Would like to make an eTrike less prone to tipping over

General Discussion about electric bicycles.
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Would like to make an eTrike less prone to tipping over

Post by momus3 » May 20 2020 5:04pm

I'm going to buy a Sun three wheel trike and put an electric kit on it. These are well built bikes, and about as cheap as you can get in the trike line. But having once owned a non electric one, I do remember they can tip over. Placing the battery as low as possible should help, but these things are probably inherently unstable compared to the lower slung trikes (which I see as dangerous, because even w/ a flag they're below the sight line of a car that's next to you).

How about a gyroscope to help keep it level? Granted, all I know about a gyroscope is from playing with a toy one 50 years ago, but the physics seem sound enough. Just looking for something to help, not necessarily fix a problem that any three wheel bike presents. In the likely event that this is a loony tunes idea, I would be grateful for any suggestions that might help with keeping the bike upright at top speeds of 15-18 MPH.

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Re: Would like to make an eTrike less prone to tipping over

Post by MadRhino » May 20 2020 5:36pm

There are 2 ways to keep a trike from tripping. You either build it drifting, or tilting.
Make it fool-proof, and I will make a better fool.
Current bikes
Street:
Trek Session 10 mod. Variable geometry. 70mph
Dirt:
Santa Cruz V10. 50mph

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Re: Would like to make an eTrike less prone to tipping over

Post by dogman dan » May 20 2020 6:41pm

Well, there is the option of mastering the two wheel turn on one. not for everybody.

Best advice on those trikes is buy the kit designed especially for them, which is sold by E-Bikekit. Its a slow wind motor, which gives the kit what you need, slow. 15 mph top speed, which is about as fast as you can safely ride those trikes. The basic issue is not that they tip in a turn, you'd have to be pretty brave to try the two wheel turn at 15 mph plus. But what happens is any camber in a road will pull you to the ditch. This pull gets really strong over 15 mph, and also it just gets hard to change your line, let alone turn above 15 mph. So jinking around a broken bottle gets impossible at 25 mph. Ride 15 mph tops, and you should be ok. Brake on the hills, so you don't bomb down one at faster than you can steer.

It helps some to make the wheelbase longer, It helps some to make the seat lower. That's what we did when Amberwolf and I got together and built his cargo trike. We combined a typical trike rear end, with a custom built front end that resembled a recumbent bike I have. It came out lower than normal, but still visible above the hood of most cars or trucks. The modifications made it safer at 20 mph.

Still tips, but its harder to tip, the lower you can get your seat to be.

Sun also makes some legit recumbent trikes, which perform a LOT better than the tall trikes. I test rode pretty much all of them at one point, when I worked at EBK. They do sell electric trikes, as well as the trike conversion kits. https://www.electrictrike.com/

The EZ, or the sun seeker are good recumbent delta trikes. I found the EZ easier to get used to, and liked that it is a bit taller. The best trikes though were all very low tadpole trike types. Those are really hard to tip.

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Re: Would like to make an eTrike less prone to tipping over

Post by aroundqube » May 20 2020 8:25pm

Looney Tune idea https://www.youtube.com/watch?v=l6ZV9tsTENY . This guy later added return springs and made a new video.

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Re: Would like to make an eTrike less prone to tipping over

Post by MadRhino » May 20 2020 8:30pm

aroundqube wrote:
May 20 2020 8:25pm
Looney Tune idea https://www.youtube.com/watch?v=l6ZV9tsTENY . This guy later added return springs and made a new video.
I like it. It is a very simple method to build a tilting trike.
Make it fool-proof, and I will make a better fool.
Current bikes
Street:
Trek Session 10 mod. Variable geometry. 70mph
Dirt:
Santa Cruz V10. 50mph

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Re: Would like to make an eTrike less prone to tipping over

Post by Returnformer » May 20 2020 9:49pm

aroundqube wrote:
May 20 2020 8:25pm
Looney Tune idea https://www.youtube.com/watch?v=l6ZV9tsTENY . This guy later added return springs and made a new video.
doesnt that defeat the whole point of a trike? you lose the stability that the rear wheels offer like that...

