Collapsible Trike

I guess it’s time to start a build thread, looking for constructive suggestions.

If any of this looks familiar I posted on this a while ago when researching the hub motors.

Not sure if it belongs in Bicycles/Scooters/Motorcycles/Large EV? Doesn’t really fit in any category. It is made almost completely from Bicycle parts. All the answers I’ve found have been in the Bicycle section so that is where it will start.

This was basically my list of requirements.

1. The first constraint is that it must be easily disassembled and collapse down into a small enough package to fit in the storage bay underneath my RV and be light enough to be managed by me without assistance. I have determined the optimal storage size is a 24x24x42 inch box, basically the size of an extra-large storage bin.
2. It must be able to carry two adults side by side giving them a Golf cart like experience, easy to get on and off, will mostly be used to run around campgrounds and resorts, an auxiliary vehicle for our RV.
3. Will mostly be used on flat ground occasional hills, mostly paved, dirt or gravel roads found in resorts, campgrounds and state parks, possibly the occasional foray off road on fields, beaches or trails found in campgrounds and Parks, top speed 15 – 20 mph, faster would be nice on occasion.
4. Driven by Two 48v 1500W 20 inch Fat Tire hub motors (already own them) on the rear of a trike type vehicle. Since it will be used on both paved and dirt roads I wanted the ability for the drive tires to work independently. With the size of the occupants (we are not small people) I wanted plenty of power, I also wanted the fat tires due to some of the conditions we find in a lot of the Florida campgrounds, two drive tires for traction issues in sand, mud, loose gravel or possibly snow. Using self-contained Hub motors will simplify construction and maintenance.
5. Electrically speaking a 48 Volt, 100 AH Lifepo4 battery pack, I want to be able to charge from a plug in charger or in most cases I want a Solar panel roof that will not only charge the batteries but serve as a roof from the sun and rain. Four 100 watt Solar panels should provide enough charging wattage, and have a small enough footprint to be stored more easily than one large panel.
6. I also want to include USB and 12volt charging ports and a 110 volt inverter so it can be used as a power/charging station for multiple uses, or even back home during a power outage. Most importantly, we are amateur astronomers and want to power all of our telescope and imaging needs in the field.
7. Must be semi pleasing to look at, pass the wife’s cosmetic requirements.

After several discussions with my local steel guy we finally decided the base of the frame would be made out of 1.5 inch, 14 gauge steel square tubing and the upper part of the frame would be 1.5 inch angle iron, mostly for strength, the steel would be stronger and more flexible for the size and price and I can weld it myself with the arc welder I already own.

After much research I decided on 20 inch 48 volt 1500 watt hub drive motors, with included controllers, throttle and wiring. Based on cost, availability and being able to procure replacement parts, tires, tubes. 1500 watts is probably more than I need but with the weight I will be carrying and the difference in cost between 750 and 1500 watts was like $10, currently on AliExpress the 1500 watt is less than the 750.

The hub motors would be mounted inside both sides of the frame to make it easier for storage and provide more seat area. Gooseneck and front fork would be detachable using a receiver hitch type system and store inside the box when in storage mode. I picked up a damaged BMX type 20 inch fat tire bicycle to scavenge the tires, front rim, fork, handle bars, steering tube and some of the brake parts.

The top of the box will be the seat.

The rear axle dropouts are more of an axle drop-in. With slots cut into ¼ inch plates welded to and extending above the frame to keep the wheel mostly enclosed in the frame, providing a solid mounting place for the axles and maintaining the 24 inch overall height and providing a box large enough to store the front fork, gooseneck, front tire and battery, secondary plates slotted in the opposite direction are also bolted on. This provides a very stout axle mount that prevents axle rotation and is relatively easy to remove.

I tried having the Dropout plates cut on a plasma table, in the end it was easier to just drill and cut the slots with an angle grinder.

I am building the base of the frame first to provide proof of concept, if it doesn’t work I could still bail without much cost or effort.

I have the frame base welded together and finally welded the dropouts in after taking way too much time to make sure the tires were aligned with each other.

The next step was to do a proof of concept and see just how viable this thing might be.

After installing the hub motors I took the frame of the donor bike and using a couple of large U-bolts attached it to the frame base then wired everything up using the 48V 14ah battery from my bike.

These are the Hub Motors I used :
AliExpress Hub Motors

Apparently I looked at them too many times and they were keeping track and emailed me a price I couldn’t refuse.

I ordered them with the cheapest controllers and displays possible, I plan on upgrading to a dual motor controller that will do reverse and regenerative braking in the future. For this testing phase I used the included hardware with a throttle for each thumb.

First with just one motor powered, then both motors. One motor was not good, skewed to one side badly, two motors, much better, first with two throttles then with both controllers wired to one throttle.

