E-Trike Design: Balloon Tires vs Dedicated suspension

qwerkus

10 kW
Joined
Jul 22, 2017
Messages
785
Hello,

I'm working on a Delta trike and was going for a full suspension dual wishbone design, when I realized for that price I could build 2x sturdy FWD Deltas without suspension but larger tires instead.

Here the current status of the fully:
fully_delta.jpg
Expected advantages are: comfort, better cornering abilities and enough torque thanks to a 2000w belt-mid-drive option.
Drawbacks: price, complexity, limited cargo capacity

The other option would be a simple frame with 2x single shaft rear mac hub motors - all 3 wheels 20x3.3":
balloon_tires_delta.jpg
Expected advantages: sturdy, simple design, more cargo volume and cheaper
Drawbacks: limited speed due to poor cornering abilities, slightly heavier than first version. FWD could be tricky and limits steering angle.

Here is a concept of the front drive:
fwd_Concept.jpg
To somewhat mitigate risk of chain slip, I'd go for a IGH anyway. A derailleur / tensionner is still required to allow for some chain slack during turns.

My experience with trikes is limited, so any feedback / thoughts on this would be very welcome!

PS: Modelling done with blender 2.81
 
I know nothing about tricycles, but I ride a bicycle of similar configuration.

The need for suspension depends on what you're riding on, and how fast, right? I never thought much about it, until I put on the motor and my average speed went up. The problem wasn't so much the discomfort as the rattling, I felt like I was abusing the bicycle. Whether tires are enough or not, will depend on what you're riding on and how fast. In any case, as you know, you can't do anything about it physically, like you can on an upright platform where you can stand up on the pedals and absorb shock with your knees, it's a plain "dead" load.

As for the design ... I suppose it's it's the least of your worries, but front shocks are probably not going to make a big difference.

Thinking about rear suspension design, I guess that may be one of the reasons for the popularity of the "tadpole" design with two wheels in front. A minor reason, though; the main reason as I understand it being tipover stability.
 
donn said:
I know nothing about tricycles, but I ride a bicycle of similar configuration.

The need for suspension depends on what you're riding on, and how fast, right? I never thought much about it, until I put on the motor and my average speed went up. The problem wasn't so much the discomfort as the rattling, I felt like I was abusing the bicycle. Whether tires are enough or not, will depend on what you're riding on and how fast. In any case, as you know, you can't do anything about it physically, like you can on an upright platform where you can stand up on the pedals and absorb shock with your knees, it's a plain "dead" load.

As for the design ... I suppose it's it's the least of your worries, but front shocks are probably not going to make a big difference.

Thinking about rear suspension design, I guess that may be one of the reasons for the popularity of the "tadpole" design with two wheels in front. A minor reason, though; the main reason as I understand it being tipover stability.

Good point about speed. Max speed depends on cornering stability, which depends on bike geometry and the ability to tilt. From what I gather, this type of delta is meant for comfy commute speeds. A 4 to 5° rear wheel camber would probably help - see design 1. My target would be 25-30km/h cruising with 45km/h beeing the absolute max in straight lines. Yeah: riding recumbent = every bump hits your entire back. Not a fan of tadpoles: very limited cargo possibily and tricky to step in or out - at least for someone as flexible as I am! I did not model the cargo yet, but both deltas should able to carry a 60 x 40 x 35 eurobox.
 
Flexible halfshafts will be the big challenge.

If anything was suspended on a Delta Trike, I think its probably more practical to keep a live axle with long trailing arms mounted just behind the Bottom Bracket and a panhard rod for lateral stability.

Or just go with Fat tires. They do improve the ride quality but no where near what suspension can provide.
 
I'm not invested enough to think about it very hard, but ... do you need equal, symmetric power to the rear wheels? Might be less complicated to put pedal drive on one wheel and electric on the other.
 
Better cornering abilities will come with full suspension, either wishbone,
or
Copy to some degree what that company in the Netherlands did with the Velotilt .

https://gearjunkie.com/velotilt

They are out of business BTW . so you could probably copy much of their design .
 
Triketech said:
Flexible halfshafts will be the big challenge.

If anything was suspended on a Delta Trike, I think its probably more practical to keep a live axle with long trailing arms mounted just behind the Bottom Bracket and a panhard rod for lateral stability.

