THE LOGIC OF TRIKES an outsider's viewpoint by Andre Jute

Hi,

Andre Jute wrote:
On Jun 8, 1:57 pm, Bernhard Agthe wrote:
(leaning car vs leaning trike)
No, unfortunately not. It is apples and oranges. Compare a non-leaning
car and a leaning car. The non-leaning car has wide flat tires; the
suspension is designed to keep them upright; the car gets its
stability from its track width. (Ever ask why Lotus made such great
big wide sports cars -- they weren't incompetent and they weren't

Don't need to tell me why fast cars are low *and* wide. Look at a
Formula-1 racer...

But if you want a fast HPV, I'd rather refer you to two-wheeled
lowracers... Or would you use your Ferrari to pull a camping trailer?!

looking for extra space for luxuries, I assure you.) The leaning car,
by contrast, is narrower, and has narrow roundshouldered tyres; it
gets its stability from leaning over effectively to make its contact
patch (eventually!) as wide as that of the fat tire on the "upright"
car.

You know, I cannot say anything to that, because I have never seen a
leaning car (especially not a successful commercially sold one).

My theory is, if "leaning" was so essential in cars, why aren't there
any leaning cars to buy? So I figure "leaning" is not necessary on a
vehicle that runs in more than one track - which a trike is... It might
be a nice feature, but I wouldn't spend money for it, because I don't
consider it necessary...

From my reading, I suspect that the rear suspension is important on
all tripods, as is a well-suspended seat. Front suspension is
apparently much less valuable (and you too said so after your trial

As said before, I cannot say how it feels to ride a bike without rear
suspension, but I've been comfortable without front suspension. Looking
at the weight distribution, I'd guess that front and rear "axle" each
carry roughly half of the total weight (depending on the actual design).
While there are two front wheels, there is only one rear wheel, so any
effort in terms of suspension has about twice the effect...

ride). So I see the chassis as running from the seat past the bottom
bracket (I still like my feet inside the wheelbase! to the front axle.
The rest of the chassis is the swing arm for the suspended rear wheel,
and the crossarm which acts as an axle for the front wheels.

By putting the front axle that much forward, you actually "produce" the
problem that needs "leaning" as a solution. We agreed that the triangle
between the contact patches of the tires is essential for stability. By
putting the front wheel so far forward, you put the COG at the narrow
part which is bad. By putting the front axle "below your knees", you
lessen the problem so much, it's not worth the bother of tilting...

Also, a trike with such a long wheelbase would likely have an
excessively large turning radius...

As said above, if you're afraid about your feet, just put a "T"-shaped
extension on the bottom bracket beam, that will have the same effect.

(a) both front wheels connected by a single, straight beam that is
allowed to bend just a little to absorb a little part of road bump
(compare leaf spring). Use a standard steering linkage.

Yes, no problemo. It could be a U-shape (as on a truck-chassis) but
turned open-side down. VW-Audio have been very successful with this
sort of controlled-flexure rear axle. Mount it on rubber straight out
of a Ford (or a Renault) exhaust hanger, and you have a certain amount
of damping and isolation too.

As Tom Sherman warns - you need to clear the rider's feet and legs...
Apart from that - yes.

(b) trapezoid front wheel linkage with little or no springiness as
described above (corner outside wheel moves backward a bit).

Clever baggins, you. I hate it! It is all unsprung weight whereas my

Actually I was more afraid of the bearings sticking because the beams
flex just so much...

parallel, equal lengths arms, forming a rectangle perpendicular to the
centreline of the car is hallowed by tradition, only half unsuspended

Use Big-Apple or similar tires and dump the front wheel suspension (with
suspension applying purely to the spring-and-damper component, I don't
want to connect the front wheels with magnetic forces ;-)

But even then I'm sure you can work out the whole front wheel suspension
and linkage thing like I described it, I just simply cannot imagine how
that would look like. And then we're again at a point where I don't see
the need to bother with something so complicated... There are many
problems to solve that are more serious (see my comment about
semi-automated shifting)...

weight, and can be built with parts bought off the shelf at any hot-
rodder or ultralight racing supplier, so a minimum of custom
manufacture. However, your idea, if it can be made light enough, will
work though i find it hard to visualize it working better than tilting
wheels.

