are not stable at the higher speeds.
Regards,
Ed Dolan the Great - Minnesota
aka
Saint Edward the Great - Order of the Perpetual Sorrows - Minnesota
|
| |
Date: 26 Jan 2007 00:55:52
From: 32GO
Subject: Re: Fear of Flying
|
Hey folks -
Who says we can't have interesting on-topic discussions
here at ARBR? For starters, I recognize that many
cyclists may feel more at ease on a two-wheeler at high
speed than on a trike. I think one of the reasons for
this is that it's a fairly simple learning process for
us to make controlling a bike with subtle leaning and
weight shifts pretty much instinctive, and most of us
learned it long ago when our brains were young and wide
open. Another reason is that unlike a trikey at low to
moderate speeds, a biker is ALWAYS required to
continuously interact with his cycle, even though it is
a largely subconscious process. There's not much in the
way of a transition from riding a bike at 12 MPH to
zipping along at three times that speed.
Chalo wrote:
> Trikes as a rule have a natural "critical speed"... as
> speed increases, the weight shift becomes more sudden
> and eventually causes a violent response to even mild
> steering inputs, up to and including high-siding the
> trike.
While I can appreciate most of chalo's comments, this
bit seems to me to be what a logics professor might call
'A giant leap from a fallacious assumption to an
erroneous conclusion'. ;-) What exactly is this strange
"weight shift" and why would it become "more sudden"?
A well-designed stiff tadpole with an experienced, even
modestly talented rider doesn't go through some kind of
radical transition (like an aircraft at Mach One) so
that it begins to provide a "violent response" to his
control inputs.
The front end geometry of a tadpole is pretty much the
same as an automobile's, and as far as I know, there's
no such thing as a "critical speed". Of course, with
good lateral traction a driver can roll a Miata, just
as a rider can roll a trike. Speed plays a big role in
rollover susceptibility, and tadpoles have comparatively
sensitive steering, meaning: the front wheels turn much
farther for a one-inch movement of your hands on the
bar than on an auto. At higher speeds, small steering
inputs cause higher lateral acceleration than at lower
speeds, and of course it takes a smaller jerk of the
bars to flip a trike at 50 MPH than it does at 5 MPH.
One simple fact of cycle dynamics, however, is that a
trike is inherently very stable in the roll axis at
any speed, even parked. A bike, meaning a vehicle with
two tires on the same lateral axis, has no - ZERO! -
long-term roll stability. It wouldn't be a very serious
engineering challenge to implement a stone simple
servo-controlled single-axis automated steering system
for a trike, using an airplane type gyro, so that it
would roll down a hill in a straight line. I won't stay
up waiting for someone to do that with a bike...
The biggest single difference that I see between bikes
and trikes is that anyone riding a two-wheeler has to
constantly make minor steering and/or weight shift
corrections to keep the bike upright AT ANY SPEED, and
the process of making those continuous compensations
becomes almost subconscious for him. The process is made
a bit more appropriate to normal human aptitudes by the
short-term stability provided by the precession effect
of the wheels and the rounded profile of bike tires.
But on a trike, at low and medium speeds, there is
absolutely no need for the rider to do anything but make
minor steering corrections. When the trike begins going
fast enough to make it more of a challenge to control
its direction with its sensitive steering, compensating
and correcting for stiction, linkage slack and
hysteresis, it begins to demand a lot more in the way of
attention, precision and good reflexes. If that seems to
set some kind of "critical speed" for the trike, or to
give it a Jekyll-Hyde nature, it's probably a good idea
to remember that the real difference from a bike is that
a bike is always in the Hyde mode.
I've used the analogy before, but if you put a big
long-stroke steam engine pumping the pedals on a trike,
and send it off down the road, it may go in the wrong
direction, and it may waggle back and forth, but... if
you do the same thing on a bike, it most likely won't
make it out of shrapnel range before it falls over and
explodes!
Regards,
Wayne
|
| | |
Date: 26 Jan 2007 12:19:16
From: Edward Dolan
Subject: Re: Fear of Flying
|
"32GO" <wayne@32go.us > wrote in message
news:1169801752.409022.77610@a34g2000cwb.googlegroups.com...
> Hey folks -
>
> Who says we can't have interesting on-topic discussions
> here at ARBR?
Well, yes, recumbent trikes are your business so of course we would expect
that you would show some minimal interest. At least you are proving to me
that you can write acceptable prose and not just verse about shit and piss
and ass and fuck.
[...]
> The biggest single difference that I see between bikes
> and trikes is that anyone riding a two-wheeler has to
> constantly make minor steering and/or weight shift
> corrections to keep the bike upright AT ANY SPEED, and
> the process of making those continuous compensations
> becomes almost subconscious for him. The process is made
> a bit more appropriate to normal human aptitudes by the
> short-term stability provided by the precession effect
> of the wheels and the rounded profile of bike tires.
Well, good grief, that is the whole fun of riding an upright bike!
> But on a trike, at low and medium speeds, there is
> absolutely no need for the rider to do anything but make
> minor steering corrections.
Which is why it is quite dull to ride a trike at low and medium speeds for
the average person.
When the trike begins going
> fast enough to make it more of a challenge to control
> its direction with its sensitive steering, compensating
> and correcting for stiction, linkage slack and
> hysteresis, it begins to demand a lot more in the way of
> attention, precision and good reflexes.
[...]
