Delta trike design - constraints and solutions ?

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Hi all
So I have a urge to build a ' standard ' delta trike , by standard I mean not a Python , twisting chain or MBB.
So driven rear wheel and front wheel out front on a fork.

What do I want ?
Short as possible - storage - fit in car etc etc
Narrow as possible - fit through barriers - fit in car etc
170' front wheel movement
Light as possible

Nice to have
2wd
Suspension - 2 or 3 wheels


First think is constraints and then possible solutions.
Nothing is necessarily true nor cast in stone just observations ?

So first thing to do is look at the engine and it's mounting [ i.e seat ]



Now the 60" is not fixed and depends on several variables some change able and some constants ?


ConstantsVariables
Leg lengthSeat back anglethe more laid back the seat back the longer the engine becomes
foot lengthPedal crank length [ not really ]short cranks just move BB forward , maybe useful ?
height difference between seat base & BBObviously if yours knees were bent 90' it would considerably
shorten the trike at the expense of more height and less power

From the example above it can be seen if the rear wheel axle was on the left hand dotted line that would add 1/2 a wheel diameter to the length 10" [ 25cm ] for a 20" [ 405 ] wheel
If a normal fork was mounted in front of pedals 2" [ 5cm ] for clearance and a 20" [ 50cm ] wheel adds another 22" [ 55cm ]
This gives a total length of 92" [ 232 cm ]



Strangely the Hase kettweisel has a total length of 81" [ 205cm ] probably because the pedals are raised and so half the wheel width is under the pedals.



This is Brad's DeltaWolf which will be longer than the Kett due to the lower pedals , also this show's well what happens as we bring the drive wheels under the seat to shorten the trike.
The plus side is the engines CofG comes closer to the axle so increasing stability in corners [ sitting on a wider part of the stability triangle.
the negative side is the wheels can come in contact with the elbows.

On a home build that is not much of a problem as body work i.e fenders can be built to stop that.

The Finns like to get the rear wheels well forward :-



This is Sakari SH18 delta trike , also notice perimeter frame rather than mono boom , another option to be discussed.

Of course 16" [ 305 ] wheels could also shorten the trike by at least 4" [ 10 cm ] however the velomobile boys consider 16" wheels really need suspension , certainly my 2 wheeler with a 16" front wheel needs very careful handling when mounting dropped curbs etc due to it's smaller radius.

So a look at engine mounts next ?

Paul
 
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So my next consideration is the engine mounts ?



So my seat needs 2 mounts
A) middle of back
B) under front of seat

I also need to consider the mount for the feet - the BB

For stability/handling issues I will set the seat height at 10" - 12" [ 25 - 30 cm ] enough to keep me out of some of the dirt , not to low I can't get in and out of it.

So frame options next

Paul
 
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I know this may be a bit off the wall but if your are building it just for you and it doesn't need to be very adjustable for leg-length could you not make it so the main keel folds under and backwards to park the front-wheel close to the frame and in-between the 2 rear wheels?

So,
  • Seat off.
  • Steering link removed on a quick-release at either end.
  • Hinge loosened and un-clipped from safety lock.
  • Frame lifted at hinge-point, front swung under main keel and held with velcro sling/strap.
Note: Trike should be significantly shorter but NOT much taller (if the hinge provides and angle to make the front wheel side-step the main tube).
If that's too much of a "faff" to engineer then put the front wheel on a QR axle and remove it and let the front forks sit either side of the keel and stow the front wheel separately.

Just some ramblings.
 
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Nice idea Danny but too much faff for me at least. Front wheel will be hub motor with rim brake so no easy disconnect. Chain goes to rear wheels so will get in the way- floppy, oily thing to deal with. Cables and wiring being regularly folded in half would probably end in something becoming flakey after a short while.

I've got the height in my shop to stand my present trike upright (almost 8' long) but with wife's granny trike and heaps of 'bits' it doesn't leave much room to work in now. Tried to tell wife I need more space but with two garden sheds and a 38ft long workshop she doesn't see the need. They just don't understand :)

John

Just to note the roof is apex type so side wall height is nearer 6ft which means trike has to stand near to middle where it gets in the way. If I could somehow get the main spine to concertina down a couple of feet it would be great.
 
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I know this may be a bit off the wall but if your are building it just for you and it doesn't need to be very adjustable for leg-length could you not make it so the main keel folds under and backwards to park the front-wheel close to the frame and in-between the 2 rear wheels?

So,
  • Seat off.
  • Steering link removed on a quick-release at either end.
  • Hinge loosened and un-clipped from safety lock.
  • Frame lifted at hinge-point, front swung under main keel and held with velcro sling/strap.
Note: Trike should be significantly shorter but NOT much taller (if the hinge provides and angle to make the front wheel side-step the main tube).
If that's too much of a "faff" to engineer then put the front wheel on a QR axle and remove it and let the front forks sit either side of the keel and stow the front wheel separately.

Just some ramblings.
Suppose it depends why and how often you want it shorter ?

