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

On 6 June, 17:46, Opus wrote:
On Jun 5, 10:28 pm, someone wrote:

snip
This topic has continued to run because of the desire to go as fast on
a trike as a bicycle if not perhaps a wee bit quicker. *The limitation
on speed of a human powered vehicle is primarily in the bends. *To get
round the bends quicker makes all riding quicker. *I certainly dont
like the idea I should go a little slower so that I can right myself
by reducing my turn radius. *I am accustomed to being able to ride
bicycle and drive motor car to the limits of adhesion. *Once the
feeling of cornering response near the limit is learnt it is difficult
to ignore its benefits. *Your righting technique prevents the learning
of the vehicle response at the limit point.

I know the vehicle response at the limits in this situation, front end
washout followed by a painful slide into whatever is beyond the edge
of the pavement. The advantage of the tilting tadpole was that the
vehicle could be kept upright (more or less) after the front end
traction was lost by the use of the tilting brake, at the expense of
adding some side loads to the front wheels and some complexity to the
controls and construction.

I would expect that the use of trailing brake to the point of minimum
turn radius would shift the weight sufficiently onto the outer front
wheel to prevent slipout. The release of the brake in conjunction
with forward torque on the rear wheel would then transfer much of the
turning to the rear wheel and the front steering could be eased back,
the reducing turning effort at the front preventing slipout.
Maintaining the correct gear for corners taken near maximum speed
would be essential to induce the greater slip angle at the rear tyre.
Must watch some TT in IOM for the combination racing.

On Jun 6, 5:21 pm, Andre Jute wrote:
snip
I had already planned angle-limiting by rubber bump-stops but was
wondering about a lockable disc to hold the thing upright at rest.

Was you tadpole the usual height and just narrower or did you sit
higher as well? My design sketch started putting on width and then
started leaning, so to speak, because i want to sit comfortably
upright at office chair height (say 15in off the ground).

It might be that the only place to use a really speedy tadpole is not
the public road but sand-sailing on a beach or in a desert in the wide
open spaces of North Africa or North America, as Bernhard suggested...

Andre Jute
Visit Jute on Bicycles at
http://www.audio-talk.co.uk/fiultra/...20CYCLING.html

The first ones were based on DF bikes like the Atomic Zombie
Hammerhead, the last ones were 'bent, but more like LWB 'bents than
the ground scraping tadpoles. I hadn't seen a "regular" tadpole trike
then so I had nothing to base it on.

On Jun 7, 11:38*pm, Opus wrote:
On Jun 6, 5:21 pm, Andre Jute wrote:



snip
I had already planned angle-limiting by rubber bump-stops but was
wondering about a lockable disc to hold the thing upright at rest.

Was you tadpole the usual height and just narrower or did you sit
higher as well? My design sketch started putting on width and then
started leaning, so to speak, because i want to sit comfortably
upright at office chair height (say 15in off the ground).

It might be that the only place to use a really speedy tadpole is not
the public road but sand-sailing on a beach or in a desert in the wide
open spaces of North Africa or North America, as Bernhard suggested...

Andre Jute
Visit Jute on Bicycles at
*http://www.audio-talk.co.uk/fiultra/...20CYCLING.html

The first ones were based on DF bikes like the Atomic Zombie
Hammerhead, the last ones were 'bent, but more like LWB 'bents than
the ground scraping tadpoles. I hadn't seen a "regular" tadpole trike
then so I had nothing to base it on.

Thanks for the information, Opus. -- AJ

Hi,

Tom Sherman °_° wrote:
My trike has a mirror on the handlebars:
(link to image)

Nice trike - and I know that there is more than one option ;-)

As stated, I do like the SRAM Trigger shifters, but I cannot imagine
mounting them to an under-seat handlebars... So they're out... And I
like the idea of SRAM's racing-style brifters, so I'd consider them...
It seems a nice solution for under-seat steering, apart from the cable
routing...

Another question, just from seeing your trike's pictu you don't seem
to have fenders. On an upright bike, fenders are very useful, so that
you don't get the street dirt on yourself. With a trike, where you are
practically "behind" the front wheels (at least when steering), I'd
expect this to be much more important? Or are the streets so clean where
you live? At least here there's *lots* of dirt on the streets (including
glass shards) and in case of rain, it's the same... So, in conclusion
I'd expect (front) mudguards to be close to safety-critical on a trike?
How much dirt and water and mud do you get "up your nose"?

Ciao..

Hi,

Andre Jute wrote:
[[[whole lotta snips -- I think we understand the context between
us...]]]

Sure ;-)

(Hebie Chainglider)

Well, it seems to get consistently good reviews and I don't think
availability is an unusual problem - I've had to wait up to a month to
acquire standard components like chainrings and bike stands... I've
found parts that I cannot obtain through my local dealer, just through
obsure internet reseller...

Apart from that, It doesn't really matter, who builds it, the Hebie
Chainglider comes to my mind because it got good reviews and because it
uses chain tubes just like the common chain tubes on recumbents... Even
then I'd expect to have quite a bit of "customization" to do...