In other words, a trike is not stable at speed and does not handle well. It
is really only fun to ride a recumbent trike at fairly high speeds at which
point it becomes dangerous to do so. The bottom line is that you can't win.
Recumbent trikes are for going places in comfort and security at a medium
speed at best and they are not for having much fun unless you like to live
dangerously.
A 2-wheel recumbent does not have any of the difficulties that trikes have.
That is the main reason why trikes are so hard to sell in comparison. They
look like they are more fun than they turn out to be. At least a 2-wheel
recumbent is closer to an upright and it is possible to have some fun on
them without getting yourself killed.
[...]
Regards,
Ed Dolan the Great - Minnesota
aka
Saint Edward the Great - Order of the Perpetual Sorrows - Minnesota
|
| | |
Date: 26 Jan 2007 10:08:52
From: Curtis L. Russell
Subject: Re: Fear of Flying
|
On 26 Jan 2007 00:55:52 -0800, "32GO" <wayne@32go.us > wrote:
>The front end geometry of a tadpole is pretty much the
>same as an automobile's, and as far as I know, there's
>no such thing as a "critical speed".
That reminds me of the joke about what the critical speed was for the
old Morgan three wheelers and the answer was any speed when the back
tire blew out. But I rather doubt YOUR premise about a diamond frame
rider making constant adjustments (except perhaps during hands off
riding). At speed a DF is rather forgiving and you can actually work
against the bike (within reason, like when removing a jacket) for some
distance before things become truly dicey.
OTOH, the Vision was completely stable when I removed my jacket. Of
course, I was stopped and had both feet on the ground before I would
attempt it.
Curtis L. Russell
Odenton, MD (USA)
Just someone on two wheels...
|
| | |
Date: 26 Jan 2007 05:05:24
From: Jeff Grippe
Subject: Re: Fear of Flying
|
"32GO" <wayne@32go.us > wrote in message
news:1169801752.409022.77610@a34g2000cwb.googlegroups.com...
> Chalo wrote:
>
>> Trikes as a rule have a natural "critical speed"... as
>> speed increases, the weight shift becomes more sudden
>> and eventually causes a violent response to even mild
>> steering inputs, up to and including high-siding the
>> trike.
>
> While I can appreciate most of chalo's comments, this
> bit seems to me to be what a logics professor might call
> 'A giant leap from a fallacious assumption to an
> erroneous conclusion'. ;-) What exactly is this strange
> "weight shift" and why would it become "more sudden"?
> A well-designed stiff tadpole with an experienced, even
> modestly talented rider doesn't go through some kind of
> radical transition (like an aircraft at Mach One) so
> that it begins to provide a "violent response" to his
> control inputs.
>
Regarding Critical Speed:
I don't know about the science behind this but the idea matches my
experience on the trikes that I've owned. Everything is fine under 25 mph.
Even the top heavy Tricruiser is fine at that speed. At somewhere between 25
and 30, however, something happens and the steering characteristics change.
Under normal riding conditions you constantly make minor steering
adjustments to keep moving in whatever direction you are going. The side
effects of these minor adjustments is magnified by speed and then further
magnified by braking.
I think that if there were some way to keep going straight without turning
or braking (such as going down one hill and then immediately up another),
I'd be comfortable in the mid 30's.
BTW
I forgot to stick up for the Tricruiser before so I'll just do it here. Sid
(the builder) makes a nice trike and get people in at an entry level for
under $1,000. You can't compare it to higher end trikes and expect it to win
but for what it is, its great. Sid was a pleasure to deal with and the
Tricruiser was fun to ride.
Jeff
|
| | | |
Date: 26 Jan 2007 10:11:58
From: Peter Clinch
Subject: Re: Fear of Flying
|
Jeff Grippe wrote:
> I don't know about the science behind this but the idea matches my
> experience on the trikes that I've owned. Everything is fine under 25 mph.
> Even the top heavy Tricruiser is fine at that speed. At somewhere between 25
> and 30, however, something happens and the steering characteristics change.
> Under normal riding conditions you constantly make minor steering
> adjustments to keep moving in whatever direction you are going. The side
> effects of these minor adjustments is magnified by speed and then further
> magnified by braking.
Steering side effects are often /less/ at higher speed (which is why you
wobble at very low speed). The forward momentum takes you a lot further
along compared to any sideways motion, with the net effect of going
straighter.
Typically any adjustments can be made practically subconsciously if one
can relax on the job: the less one relaxes, the less easy the steering
is. Trikes certainly don't necessarily come unstable at 25-30,
velomobiles routinely travel at those sorts of speeds over significant
proportions of their journeys.
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: 25 Jan 2007 19:40:21
From: chalo colina
Subject: Re: Fear of Flying
|
Jeff Grippe wrote:
>
> The Infinity, which
> was the oldest and lowest end of the bikes I've owned was my favorite.
I test rode an Infinity back in the late '80s. It wasn't my bag, but
it was worlds easier to tolerate than the BikeE I spent a long weekend
with in 2001.
> I am interested in learning how Quad's would handle although I suspect that
> they could also easily go up on two wheels. Its too bad I could have a bike
> that became a trike on the really steep ascents.
Quads must either have full suspension or a frame that articulates in
the middle, allowing the front end to tilt one way and the rear axle to
tilt another way. This adds greatly to the weight and expense of a
quad. In most states they don't have a right to the road either. And
they lose a lot of energy to wheel scrub in corners, substanttially
more than trikes. But aside from all that, they can corner better for
any given width, length, height, and weight distribution than a trike.