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Re: Would like to make an eTrike less prone to tipping over

Post by MadRhino » May 20 2020 10:04pm

Returnformer wrote:
May 20 2020 9:49pm
aroundqube wrote:
May 20 2020 8:25pm
Looney Tune idea https://www.youtube.com/watch?v=l6ZV9tsTENY . This guy later added return springs and made a new video.
doesnt that defeat the whole point of a trike? you lose the stability that the rear wheels offer like that...
Are you talking about the stability that makes a trike trip upside down when cornering at 15 mph?

Of course it could be built with limiting linkage and shocks to make it tilting stiffer but still, it is a considerable improvement in handling and safety. A return spring alone is probably enough to park it straight. I find it is a simple, cheap way to build a tilting trike. It is safe to speed and corner now.
Make it fool-proof, and I will make a better fool.
Current bikes
Street:
Trek Session 10 mod. Variable geometry. 70mph
Dirt:
Santa Cruz V10. 50mph

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Re: Would like to make an eTrike less prone to tipping over

Post by amberwolf » May 20 2020 11:24pm

momus3 wrote:
May 20 2020 5:04pm
I'm going to buy a Sun three wheel trike
Which specific Sun Trike?

They make various designs, and each one will have different anti-tip recommendations.


How about a gyroscope to help keep it level? Granted, all I know about a gyroscope is from playing with a toy one 50 years ago, but the physics seem sound enough.
It would have to have a large mass to help much--something on the same order as the trike & rider & cargo / etc. Or it would have to very high RPM, if it's small. The energy total has to be enough to help cancel out the change in direction.

It will also make it more difficult to maneuver the trike; depending on how it's mounted (orientation, etc) it may actually be more dangerous than just riding slower, because you may not be able to change directions when you actually need to.

I would be grateful for any suggestions that might help with keeping the bike upright at top speeds of 15-18 MPH.
If it's one of the upright bike-height-saddle trikes with large wheels, then your only real option is to slow down a lot (<5MPH) for almost any kind of turn, and do not swerve at all for anything while riding straight at over 10-12MPH, depending on road/wind/etc conditions at the time.


If you have a lower-center-of-mass version, then there may be some other things you can do.


If you're willing to rebuild it, you could probably make it much less tip-prone, but you'll still have to slow down for turns.


See my SB Cruiser trike thread for a design that can make some righthand turns at 15MPH+, depending on conditions, and lefthand turns (which are much wider) at a bit faster speeds, depending on conditons.

But it is a VERY heavy trike, with a very low deck (even though I am riding at about car-driver-height), and much of the weight is at the outboard rear in the very heavy hubmotors, and the heavy battery in the cargo/seatbox. So is probably not what you're looking for. (it's designed to haul 150-300lb+ loads (dogs, groceries, dogfood, etc) in the cargo area, and pull a big trailer for more than twice that much).

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Re: Would like to make an eTrike less prone to tipping over

Post by donn » May 20 2020 11:56pm

Image

I believe John Morciglio has something to do with that, and it's tricky to handle.

An experimental tilting design from Wisconsin: https://sites.uwm.edu/bike-motorcycle-l ... -tricycle/

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Re: Would like to make an eTrike less prone to tipping over

Post by MadRhino » May 21 2020 12:48am

That one is a revolution in tilting trike design. Variable tilting is another world, for velomobiles especially.
Make it fool-proof, and I will make a better fool.
Current bikes
Street:
Trek Session 10 mod. Variable geometry. 70mph
Dirt:
Santa Cruz V10. 50mph

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Re: Would like to make an eTrike less prone to tipping over

Post by Balmorhea » May 21 2020 2:10am

momus3 wrote:
May 20 2020 5:04pm
I'm going to buy a Sun three wheel trike and put an electric kit on it. These are well built bikes, and about as cheap as you can get in the trike line. But having once owned a non electric one, I do remember they can tip over.
Yes, that’s a characteristic of their weight distribution and track width. You can’t get around it; you can only go at the speed they were intended to go.

I recently converted an ancient Sun granny trike for a buddy of mine. i used an also ancient 500W Heinzmann hub motor that gave it a roughly 15 mph top speed. It’s very noisy, but almost cool. He has ridden the trike quite a lot before the conversion, so he understands its limitations. I feel confident that he will be able to avoid getting hurt. If it were capable of 20 mph, I would not feel so confident.

Anymore, it’s getting difficult to find hub motor systems that are intrinsically limited to 15 mph or less. But that’s what you want. Not a system that wants to go 25 mph but is electronically limited, but one that winds out at a safe speed for your particular deathtrap. That gives you the abundant low speed torque and high cruising efficiency that will do you any good.