Or just go with Fat tires. They do improve the ride quality but no where near what suspension can provide.

Not sure what you mean by "flexible halfshafts". Samagaga has pretty much everything you need for a flexible drive shaft. All you need is the correct length and they ship the whole kit cut to size. Not cheap though.

There is actually not much experimentation in my fully design: only proven concepts - thought I've never seen a rear dual whishbone suspension. The only manufacturer I know of making full suspension delta is hase, and they opted for a complex dual chain trailing swingarm solution which seems just over engineered. Also 7500€ :shock:
If you look past the cycle world, all karts and higher power vehicles use wishbones. I allows for a great deal of flexibility in the setup, and a fair deal of adjustments (camber for once!)

donn said:
I'm not invested enough to think about it very hard, but ... do you need equal, symmetric power to the rear wheels? Might be less complicated to put pedal drive on one wheel and electric on the other.

Not convinced by that one. In the fully design you need flexible axles anyway. Adding a differential between the two is a no brainer. And once the diff is in, using it for a mid drive solution seems to be the more efficient solution.
In the hardtail version, I'd like to keep it as simple as possible, without long chain & co, so motor power in the back and human power front. I chose a dual motor design because a single hub would probably overheat under load. Theoretically a single large DD on one side would be enough, but I'm concerned by by balance issues: cornering on the side of the heavy motor would tip the trike even quicker.
 
qwerkus said:
In the fully design you need flexible axles anyway.

I can take your word for it, but maybe you can explain that, for those not well versed in such things? If the drives are independent - say the hardtail version had no pedal drive, just a motor in each hub, then there's no real need for more axle than what it takes to mount a dropout on, no? I'm assuming freewheel gearing that allows either wheel to carry the other.

In reality, with a chain from the front, that would need to drive a more centrally mounted gear and hence a longer axle. Given that, it would make sense to take the motor off the hub and put it on a similar longer axle on the left side, but those two axles wouldn't need to be joined through any differential, just mounted on a common suspension joint.
 
There was a mention about cambered rear wheels to help with cornering. My current trikes are both Sun Delta X3-AX models, which have cambered rear wheels. It does help with cornering, but it doesn't prevent tipping. Never tipped over, but have raised the inside wheel off the ground which will happen on a delta and on a tadpole if you are going too fast for the corner.

The down side of cambered rear wheels includes lower load capacity and accelerated tire wear. The Sun EZ-3 USX also has cambered rear wheels and the original model was replaced with an identical HD model, and the only change I can see is 48 spoke wheels with wider tires.

One of my X3-AX trikes has 1.35 X 20 tires at about 60 PSI and the other has 1.75 X 20 tires at about 40 PSI on the same narrow rims. There is a definite difference in the ride quality, plus the wider tires do not wear as fast. When the current 1.35s wear out they will be replaced with 1.75s. If I could justify it I would replace the narrow rims with a wider rim and go to an even wider tire.

For my style of riding I would prefer non-cambered wheels, but I'm happy they are there when cornering at speeds over 20 MPH.
 
I wonder if there's a way to use something like suspension, to apply the sideways payload inertial force to the axle in a way that tilts the wheels to the opposite direction.
 
Tires are not replacing any kind of suspension. Fat tires are not improving the ability of a vehicle to handle speed. They can improve grip, or digging on loose surfaces, at lower speed especially.

Thinking that tires can be a suspension is a common myth. Shock absorption is the result of positive and negative travel, combined with rebound dampening. A tire can give you only one of those three required parameters, and very little of it. The result is a handicap instead of an improvement, since the main purpose of a suspension is to maintain the most constant and even contact of the wheel with the ground. Bigger tires only make for the need of longer suspension travel to achieve that purpose.
 
MadRhino said:
Thinking that tires can be a suspension is a common myth.