For me it is every ride it needs to be as short as possible so won't work.
To get it in the car it might work , however does it then turn it into a heavy immovable lump with no where to grab hold of it ?



The latter Kett's fold , however as you can see it is now sat on it's mudguards so cannot be ' wheeled ' anywhere and is VERY unwieldy to lift into a car [ especially if you are on your own ! ]

Paul
 
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Yes I can't honestly see folding somethig like this would be very practical for 'between rides' use. Maybe for winter storage (I'm a fair weather biker) it could be worth the time and effort to fold up but for me it isn't worth the effort to actually build it all into the structure.

Great thread Paul. Hope Danny and others keep offering their ideas.

Just took a first look through that catalogue of designs you linked to. WOW! The sublime to the ludicrous! Some great builds there and some you look at and think 'WHY'!!!!! Truly great to see so many different ideas of the best way to make a machine.

John
 
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Ok so looking at 5 frame options :-



Scaled for wheels to be 20" rear track approx 30" and length about 80"
A) standard mono boom - DeltaWolf etc etc
B) weird asymmetrical Finnish trike with of without RWS
and


Scaled for wheels to be 20" rear track approx 30" and length about 80"
C) a peripheral frame trike using least amount of tubing and joints
D) same as C except tubing is parallel to ground from rear wheels to joint where it sweeps up the front fork.

Now in the future of this trike I would like some body work like this :-



imagine this body work is 4 parts rear incorporating wheel arches - front and 2 side pontoons where the trike can run with either:-
front only
rear only
front and rear
front and rear joined by side pontoons and fabric doors/tonneau to keep weather out.

So A) then becomes a problem because you would have to step over the side body work and the main frame to get into it.
Also A) has almost no frame in points you would like to mount the body
Also A) has the drive buried in the middle of the trike hard to access

B) C) or D) do not have that problem as they are peripheral frames and the centre in front of the seat and around the pedals is free of body work
Also B) C) or D) can have the drive running down the outside of the body so making it much easier to work on and cover up to keep rain/grit off it ?
This does require making Z cranks which will take some trial and error and time as it is completely new to AZ [ as far as I can tell ]

5 frames ? well the 5th is a mad idea of a sheet plywood trike similar to the frame Popshot tried , he has tried to warn me off with to heavy [ 9mm plywood ] and to flexible ?
My plan was to try 6mm plywood and build in some box sections down it's length.
I will try and make a card board model of it to the same scale as these ASAP.

So plenty to ponder Paul
ps with no clear cut winner so far
 
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With ply I tried to shortcut what was needed by using thick ply and only really making an open double part box structure. If using wood I suggest it must be thinner and involve a lot more boxing to add the needed strength effectively making box girders that interlock properly. It will almost certainly be a lot more work than welding box section steel. My effort was neither light enough nor strong enough.
 
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FWIW (probably not much) I think a wooden structure is for those who either a) love carpentry and working with timber or b) are not good with working with steel or don't have the tools or know-how to make a strong steel structure. A third type may be those who just love experimenting and fancy trying a different medium (a la Popshot?)

If you are wanting to make yourself a strong and efficient vehicle to actually use daily to get from a to b you would be better using a system you know and are proficient at. If a joint cracks in steel you get out the welder and stick it together. If a joint cracks in a monocoque style wood structure with stressed boxing and doublers (steel or wood) at stress points you have major problems. Also wood gives you splinters :)

John

PS I love the shape of that red Sinclaire C5 lookalike. Wish I had the skills to make something like that!
 
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Perhaps a delta isn't the best solution. A SWB quad could be very short and very good at turning. The delta pictured is approx the size of the kettweisel at 82" and has a turning circle of 123". The bottom quad has an overall length of 60" and a turning circle of 147". The top quad has the same length of 60" but a shorter wheelbase and a turning circle of 115" marked by the yellow circle which follow the pedals' path as they protrude beyond the front wheels.

 
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I should look it up I know but is a quad style cycle considered exactly the same as a trike in the UK? ie no constraints over and above what a trike has in construction and use.

John
 
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FWIW (probably not much) I think a wooden structure is for those who either a) love carpentry and working with timber or b) are not good with working with steel or don't have the tools or know-how to make a strong steel structure. A third type may be those who just love experimenting and fancy trying a different medium (a la Popshot?)
Well yes and no ?
In my mind [ not a safe place to be IAH ] if the plywood was used correctly it could form the lower half on a covered trike and be the chassis ?
A monocoque no less ?

If you are wanting to make yourself a strong and efficient vehicle to actually use daily to get from a to b you would be better using a system you know and are proficient at. If a joint cracks in steel you get out the welder and stick it together.
Well I currently have the Python to fall back on , and my property is littered with the remains of ' almost worked ' stuff.
As Churchill once said of success ' going from failure to failure without loss of enthusiasm ' I'm in:D


If a joint cracks in a monocoque style wood structure with stressed boxing and doublers (steel or wood) at stress points you have major problems. Also wood gives you splinters :)
Both sadly true

PS I love the shape of that red Sinclaire C5 lookalike. Wish I had the skills to make something like that!
I see it differently ? I just think how can I make that with the current skillset & tools.
Also I see all my stuff as ' looks good from 6ft ' that helps a lot !
As DannyC will attest the Python is a mosaic of bodged shape changes and being adpated for changing requirements all drowned under a thick coat of 70's metallic hammered copper paint...