Chalo
|
| |
Date: 25 Jan 2007 14:20:26
From: chalo colina
Subject: Re: Fear of Flying
|
32GO wrote:
>
> Jeff and I got a bit off the topic in the TdPS. His last
> post there said:
>
> > I have no problem piloting a trike in the mid to high
> > 20's but when I go down a hill of any decent size,
> > I'm very quickly in the 30's and the trike does not
> > feel stable.
>
> I'm often intrigued at
> the conversations of 'bent bikers comparing their
> impressions of long wheel-base, short wheel-base and
> lowracers, and who feels safest at what speed on which
> machine. Trikes are probably a bit different in that
> they require almost nothing in the way of operator skill
> or training at speeds up to 'casual cruising', and some
> riders seem to be lulled into forgetting that as they
> push the limits, trikes begin to demand some of the same
> skills and heightened attention that it takes to ride a
> bike fast.
I'm going to offer my observations based on lots of riding on upright
bikes and trikes. I have ridden 'bent bikes of different kinds, but I
must admit that they all felt dangerously unstable to me at any speed,
like they would dump me in a heartbeat if I even /thought/ about
letting go of the bars. I have almost no direct experience with 'bent
trikes, but I used to work with Rick Horwitz and I very briefly tried
one of his Thunderbolts.
Trikes as a rule have a natural "critical speed" that has more to do
with vehicle dynamics than it does with the rider's fear and
perceptions. Trikes can't lean, so they have a weight shift in turns.
They also have a natural steering response that is relatively
independent of speed. But as speed increases, the weight shift becomes
more sudden and eventually causes a violent response to even mild
steering inputs, up to and including high-siding the trike. Since the
effect of a harsh weight shift is to jar the rider, and this can result
in unplanned steering inputs, there comes a speed at which every trike
can be considered unstable. The lowest critical speed I have seen so
far was in a Trailmate E-Z Roll Regal adult delta trike, which tried to
buck the rider off starting at about 10mph. This was a result, I
believe, of several factors including extravagant frame flex, high C of
G, narrow track, and the misguided use of a normal bicycle fork offset
on a trike with a slack head angle. A trike will naturally become more
stable as it becomes lower, wider, stiffer, or more resistant to
steering input. That's why tadpole 'bents can be considered "sporty"
while upright deltas never are. However, while a sporty 'bent trike
might have a much higher critical speed than a senior citizen's
neighborhood trike, it still has a point beyond which it can be
considered unstable.
Bikes are different. Their front end steering characteristics cause a
natural self-stabilizing force that increases with speed. This force
causes frame, fork, and wheel flex, however, and thus can result in
shimmy problems as speeds and dynamic forces on the frame rise. But in
a bike and rider combination that does not exhibit shimmy, the ride
becomes steadier as speeds increase-- quite the opposite of what
happens with a trike. I used to have a roughly 1/2 mile downhill
averaging about 8% on my way to work, and with a mild crouch over flat
handlebars I routinely hit a measured 55mph on my upright bike--
without any unsteadiness or handling quirks whatsoever.
'Bent bikes tend to be longer, less triangulated, and smaller-wheeled
than uprights, and most of them suffer from compromised steering
geometry that does not not allow the sort of no-hands riding stability
common to uprights. Thus they will flex more (promoting shimmy) and
exhibit less self-stabilizing than a typical upright bike, and this may
contribute to a lower practical maximum operating speed. So because
'bent bikes are (generally speaking) worse than upright bikes with
regard to stability at speed, 'bent trikes are /more stable/ than
upright trikes, and this makes two- and three-wheeled 'bents comparable
to each other in their sure-footedness at high speed. In contrast,
there is really no comparison between DF bikes and upright trikes in
their handling at speed.
Chalo
|
| | |
Date: 26 Jan 2007 10:00:38
From: Curtis L. Russell
Subject: Re: Fear of Flying
|
On 25 Jan 2007 14:20:26 -0800, "chalo colina"
<chalo.colina@gmail.com > wrote:
>So because
>'bent bikes are (generally speaking) worse than upright bikes with
>regard to stability at speed, 'bent trikes are /more stable/ than
>upright trikes, and this makes two- and three-wheeled 'bents comparable
>to each other in their sure-footedness at high speed.
I've raced diamond frames and ridden for some time a SWB Vision. I
find taking the Vision down a curving downhill more stable than the
diamond frames - and I've held my own in a decending pace line under
race conditions. So I simply do not agree with your assumption. Yes,
Armstrong or Merkx could out descend me - but the same would be true
with me on a diamond frame.
FWIW, a person that knows how to race an upright trike can make it do
wonders in a turn - something I have observed but been unable to
duplicate (and had the scars for a while to prove my lack of success -
it wasn't as easy as it looked, and it didn't look easy in the first
place). Not sure if they would try the same leaning process on a fast
downhill though.
Curtis L. Russell
Odenton, MD (USA)
Just someone on two wheels...
|
| | | |
Date: 26 Jan 2007 12:46:23
From: Edward Dolan
Subject: Re: Fear of Flying
|
"Curtis L. Russell" <curtis@md-bicycling.org > wrote in message
news:7i5kr297qepd4kahu7de68vas13j92cur3@4ax.com...