It's not so much the tires than the air inside the tube that act as a form of suspension. Nobody is ever going to argue that more air in wheels can replace a dedicated suspension, but at speeds below 35km/h, it's good enough for commuting, and beats any 4 arms linkage design in terms of simplicity - especially if you tried to put a fat DD hub in there.
I was going the fully route all the way until a couple of years ago I discovered DD hubs in 20x3" wheels. Now I ride this bike nearly every day because it's so comfy! I just rolls over any small obstacles on the road. Of course it comes at the cost of noticeably increased rolling resistance and I'd never go on a trail with this bike but as said: in many scenarios, it's good enough. After all, that's why tubed rubber wheels got so popular in the first place: because they make for less harsh ride!
 
Rassy said:
There was a mention about cambered rear wheels to help with cornering. My current trikes are both Sun Delta X3-AX models, which have cambered rear wheels. It does help with cornering, but it doesn't prevent tipping. Never tipped over, but have raised the inside wheel off the ground which will happen on a delta and on a tadpole if you are going too fast for the corner.

The down side of cambered rear wheels includes lower load capacity and accelerated tire wear. The Sun EZ-3 USX also has cambered rear wheels and the original model was replaced with an identical HD model, and the only change I can see is 48 spoke wheels with wider tires.

One of my X3-AX trikes has 1.35 X 20 tires at about 60 PSI and the other has 1.75 X 20 tires at about 40 PSI on the same narrow rims. There is a definite difference in the ride quality, plus the wider tires do not wear as fast. When the current 1.35s wear out they will be replaced with 1.75s. If I could justify it I would replace the narrow rims with a wider rim and go to an even wider tire.

For my style of riding I would prefer non-cambered wheels, but I'm happy they are there when cornering at speeds over 20 MPH.

Great input, thanks! I read a lot about camber angle, and it seems the increased cornering ability is a matter of debate. Main advantage is actually a wider wheel base whith the same frame, which does improve stability.
 
qwerkus said:
MadRhino said:
Thinking that tires can be a suspension is a common myth.

... below 35km/h, it's good enough for commuting

Yep. At 35 kmh on the streets, suspension is not required. 3 inch tires are best for most ebikes, and the larger the wheel the better the handling, the smoother the ride. Fat tires, 4 to 5 inch, are a handicap in performance but they are OK at 35 kmh.

The choice of wheel size and tire width is personal, according to the terrain, purpose of the bike, efficiency and riding style. Yet, not so many riders have had comparative test rides with various wheel sizes and tires on their usual course.
 
first question is, why do you want suspension?

do you have poor road conditions, or is it for offroad, etc?

if you have smooth roads, you don't need suspension.


example: my sb cruiser trike (link in signature) is a large and heavy completely unsuspended delta cargo trike, used on relatively smooth city roads. there *are* bad areas, where i wish i had suspension ;) but it functions fine without it, as long as i avoid potholes and road debris and the like.

adding suspension to it would increase it's cost, reduce it's capacity (or increase it's size) and increase it's complexity (and likelihood of failure and/or increased maintenance).

i'd still like to add some basic suspension for the rear end at some point, probalby in a future version, just so i don't have to be as careful when heavily loaded to not hit potholes, curb edges at the wrong angle, etc.


but back to your design...what are the specific things you need your suspension to do? what do you need it to protect you, your cargo, and/or your trike itself from?
 
qwerkus said:
Expected advantages are: comfort, better cornering abilities and enough torque thanks to a 2000w belt-mid-drive option.

i would not assume that a suspended trike will handle better. In fact, it will lean to the outside of a turn, which could increase the likelihood of tipover (or lurching all over the road to avoid tipping over). Trikes are much more treacherous and ill-handling than they appear. In the absence of anti-sway features (which I’ve never seen firsthand on any trike), suspension can exaggerate the worst vices of three-wheelers. It doesn’t help to keep the tires in better contact with the pavement most of the time, if the end result Is ending up on your head that much sooner.
 
MadRhino said:
Shock absorption is the result of positive and negative travel, combined with rebound dampening.

Tires have sag, positive and negative travel, compression damping, and rebound damping. They don’t have velocity sensitive damping, and whatever damping they have adds to rolling resistance. But it’s inaccurate to say tires don’t have these things.