Build the whole thing three-dimensional and you get your tilting wheels
for free. You'll have some seriously diagonal linkage then, though...
You might need a lot of two-or three-dimensional bearings, though...

I'm not so certain any of the sporting tadpole we're considering will
have good luggage capacity or handling. Even that suggestive big

Are you trying to pull your camping trailer with a Ferrari? So don't try
to use a luggage-cart-style-bicycle for racing ;-) They simply don't
match...

basket that the Anthrotech can be fitted with is in the wrong place
for putting anything heavy in it: as little as ten kilo in there would
unbalance the handling of the bike at speeds easily attained on the
hill on which I live; IIRC the rating is 30kg of luggage and that
would be lethal on the sharp corners at the speed the trike seems
likely to attain on some of my better hills. For good handling of

Oh come on, the Anthrotech is not known for flipping over. And you can
still get the "narrow" rack and use either Ortlieb bags or even mount
hard-shell containers. They'll be low enough to work well...

luggage on a trike, it should be under your legs. The Culty that Chalo
referred us to the other day has the luggage in the right place but
the wheels in the wrong place. Most of the others you and I are likely
to consider are too low to put anything under the legs.

Chalo seems to like his Culty, so *for him* the wheels are in the right
place.

Apart from that, why not consider a delta trike - look at the ones mady
by Hase-Bikes. You can build it so that you have a large cargo-carrying
space just between the seat and the rear wheels. Actually you can even
have the front wheel in front of your feet and have full suspension
easily. The more I think about it, the more interesting they seem... And
they have a community of enthusiast fans... So, why rule that design out
up front?

I see no problem with building your bendibeam. The transperse axle
beam can be bolted onto the longitudinal "frame" beam with U-bolts
over a hard rubber pad for both isolation and the small amount of play
you want. At an all-up weight of say 150kg (loaded for your world
tour) and human pedal-power, you're never going to wear it out, so the
assembly is maintenance-free. Saves on front suspension. I'm very

So by building a "bendibeam" trike, I would get sufficient and reliable
"suspension" at no additional cost (just use the different material).
You'll laugh, but I think that's the way trike design should go: use
materials smartly and put them to multiple use, in this case one part
for both wheel attachment and suspension. Saves weight, cost and
maintenance...

impressed with Schwalbe's Big Apple balloons, which are available in
406 rim diameter too.

You see, I wouldn't consider them on an upright bike (I love my narrow
tires), but I would prefer them to a "fully" sprung bike anytime: use
one single component for multiple purpose (again)...

Ciao..

..

On Jun 9, 12:31*pm, someone wrote:
On 9 June, 03:27, Tom Sherman °_°
wrote:

The BB must be away from the cross-bar of the frame at least a distance
equal to the outer radius of the circle created by the pedals and feet.

Oh dear. Here come the railroad minds, parallel tracks to the horizon,
everything as it was done before, forever, amen, because it was always
done that way, hallelujah, and we have no thoughts of our own,
Dullness be praised, today and forevermore.

No cross beam necessary. *The axle supports do not need to be in line
with the individual left and right axles. *A wishbone shape would make
a suitable carrier for the front wheel axles.

Yeah, I was thinking a wheelbarrow handlebars shape making a surround
for the rear wheel and angling out under the seat towards the front
wheels could be good, but I councluded asking a thinnish pipe to take
road bumps in compression could lead to a juddering ride.

However, what is wrong with a single arm that mounts rear wheel, crank
and pivot, pivoting at the junction of a trident with a long central
arm, the two short side arms reaching back to the front wheels from as
far in front of the notional axle line as is necessary, the central
arm carrying all the payload of rider and luggage, the rider's feet
then ending up inside the "structure" and the chainline being
straightly unarticulated and not requiring idlers when hub gears are
used. Probably semi-recumbent to keep the wheelbase from growing too
long, but that is where I started anyway, with seat comfortable to sit
down in and from which it is possible to rise with grace.