MAC 12T at 36 volts? Leaf 11T at 48 volts? The good news is that you won’t require very much power to maintain the speeds a granny trike can do safely. You’ll get lots of range from not too much battery.
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Re: Would like to make an eTrike less prone to tipping over

Post by amberwolf » May 21 2020 2:41am

Balmorhea wrote:
May 21 2020 2:10am
Anymore, it’s getting difficult to find hub motor systems that are intrinsically limited to 15 mph or less. But that’s what you want. Not a system that wants to go 25 mph but is electronically limited, but one that winds out at a safe speed for your particular deathtrap. That gives you the abundant low speed torque and high cruising efficiency that will do you any good.

MAC 12T at 36 volts? Leaf 11T at 48 volts? The good news is that you won’t require very much power to maintain the speeds a granny trike can do safely. You’ll get lots of range from not too much battery.
one option (I think it's expensive for what it is, but...)
https://www.ebikekit.com/collections/tricycle-kits

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Re: Would like to make an eTrike less prone to tipping over

Post by donn » May 21 2020 9:52am

momus3 wrote:
May 20 2020 5:04pm
In the likely event that this is a loony tunes idea, I would be grateful for any suggestions that might help with keeping the bike upright at top speeds of 15-18 MPH.
Of course on the other end of the radical solutions spectrum, there's 2 wheels - a bike for real. I mention it because while it's natural to equate "bike" with the common upright design, there are recumbent bicycles that put you in the same more enjoyable position as the expensive trikes, but higher up so you aren't looking up at the undersides of cars and yet much more able to take curves at speed.

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Re: Would like to make an eTrike less prone to tipping over

Post by MadRhino » May 21 2020 10:43am

Riding with cars around, you want to be nimble and balanced, being able to react quickly to any dangerous situation.

City trafic environnement is not the ideal place to ride a recumbent, that is at its best in long rides with few obstacles.

Trikes, even when they are high and visible, still have the handicap of width that is limiting their options to avoid obstacles. Tilting design does make a narrower width safe, with much faster cornering ability.

Most trikes that we meet in the city, are condemn to keep off the car lanes, and a tad too wide to ride the bike paths without intruding on the upcoming lane.
Make it fool-proof, and I will make a better fool.
Current bikes
Street:
Trek Session 10 mod. Variable geometry. 70mph
Dirt:
Santa Cruz V10. 50mph

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Re: Would like to make an eTrike less prone to tipping over

Post by donn » May 21 2020 11:36am

MadRhino wrote:
May 21 2020 10:43am
Riding with cars around, you want to be nimble and balanced, being able to react quickly to any dangerous situation.

City trafic environnement is not the ideal place to ride a recumbent, that is at its best in long rides with few obstacles.
Maybe not ideal in that respect, but as often happens we may make some compromises that are not ideal. I probably wouldn't make that compromise and select recumbents for my city's bicycle mounted police force, but I have for myself! A two wheeled recumbent bicycle, that is. In other cities it might be different, don't know - but people there might tell you that bicycles are not ideal for that environment, any of them - so riders in those places must recognize that they're crazy, and only need to decide how crazy.

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Re: Would like to make an eTrike less prone to tipping over

Post by momus3 » May 21 2020 8:24pm

I was thinking of the model that Sun calls their "Traditional" (cheapest) with 7 speeds. My old non electric Sun was a one speeder, which was actually fun once you got into the cadence rhythm. It looks easy to drastically lower the seat and move it rearward to get more of a pedal forward thing going, but I'm stuck with the short wheelbase unless I want to cut the frame and extend it. Not looking to do that as I don't have a welder anymore.

Thanks for the tip (unfortunate word) about the E-Trike kit. I saw that guy's video recently on youtube. That's exactly the Sun model I want to electrify. But I'm going to try and place the battery more centrally if possible. Maybe on the down tube or seat tube, and add some ballast under the rear basket. Or go w/ two batteries, and put the second one under the rear of the bike. The more weight I can get nice and low, the less tip happy it should be. I agree, 15 MPH is probably plenty fast enough for a trike, especially one with only one brake on the front! That will need to be changed for sure. I'm comfortable going 20-25 MPH on my eBike, but that seems way too fast for a trike.
Last edited by momus3 on May 21 2020 9:50pm, edited 1 time in total.

