Best Geometry for a Reverse Tilting Trike #6

In this video, I show different tests to find the best geometry for the DIY Tadpole / Reverse Tilting Cargo Trike / Tricycle.
With the tests I find the best caster, camber, toe and steering ratio and tune for the Ackerman geometry.

If you are interested in the build, please check out the playlist:

You are welcome to find and download the CAD files:

Video chapters:
0:00 Intro
0:48 Tests
03:32 Caster
08:53 Toe
11:54 Camber
20:19 Steering Ratio
22:08 Final Geometry
25:50 Steering Ackerman
29:18 Future Improvements
33:32 Riding

Thank you to the artist of the end song for making it available in the YouTube Audio library:
Old Bossa by Twin Musicom is licensed under a Creative Commons Attribution 4.0 license.

[thewerst]

As the lead engineer of the original Arcimoto cyber trike project, good show friend.

[tarikr]

This is the most important video on tadpole tilting cargo trikes on youtube. Thank you very much

[stirfrybry]

I knew a genius fabricator who created a 4 wheel mountain bike with a roll cage body and I followed him at 50 mph on the first run at Plattekill where we were downhill racers. anyway. his toe-in was about 1 degree and camber was about 7 degrees. His vehicle had a solid rear axle so he could use the inside rear wheel to friction brake in sweeping turns. It was awesome to behold

[ichebensonstniemand]

Castor and Camber work in tandem. As you have observed, a lot of caster will make your bike stable at speed but when riding slow, it tends to 'fall' into the curve. This is because as you turn the wheels, the frame of the bike moves lower. Therefore the weight of the bike acts as a force that wants to increase steer angle. Camber has the opposite effect, when you steer away from straight, camber will lift your bike (with 0° caster) . Therefore the weight will always push it back to its lowest position, which is going straight. By choosing caster, you can control high speed stability, by matching camber you can restore / adjust low speed stability.
Toe at 0° is usally for best efficiency, which i guess is most important in bikes. If your ball joints do have a little play toe out / toe in will put preload on them and they wont flop around all the time. This preload techinque is also used because ball joints have a reduced livetime if the direction of force does change often. This may be irrelevant on a bike that does a lot less miles and is way lighter.
As a rule of thumb, 20° caster is already unuasally high and compensation by camber will not work perfectly anymore. typ. is 5-15° in the applications i know
Another factor you havent touched on is the length of the control arms. Usually, the lower arm is longer than the upper arm. This gives the effect off added camber when the suspension is compressed. One reason for this is to eliminate tire scrub when going over bumps, the other reason i believe is added stability when carrying heavy cargo. This may also be a reason why lengthening your lower control arm for added camber gave you such benefits. However it can also be done by moving the frame mounting of the upper control arm further outside.
And when changing suspension geometry, always check that the sterring rods and their joints are still correctly spaced in the plane of the other joints, otherwise you will introduce bump steer. Bump steer is when compressing the suspension changes toe.
Very cool project of yours and i completely understand that a test must be reduced to some variables, thank you for the work you put into this experiment!

[Shiryas]

Bravo! I am not building a cargo bike but loved every minute of your analysis and commentary. Please continue, looking forward to the next revision.

[SEThatered]

Tadpole cargo trikes make the most sense:
- two tyre contacts in the front
- redundant front brakes
- can use a tilt-lock
- retains the simplicity of a single rear wheel
Love it!
P.S. : there are similar trikes called "HNF Nicolai CD1" and "Mäx & Mäleon"
You could look up what values they used as a reference.

[bootsowen]

This has to be one of the best cargo bike builds on YT. Well done Pedro. I have thought about building a3 wheeler so many times, but I have been riding a 2 wheel 8freight for years and for me the benefits of 2 wheels on the infrastructure in the uk outweigh the benefits of 3 wheels. But I would still love to build one like yours.

[S-I-R-E]

I'm not sure if anyone else did but I found this useful to understand what toe, camber and castor means and now I plan on using this information to make better tunes in Forza horizon 5. Had the general idea on camber but visualizing it helps a whole lot more. Thanks.