A material/structure
with self-dampening properties may be useful if long suspension travel
is warranted. *Increasing load will twist the carrier so giving some
negative camber and increasing track. *In this way the cranks may be
located between the wheels. *Bicycle tyre slip angle response should
be able to cope with any varience in steering due to a bumpy road. *A
vehicle which is jostling does not mean a vehicle which is
uncomfortable or slow. *It's not a Merc.

I think an arm which leads the wheel before it could give an
intolerably bumpy ride, but an arm trailing the wheel as I describe
above could have all the advantages you describe. Check out the way
Citroen used to do it, though of course their suspension arms are on
stiff structures and you want the structure to flex a little.

Andre Jute
A little, a very little thought will suffice -- John Maynard Keynes

"Bernhard Agthe" wrote in message
...

You know, I cannot say anything to that, because I have never seen a
leaning car (especially not a successful commercially sold one).

Rather the opposite - consider eg a Citroen Xantia Activa. That's got
special gubbins in to counter lean, and was rather good at doing so. That's
the only production one I know, though there have been various prototypes
using various means.

OTOH a 2CV might be described as a "leaning" car, but that's the other way
round to which Andre intends :-)

On 9 June, 13:05, Andre Jute wrote:

No cross beam necessary. *The axle supports do not need to be in line
with the individual left and right axles. *A wishbone shape would make
a suitable carrier for the front wheel axles.

Yeah, I was thinking a wheelbarrow handlebars shape making a surround
for the rear wheel and angling out under the seat towards the front
wheels could be good, but I councluded asking a thinnish pipe to take
road bumps in compression could lead to a juddering ride.


A single tube wheelbarrow frame is pretty close to a working shape
chassis. Only the addition of a brace with a dropped centre between
the two longitudinal members is required to maintain track and camber
(or induce positive). The riders weight to be taken on a longitudinal
rail on top of this, the fore-end being the crank axle mounting.
Careful selection of beam section shape and size will allow an
acceptable 'bounce' within the chassis.

The central support spine is not necessary, the pedalling cranks can
have a through axle on a link between the wheel mounts like a childs
pedal car.

A rotating front 'beam axle' into which twist is introduced could
provide lean and steer without linkage. The wind-up on the steering
cross beam will give self correction (centering and lean) and
stability. I expect a rather limited turning circle. keeping the
wheelbase as short as a bicycle may make this feasible. Two steering
rods to induce the axle twist should be used at least in a prototype.
The direct control with dampening by the rider reduces component count
and so reliability.

It's sketch book time.

Validation characters for giggling groupies is pedul. Hows zat?

Hi,

Clive George wrote:
Rather the opposite - consider eg a Citroen Xantia Activa. That's got
special gubbins in to counter lean, and was rather good at doing so. That's
the only production one I know, though there have been various prototypes
using various means.

at a quick glance it looks like a very sophisticated system to "counter
lean", rather than a car leaning into the corner actively. You'll find
similar systems (with force-actuated cylinders) in expensive cars today,
e.g. a high-power anti-lean-suspension enhancement in some BMW SUVs. But
their intention is to keep the car level at speeds that would be
considered too-fast except for ABS, ESP, active-suspension and some more
technical gadgets... Did you know that a modern military tank
outperforms the majority of consumer cars in terms of "acceleration",
"control" and "safety" ;-) Plus - they don't lean ;-)

Apart from that, it sounds nice ;-)

Now, by looking at trikes, I don't see any need to do anything like
"counter lean" on a tadpole trike, except if you build it with
sophisticated front wheel suspension. With just minimal springiness in
the front wheel outriggers and tires, the trike will stay mostly flat,
unless the cornering forces grow too excessive (and then it's too late
anyway ;-)

OTOH a 2CV might be described as a "leaning" car, but that's the other way
round to which Andre intends :-)

:-)

Cioa...

..

On 9 June, 14:02, someone wrote:
On 9 June, 13:05, Andre Jute wrote:

No cross beam necessary. *The axle supports do not need to be in line
with the individual left and right axles. *A wishbone shape would make
a suitable carrier for the front wheel axles.