> On 25 Jan 2007 14:20:26 -0800, "chalo colina"
> <chalo.colina@gmail.com> wrote:
>
>>So because
>>'bent bikes are (generally speaking) worse than upright bikes with
>>regard to stability at speed, 'bent trikes are /more stable/ than
>>upright trikes, and this makes two- and three-wheeled 'bents comparable
>>to each other in their sure-footedness at high speed.
Actually, 2- and 3-wheel recumbents are not in any way comparable. All you
ever have to do is to ride them for several years and you will discover that
they are totally different creatures.
> I've raced diamond frames and ridden for some time a SWB Vision. I
> find taking the Vision down a curving downhill more stable than the
> diamond frames - and I've held my own in a decending pace line under
> race conditions. So I simply do not agree with your assumption. Yes,
> Armstrong or Merkx could out descend me - but the same would be true
> with me on a diamond frame.
Old Russell should not be riding his recumbent in a pace line with uprights.
They just hate that sort of thing.
> FWIW, a person that knows how to race an upright trike can make it do
> wonders in a turn - something I have observed but been unable to
> duplicate (and had the scars for a while to prove my lack of success -
> it wasn't as easy as it looked, and it didn't look easy in the first
> place). Not sure if they would try the same leaning process on a fast
> downhill though.
You do not ever want to lean a recumbent much in a turn. If you do so, you
will end up in the emergency room of a hospital.
Regards,
Ed Dolan the Great - Minnesota
aka
Saint Edward the Great - Order of the Perpetual Sorrows - Minnesota
|
| | | |
Date: 26 Jan 2007 18:18:17
From: Dave Larrington
Subject: Re: Fear of Flying
|
In article <7i5kr297qepd4kahu7de68vas13j92cur3@4ax.com >, curtis@md-
bicycling.org says...
> FWIW, a person that knows how to race an upright trike can make it do
> wonders in a turn - something I have observed but been unable to
> duplicate (and had the scars for a while to prove my lack of success -
> it wasn't as easy as it looked, and it didn't look easy in the first
> place). Not sure if they would try the same leaning process on a fast
> downhill though.
Though to do so like the /serious/ barrow boys requires enough
flexibility to be able to get one's head down to knee level while still
pedalling.
That's me out, then.
--
Dave Larrington - <http://www.legslarry.beerdrinkers.co.uk/ >
Do not top-post like a Cretinous Foul-Yob fit only for Stoning.
|
| | |
Date: 26 Jan 2007 10:58:08
From: Buck
Subject: Re: Fear of Flying
|
On 2007-01-25 22:20:26 +0000, "chalo colina" <chalo.colina@gmail.com > said:
> 32GO wrote:
>>
>> Jeff and I got a bit off the topic in the TdPS. His last
>> post there said:
>>
>>> I have no problem piloting a trike in the mid to high
>>> 20's but when I go down a hill of any decent size,
>>> I'm very quickly in the 30's and the trike does not
>>> feel stable.
>>
>> I'm often intrigued at
>> the conversations of 'bent bikers comparing their
>> impressions of long wheel-base, short wheel-base and
>> lowracers, and who feels safest at what speed on which
>> machine. Trikes are probably a bit different in that
>> they require almost nothing in the way of operator skill
>> or training at speeds up to 'casual cruising', and some
>> riders seem to be lulled into forgetting that as they
>> push the limits, trikes begin to demand some of the same
>> skills and heightened attention that it takes to ride a
>> bike fast.
>
> Trikes as a rule have a natural "critical speed" that has more to do
> with vehicle dynamics than it does with the rider's fear and
> perceptions.
I regularly decend hills at speeds in excess of 50mph, the only thing to be
wary of is sudden steering or brake inputs although the brake issue is less
so on the new 700 and Expedition.
--
Three wheels good, two wheels ok
www.catrike.co.uk
|
| | | |
Date: 26 Jan 2007 12:36:24
From: Edward Dolan
Subject: Re: Fear of Flying
|
"Buck" <SPAMTRAPian@trikesandstuff.DOTco.DOTuk > wrote in message
news:2007012610592850073-SPAMTRAPian@trikesandstuffDOTcoDOTuk...
[...]
> I regularly decend [descend] hills at speeds in excess of 50mph, the only
> thing to be
> wary of is sudden steering or brake inputs although the brake issue is
> less
> so on the new 700 and Expedition.
You confounded moron, it is those steering inputs, not sudden but ever so
gradual, which make recumbent trikes, especially tadpoles, so dangerous at
speed. I hope to God Jeff is not listening to any of this foolishness. He is
quite right to trust his instincts in this matter and does not need another
bang-up crash to go along with all his other ailments.
Besides, why are you lying about your downhill speeds? You must think we
were all born yesterday. What a load of bullshit you peddle on a regular
basis to this newsgroup. Have you no shame?
Regards,
Ed Dolan the Great - Minnesota
aka
Saint Edward the Great - Order of the Perpetual Sorrows - Minnesota
|
| | |
Date: 26 Jan 2007 09:15:11
From: Peter Clinch
Subject: Re: Fear of Flying
|
chalo colina wrote:
> 'Bent bikes tend to be longer, less triangulated, and smaller-wheeled
> than uprights, and most of them suffer from compromised steering
> geometry that does not not allow the sort of no-hands riding stability
> common to uprights.
