# Gonna build a trike, but it will tilt.



## briogio (Dec 29, 2010)

Hi there, my first post,
I've ridden a BMW and Ducati's for 30 years. Although I love motorcycles they're not stable in any adverse conditions, and now that I like to ride with my wife I want something more comfortable and stable hence a Tilting Three Wheeler, gotta keep that leaning/flying feeling. Anyway I have an 1973 Ducati 750 vintage race bike that I'm going sell part by part which should net me at least $10,000 on Ebay, with that money I want to build myself an e-powered tilting 3-wheeler, inline 2 car seat, exhaust pipe frame, at least 75mph and 150 mile range. Still haven't chosen between Delta or Tadpole but the research process shure is fun. Anyone know of anybody else who has attempted something like this? It's complicated!


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## Duncan (Dec 8, 2008)

Hi briogio

Great idea - I planned a Human powered tilting tadpole but I never got around to making it,

I would definitely go the tadpole - the other type are scary!

I had intended to have the vehicle "kneel" the idea was that in the *low* position the front suspension would be stiff in roll - in the *high* position the suspension would have zero stiffness in roll so you would ride it like a bike at speed and for low speed maneuvers and stops like a car.

To do this you need a *lot* of front suspension travel - about as much travel as you have front track!

I was going to do this by using long forward facing swinging arms - I was going to use the same pivot point as the rear swinging arm! 

Everything is then loaded in the same plane like a bike 

The main - oh bugger - I identified was the steering:
cable steering? 
hydraulic steering?
electronic steering?

Keep us all informed as to how you get on


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## Woodsmith (Jun 5, 2008)

Have a look at the carver for a delta trike.





I also prefer tadpole trikes.
My feeling is that the front wheels have to deal with steering loads, braking loads and stability in cornering so better two of them then one.
The rear wheel only has to push it along so one would do to save having a diff and two wheels.

But all this goes out the window (a bit) when you start tilting so things are different and the Carver seems to have the right idea.

I have avoided tilting trikes due to the potential complexity of getting it right and because I have little balance and was never very keen on leaning on a motor bike. The idea sounds great but then I get travel sick and that is not so great in a helmet.


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## briogio (Dec 29, 2010)

Thinking about the delta/tadpole dilemma before falling asleep, (great time to think), unless I can find a reasonably simple leaning tadpole to duplicate, it just looks too complicated. I think the Carver shows that a delta does works well especially as a long wheelbase vehicle (inline seating). What I'ld like to figure out is, I want to camber the rear wheels out at least 15 degrees for stability and figure out a system to knock the inside wheel in a corner to match the outside wheel. Does it increase rolling resistance very much to camber wheels?
Thanks for the feedback.


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## Woodsmith (Jun 5, 2008)

My instinct says cambering the wheels will add to rolling resistence as the wheels will be trying to scribe a circular path and the suspension will be forcing them to travel straight.

If the track is set wide then you may as well have the wheels upright for more space between then for the pack and motor and stuff.

Did you notice that the Carver's tilt is controlled electronically so the amount of tilt is relative to the speed of steering input. It then works the hydraulic tilting system to force the tilt over.


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## briogio (Dec 29, 2010)

I'm hoping that I'll just be counter steering to lean, the motors (2, just like an aeroplane jet engine has 2 ignitions), batteries, auxiliary bits and luggage will be over the 2 wheels at the back. I could make it a wide track but I'll make covers for them because aerodynamics is very important to this project


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## Woodsmith (Jun 5, 2008)

That's sounds like a good starting point. Not sure on twin motors, depends on the motors and the configuration, but one for each wheel to save on the need for a diff?

Caution on the unaided lean, unless you can put a foot down when stopping you could just lean and fall over.


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## Duncan (Dec 8, 2008)

The problem with the Carver trike is that it only leans the light bits
The back is like a car so it needs a decent track to avoid falling over on corners,
You are then into suspension, weight transfer, and all of those things

On a real leaning trike the whole thing leans so it works like a bike 

Then you get into the steering problems

*Composites*

I agree with HotRod - getting it optimum is difficult - however getting a composite structure strong enough to do the job is not difficult - it won't be as light as it could be - but it will be light

The resin/glass ratio - the main flip side of too much resin is not strength - weight!!
Incidentally this is why you should use S glass and avoid carbon fiber 
carbon fiber is so hard to "wet out" that you use so much resin you get a heavier component than using S glass
(does not apply to pre-pregs) 

_*batteries, auxiliary bits and luggage will be over the 2 wheels at the back.*_

If you are making this design it is imperative that your non tilting part has a low C of G 
the batteries and the heavy stuff MUST go between the wheels as low as possible


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## briogio (Dec 29, 2010)

Actually I like the Carver's design because it's really just me and the wife that I want to lean and I intend to put most of the heavy bits at the back anyway, better to have it stable. What I'm really wanting to do is build a 2 seat leaner as easily as possible, I'm pretty good at fabrication but not so good at complex physics.


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## Woodsmith (Jun 5, 2008)

Duncan said:


> The problem with the Carver trike is that it only leans the light bits
> The back is like a car so it needs a decent track to avoid falling over on corners,
> You are then into suspension, weight transfer, and all of those things
> 
> ...


This is all true and should be taken into account.

If your physics isn't so good then it would be a good time to get out a text book (oops showing my age) and refresh your memory on centre of gravity, moments and forces. You don't need in depth but knowing what it is you need to know about when leaning a trike will help you form questions to ask.

One reason I can see for the Carver is that it is the easier compromise to make. Keep all the complicated stuff together and in a fixed platform and two fixed wheels and lean the simpler part that only has one wheel.


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## briogio (Dec 29, 2010)

Woodsmith said:


> This is all true and should be taken into account.
> 
> If your physics isn't so good then it would be a good time to get out a text book (oops showing my age) and refresh your memory on centre of gravity, moments and forces. You don't need in depth but knowing what it is you need to know about when leaning a trike will help you form questions to ask.
> 
> One reason I can see for the Carver is that it is the easier compromise to make. Keep all the complicated stuff together and in a fixed platform and two fixed wheels and lean the simpler part that only has one wheel.


I said "complex physics" like trying to get 2 front wheels to move in 3 different planes, not necessarily equally, but in perfect harmony, to achieve; turning, suspension, leaning. Centre of gravity, moments and forces, I get that.
"The easier compromise to make"- Music to my ears


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## Woodsmith (Jun 5, 2008)

Ahhh, you mean geometry then.

That does get very complex. There are whole books written on steering geometry and that doesn't include leaning the vehicle on top of steering the wheels.

When you figure it out do post your findings. We'll save you a whole forum for all the posts you may create in the process. 

Seriously though, I studied this a couple of decades ago and have a few books on steering and suspension geometry. You may find some other forums whre members post up spreadsheets showing their calculations and tables for three point links and four point links and independent suspension set ups and other race formats. Some even include king pin inclination, caster changes, camber changes and so on to find *the least bad* (my materials teacher taught me that term on the basis there is no 'best') set up for their needs.
The complexity will make your head spin and sometimes you just need to use experience and a good feel to find a ball park setting to even start from.


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## briogio (Dec 29, 2010)

Woodsmith said:


> Ahhh, you mean geometry then.
> 
> The complexity will make your head spin and sometimes you just need to use experience and a good feel to find a ball park setting to even start from.


Thus my "taking the easy way out" and choosing the Carver route to a leaning a 3 wheel vehicle, even though technically I guess there's only 1 wheel leaning with that set up.

Grand Master of the K.I.S.S. Temple, Local Lodge 1977


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