In any event, I just don't see a crank in front of the front axle
having a straight run to even hub gears at the back, so somewhere
there will be exposed idlers where the chain will pick up dirt Just
one open spot for dirt to get in negates the enclosure -- you may as
well not bother.

OK, here we go again - for my utility vs. sport thing. On a "sport"
trike, that is one which is built low, you need idlers. You can still
build a housing for the idlers, but I'd expect that to be complicated
;-) Probably use a tupper-box with glued-in chain tubes?

On a more utility-like trike (with a higher seat), I'm not sure whether
there is need for idlers, at least the Anthrotech has none within the
pulling path of the chain, though it uses an extra derailleur in the
return path. If you want to avoid the chain-tensioning issue on a
hub-gear bike, you do need some kine of tensioner, but I've seen an ad
for a hub-gear bike, that used two pulleys to wrap the chain three
quarters around both chainwheel and sprocket by bringing the return run
of the chain up to just below the load run. They put that in a case
which looked really nice (at least in the picture). So I'd rather have
the derailleur turned forward by about 60 degrees, which would at least
give more ground clearance. But I don't expect this to be possible with
current off-the-shelf hardware...

(design complete and ready to build?)
It's not. My first sketch design was 5ft/1520mm wide. I described in a
reply to Trevor how dangerous that would be on my favourite lanes --
too wide. I'd be in the ditch in the sowing, silage and harvest

Common trikes are just below one meter (~3 ft.) in width, in order to
fit through the common bike-lane obstructions... I'd consider this
sensible, because most trailers, wheel-chairs and child-caddies are
about the same width..

seasons more often than I'd be on the road. Tilting is one way of
making a utility bike which is also narrow enough to be useful perform

Well, I still consider the Anthrotech or the HP-Velotechnik Scorpion
(foldable version) to be acceptably performant, while having a great
utility value... Both are non-leaning. It was difficult to talk the
local dealer into allowing me an hour-long test ride, but it was worth
it - I'll get one, as soon as I know where to store it at home ;-) Both
trikes give a great ride even when going a bit slower, I enjoyed it as
much as a faster trip on my upright...

acceptably. I'm thinking about this, but the truth is that unless the
lightbulb labelled Eureka flashes in my head with some novelty (see my
discussion with Trevor for some wild ideas), I won't be building a

Actually, I think the idea with the seat shifting with respect to the
front wheels is good. I'd been toying with the front wheel arms part of
the steering linkage in a way that the outer wheel moves backward (just
a bit) when steering. Just think of a trapezoid linkage... You could
even build that linkage three-dimensional so that you get leaning, but I
cannot picture this inside my (mashed-up) brain ;-) And moving the outer
wheel backwards should work, too ;-)

Talking about complicated linkage, I would not suspend the front wheels
to compensate for rough roads, but use large-volume front tires (say
40-406). If you're interested in suspension, I think it's enough to do
that on the rear wheel only, as the mesh seat provides quite good
suspension and the three-dimensional linkage is likely not worth the
bother...

trike that is betwixt and between, compromised so that it is neither
fast nor particularly usable on my roads. (At least not until I'm so
decrepit I need a narrow, pavement type tricycle, in which case the
need for speed might be a distant memory. Mind you, we have a guy...

As I said, with a comfy trike you have as much fun going a bit slower
and I do think you can easily go more than 20km/h on roads where you go
as fast on a "normal" bike. If the corner is so sharp that you have to
break, it doesn't matter what kind of bike you're on. Mind, we're not
talking about upright tricycles here...

Well now, that's a hard fact. I don't believe anyone has mentioned
that, though this thread has been going for about a week now. See, my

No, it's not a hard fact. Actually the Scorpion trike is available in a
full-suspension version since recently. Though I don't know whether
that's just for "feature-hungry" riders - I felt *very* comfortable in
rear-suspension-only trikes, though I cannot compare that to a trike
without suspension...

Cars have wide tyres. Cars have suspension links that try very hard to
keep the wheel upright (actually with very small angles in three
dimensions) under all circumstance, whereas the suspension on the
tilting bicycle is intended to do exactly the opposite, tilt a narrow,
round tyre to hell and gone.

My point was, car work well without any leaning at all. They have the
same problem (COG needs to be low) as a trike has: they will flip over
if cornering too hard. Sure, cars have much more massive suspension and
wheels, but they weigh more, also. So a non-leaning trike should work
well, at least as well as a non-leaning car?!

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 and (2) give a good
utility trike (with load-carrying ability) while staying (3) easy-to-build?

Nah, I'm just investigating. But even if, after going through the
....

You know, I've found people react much more friendly if you try to
separate technical talk from stating your opinion. You'll notice I don't
do this and I get a lot of mud thrown at me for it ;-)

(twist-shift on under-seat-handlebars)
Sock it to Rohloff and Shimano both! (I have no experience of the
others, but I bet they're as bad.)