I think it's wrong to assume lack of no-hands means "compromised", it
will often just mean little or no trail. That's a Feature, not a Bug.
My Streetmachine won't ride no-hands (at least not with me!) but it's
steady as a rock with fingers on one hand only at some pretty high
speeds, and I've never experienced any sort of shimmy.
I do know people who've suffered on it, and they're all 'bent newbies
exhibiting the reasonably common problem of getting too nervous, hanging
on too hard and probably putting far too much power through the bars,
being used to uprights where you can heave all you want.
IME, 'bent bikes typically have most of their steering "problems"
resolved by relaxing not trying too hard, but of course that's much
easier said than done when you're nervous... I've never entriely got on
with tiller bars, and because of that I find tiller steering twitchy,
though I can ride an /otherwise identical bike/ with superman bars or
USS with no wibbles at all. I think psychology has a lot to do with
handling as well as the physics of the bike/trike.
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: 25 Jan 2007 18:31:31
From: Jeff Grippe
Subject: Re: Fear of Flying
|
You have made some interesting observations. One of mine is that back in the
days when I rode DF's, I could easily ride without holding onto the
handlebars. I have never had a recumbent bike where I could ride without
holding on (I owned an Infinity LWB, Vision SWB, and Trek). The Trek, which
I thought I would love, was the "twitchiest" steerer. The Infinity, which
was the oldest and lowest end of the bikes I've owned was my favorite.
I am interested in learning how Quad's would handle although I suspect that
they could also easily go up on two wheels. Its too bad I could have a bike
that became a trike on the really steep ascents.
I guess if I'm going to stick to rail trails then I could get meself a
really good two wheeled 'bent and I should be perfectly content.
Jeff
"chalo colina" <chalo.colina@gmail.com > wrote in message
news:1169763626.053050.37340@a75g2000cwd.googlegroups.com...
> 32GO wrote:
>>
>> Jeff and I got a bit off the topic in the TdPS. His last
>> post there said:
>>
>> > I have no problem piloting a trike in the mid to high
>> > 20's but when I go down a hill of any decent size,
>> > I'm very quickly in the 30's and the trike does not
>> > feel stable.
>>
>> I'm often intrigued at
>> the conversations of 'bent bikers comparing their
>> impressions of long wheel-base, short wheel-base and
>> lowracers, and who feels safest at what speed on which
>> machine. Trikes are probably a bit different in that
>> they require almost nothing in the way of operator skill
>> or training at speeds up to 'casual cruising', and some
>> riders seem to be lulled into forgetting that as they
>> push the limits, trikes begin to demand some of the same
>> skills and heightened attention that it takes to ride a
>> bike fast.
>
> I'm going to offer my observations based on lots of riding on upright
> bikes and trikes. I have ridden 'bent bikes of different kinds, but I
> must admit that they all felt dangerously unstable to me at any speed,
> like they would dump me in a heartbeat if I even /thought/ about
> letting go of the bars. I have almost no direct experience with 'bent
> trikes, but I used to work with Rick Horwitz and I very briefly tried
> one of his Thunderbolts.
>
> Trikes as a rule have a natural "critical speed" that has more to do
> with vehicle dynamics than it does with the rider's fear and
> perceptions. Trikes can't lean, so they have a weight shift in turns.
> They also have a natural steering response that is relatively
> independent of speed. But as speed increases, the weight shift becomes
> more sudden and eventually causes a violent response to even mild
> steering inputs, up to and including high-siding the trike. Since the
> effect of a harsh weight shift is to jar the rider, and this can result
> in unplanned steering inputs, there comes a speed at which every trike
> can be considered unstable. The lowest critical speed I have seen so
> far was in a Trailmate E-Z Roll Regal adult delta trike, which tried to
> buck the rider off starting at about 10mph. This was a result, I
> believe, of several factors including extravagant frame flex, high C of
> G, narrow track, and the misguided use of a normal bicycle fork offset
> on a trike with a slack head angle. A trike will naturally become more
> stable as it becomes lower, wider, stiffer, or more resistant to
> steering input. That's why tadpole 'bents can be considered "sporty"
> while upright deltas never are. However, while a sporty 'bent trike
> might have a much higher critical speed than a senior citizen's
> neighborhood trike, it still has a point beyond which it can be
> considered unstable.
>
> Bikes are different. Their front end steering characteristics cause a
> natural self-stabilizing force that increases with speed. This force
> causes frame, fork, and wheel flex, however, and thus can result in
> shimmy problems as speeds and dynamic forces on the frame rise. But in
> a bike and rider combination that does not exhibit shimmy, the ride
> becomes steadier as speeds increase-- quite the opposite of what
> happens with a trike. I used to have a roughly 1/2 mile downhill
> averaging about 8% on my way to work, and with a mild crouch over flat
> handlebars I routinely hit a measured 55mph on my upright bike--
> without any unsteadiness or handling quirks whatsoever.
>
> 'Bent bikes tend to be longer, less triangulated, and smaller-wheeled
> than uprights, and most of them suffer from compromised steering
> geometry that does not not allow the sort of no-hands riding stability
> common to uprights. Thus they will flex more (promoting shimmy) and
> exhibit less self-stabilizing than a typical upright bike, and this may
> contribute to a lower practical maximum operating speed. So because
> 'bent bikes are (generally speaking) worse than upright bikes with
> regard to stability at speed, 'bent trikes are /more stable/ than
> upright trikes, and this makes two- and three-wheeled 'bents comparable
> to each other in their sure-footedness at high speed. In contrast,
> there is really no comparison between DF bikes and upright trikes in
> their handling at speed.