Mechanical suspension came before pneumatic tires, but the tires were a bigger innovation.
 
amberwolf said:
first question is, why do you want suspension?

do you have poor road conditions, or is it for offroad, etc?

if you have smooth roads, you don't need suspension.


example: my sb cruiser trike (link in signature) is a large and heavy completely unsuspended delta cargo trike, used on relatively smooth city roads. there *are* bad areas, where i wish i had suspension ;) but it functions fine without it, as long as i avoid potholes and road debris and the like.

adding suspension to it would increase it's cost, reduce it's capacity (or increase it's size) and increase it's complexity (and likelihood of failure and/or increased maintenance).

i'd still like to add some basic suspension for the rear end at some point, probalby in a future version, just so i don't have to be as careful when heavily loaded to not hit potholes, curb edges at the wrong angle, etc.


but back to your design...what are the specific things you need your suspension to do? what do you need it to protect you, your cargo, and/or your trike itself from?

Good questions - as always from amberwolf. There is no need for suspension, only a wish for a smoother ride. I have cargo experience with long john and trailers - no cargo trike so far, and in both cases, suspension improves not only my back/knee-pain (that's the reason why I want to go recumbent) but also the transport quality: stuff doesn't get bounced around by every small hole in the street. Now do I need dedicated shocks for this or can it be done to an acceptable level with wider tires, that's the remaining question.

Balmorhea said:
i would not assume that a suspended trike will handle better. In fact, it will lean to the outside of a turn, which could increase the likelihood of tipover (or lurching all over the road to avoid tipping over). Trikes are much more treacherous and ill-handling than they appear. In the absence of anti-sway features (which I’ve never seen firsthand on any trike), suspension can exaggerate the worst vices of three-wheelers. It doesn’t help to keep the tires in better contact with the pavement most of the time, if the end result Is ending up on your head that much sooner.

Interesting point. Can you elaborate on this ? I've never ridden fully Kettwiesel, but according to manufacturers specs the suspension supposed to help lean the torso inside curves when cornering. Not sure that would be possible with 40kg additional load, but it does make sense to me.
 
MadRhino said:
Tires are not replacing any kind of suspension. Fat tires are not improving the ability of a vehicle to handle speed. They can improve grip, or digging on loose surfaces, at lower speed especially.

Thinking that tires can be a suspension is a common myth. Shock absorption is the result of positive and negative travel, combined with rebound dampening. A tire can give you only one of those three required parameters, and very little of it. The result is a handicap instead of an improvement, since the main purpose of a suspension is to maintain the most constant and even contact of the wheel with the ground. Bigger tires only make for the need of longer suspension travel to achieve that purpose.

How TRUE ! Your's should be the sticky answer to one FAQ, Rhino.
 
I can only say it would be interesting to try a delta trike with rear suspension. My thoughts ran towards trying to use the cheap rear swingarm assemblies on Walmart mtb's to try it.

But you might be able to achieve similarly comfortable ride by simply making the trike a long tail. what I mean is get the rear wheels more behind the riders ass, allowing the teeter totter action of a longtail to happen. Wheels go up and down, but the saddle of a proper longtail simply rocks back and forth. Cargo still gets a rough ride though.

This of course, does mean a larger, harder to park at home vehicle. But its not like you are going to carry a trike on the bus, or car.
 
dogman dan said:
I can only say it would be interesting to try a delta trike with rear suspension. My thoughts ran towards trying to use the cheap rear swingarm assemblies on Walmart mtb's to try it.

Same here. Was looking for 2x fully swingarms for some time now in the second hand market, and it's super hard to find two identical pieces. Getting brand now mtbs just to harvest the swings is too wasteful in my opinion, and would still cost at least 800€ here. So I figured that if I'm going the DIY weld route, better add the wishbone to the todo list and keep the money for something else.
 
I love the idea of a trike or something similar. Strange that this should come up as I got this suggestion on my YouTube feed https://youtu.be/gYHsDuGBCyU. Don’t know if it would be of any help to you looking through at what the build. On the putting suspension vs fat tires. Can you put suspension on the seat like the do in lorries and tractors?

I look forward to seeing the progress
 
if youre building it I would run the fat tires and put a spring suspension in your seat.. I have a hardtail cruiser with a suspension seat and my ass sits over the rear tire. I ran 26x2.50 and id still feel the cracks in the road. switched 24x3.0 and the ride softened out so much I tried a normal seat and felt the cracks in the road again straight to my spine so suspension seat and fat tire is what I run and its good to about 30mph.

my tadpole I used to run a 20x1.50 on the rear and even with suspension id feel every pebble. switched to 20x2.20 and don't even feel the train tracks now.

