Wheelbuilding: offsetting rim outside of hub width?

I am pondering building a tadpole trike.

Because it will use lean-steering, I'd like to be able to align the
kingpins of the front wheels on the plane of the tires. (I am aware of
how the kingpins of most conventional tadpole trikes are canted
outwards, and I don't think that's going to yield an accurate enough
wheel alignment to work properly for this case)

Is it possible to lace a conventional spoked wheel with the rim offset
/beyond/ the width of the hub? At first I guessed not (as I'd never seen
it done) but after thinking a while I can't find any reason why not....
~

On Dec 7, 9:12*pm, DougC wrote:
I am pondering building a tadpole trike.

Because it will use lean-steering, I'd like to be able to align the
kingpins of the front wheels on the plane of the tires. (I am aware of
how the kingpins of most conventional tadpole trikes are canted
outwards, and I don't think that's going to yield an accurate enough
wheel alignment to work properly for this case)

Is it possible to lace a conventional spoked wheel with the rim offset
/beyond/ the width of the hub? At first I guessed not (as I'd never seen
it done) but after thinking a while I can't find any reason why not....
~

Only if you use spokes that are able to take a compressive load (i.e.
no)

Isn't there a kinematic linkage you can use to achieve the desired
steering effect?

On Dec 7, 9:38*pm, pm wrote:
On Dec 7, 9:12*pm, DougC wrote:

I am pondering building a tadpole trike.

Because it will use lean-steering, I'd like to be able to align the
kingpins of the front wheels on the plane of the tires. (I am aware of
how the kingpins of most conventional tadpole trikes are canted
outwards, and I don't think that's going to yield an accurate enough
wheel alignment to work properly for this case)

Is it possible to lace a conventional spoked wheel with the rim offset
/beyond/ the width of the hub? At first I guessed not (as I'd never seen
it done) but after thinking a while I can't find any reason why not....
~

Only if you use spokes that are able to take a compressive load (i.e.
no)

Isn't there a kinematic linkage you can use to achieve the desired
steering effect?

replying to my own question: of course there is, just use a
conventional bicycle type fork and headset, putting the 'kingpin'
outside the wheel but in plane.

DougC wrote:

I am pondering building a tadpole trike.

Because it will use lean-steering, I'd like to be able to align the
kingpins of the front wheels on the plane of the tires. (I am aware of
how the kingpins of most conventional tadpole trikes are canted
outwards, and I don't think that's going to yield an accurate enough
wheel alignment to work properly for this case)

Is it possible to lace a conventional spoked wheel with the rim offset
/beyond/ the width of the hub?

No.

At first I guessed not (as I'd never seen
it done) but after thinking a while I can't find any reason why not....

You can't push a string, and you can't do what you're talking about,
either. A mag-type wheel would be your solution if that's the way you
want to go. The spokes must function as beams, in tension,
compression, bending, and torsion, to allow the rim to be cantilevered
out from the hub.

I can imagine a huge diameter hub and axle (2" axle), with thin
section torque tube bearings, that would allow enough room inside the
axle to pivot a rod end bearing at the hub center. If there were an
arm fixed to the hub axle that supported another rod end bearing on
the same axis (just above the tire), then you'd have a virtual kingpin
that could lie in the plane of a tension-spoked wheel. It would be a
fussy and expensive piece of custom machine work, though.

The Bimota Tesi and Yamaha GTS1000 motorcycles used swingarm front
suspension that was made possible by hub center steering. They had
enormous hubs with the entire steering pivot fitted inside.

What do you propose to do with lean-steering? There have been many
attempts to design and manufacture a satisfactory lean-steer trike,
but none of them have succeeded. They all require more operator skill
than a normal bike or trike without offering unique capabilities.

Chalo

pm wrote:
On Dec 7, 9:38 pm, pm wrote:
On Dec 7, 9:12 pm, DougC wrote:

I am pondering building a tadpole trike.
Because it will use lean-steering, I'd like to be able to align the
kingpins of the front wheels on the plane of the tires. (I am aware of
how the kingpins of most conventional tadpole trikes are canted
outwards, and I don't think that's going to yield an accurate enough
wheel alignment to work properly for this case)
Is it possible to lace a conventional spoked wheel with the rim offset
/beyond/ the width of the hub? At first I guessed not (as I'd never seen
it done) but after thinking a while I can't find any reason why not....
~
Only if you use spokes that are able to take a compressive load (i.e.
no)

Isn't there a kinematic linkage you can use to achieve the desired
steering effect?

replying to my own question: of course there is, just use a
conventional bicycle type fork and headset, putting the 'kingpin'
outside the wheel but in plane.