Paul
 
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Well this tour de force is going to take some answering , thanks for capturing the electrons for me to read [ serious - not p*ss take ]


Perhaps a delta isn't the best solution. A SWB quad could be very short and very good at turning.
Can you quantify short ? and is that w/b or length ? one thing restricting turning can be the position of the pedals in relation to the front wheels ? if they overhang the front wheels to much in a confined space they hit the obstruction before you have turned enough to go around it ?

The delta pictured is approx the size of the kettweisel at 82" and has a turning circle of 123".
Size is that w/b or length ?
Turning circle measured from outside of outer wheel I assume ?

The bottom quad has an overall length of 60" and a turning circle of 147".
What do you reckon w/b to be ?
Usually in a package if you shorten something you make it higher , what do you estimate the seat height to be ?

The top quad has the same length of 60" but a shorter wheelbase and a turning circle of 115"
again w/b ?

marked by the yellow circle which follow the pedals' path as they protrude beyond the front wheels.
Your drawing implies the gap between the front and rear wheels could be 20" wow that's not a lot.
Using my ' engine drawing in post #2 that would be rear of rear wheel touching left line and front of front wheel touching right line [ my drawing is not to scale ! ]


Very nice drawing.

What dimensions would you need to depict my Python like that ?

I am not adverse to a quad however I am not into spending all my life correcting the tracking to stop it being like riding through treacle !

Where would this figure turning circle wise if drawn as above ?



It's a drawing for a very successful 20" wheeled UK pedal car , made to meet these rules :-

3. Dimensions
3.1. Maximum overall length: 3000mm
3.2. Maximum overall width: 1125mm
3.3. Maximum overall wheel diameter (measured over the inflated tyre): 560mm.
3.4. Maximum height of uncompressed seat cushion (above ground level): 400mm
3.5. Minimum distance between the centre of the wheels (track width) measured between the contact patches of the tyres on the ground: 650mm
3.6. Minimum distance between front and rear axles: 650mm
3.7. Maximum height of car and seated driver (including helmet): 1050mm (to clear timing gantry)

Safety Note: Experience shows that short wheelbase cars are significantly less stable in corners and
designers are urged to ensure an adequate size for their cars.



Thanks much food for thought

Paul
 
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So a quick bit of Lego later .......



So this is A) with a Quad track is 30" and w/b is only 40 "



and same quad with option D]

I think turning circle will be limited by width of frame needed to clear my lower legs [ or uppers if sat to far forwards ]



Hmm .......
This looks much longer than the Lego model ?

Need to find the scale drawing and have a measure.
Paul
 
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Delta size is length.
Bottom quad wheelbase is 30". Top is 40".
Circle measured to outer front wheel except where the pedals overhang the front enough to proscribe the bigger yellow circle for the shorter quad.
Seat height would depend on width. To get good turning you'd need to maximise wheel articulation which can and will narrow the area for legs. Too narrow and you need to get above the wheels to allow them to turn. These are just very basic layouts and not fully fledged plans just to show the potential. Actual turning circle will depend not just on wheelbase but the amount of angle the steering can generate.
To depict the python so I need the wheelbase and the maximum steering angle you can pedal the front at plus distance from pivot to front axle. If you can turn tighter freewheeling then give that angle too.
Will have a look at the pedal car when I'm back at the desktop. I'll have to guess at the steering angles that could be generated just as I've done for the others though they are at least based loosely on reality.
 
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Are they 20" wheels? The chap could be very tall and he is very laid back. There's 6" of wheel behind him too.

Very short quads will indeed be twitchy. No argument about that. That yellow part finished pedicab thing on ebay and gumtree recently was pretty short on wheelbase as was the blue jobby with the fabric body - can't remember it's name.
 
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Are they 20" wheels? The chap could be very tall and he is very laid back. There's 6" of wheel behind him too.

Very short quads will indeed be twitchy. No argument about that. That yellow part finished pedicab thing on ebay and gumtree recently was pretty short on wheelbase as was the blue jobby with the fabric body - can't remember it's name.
Yes they will be 20" , not many tyres for 16" also you can see from the disc size.
That has a 50" w/b, that makes sense as the front wheels are in line with the pedals and so that looks right next to my Python @ about 40" +- 2" ;)

Blue jobby ?



Podride home

The videos of it being ridden on a BMX track were frightening , I suspect it did fall over just that bit was edited out ?


and yes it is VERY short maybe a crazy 30" w/b hence the height

Paul
 
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Safety Note: Experience shows that short wheelbase cars are significantly less stable in corners and
designers are urged to ensure an adequate size for their cars.
Well if you go quad you could always also go AWS so you don't end up like this -> 🙃
 
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