>
> Chalo
>
|
| | | |
Date: 26 Jan 2007 11:42:30
From: Edward Dolan
Subject: Re: Fear of Flying
|
"Jeff Grippe" <jeff@door7.com > wrote in message
news:12rifelo4obp718@news.supernews.com...
ALL TOP POSTERS ARE IDIOTS!
> You have made some interesting observations. One of mine is that back in
> the days when I rode DF's, I could easily ride without holding onto the
> handlebars. I have never had a recumbent bike where I could ride without
> holding on (I owned an Infinity LWB, Vision SWB, and Trek). The Trek,
> which I thought I would love, was the "twitchiest" steerer. The Infinity,
> which was the oldest and lowest end of the bikes I've owned was my
> favorite.
No one has ever been able to ride any recumbent hands-off. Thus spake
Zarathustra.
What the hell was low end about the Infinity? I bought one new and one used.
The one I bought new was quite expensive and there was nothing low end about
it. I still think for a multiple tube frame recumbent that it is one of the
best looking ones ever made. It always reminds me of the very early Avatar.
[...]
Regards,
Ed Dolan the Great - Minnesota
aka
Saint Edward the Great - Order of the Perpetual Sorrows - Minnesota
|
| | | |
Date: 26 Jan 2007 00:54:44
From: Grolch
Subject: Re: Fear of Flying
|
Well having a tadpole trike (Catrike Road) and having crashed it within a
month of getting it let me chime in with some observations. The only
stability problems I've encountered are the "brake steer" effect of side to
side brakes. If one is not aware of the degree of the effect the resulst can
be an oscillating descent which causes one to stiffen up even more
compounding the problem. I've had the trike up to 58kph on relatively flat
terrain with absolutely no problems. I've had the trike up to 76kph down a
curvy descent with no problems IF I stay relaxed. The moment I begin to
tense up (ie Fear), is when instability shows up. I've had many
configurations of DF bikes, hybrids, top-end rigid MTB's and pretty good
road bikes. I've been "on the ground" with all of them too. But I have to
say for high speed cornering, DF's are best, except when you hit some junk
(gravel, RR Xings etc). At least on a trike some junk won't put you down.
And besides, at least my head isn't 7' off the ground. Falls on a DB are
usually sliding road rashers or "dive for the pavement" acrobatics. I stil
feel much safer on my bent trike
Grolsch
"Jeff Grippe" <jeff@door7.com > wrote in message
news:12rifelo4obp718@news.supernews.com...
> You have made some interesting observations. One of mine is that back in
> the days when I rode DF's, I could easily ride without holding onto the
> handlebars. I have never had a recumbent bike where I could ride without
> holding on (I owned an Infinity LWB, Vision SWB, and Trek). The Trek,
> which I thought I would love, was the "twitchiest" steerer. The Infinity,
> which was the oldest and lowest end of the bikes I've owned was my
> favorite.
>
> I am interested in learning how Quad's would handle although I suspect
> that they could also easily go up on two wheels. Its too bad I could have
> a bike that became a trike on the really steep ascents.
>
> I guess if I'm going to stick to rail trails then I could get meself a
> really good two wheeled 'bent and I should be perfectly content.
>
> Jeff
> "chalo colina" <chalo.colina@gmail.com> wrote in message
> news:1169763626.053050.37340@a75g2000cwd.googlegroups.com...
>> 32GO wrote:
>>>
>>> Jeff and I got a bit off the topic in the TdPS. His last
>>> post there said:
>>>
>>> > I have no problem piloting a trike in the mid to high
>>> > 20's but when I go down a hill of any decent size,
>>> > I'm very quickly in the 30's and the trike does not
>>> > feel stable.
>>>
>>> I'm often intrigued at
>>> the conversations of 'bent bikers comparing their
>>> impressions of long wheel-base, short wheel-base and
>>> lowracers, and who feels safest at what speed on which
>>> machine. Trikes are probably a bit different in that
>>> they require almost nothing in the way of operator skill
>>> or training at speeds up to 'casual cruising', and some
>>> riders seem to be lulled into forgetting that as they
>>> push the limits, trikes begin to demand some of the same
>>> skills and heightened attention that it takes to ride a
>>> bike fast.
>>
>> I'm going to offer my observations based on lots of riding on upright
>> bikes and trikes. I have ridden 'bent bikes of different kinds, but I
>> must admit that they all felt dangerously unstable to me at any speed,
>> like they would dump me in a heartbeat if I even /thought/ about
>> letting go of the bars. I have almost no direct experience with 'bent
>> trikes, but I used to work with Rick Horwitz and I very briefly tried
>> one of his Thunderbolts.
>>
>> Trikes as a rule have a natural "critical speed" that has more to do
>> with vehicle dynamics than it does with the rider's fear and
>> perceptions. Trikes can't lean, so they have a weight shift in turns.