Yeah, I was thinking a wheelbarrow handlebars shape making a surround
for the rear wheel and angling out under the seat towards the front
wheels could be good, but I councluded asking a thinnish pipe to take
road bumps in compression could lead to a juddering ride.

A single tube wheelbarrow frame is pretty close to a working shape
chassis. *Only the addition of a brace with a dropped centre between
the two longitudinal members is required to maintain track and camber
(or induce positive). *The riders weight to be taken on a longitudinal
rail on top of this, the fore-end being the crank axle mounting.
Careful selection of *beam section shape and size will allow an
acceptable 'bounce' within the chassis.

The central support spine is not necessary, the pedalling cranks can
have a through axle on a link between the wheel mounts like a childs
pedal car.

A rotating front 'beam axle' into which twist is introduced could
provide lean and steer without linkage. *The wind-up on the steering
cross beam will give self correction (centering and lean) and
stability. *I expect a rather limited turning circle. *keeping the
wheelbase as short as a bicycle may make this feasible. *Two steering
rods to induce the axle twist should be used at least in a prototype.
The direct control with dampening by the rider reduces component count
and so reliability.

It's sketch book time.

Validation characters for giggling groupies is pedul. *Hows zat?

Kids pedul cars. Giggle's serendipitous suggestion requires further
investigation as an idea source for chassis design.

Sould a seat atop a luggage box be envisioned (which I'm now
favouring) then rear suspension will likely best employed with a
rubber/wood laminate similar to the Alsop softbeam(?) between seat
mounts and axle. Rear stays should still continue around the rear of
the wheel. It is essential that chassis rigidity is tuned with this
as it will be required for extra luggage capacity when using panniers
or a trailer.

Hi,

Andre Jute wrote:
Yeah, I was thinking a wheelbarrow handlebars shape making a surround
for the rear wheel and angling out under the seat towards the front
wheels could be good, but I councluded asking a thinnish pipe to take
road bumps in compression could lead to a juddering ride.

Trying to picture that I fail to see how the front wheels can actually
rotate - if you mount the hubs to an arm running parallel to the
centerline (bottom bracket beam), you'll bump them against the arm? Or
do you articulate the arm - but that would move the front wheels to the
inside of the curve (with respect to the rider) which we agreed is not a
good idea. So you'd need to have the front wheels trailing the "arms"
which moves the wheels outward (which is good) but will finally bump the
wheels against your hip or legs (which is bad).

However, what is wrong with a single arm that mounts rear wheel, crank
and pivot, pivoting at the junction of a trident with a long central
arm, the two short side arms reaching back to the front wheels from as
far in front of the notional axle line as is necessary, the central
arm carrying all the payload of rider and luggage, the rider's feet
then ending up inside the "structure" and the chainline being
straightly unarticulated and not requiring idlers when hub gears are
used. Probably semi-recumbent to keep the wheelbase from growing too
long, but that is where I started anyway, with seat comfortable to sit
down in and from which it is possible to rise with grace.

That's a lot of tech talk in very little space ;-)

Actually I'd agree at once, but I do see the danger of the trike
actually leaning towards the outside of a corner if there is too much
flex in the frame. That's why I would connect the front wheels with a
straight (or almost straight) beam... Too much of anything is not good ;-)

So, for myself, I conclude that a trike should have the "leaning"
feature, if it has significant suspension on the two-wheeled axle. If it
has no or very little suspension on that axle, it would be better to
have no leaning, just to keep it simple ;-)

So, we now have the sporty-trikes with cool suspension and leaning and
we have the more-utility-trikes with "bendibeam" and/or Big-Tire
technology and no extra leaning ;-)

We might not be able to find a "one-for-all" design, but that's fine
with me ;-)

Ciao...

..

"Bernhard Agthe" wrote in message
...

Now, by looking at trikes, I don't see any need to do anything like
"counter lean" on a tadpole trike, except if you build it with
sophisticated front wheel suspension. With just minimal springiness in the
front wheel outriggers and tires, the trike will stay mostly flat, unless
the cornering forces grow too excessive (and then it's too late anyway ;-)

Agreed. I had a GTT for a short while - there was no issue with flipping
unless deliberately induced. These beasts are safe, and corner well - I'd
expect a solo to be even better.