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Re: Would like to make an eTrike less prone to tipping over

Post by momus3 » May 21 2020 9:36pm

I still think the solution to trike tipover is plain old physics. The more mass an object has, the more it resists changes to it's direction, and more mass means more inertia at speed, so it will tend to remain on it's trajectory. Gyroscopic action stabilizes objects, keeps them on-center, and a low center of mass increases stability. Leaving aside the horizontal gyro idea, wheels are simple vertical gyros. If I bring the seat way down on a trike, add mass to the lowest possible part of the bike, add more mass to the three wheels with oversize tires, heavy duty thorn proof tubes, slime, and also add a heavy, gyro front hub motor, the tendency to tip over should be substantially reduced. Adding weight is not an issue with this sort of powered vehicle.

This is why motorcycles are much more stable at speed than eBikes. They're much heavier, the weight is generally low, and the bigger and heavier wheels act like gyroscopes. Anyone who has ever ridden a scooter with little wheels immediately notices how much less stable they are than a motorcycle.

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Re: Would like to make an eTrike less prone to tipping over

Post by amberwolf » May 21 2020 10:05pm

momus3 wrote:
May 21 2020 8:24pm
. I agree, 15 MPH is probably plenty fast enough for a trike, especially one with only one brake on the front! That will need to be changed for sure. I'm comfortable going 20-25 MPH on my eBike, but that seems way too fast for a trike.
For *that* trike. Not for all of them by any means, even non-tilting/leaning ones. ;)

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Re: Would like to make an eTrike less prone to tipping over

Post by amberwolf » May 21 2020 10:33pm

momus3 wrote:
May 21 2020 9:36pm
Adding weight is not an issue with this sort of powered vehicle.
Speaking from the experiences of my heavy cargo trikes, it *is* an issue for a number of things, though some may not become apparent at the lower end of the scale.

The frame has to be stronger (and usually that means it itself must be heavier).

The wheels have to be higher pressure (or significantly taller) to resist squishing down and getting pinch flats or damaging rims / breaking wheels (or axles!).

Accelerating (or going up any slope) takes a lot more energy, so it means a much lower gearing and lower speed to use the same energy to go up a slope, or a lot more power to go the same speed, or accelerate at the same rate. More wasted heat, etc. If the motor fails, and you don't have low enough gearing for your strength, you then can't go up the slope or get started moving from a stop (or accleration will be much slower).

Braking becomes more difficult, as there is much more energy to dissipate. So braking distances become longer, even if you have good brakes (because a brake can only do so until the wheel skids, at which point you're no longer braking, you're skidding and have lost control, if your front wheel is skidding, you can't really steer).

Where the added weight goes is important, and conflicting for different purposes.

To keep the wheels loaded evenly, it needs to be in the center, proportionally between all the wheels (hence SB Cruiser's cargo/seatbox with battery/tools/etc in it, and me on it, as close to the middle as I could get it...but when carrying cargo it goes behind that over the rear wheels, so loading is almost all on the rear wheels)

But to decrease tipping, the weight should be divided between the outboard wheels and placed as far outboard as possible (hence SB Cruiser's heavy hubmotor rear wheels, which make it much less prone to tipping than a front hubmotor and regular rear wheels).

Etc.

I still think the solution to trike tipover is plain old physics.
Of course it is. ;) But it isn't always a simple single solution. Physics is complex, and the more complex the system and the more complex the problem to solve, the more complex the solution may be, as it has more than one thing it has to do.

The problem of trike tipping is not simply the tipping, as noted here and elsewhere. The trike has many things it must do, and may have more depending on your particular uses for one.

The more mass an object has, the more it resists changes to it's direction, and more mass means more inertia at speed, so it will tend to remain on it's trajectory. Gyroscopic action stabilizes objects, keeps them on-center, and a low center of mass increases stability. Leaving aside the horizontal gyro idea, wheels are simple vertical gyros. If I bring the seat way down on a trike, add mass to the lowest possible part of the bike, add more mass to the three wheels with oversize tires, heavy duty thorn proof tubes, slime, and also add a heavy, gyro front hub motor, the tendency to tip over should be substantially reduced.
<snip>
This is why motorcycles are much more stable at speed than eBikes. They're much heavier, the weight is generally low, and the bigger and heavier wheels act like gyroscopes. Anyone who has ever ridden a scooter with little wheels immediately notices how much less stable they are than a motorcycle.
It's not the wheel size (or gyroscopic mass), it's overall geometry, proportions of mass above/below axles, etc., and all the other things you're talking about.