>> They also have a natural steering response that is relatively
>> independent of speed. But as speed increases, the weight shift becomes
>> more sudden and eventually causes a violent response to even mild
>> steering inputs, up to and including high-siding the trike. Since the
>> effect of a harsh weight shift is to jar the rider, and this can result
>> in unplanned steering inputs, there comes a speed at which every trike
>> can be considered unstable. The lowest critical speed I have seen so
>> far was in a Trailmate E-Z Roll Regal adult delta trike, which tried to
>> buck the rider off starting at about 10mph. This was a result, I
>> believe, of several factors including extravagant frame flex, high C of
>> G, narrow track, and the misguided use of a normal bicycle fork offset
>> on a trike with a slack head angle. A trike will naturally become more
>> stable as it becomes lower, wider, stiffer, or more resistant to
>> steering input. That's why tadpole 'bents can be considered "sporty"
>> while upright deltas never are. However, while a sporty 'bent trike
>> might have a much higher critical speed than a senior citizen's
>> neighborhood trike, it still has a point beyond which it can be
>> considered unstable.
>>
>> Bikes are different. Their front end steering characteristics cause a
>> natural self-stabilizing force that increases with speed. This force
>> causes frame, fork, and wheel flex, however, and thus can result in
>> shimmy problems as speeds and dynamic forces on the frame rise. But in
>> a bike and rider combination that does not exhibit shimmy, the ride
>> becomes steadier as speeds increase-- quite the opposite of what
>> happens with a trike. I used to have a roughly 1/2 mile downhill
>> averaging about 8% on my way to work, and with a mild crouch over flat
>> handlebars I routinely hit a measured 55mph on my upright bike--
>> without any unsteadiness or handling quirks whatsoever.
>>
>> 'Bent bikes tend to be longer, less triangulated, and smaller-wheeled
>> than uprights, and most of them suffer from compromised steering
>> geometry that does not not allow the sort of no-hands riding stability
>> common to uprights. Thus they will flex more (promoting shimmy) and
>> exhibit less self-stabilizing than a typical upright bike, and this may
>> contribute to a lower practical maximum operating speed. So because
>> 'bent bikes are (generally speaking) worse than upright bikes with
>> regard to stability at speed, 'bent trikes are /more stable/ than
>> upright trikes, and this makes two- and three-wheeled 'bents comparable
>> to each other in their sure-footedness at high speed. In contrast,
>> there is really no comparison between DF bikes and upright trikes in
>> their handling at speed.
>>
>> Chalo
>>
>
>
|
| | | |
Date: 26 Jan 2007 00:20:26
From: MkTm
Subject: Re: Fear of Flying
|
Jeff Grippe wrote:
> You have made some interesting observations. One of mine is that back in the
> days when I rode DF's, I could easily ride without holding onto the
> handlebars. I have never had a recumbent bike where I could ride without
> holding on (I owned an Infinity LWB, Vision SWB, and Trek). The Trek, which
> I thought I would love, was the "twitchiest" steerer. The Infinity, which
> was the oldest and lowest end of the bikes I've owned was my favorite.
>
> I am interested in learning how Quad's would handle although I suspect that
> they could also easily go up on two wheels. Its too bad I could have a bike
> that became a trike on the really steep ascents.
>
> I guess if I'm going to stick to rail trails then I could get meself a
> really good two wheeled 'bent and I should be perfectly content.
>
> Jeff
> "chalo colina" <chalo.colina@gmail.com> wrote in message
> news:1169763626.053050.37340@a75g2000cwd.googlegroups.com...
>
>>32GO wrote:
>>
>>>Jeff and I got a bit off the topic in the TdPS. His last
>>>post there said:
>>>
>>>
>>>>I have no problem piloting a trike in the mid to high
>>>>20's but when I go down a hill of any decent size,
>>>>I'm very quickly in the 30's and the trike does not
>>>>feel stable.
>>> ...
>> ...
>>I'm going to offer my observations based on lots of riding on upright
>>bikes and trikes. I have ridden 'bent bikes of different kinds, but I
>>must admit that they all felt dangerously unstable to me at any speed,
>>like they would dump me in a heartbeat if I even /thought/ about
>>letting go of the bars. I have almost no direct experience with 'bent
>>trikes, but I used to work with Rick Horwitz and I very briefly tried
>>one of his Thunderbolts.
>>
>>Trikes as a rule have a natural "critical speed" that has more to do
>>with vehicle dynamics than it does with the rider's fear and
>>perceptions. Trikes can't lean, so they have a weight shift in turns.
>> ...
>>
>>Chalo
>>
>
>
>
On reading these posts about instability at speed in trikes or at least
a sense of instability, I began to wonder if there were any trikes that
incorporated wheel lean in their designs. I've noticed on the cutting
edge tech sites many designs for motorized vehicles with wheel lean. Why
not for human powered?
Maybe weight is a factor with the added engineering complexity involved.
On last year's 5 Boro bike tour in New York City a rode along side a
trike for a short distance. I don't know anything about the makes or
designs of trikes but the one I saw reminded me of a formula 1 race car.
It had independent front suspensions with upper and lower control arms.
Also disk brakes and what looked like a monocoque frame design (or least
the look of one).
With upper and lower control arms it doesn't seem to be much of an
extension to have lean incorporated, whether in a preset manner or under
the control of the rider - say in a steering mechanism that allowed for
a turning motion for turning along with a side-to-side sliding motion to
control lean. Even simpler, in the manner of current autos, the
suspension could be designed to force wheel lean depending of the
downward force on it.
