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

On 9 June, 03:27, Tom Sherman °_°
wrote:
Bernhard Agthe wrote:
[...]
Just to be funny, let me describe a non-leaning trike and tell me
whether you'd consider that (apart from the leaning feature): The main
beam starts at the bottom bracket (add a front foot protection bar if
you want) and is almost level until it reaches the rear wheel axle. If
you like, add rear wheel suspension. Two front wheel assemblies are
considered:
(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.
(b) trapezoid front wheel linkage with little or no springiness as
described above (corner outside wheel moves backward a bit).

Connect the seat firmly at the front of the seat, but probably put the
rear of the seat on beams that are allowed to bend just a little (again
compare the leaf spring).

What do you think, would that be (1) possible[...]

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.

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. 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.

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

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?

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:
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.

On Jun 9, 2:30*pm, Bernhard Agthe wrote:
Hi,

Andre Jute wrote:
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 ;-)

The ideas are now firming up in my mind. Thanks for help in working
them out.

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 ;-)

The beam itself could be solid with a little play in the mounting.
However, I remember driving a Bugati when I was young which was said
to have had a solid front axle with small articulation from the
factory, which was soldered up because it never worked. I had a good
description from the engineer who owned and rebuilt it of the purpose
of the articulation, and also why it dinna work, but the details are
long gone.

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 ;-)

Leaning depends on the geometry of the axle mounting. It is not tied
to suspension. However, suspension-type links are the easiest by which
to arrange a tilting trike.

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 ;-)

I never set out to persuade anyone my idea was "best". Only building
all the ideas and racing them will prove which is best -- and then
some of us will argue that a little sacrifice of speed for a more
upright seat is well worth it!

Super thread!

Andre Jute
Down with the spoilsport Telemachus!

Hi,

Andre Jute wrote:
The beam itself could be solid with a little play in the mounting.
However, I remember driving a Bugati when I was young which was said
to have had a solid front axle with small articulation from the
factory, which was soldered up because it never worked. I had a good
description from the engineer who owned and rebuilt it of the purpose
of the articulation, and also why it dinna work, but the details are
long gone.

Sorry, but I cannot picture this :-( Well, as you stated, I have "my"
trike (at least the idea of it), so it probably doesn't matter ;-)

Leaning depends on the geometry of the axle mounting. It is not tied
to suspension. However, suspension-type links are the easiest by which
to arrange a tilting trike.

Sure... But as I stated elsewhere, it is likely not worth the bother to
build a tilting mech into an unsprung trike...

But if you want lots of suspension, you'll end up with either
"anti-roll" or a leaning mechanism, so it might be a good idea to
combine suspension and leaning. I'll agree with you, if you have to
counter unwanted outward-tilt, you can build the suspension to provide
leaning right away ;-) You convinced me ;-)

I never set out to persuade anyone my idea was "best". Only building
all the ideas and racing them will prove which is best -- and then
some of us will argue that a little sacrifice of speed for a more
upright seat is well worth it!

Well, I wouldn't want to race them - I'd end up last with my complete
camping gear on the "bendibeam" trike... But it might still be the best
trike for carrying half a household ;-) At least for me. So I'd rather
build (and advertise) a bike for the utility factor ("carry a month's
groceries without strain"), while you would probably talk UCI into
letting you take part in the Tour de France for advertisement reasons
;-) You win the race while I watch before going on in my world camping
trip ;-)

So now we have wishlists for two A.R.B.R.-trikes, one sporty with all
the latest features, supple suspension and leaning, and one looking like
a shopping cart on three wheels (with a lawnchair attached)...

Does anyone have an idea, where I could go to have my frame built (as
stated, I don't have the resources)?

Ciao ;-)

..

On 10 June, 11:09, Bernhard Agthe wrote:
Hi,

Andre Jute wrote:
The beam itself could be solid with a little play in the mounting.
However, I remember driving a Bugati when I was young which was said
to have had a solid front axle with small articulation from the
factory, which was soldered up because it never worked. I had a good
description from the engineer who owned and rebuilt it of the purpose
of the articulation, and also why it dinna work, but the details are
long gone.

Sorry, but I cannot picture this :-( Well, as you stated, I have "my"
trike (at least the idea of it), so it probably doesn't matter ;-)

Leaning depends on the geometry of the axle mounting. It is not tied
to suspension. However, suspension-type links are the easiest by which
to arrange a tilting trike.

Sure... But as I stated elsewhere, it is likely not worth the bother to
build a tilting mech into an unsprung trike...

But if you want lots of suspension, you'll end up with either
"anti-roll" or a leaning mechanism, so it might be a good idea to
combine suspension and leaning. I'll agree with you, if you have to
counter unwanted outward-tilt, you can build the suspension to provide
leaning right away ;-) You convinced me ;-)

I never set out to persuade anyone my idea was "best". Only building
all the ideas and racing them will prove which is best -- and then
some of us will argue that a little sacrifice of speed for a more
upright seat is well worth it!

Well, I wouldn't want to race them - I'd end up last with my complete
camping gear on the "bendibeam" trike... But it might still be the best
trike for carrying half a household ;-) At least for me. So I'd rather
build (and advertise) a bike for the utility factor ("carry a month's
groceries without strain"), while you would probably talk UCI into
letting you take part in the Tour de France for advertisement reasons
;-) You win the race while I watch before going on in my world camping
trip ;-)

So now we have wishlists for two A.R.B.R.-trikes, one sporty with all
the latest features, supple suspension and leaning, and one looking like
a shopping cart on three wheels (with a lawnchair attached)...

Does anyone have an idea, where I could go to have my frame built (as
stated, I don't have the resources)?

Ciao ;-)

.

Dexion (drilled and slotted steel angle for shelving system) will make
up a frame in double quick time. For your basic requirements it may
even survive as a finished working model. Use the shelves to make a
luggage box/seat.