Electric full suspension tadpole trike for urban delivery job

Hi everyone, I just want to present my project. I work as a bike messenger and I need a vehicle for the rainy winter in my city. The materials here are 50x50mm 1,5mm wall square steel tube for the lower frame, 20x30mm for the upper and plastic body, coroplast or forex. 26inch rear wheel, 20inch front wheels. 7 gear sprocket, Bafang BBS02 750W motor.


I would love to hear what you all think about it!
 
The grey supports at the rear are kinked. A straight line from the lower chassis to the rear shelf would be much stronger and use a bit less steel. Going straight leaves the tube in perfect compression so you could then go to a smaller tube. A tall structure like that will need a lot of support especially if you want a door in it as both sides of the opening then need support.

It reminds me a bit of the epod...


...and that weighed in at 127kg

I'd definitely leave an opening or two for ventilation. You'll sweat a lot even in winter fully enclosed and you'll need a redesign of the steering if you want left at the bars to mean left at the wheels.
 
The grey supports at the rear are kinked. A straight line from the lower chassis to the rear shelf would be much stronger and use a bit less steel. Going straight leaves the tube in perfect compression so you could then go to a smaller tube. A tall structure like that will need a lot of support especially if you want a door in it as both sides of the opening then need support.

It reminds me a bit of the epod...


...and that weighed in at 127kg

I'd definitely leave an opening or two for ventilation. You'll sweat a lot even in winter fully enclosed and you'll need a redesign of the steering if you want left at the bars to mean left at the wheels.
All right! Thank you for the input.

You're on point for the rear support. I'll apply it in the next iteration of the sketch.

I was thinking to use L profile 20x20mm steel "extrusions" or "half a square tube" to build a frame to hold the body. I don't necessarily need to have actual doors, maybe just some tent canvas to pull over... Not sure yet.

Epod looks awesome, I'll look into it to see some details. 127kg seems a lot. I know the Rhoades car weighs 75kg. I got the frame specs from the Rhoades car, 50x50mm 16 gauge steel. I can't weld aluminium and don't want to use screws even tought I could aquire some nice 6061 square tubes.

Yeah, ventilation. I was wondering if it's a bit too much to put it on the front, on the nose so to say, or maybe I'll probably benefit from cross ventilation anywhere I put the openings.

Oh, good observation, the steering is backwards :) Haven't gotten around to do a proper research on how that system works or design a proper one. It's just a placeholder at the moment.

What do you think about smaller wheels both front and back? I was wondering if the thing is too tall as it gets quite windy in the winter. I did put in an angle at the top and bottom for aerodynamics, no idea if it's any good. With smaller wheels I could have a more recumbent position while pedaling and lower overall position and longer wheel base. The taller version, the one in the video allows me to take more of a sitting position and a higher vantage point wich I think are pros.
 
I like the look of the body.
First thought on the frame.... ditch the standard forks design and go with traditional tadpole front geometry.

For simplicity....

For braking power....

For the amount of effort you will be into, might as well make it as robust as possible.
You will also find it easier to connect the fairing, and could add buffering so it isn't rattled to bits over rough terrain.

Keep on posting, looking forward to the evolution of your project.
Brad
 
I think tent material is a good idea. Equally though corrugated plastic is known to make good bodywork on such as this. An opening door could be a roll up window fastening with velcro which would need no support of it's own. I'd go for side ventilation. To get it lower I'd recline more rather than use smaller wheels and would start with something like a Streetfox which uses a lot less chassis. Build a frame from steel and don't worry if it's not a perfectly airtight join at every point on the bodywork. Don't put a floor in as that stops you reversing and is a useful means of ventilation. Keep it as light as you can make it. It's the simplest thing in the world to build something that can't be pedalled because it's too fat.
 
I have also seen some amazing bike fairing work done by stretching spandex over tubing and then applying epoxy.
 
I like the look of the body.
First thought on the frame.... ditch the standard forks design and go with traditional tadpole front geometry.

For simplicity....

For braking power....

For the amount of effort you will be into, might as well make it as robust as possible.
You will also find it easier to connect the fairing, and could add buffering so it isn't rattled to bits over rough terrain.

Keep on posting, looking forward to the evolution of your project.
Brad
Hey Brad, thank you for your input.

I tought about the typical recumbent front wheels geometry but the forks already have suspension built in and that's what I'd prefer because it's a standard part, widely available everywhere.

What do you mean by buffering? How does one go aboit doing that? Like rubber bits between the body and frame?

I've never owned a bike with disc brakes so I never tought of it for this build. You think it offers something special when it comes to trikes compared to v brakes?

I'll keep everyone posted, for sure :)
 
Discs are usually better than V or caliper though Something like Ultegra caliper with properly matching levers and blocks can be excellent. Hydraulic discs are easily better than anything else and are not massively expensive from Ali Express. For a heavy and electric machine I'd certainly want discs and especially over anything cheap from a kids bike. For a tadpole I'd only have front brakes. I've had instances of a rear locking up as it unloads and then overtaking the front. Fun if you want to do that and trouser soiling if not.

Even if you keep the front forks I'd still suggest lowering everything. Backside down, feet further forward and leant further back. You can take 18" off the height without being on the floor or horizontal. As well as cutting down side wind problems you'll get more force into your pedalling
 
Hey everyone, Ive been thinking about all your suggestions and see how they could help. When it comes to front wheels and steering, Im wondering what would be possible options for making traditional tadpole steering geometry with suspension. Suspension is a must, I know all the roads in the city, Its necessary Any suggestions, examples of front steering with suspension?
 
I've been looking it up a bit online and it seems too complicated to fabricate from scratch for first build. I'm confident I can weld up existing parts into a frame I've designed. Traditional butterfly triangle suspension and all that would also take up all the space in the middle so the trike would have to be longer. I think I'll stick to forks even it means a more complicated and heavy frame.
 
I have redesigned the frame, simplified it, all straight corners and all... I ditched the triangles on the sides for holding the forks and replaced it with just one pipe. Wich one do you think is better, the more horizontal one or the one thats more vertical?

 
The one on the right at the start of the video looks easier to get in and out of. The chassis member on the left one intrudes on that space a bit.
 
You may want to pull the crossmember that sits below the legs back a little too as your feet will naturally want to go there on getting in and out. You have the head tubes attaching to the side of the chassis. This will want to twist that rail. It would be best to "pass" the head tube through the chassis. This will be a lot stronger join as it will be welded both sides of the head tube and the joint will no longer be wanting to twist.
 
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