[Alby_Torino]

Your creations are getting better and better. This trike is just brilliant. Greetings from Italy

[audaxrallymedia]

Hello! Engineer here :) Nice to see that this idea keep moving these days. I have done a lot of leaning trikes with motor. Let me share some insights?
First one - consider a Roll center. Surprisingly, but CG for Leaning trikes must be at groung level instead of over it like a car design. Thats why you struggling with balance while ride without hands. The second - Ackerman angle: Try to decrease amount of it because : A. slip angle of tyre, B. tyre works on a sidewall while leaning and you get camberthrust.
And last one. Due to long base your front (air) spring too stiff so it would be harsh with strait (especially at high speed)..
(and.. front wheel pressure. IDK but there might be 30-50% lower than ordinary bike)

[hojbota-ptv]

I'm building a tilting trike but with enclosed cabin for weather protection and better aero, this vide is super useful, thanks

[SEThatered]

Toe is not typically used on leaning vehicles.
Because they lean, the just don't need it: tilted wheels solve that issue already.
0 toe is fine.

[emmabird]

Hi Pedro, well done. Nice piece of work.
As regards Toe, I would suggest 0deg. In cars they sometimes set a toe that allows for the flexure of the rubber bushes so that the end result ubder load is 0deg. 0deg is minimum scrub so maximum tyre life and minimum drag.
As regards castor, you are altering trail (the distance between the steering axis intersection with the road to the tyre intersection) as well. Increasing trail will make the steering a bit heavier, decreasing trail will make it twitchier. It also means that in transferring your results to a larger wheel (if you did that) may alter the optimum.
For the ball joints binding I suggest putting a bend in the arms so that the ball joint is at 90deg to the steering axis to even out the play in the 2 directions so lean-ability is maximum.
Finally, neg camber will wear the tyres on one side. So from time to time swap the tyres left to right and vice-versa to get best life out of them.
Doing away with your castor plates will let you shorten it a bit without affeting your load bed.
Finally, if you had a lean lock, that would be handy when you have to stop for junctions, traffic lights (both feet on the pedals) and parking. It may also help balance on really steep hills. You could delete the side stand too.
Lovely job, I look forward to the next part.

[atomicsmith]

A mechanic once explained to me that toe-in gives very little real benefit to steering or stability, but that exactly 0 toe is very hard to maintain and even slight toe-out has a very negative effect on steering. Therefore slight toe-in gives a slight safety advantage.
Really enjoyed this video and your process!

[dnbnetwork]

I'm not engineer but having a good feel with technical stuff my opinion is that if camber no toe, it is one or the other, both is too chaotic for a smooth ride and you actually already proove that camber is usefull to add. Congrat for your patience!!and thanks, this was great and really usefull for the community.Ps you gave me some more reasons to make mine!!Thanks again Pedro.

[transistor]

Nice project thanks for sharing. Any Camber will "work the spokes" as the wheel rotates, i.e. the load in the spokes will go positive and negative with each rotation of the wheel. Athletic Wheel chairs with camber have problems with spokes loosening.

[framegrace]

The corect turn geometry is the one that when turning, the projections of the two wheel angles alyways cross in the extension of the back axel.
Toe mostly used on cars to enhance break and acceleration performance, and fix changes of geometry on wide wheels.
Usually, for the geometry and handling toe-out is what you want. It may help tweak the lost of handling from caster.
Maybe 6/5 degrees is too much for toe.

[pdxRoberge]

You are a skilled scientist and inventor. This video is much appreciated for your detail are care for these very relevant topics.

[chuckvoss]

very helpful technical tests. thank you for sharing your knowledge.

[mikedoingmikethings]

When we visited Amsterdam, I amazed by the cargo bikes that I saw there and been meaning to fabricate one similar to what I saw there. Yours is a bit more complex for me ahaha but by seeing this build, it gives me motivation to go ahead with my project...