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



 
 
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  #71  
Old June 9th 09, 08:07 PM posted to rec.bicycles.tech,alt.rec.bicycles.recumbent
Andre Jute[_2_]
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Posts: 8,821
Default THE LOGIC OF TRIKES an outsider's viewpoint by Andre Jute

Looks like your bendibeam with balloon tyres will give you everything
you want in a trike -- though I can't say I'm equally impressed with
your willingness to consider an unstable delta on equal terms with a
stable tadpole. Big moneysaver and complication-saver if the bendibeam
works as well for bikes as it works the rear of hatchbacks. -- Andre
Jute

On Jun 9, 12:58*pm, Bernhard Agthe wrote:
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..

.


Ads
  #72  
Old June 9th 09, 08:57 PM posted to rec.bicycles.tech,alt.rec.bicycles.recumbent
Andre Jute[_2_]
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Posts: 8,821
Default THE LOGIC OF TRIKES an outsider's viewpoint by Andre Jute

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!

  #73  
Old June 9th 09, 09:02 PM posted to rec.bicycles.tech,alt.rec.bicycles.recumbent
Chalo
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Posts: 4,943
Default THE LOGIC OF TRIKES an outsider's viewpoint by Andre Jute

Bernhard Agthe wrote:

Andre Jute wrote:

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.


I don't ride a Culty. I simply pointed it out as a leaning, high-
riding trike when Andre complained that other leaning trikes were too
low. I expect that the idiosyncrasies of tilting and rear steering
trump all generic concerns about delta versus tadpole layout-- whether
good or bad, there is no other machine to compare to the Culty from a
functional standpoint.

I think that Andre's case against delta trikes is circumstantial; the
few that carry their riders low and between the rear wheels (e.g. the
Hase Lepus and Kettwiesel trikes you have already mentioned) are good
handlers on a par with similarly low-slung tadpoles. The practical
drawback to these is that the best place for carrying loads is
occupied with the rider, but that is the tadpole trike's predicament
as well.

Chalo
  #74  
Old June 10th 09, 11:09 AM posted to rec.bicycles.tech,alt.rec.bicycles.recumbent
Bernhard Agthe
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Posts: 210
Default THE LOGIC OF TRIKES an outsider's viewpoint by Andre Jute

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 ;-)

..
  #75  
Old June 10th 09, 07:21 PM posted to rec.bicycles.tech,alt.rec.bicycles.recumbent
someone
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Posts: 2,340
Default THE LOGIC OF TRIKES an outsider's viewpoint by Andre Jute

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.
 




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