Well, as far as I know, SRAM invented the twist-shift. Many people seem
comfortable with it on upright bikes, no matter whether its SRAM,
Shimano or Rohloff. I was never able to use it well, as I seem to twist
the grips during normal riding (at least when applying high power). So,
I don't like twist shift on upright bikes. On the trike it was much
better, but the shifters are just plain on the wrong end of the hand.
They're not built to be operated with your little finger... But - as
stated elsewhere - I cannot imagine mounting trigger shifters on a trike
either, so it's bar-end-shifters (race-bike-style brifters of current
design do not allow for decent cable routing I guess). But the
bar-end-shifters I know of seem to be incompatible to the SRAM rear mech
(which I like very well after 10.000 km with it)...

Andre, we had that long thread about automatical shifting - would you
care to apply it to a trike? First of all, you need either chain-shift
or something like DualDrive as I cannot see a 8-or-9-speed hub having
enough shifting range. So it's likely the Dura-Ace version. But is it
able to handle the gear range and tire size of a trike (with 20"
tires!)? I know it's not an automatic shift... So, next question, can it
be set up to do semi-automatic shifting (you click on higher/lower gear
and it selects the next appropriate gear by itself)? Otherwise I'd say
it's to expensive...

Ciao...

On Jun 8, 1:57*pm, Bernhard Agthe wrote:

I've started a couple of other threads for matters arising from this
single rich post of yours.


Andre wrote:
Cars have wide tyres. Cars have suspension links that try very hard to
keep the wheel upright (actually with very small angles in three
dimensions) under all circumstance, whereas the suspension on the
tilting bicycle is intended to do exactly the opposite, tilt a narrow,
round tyre to hell and gone.

My point was, car work well without any leaning at all. They have the
same problem (COG needs to be low) as a trike has: they will flip over
if cornering too hard. Sure, cars have much more massive suspension and
wheels, but they weigh more, also. So a non-leaning trike should work
well, at least as well as a non-leaning car?!

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
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.

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.

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
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.

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.

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.

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

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 and (2) give a good
utility trike (with load-carrying ability) while staying (3) easy-to-build?

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

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

Andre Jute
Visit Andre's recipes:
http://www.audio-talk.co.uk/fiultra/FOOD.html

On 8 June, 13:57, Bernhard Agthe wrote:

acceptably. I'm thinking about this, but the truth is that unless the
lightbulb labelled Eureka flashes in my head with some novelty (see my
discussion with Trevor for some wild ideas), I won't be building a

Actually, I think the idea with the seat shifting with respect to the
front wheels is good.

It was based on driving technique for downhill karting. A chassis
with four wheels. The design of which was more a development. It was
put together with pram wheels, wooden beam, a plywood seat, hard cord
and steel rod links. There were no specific suspension components.
The parts that made up the racer were selected and modified to 'give'
the required amount. Ribs were added to stiffen up parts 'too
bendy'. The tyres on the wheels were hard, not pneumatic. The idea
of getting bogged down with suspension details baffles me. I was eight
or nine when I did this. A constraining feature was low weight, there
was some distance to get to the nearest hill. The machine evolved
more than it was designed. Made it as simple as possible, then fixed
the worst errors. I see this as the best way forward in the
development of a trike. Give it all that you want in height, width,
luggage carrier and turn radius. Use chassis sections of suitable
section for the load , allowing for beam suspension. Use tiller
steering with a reversal link and shove on some cranks etc.

When chassis members are correctly selected, they are the
suspension. Complicated steering mechanisms are not required, no need
to make accurate tracking because it's a trike and the narrow tyres
required are bike tyres. Luggage can be bagged and strapped in a
hammock under the rider. A few eyes affixed to the chassis along with
a hammock is light and simple. Using a hammock for luggage as well as
rider will also give a smoother ride.

Bernhard Agthe wrote:
Hi,

Tom Sherman °_° wrote:
My trike has a mirror on the handlebars:
(link to image)

Nice trike - and I know that there is more than one option ;-)

As stated, I do like the SRAM Trigger shifters, but I cannot imagine
mounting them to an under-seat handlebars... So they're out... And I
like the idea of SRAM's racing-style brifters, so I'd consider them...
It seems a nice solution for under-seat steering, apart from the cable
routing...

Another question, just from seeing your trike's pictu you don't seem
to have fenders. On an upright bike, fenders are very useful, so that
you don't get the street dirt on yourself. With a trike, where you are
practically "behind" the front wheels (at least when steering), I'd
expect this to be much more important? Or are the streets so clean where
you live? At least here there's *lots* of dirt on the streets (including
glass shards) and in case of rain, it's the same... So, in conclusion
I'd expect (front) mudguards to be close to safety-critical on a trike?
How much dirt and water and mud do you get "up your nose"?

I find my trike too nice to ride in the slop. However, if I were going
to, fenders/mudguards would be the first addition.

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

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.

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

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.