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..

.