Gyroscopic action might make it go in a straight line better, but the stronger it is, the more it makes it harder to turn when you need to, which can make it more dangerous in traffic or some other conditions. If it's not so strong as to keep you from turning easily, it isn't likely to keep it from tipping over in the turn once you get started turning, though.

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Re: Would like to make an eTrike less prone to tipping over

Post by donn » May 21 2020 10:38pm

momus3 wrote:
May 21 2020 9:36pm
This is why motorcycles are much more stable at speed than eBikes.
Well, indeed a motorcycle is a better ride at the speeds they're designed for, than a bicycle, and at higher speeds in that range I expect the same holds true for larger vs. smaller motorcycles ... but this is at the highest level of hand waving generality. Whether one is more stable than another is going to depend on what you mean by "stable." Were we talking about curves? In a "spirited" ride in the twisties, a lighter motorcycle is going to have a bit of an advantage, I believe.

That doesn't mean you're wrong about moving the center of gravity down, I think everyone's on board with that. It's just, that's a tricycle problem, and doesn't really have anything to do with bicycles.

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Re: Would like to make an eTrike less prone to tipping over

Post by MadRhino » May 21 2020 11:39pm

Only suspension and tilting design can make a trike ride as good as a bike, and that is the dynamic physics where the solution resides. If it is rigid, it is like a deficient 4 wheeler in the sense that it can either trip or drift, only it will start doing it at much slower cornering speed.
Make it fool-proof, and I will make a better fool.
Current bikes
Street:
Trek Session 10 mod. Variable geometry. 70mph
Dirt:
Santa Cruz V10. 50mph

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Re: Would like to make an eTrike less prone to tipping over

Post by Balmorhea » May 21 2020 11:50pm

momus3 wrote:
May 21 2020 8:24pm
I was thinking of the model that Sun calls their "Traditional" (cheapest) with 7 speeds.
I just built one of those. They have a rear disc brake now, but it only acts on the driven wheel.

For what it's worth, the Sun Traditional is probably the best made, most vetted granny trike I've worked on.
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Re: Would like to make an eTrike less prone to tipping over

Post by Triketech » May 25 2020 12:24pm

Sun makes a variety of trikes from upright to recumbent in both delta and tadpoles. It would help to know which one you're choosing.

As for stability, mount the battery low with about 5-6" ground clearance as close to the centerline front-rear as possible. May need to offset a bit to clear chainline.

Mount it as close to the two wheel axle center as possible. That enables the paired wheels that control stability to do their job most effectively.

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Re: Would like to make an eTrike less prone to tipping over

Post by ddk » May 25 2020 8:19pm

momus3 wrote:
May 20 2020 5:04pm
... In the likely event that this is a loony tunes idea, I would be grateful for any suggestions that might help with keeping the bike upright at top speeds of 15-18 MPH.
older trike before fork build.jpg
older trike before fork build.jpg (98.08 KiB) Viewed 285 times
I built this loony tunes thing from an upright trike, capable of turning at speeds that scare me without tipping. Cost about $2600 and features dual motors, dual battery packs and dual throttles (dual ever liddle thang)
-would likely cost about $1K more because trump happened/ :pancake:
"How can we play Hot Wheels without lighter fluid? " -Serge

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Re: Would like to make an eTrike less prone to tipping over

Post by momus3 » May 28 2020 12:53am

That is a serious trike DDK! I love it, but it looks like a cop magnet. Them folks I don't want to attract.

I instinctively knew that a gyro was the way to go, but wasn't prepared for all the hi tech mechanisms and complexity that are required.

These guys have come up with the final solution for keeping a 2 or 3 wheel bike upright, but it comes with a huge cost in weight and involves some expensive engineering. If someone could figure out how to simplify this design and bring the costs down, it has the potential to revolutionize 2 and 3 wheel transportation. Or, people will just say, why not just buy an old Toyota with 4 wheels for 2,000 bucks, and it won't tip over either :)
https://www.youtube.com/watch?v=QlLV1ZPdB9A

https://www.youtube.com/watch?v=NH0PSiTIozI

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