I don't think that it will be stiff enough.
~

On 8 Dec, 05:12, DougC wrote:
I am pondering building a tadpole trike.

Because it will use lean-steering, I'd like to be able to align the
kingpins of the front wheels on the plane of the tires. (I am aware of
how the kingpins of most conventional tadpole trikes are canted
outwards, and I don't think that's going to yield an accurate enough
wheel alignment to work properly for this case)

Is it possible to lace a conventional spoked wheel with the rim offset
/beyond/ the width of the hub? At first I guessed not (as I'd never seen
it done) but after thinking a while I can't find any reason why not....
~

It is posible to get the rim edge outside the spoke flange but you
cannot take the rim centre to the rim flange, unless, perhaps using
custom drillings. It is probably better to use a small disc wheel
with a fat tyre on it than a suspension wheel. On second thoughts, no
it isn't. The tension wheel when constructed correctly is your
suspension, more important the more axles and tracks. Forgoing the
inbuilt suspension of the 27" bicycle wheel is throwing out the baby.
Make compromises elswhere and use the wheel as a suspension unit.

DougC wrote:
I am pondering building a tadpole trike.

Because it will use lean-steering, I'd like to be able to align the
kingpins of the front wheels on the plane of the tires. (I am aware of
how the kingpins of most conventional tadpole trikes are canted
outwards, and I don't think that's going to yield an accurate enough
wheel alignment to work properly for this case)

Is it possible to lace a conventional spoked wheel with the rim offset
/beyond/ the width of the hub? At first I guessed not (as I'd never seen
it done) but after thinking a while I can't find any reason why not....
~

How about using something like a heavily offset (dish reversed) alloy
go-kart wheel with the rim drilled for straight pull spokes, a wheel
within the wheel.

Hopefully my description paints a picture.


Marcus

thirty-six wrote:
On 8 Dec, 05:12, DougC wrote:
I am pondering building a tadpole trike.

Because it will use lean-steering, I'd like to be able to align the
kingpins of the front wheels on the plane of the tires. (I am aware of
how the kingpins of most conventional tadpole trikes are canted
outwards, and I don't think that's going to yield an accurate enough
wheel alignment to work properly for this case)

Is it possible to lace a conventional spoked wheel with the rim offset
/beyond/ the width of the hub? At first I guessed not (as I'd never seen
it done) but after thinking a while I can't find any reason why not....
~

It is posible to get the rim edge outside the spoke flange but you
cannot take the rim centre to the rim flange, unless, perhaps using
custom drillings. It is probably better to use a small disc wheel
with a fat tyre on it than a suspension wheel. On second thoughts, no
it isn't. The tension wheel when constructed correctly is your
suspension, more important the more axles and tracks. Forgoing the
inbuilt suspension of the 27" bicycle wheel is throwing out the baby.
Make compromises elswhere and use the wheel as a suspension unit.

The desire is not suspension at all.
The point here is to get the steering axis centered on the wheel's
plane, without going outside the wheel's diameter.

The trike would be rather low-slung, and having struts that reach all
the way up to join to a head tube above each front wheel is going to add
a lot of weight and lose a lot of stiffness.
~

On 8 Dec, 23:12, DougC wrote:

The desire is not suspension at all.
The point here is to get the steering axis centered on the wheel's
plane, without going outside the wheel's diameter.

It's nowhere near necessary unless you are using solid tyre, in which
case you would need to use a dished centre Pnuematic tyres as used
on bicycles hve such a great slip angle (22deg typically) available
that much thinking about steering geometry can be ignored. Especially
on a metalled road. If you are using iron tyres on a soft road then
steering gemetry is more important.

Phil W Lee wrote:
....
The desire is not suspension at all.
The point here is to get the steering axis centered on the wheel's
plane, without going outside the wheel's diameter.

The trike would be rather low-slung, and having struts that reach all
the way up to join to a head tube above each front wheel is going to add
a lot of weight and lose a lot of stiffness.
~
In that case you're going to need very big wheel bearings and
hub-centre steering.

That's what I'm thinking, but no place I have yet found sells bearings
like that (small-diameter bearings, but running in rather large 4"+ O.D.
races). I have access to the equipment to make them myself,,,, but no
way to harden them properly. Without accurate hardening I don't know how
long to expect them to last.

The design I am planning is one with free-to-caster front wheels. The
"steering" controls (that the rider moves) only control the left-right
tilt, and the front wheels' angle will not be controlled by anything
more than the amount and direction of tilt. So this is the reason to try
to get the steering geometry as close to ideal as possible.
~