Hi,

just an after-thought...

By tilting the trike into corners, you reduce sideways load on the
wheels, so in the end you can apply more power and still keep control
("Power is nothing without Control"). So you can increase performance or
decrease the spec on stability....

But on the other hand, I think that many things today suffer from
over-sophistication.

Take a mountain-bike for example. Of course your kid wants a fully
suspended bike with the latest in brakes and shifting. But - you being a
"mean" parent - there's a price tag and so you buy a "cool" bike with
the lowest price tag you can talk your kid into... In the end your kid
gets a moderate MTB with full suspension and cool looking brakes and (!)
27 gears. In the end your kid has a bike with moderate or low-quality
parts (number of features is more important than quality) and you'll
find your kid only using a few (the rest doesn't work well, anyway).

Let's return to trikes... Sure there are tadpole trikes actually
available that have fancy front suspension and leaning (there even is a
Vespa-style motor-roller with twin front wheels and leaning), but
they're complicated. Since I prefer simple designs, I'd rather not have
front suspension and leaning... I'd even try one without rear
suspension, but I haven't found one that matches my preference for seat
height (about 40cm ~ 16 in.)...

Along the same lines, while I think the semi-automated shifting feature
I described in the other thread would be cool, though I still think it's
probably not worth the bother - at least not for me ;-) Or take the
DualDrive - I like the idea and it feels good while riding, but I cannot
set up my current excessively-large-range shifting, so again a "normal"
chain-shifting might be the better (though not-so-cool) solution... In
the end, setting up a good-working chain shift which is out-of-spec of
the components is bothersome, so I might go for the DualDrive...

You will put your priorities differently than me, so you might want the
super-sophisticated leaning trike with color-changing finish... Go for
the Ferrari-Trike ;-) But you might find you'll be left to self-building
(which I'd like though I don't have the resources). You'll also spend
more time with maintenance...

I guess, the most important (and most ignored) question in this thread
is "what do you *want*?"...

My wishlist:
* simple
* seat height not too low
* luggage-carrying capability
* good lighting
* mirror
* fenders
* comfy trike
* DualDrive
* low price tag

What's yours?

Ciao...

..

Bernhard Agthe wrote:
Hi,

Andre Jute wrote:
Yeah, I was thinking a wheelbarrow handlebars shape making a surround
for the rear wheel and angling out under the seat towards the front
wheels could be good, but I councluded asking a thinnish pipe to take
road bumps in compression could lead to a juddering ride.

Trying to picture that I fail to see how the front wheels can actually
rotate - if you mount the hubs to an arm running parallel to the
centerline (bottom bracket beam), you'll bump them against the arm? Or
do you articulate the arm - but that would move the front wheels to the
inside of the curve (with respect to the rider) which we agreed is not a
good idea. So you'd need to have the front wheels trailing the "arms"
which moves the wheels outward (which is good) but will finally bump the
wheels against your hip or legs (which is bad).

However, what is wrong with a single arm that mounts rear wheel, crank
and pivot, pivoting at the junction of a trident with a long central
arm, the two short side arms reaching back to the front wheels from as
far in front of the notional axle line as is necessary, the central
arm carrying all the payload of rider and luggage, the rider's feet
then ending up inside the "structure" and the chainline being
straightly unarticulated and not requiring idlers when hub gears are
used. Probably semi-recumbent to keep the wheelbase from growing too
long, but that is where I started anyway, with seat comfortable to sit
down in and from which it is possible to rise with grace.

That's a lot of tech talk in very little space ;-)

Actually I'd agree at once, but I do see the danger of the trike
actually leaning towards the outside of a corner if there is too much
flex in the frame. That's why I would connect the front wheels with a
straight (or almost straight) beam... Too much of anything is not good ;-)
[...]

Mr. Jute's trike will either end up too heavy or too flexible, or both.
It will certainly be more expensive to fabricate than the standard
cruciform trike frame.

--
Tom Sherman - 42.435731,-83.985007
I am a vehicular cyclist.