I've also seen rollerbladers with unusual skates. Rather than having
many small wheels vertically mounted the unusual skates had two large
wheels (about 8 to 10 inches in diameter) mounted such that they leaned
from the outside of the foot to meet the ground just at the center of
the foot, though obviously some few inches below. Though this lean seems
opposite to the direction needed for turn stability it seems to test the
endurance of the bearing mechanisms involved in lean.
Sport wheel chairs have used a leaning wheel design for some time. Why
isn't this used with trikes?
|
| | | | |
Date: 09 Feb 2007 02:56:26
From: dabac
Subject: Re: Fear of Flying
|
MkTm Wrote:
> Jeff Grippe wrote:
> On reading these posts about instability at speed in trikes or a
> least
> a sense of instability, I began to wonder if there were any trike
> that
> incorporated wheel lean in their designs. ... Even simpler, in th
> manner of current autos, the suspension could be designed to forc
> wheel lean depending of the downward force on it. Don't understand your auto reference. Car suspension design strive t
achieve and maintain a neutral or slight negative camber through al
driving conditions. Suspension travel and body roll makes this quit
challenging. For a car wheel with its basically rectangular tyr
profile and laterally strong rims there is nothing to be gained fro
increasing this angle.
MkTm Wrote:
> Jeff Grippe wrote:
> I've also seen rollerbladers with unusual skates. Rather than having
> many small wheels vertically mounted the unusual skates had two large
> wheels (about 8 to 10 inches in diameter) mounted such that the
> leaned
> from the outside of the foot to meet the ground just at the center of
> the foot, though obviously some few inches below. Though this lea
> seems
> opposite to the direction needed for turn stability it seems to tes
> the
> endurance of the bearing mechanisms involved in lean.
But they have their own reason for going that way. The sworn enemy o
recreational inline skating is poor road surfaces, and bigger wheel
helps reduce the amount of vibration generated by smaller wheels. Bi
wheels w/o the angle forces you either to build very high skates, or t
stretch the wheelbase until the foot will fit between the wheels
Besides the unwanted length the stretched 2-point wheelbase also messe
up cornering ability.
MkTm Wrote:
> Jeff Grippe wrote:
> Sport wheel chairs have used a leaning wheel design for some time. Why
> isn't this used with trikes?
It's either done to increase track width, or to prevent wheels fro
buckling when cornering, or both.
A DF or 2-wheeled 'bent lean in curves, so they can get by with usin
wheels with limited lateral stability. A sport wheel chair can't lean
so a pre-loaded configuration reduces wheel loads when cornering.
Smaller wheels, like those often found on a trike, can take highe
lateral loads, and the track width of the trike isn't limited t
operator's reach.
I also suspect that steering response would be decidedly odd it yo
tried steering with a significantly leaning wheel
--
dabac
|
| | | | |
Date: 26 Jan 2007 18:18:17
From: Dave Larrington
Subject: Re: Fear of Flying
|
In article <ePbuh.19361$pb7.13011@trndny09 >, MkTmE@NOSPAM.invalid
says...
> On reading these posts about instability at speed in trikes or at least
> a sense of instability, I began to wonder if there were any trikes that
> incorporated wheel lean in their designs. I've noticed on the cutting
> edge tech sites many designs for motorized vehicles with wheel lean. Why
> not for human powered?
It /has/ been tried, but the additional weight and complexity were
usually deemed not to be worth it. The Tripendo, for example, was a
German all-carbon leaning trike weighing about half as much again as my
steel Trice.
And hanging out of the seat on a tight corner is part of the fun
--
Dave Larrington - <http://www.legslarry.beerdrinkers.co.uk/ >
Trike Vmax 86 km/h; need bigger hill
|
| | | | | |
Date: 28 Jan 2007 15:32:06
From: MkTm
Subject: Re: Fear of Flying
|
Dave Larrington wrote:
> In article <ePbuh.19361$pb7.13011@trndny09>, MkTmE@NOSPAM.invalid
> says...
>
>
>>On reading these posts about instability at speed in trikes or at least
>>a sense of instability, I began to wonder if there were any trikes that
>>incorporated wheel lean in their designs. I've noticed on the cutting
>>edge tech sites many designs for motorized vehicles with wheel lean. Why
>>not for human powered?
>
>
> It /has/ been tried, but the additional weight and complexity were
> usually deemed not to be worth it. The Tripendo, for example, was a
> German all-carbon leaning trike weighing about half as much again as my
> steel Trice.
>
> And hanging out of the seat on a tight corner is part of the fun
>
Thanks for the link. That may be the trike that I saw though I can't be
sure. I only rode along side for about a minute with my concentration on
the front suspension. With a rider seated I couldn't see the futuristic
seat. The wheels were spoked. The monocoque was similar though white or
light gray with a distinctly apparent weave pattern - probably fiber
glass. Though I noticed the double wishbone suspension I didn't think of
it as a leaning trike. It was a flat straight away though so there was
no basis to see lean.
I was looking at some of the linked trikes from this page -
http://home.mindspring.com/~kb7mxu/trikes2.htm
.. and saw some other leaning designs.
This one seems to have been dropped since there's only a picture at the
site.
http://home.mindspring.com/~kb7mxu/images/berg.jpg
This one is in development.
http://www.kerrelcycles.com/index.html
The Tripendo is also on the link page.
http://www.tripendo.com/EDEFAULT.htm
As for wheels that permanently lean in the style of sport wheel chairs,
I'd guess that steering and propulsion would have to be via the third
wheel or fairly complex.
|
|