All I can say is WOW, I definitely bought too much motor, You need to be very light on the throttle or it will flip over. I’m now adding a wheelie bar to the list of requirements.

It actually ran and rode very good, almost made me stop there and keep it like that, it is very fast, scary fast, handles pretty good, stopping with just the one front rim brake was sketchy but quite the ride.

With the concept proved it is time to move to the next phase, fabricating the removable front fork and gooseneck.

Peter

I'm looking for the 'two adults side by side' aspect?

offGridDownUnder said:

I'm looking for the 'two adults side by side' aspect?

Click to expand...

Excuse my horrible artwork, this was my original concept drawing.
The back of the seat will fold down when in storage mode.
It will be 42 inches wide, the wife and I sat down and measured what we though was the best width for us to sit comfortably and maintain a large enough box on the inside to store the disassembled parts with an overall width small enough to easily fit in the storage bay of the RV.

Peter

Peterbylt said:

sat down and measured what we though was the best width for us to sit comfortably

Click to expand...

Certainly. However, your photo above shows a front wheel and steering gear centered, and while the seat is wide enough, you will not be centered when the two of you are using it - this is what I was inquiring about.
As a low speed vehicle, a tiller might be better than handlebars. OTOH perhaps the handlebars are just as good and symmetric for riders stationed on either side.
Just curious.

I did a little CAD (Cardboard Aided Design) to help decide the best position and angle for the front fork.

Having used 2 inch receiver hitch tube for the center of the Base, I used 2 inch receiver bar for the goose neck, Class III receiver hitches can tow something like 10,000 pounds so I feel pretty secure it can support my fat A$$. An afterthought that 1.25 inch Class 1 Receiver hitch tube would have worked just fine and weighed considerably less but the 2 inch stock was what I had sitting around the shop.

I intended to use the steering tube off the BMX frame, but instead used a longer thicker walled tube off an old Huffy frame that I had sitting around, after spending the better part of an afternoon cutting it off the bike frame and carving a piece of Receiver tube to accept the steering tube I had a fabricator friend Tig weld it together.

I cut and welded the goose neck to match the cardboard templet, drilled a few 5/8 holes for the hitch pins and mounted the BMX fork using new headset bearings.

I am pleased with the overall result, although I think I might have given it a little too much rake, it looks more like a Chopper. I will have to see how it handles. It will be relatively easy to make another gooseneck with less rake, will need to change the angle and lengths to keep the height the same, your thoughts on the Rake angle?

I took it out and rode it around the parking lot using various heights to determine the best height for the seat/top of the box, my original height of 24 inches from the floor seems to be the best overall height.

It rode and handled very good, the rake will stay the same for now, I am going to extend the gooseneck and push the front tire out at least 12 inches to provide adequate foot/floorboard room and add a little more weight advantage out front.

The gooseneck, fork and front tire disassemble in minutes just by pulling the hitch pins, an initial test shows that all the parts should fit neatly in the finished box.

Next Step, fabricate the upper part of the frame, add some rear brakes, on hind sight I should have included the caliper mounts when I made the dropout plates.

Peter

I finished welding the angle iron upper part of the frame.

Could probably add in a few more supports, but trying to keep the weight down.

I also got some cheapo Bucklos disk brakes and welded in some caliper mounts, I was able to utilize one of the dropout plate bolts and a new tab mount welded on the top, the positioning should allow me to remove the wheel without removing the calipers, thought about using hydraulic and still might, but with the amount of movement and abuse the hoses would take when removing the front fork and handle bars for storage, figured I would try cable Brakes first. I bought a dual pull Brake handle off amazon, with a little adjusting I should be to apply even pressure to both calipers.

Dual cable Brake lever

The front rim brake works pretty good and will stay for now.

Then I started building the Box, mounting and wiring the controllers.

Waiting on the Lifepo4 battery to arrive from China, the 14ah Bike battery moves it along pretty good, but the two 1500 watt motors eat it up pretty quick.

Probably start work on the seat next, I need to hinge the top piece of plywood.

Before I do anything else I need to take it for a ride with both me and the wife on it to see how stable it is with two people, and how easy it is to run the controls and steer while sitting to the side.

Peter

You're going to lay that wretched little kidbike fork to waste almost immediately. With a raked out head angle like that on a trike, you will need probably three times as much fork offset as that fork has before the thing doesn't flop hard to one side or the other. The handling will get better as it bends forward with use, but at some point it will give up and either drop you to the ground or break off.

With side by side seating, it's a special concern because a moment's inattention or letting go of the bars could cause them to whip around and smack your copilot.

A triple clamp fork for chopper bikes would help you two ways. First, it's much stronger and less likely to bend. And second, it has a great deal more offset than the garbage fork you have there. So it will have less tendency to flop, less self-steering in whatever direction is downhill, and less likelihood of collapsing or breaking off.

