Fear of Flying

32GO said:

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

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" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

32GO said:

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

Jeff Grippe said:

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" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

32GO said:

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?

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" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

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" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

32GO said:

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

Jeff Grippe said:

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.

Quoted message said:

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

chalo colina said:

'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 [email hidden] http://www.dundee.ac.uk/~pjclinch/

"32GO" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Chalo said:

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

Jeff Grippe said:

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 [email hidden] http://www.dundee.ac.uk/~pjclinch/

chalo colina said:

32GO said:

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

chalo colina said:

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...

32GO said:

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...

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.
😉

Mark

In article <ePbuh.19361$pb7.13011@trndny09>, [email hidden]
says...

Quoted message said:

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

In article <[email hidden]>, curtis@md-
bicycling.org says...

Quoted message said:

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.

Hey guys -

Curtis said:

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

Dave Larrington said:

In article <ePbuh.19361$pb7.13011@trndny09>, [email hidden]
says...

Quoted message said:

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.

MkTm said:

Jeff Grippe wrote:
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. ... Even simpler, in the manner of current autos, the suspension could be designed to force wheel lean depending of the downward force on it.

Don't understand your auto reference. Car suspension design strive to achieve and maintain a neutral or slight negative camber through all driving conditions. Suspension travel and body roll makes this quite challenging. For a car wheel with its basically rectangular tyre profile and laterally strong rims there is nothing to be gained from increasing this angle.

MkTm said:

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 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.

But they have their own reason for going that way. The sworn enemy of recreational inline skating is poor road surfaces, and bigger wheels helps reduce the amount of vibration generated by smaller wheels. Big wheels w/o the angle forces you either to build very high skates, or to stretch the wheelbase until the foot will fit between the wheels. Besides the unwanted length the stretched 2-point wheelbase also messes up cornering ability.

MkTm said:

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 from buckling when cornering, or both.
A DF or 2-wheeled 'bent lean in curves, so they can get by with using 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 higher lateral loads, and the track width of the trike isn't limited to operator's reach.
I also suspect that steering response would be decidedly odd it you tried steering with a significantly leaning wheel.