I have a traditional trike like yours with 2- 24x3.0 tires on the rear with no suspension seat, its comfortable but my ass isn't over the rear axle. I need to change the rims on it to about 2.5 inches wide. the tire has blown the bead a couple times. my 24x3.0 is on a 2.675 inch wide rim and ive run it upto 65km/h regularly never had an issue with cornering or speed.
 
qwerkus said:
stuff doesn't get bounced around by every small hole in the street. Now do I need dedicated shocks for this or can it be done to an acceptable level with wider tires, that's the remaining question.
exactly how big a hole, of what shape and size and depth? and at what speed would it be hit? and what weight would the wheel hitting it have (weight balance of the trike, weight on each wheel)?

each of those will change the results of what happens, with and without suspension, and depending on the actual suspension design, travel, rate, etc.

if all you have is little unevennesses in pavement, and a relatively light trike, tires with a lot of air and lower pressure will probably be enough.

if you have giant chunks of pavement missing down to the roadbed from winter salting or heavy vehicle traffic, even suspension by itself may not be enough--you may need large diameter wheels with very wide tires and rims to spread the impact enough to prevent wheel damage...and you're likely to still feel the impacts regardless of suspension design (unless you have something optimized for this like offroad stuff).


if you need a lot of travel, it is also going to make your whole trike taller and the cog higher, making it even more likely to trip, unless the wheels and suspension are outboard of any cargo area you have, as well as your seat, etc., so that you can keep the cargo deck and your body mass low to the ground (below axle height if possible).


suspension is a complicated thing, when engineering a vehicle for a usage scenario.

there are simple suspension designs...but they arent' as effective at some things as the more complex designs; depending on what you want them for, they may work fine, if you can live with the compromises.

more complex ones may have bits to compensate for more things (some of them problems the suspension itself causes, like roll in turns).

not every suspension design is appropriate for every circumstance and vehicle design and set of needs.

some are very common designs for certain classes of vehicle, but even within the basic design there will be specific adaptations for that particular vehicle and intended use.


I've never ridden fully Kettwiesel, but according to manufacturers specs the suspension supposed to help lean the torso inside curves when cornering.
that will only happen if there is something like the antiroll bars in automotive suspensions, which allows each side to be independent, except when the mass of the vehicle pushes down (like in a turn) on that side, so that it "transfers" (not exactly, but gives the idea) the tilt to the opposite side instead.

there's articles and videos here that explain/show the function
https://www.google.com/search?q=anti+roll+bar&oq=anti+roll+bar

it doens't have to be an actual antiroll bar, just something that does the same function.


note that the wider the track is for a trike, and the heavier it is down low and outside (like with massive hubmotors in the rear wheels), the less it is going to tilt or tip for an unsuspended design.

but for a suspended design, it still depends on the suspension design and amount of travel, compression rate, etc. the heavy wheels will still tend to stay on the ground, but they're no longer directly affecting the rest of the trike, no longer "anchoring" it to the ground, until the suspension reaches the end of it's travel on both sides (travel down for hte outboard, and travel up for the inboard).

if a suspension has a lot of travel, and it compresses easily, then it will also tilt more to the outside of a turn, and the faster the turn the worse the problem, and the higher the cog is the worse the problem.
 
Great feedback - thanks! Not sure how I would implement a stabilisator on a trike.

Made some progress with the fully design. Added the whole diff + axle + knobs setup, plus an IGH. The gear hub allows for a lower COG an solves some issues in the wishbone design, but adds an extra 1kg to the already quite heavy (30kg+) trike. fully_delta_1.jpg

True that suspension adds a lot of parameters difficult to simulate for a noob like myself. This design is getting very complicated anyway, and I doubt anyone is going to build it. I'm going to finish it to have some sort of closure, maybe post the model file online should someone be interested, and than move to the hard tail delta with 3" tires. Besides price / complexity issues, the main argument is the loss of cargo space: the whole back gearbox + suspension in the fully design sucks up nearly a third of useful cargo space.
 
Back
Top