One example, not a specific recommendation but only the type of fork I'm talking about:

And here's a picture of another one:

I agree the fork needs to be replaced with something like you have shown, but not for the reasons you think, I stress tested that fork quite a bit before installing it, I clamped it in the vise and tried to break it, some of those forks might be questionable, not this one, I have jumped on it and jumped with it, very strong.

The main reason I would like to replace it is to get the lugs to install Disk Brakes that will allow the front tire to be more easily removed for storage and I like the look of the Triple Tree arrangement, plus the posts will serve as a sort of Bump stop to keep the Handle bars from whipping around. I also want to take a little of the Rake out. The steering works great as is and I have run it up over 30 MPH, but I think less Rake will be an improvement, only testing will tell.

I would also like to keep the suspension in the front fork.

I added in a temporary front floorboard and took a couple of extended rides both with and without a passenger also had a few other people take it for a ride for feedback.

The one thing everyone agrees on is the motors are definitely too powerful, you definitely need to have a light touch when first getting on the throttle, once they have that under control everyone likes the handling and ride, The brakes are surprisingly effective.

I will look into the possibility of creating or getting if something already exists, a reduced acceleration mode, much like the Tesla Chill mode, maybe there are Motor controllers with an Easy or Soft Start?

There is not an issue with either side using the controls when two people are riding on it, I do need to put some sort of side rails or handles for the passenger to hang on to.

I stretched the gooseneck by twelve inches, this gave us much better foot room, a better angle for the handle bars and made it easier getting on and off as well as improving the feel of it while driving.

I also started working out the fitment for the seat, considering using Futon hinges so I can ratchet it up for sitting or lay it flat for storage.

As always, I appreciate any constructive comments or suggestions.

Peter

Peterbylt said:

The one thing everyone agrees on is the motors are definitely too powerful, you definitely need to have a light touch when first getting on the throttle, once they have that under control everyone likes the handling and ride, The brakes are surprisingly effective.

I will look into the possibility of creating or getting if something already exists, a reduced acceleration mode, much like the Tesla Chill mode, maybe there are Motor controllers with an Easy or Soft Start?

Click to expand...

There is a chance your controllers have wiring for a "3 speed" switch,
which is effectively 3 current limit levels.

Most generic chinese controllers are "speed" (also known as duty cycle) controllers, which means throttle position directly correlates to a target wheel rpm, the controller dumps all available current to achieve target rpm.
That is probably why the throttle is sensitive at zero wheel rpm.
A three speed switch can help tame this.

More advanced controllers use "current control" where the throttle is commanding a target current, instead of "Get to this rpm as fast as you can"

Peterbylt said:

I ordered them with the cheapest controllers and displays possible, I plan on upgrading to a dual motor controller that will do reverse and regenerative braking in the future. For this testing phase I used the included hardware with a throttle for each thumb.

Click to expand...

I should say from the get-go, I have no direct experience with the typical advanced programmable controller, e.g. Fardriver, Votol, ASI, Kelly, etc., so I am probably a bit biased in my recommendation.

Since you plan on upgrading,
my recommendation would be the VESC software/hardware platform, a completely open source motor control software/firmware suite, started by Benjamin Vedder around 2015.

A quite wide selection of VESC compatible controllers are available.

I can probably answer nearly any question you have about VESC.

Cheers,
Adam

I appreciate the suggestion to look at the VESC controllers, I took a shallow dive into VESC world, a lot to see and understand.

The Dual ubox Aluminum Lite controller or the Flipsky Dual 75100 controller look like either could work, a lot to learn and I probably will end up there at some point.

In the meantime I found this,
GREENTIME Dual Drive 48/60/72V 3000W

The reviews on it are not bad and it has most of the things I want, can handle two 1500 watt hub motors, Soft start, reverse, braking and a nice display, I will probably give it a try for just over $60.

The seat didn't come out to bad given my total lack of experience in upholstery, I made the foam too thick with 4 inch foam and should have used 2 inch.

I also made a mistake using the futon hinges, although it is nice to lay it flat for storage it does not allow the seat to sit up straight enough and is just not solid enough for the rigors of a vehicle like this, I have already broken the seat back a couple of times, probably make the seat back removable for storage, any suggestions?

I have started with some aluminum diamond plate body and floor panels. The general consensus seems to be, leave the tires exposed on the side and the back as opposed to covering them over with diamond plate panels, what do you think?

It certainly is fun to drive I get people asking about it wherever we go. The range is currently limited to around 8 miles with the 14ah Bicycle Battery, I am waiting on the 100ah LifePO4 battery to arrive from China before I do any big changes to the wiring or add any accessories.

Peter