Push trailer from escooter?

[lexjones]

Forgive if im posting in the wrong section. This idea is losing me sleep and I need to run it through some wiser minds than mine.

Convert an escooter into a push trailer? (10 inch rear wheel) (the torque isnt amazing ≥29N.m)
The bike has a bob quick release already.
I'm thinking that I can remove the steering pole and front wheel (and maybe the lower front suspension if needed) from the Escooter.
Then i just have to figure a way to connect the two SAFELY.
As highlighted in the picture I have 5 useable holes for mounting hardware.
I have the left and right motion covered by the Escooter ... I just need to figure out the up and down.

I'd like to be able to build this with off the shelf bolt on parts if possible as I have no workshop.
Is there something glaringly obvious that makes this unworkable?

Also...If i fit a 250w rear motor (currently 800w) ..this would be street legal in EU right?

Any ideas on how to build this and/or parts for the attachment arm would be greatly apprechiated.

 

[E-HP]

Will you have the entire contraption with battery behind your bike, or just the wheel?

 

[lexjones]

Will you have the entire contraption with battery behind your bike, or just the wheel?

Battery will remain in the scooter footplate. (I want to carry additional battery pack in rear panniers on the bike).
I also want to carry about 40 kilos of cargo on the push trailer. (which should give me enough traction, A cargo cage should be simple to make and secure)

It just looks like a potential push trailer to me....But im no bicycle engineer.

 

[E-HP]

Got it. So is it fixed to bike or independent when it comes to turning and leaning?

 

[glennb]

The laws are scant regarding trailers, powered or otherwise. Worth your while investigating, so you have some idea of where you stand, but I wouldn't let the laws deter you.

Anyway, a hoverboard would be easier, with side by side wheels. The bike rear triangle is insufficiently stiff to accommodate a rigid attachment, meaning the hitch needs to be flexible (e.g. coil spring) and the scooter then requires lateral stabizing wheels to prevent it toppling. The stabilizers will be no fun to implement.

Pneumatic tyres are an advantage. Large wheels are an advantage. Prebuilt hitches are an advantage. Wet weather protection is an advantage. I'd therefore look to motorize a kiddie trailer (perhaps by bolting your scooter to it), rather than consider the scooter a suitable chassis.

 

[amberwolf]

Convert an escooter into a push trailer? (10 inch rear wheel) (the torque isnt amazing ≥29N.m)
The bike has a bob quick release already.
I'm thinking that I can remove the steering pole and front wheel (and maybe the lower front suspension if needed) from the Escooter.
Then i just have to figure a way to connect the two SAFELY.
As highlighted in the picture I have 5 useable holes for mounting hardware.
I have the left and right motion covered by the Escooter ... I just need to figure out the up and down.

When something pushes a bike from behind, vs the bike pulling it, the handling is different; the exact hitch and drive setup, power, traction, and riding conditions determine *how* it will be different. if you want to feel the difference for your specific situation, get someone to push you (while you're on the bike) from the point you would be attaching the trailer to.

It's going to be a lot like going down a (steep) hill with a loaded trailer.

Depending on the heights of the drive wheel of the trailer vs the height of the hitchpoint:

If you have a push over the top of the axle, and there's enough weight on the drive wheel of the trailer, it could lift your bike's rear wheel off the ground, either just enough to lose traction and control, or actaully completely off the ground.

If you have a push under the axle with the same conditions, it may increase traction on the bike's rear wheel.


If you have the trailer allowed to pivot around a steering point, then as soon as you are not in a direct straight line with it it will push on your bike's rear end and shove it to the side the trailer is not on. So every time you are making a turn, the motor is going to try to crash you by skidding out your rear wheel if the traction conditions are right for that. It's worse if the hitch point is where the trailer can lift the rear wheel at all, reducing bike traction and control.

You may want to setup something to automatically turn off the motor once the trailer angle deviates from in-line with the bike by more than a certain (small) amount, to minimize the chances of this happening.



You've already noted you're carrying weight on the trailer, but just to make the point for future readers wanting to do the same thing:

Also, you'll have to have enough weight on the drive wheel of the scooter to be able to push you--depending on road or path conditions and where the scooter pushes on the bike vs where it's wheel is, that could mean as much weight as you and your bike.



The suspension on the scooter (designed to operate with rider weight on it) may cause it to bounce on nonsmooth roads/paths if it's insufficiently loaded (if it has no damping this can happen anyway). If this happens, the wheel will spin up rapidly while in the air, then may slam to a relative near-stop as it hits the ground again, and on bumpy ground it could happen repeatedly and often. Some controllers are tolerant of this, some aren't. Some may just shutdown, some may be damaged. If the motor isn't a geared hubmotor, it will probably tolerate it just fine.


if you don't need to be hauling weight with it but only want to use it to drive you along, you'd be better off attaching the scooter as a "rack" on the bike and using it's drive wheel as a friction drive to your bike's tire. (front or rear would work, depending on your bike's design and how you use it).

Also...If i fit a 250w rear motor (currently 800w) ..this would be street legal in EU right?

You'd have to look up your local laws. In your area, does it require pedalling to activate it? or can you use a throttle? Is there a speed limit required? etc.

 

[amberwolf]

All that said:

You could build a bob trailer style attachment for it to use the bob mount points. That could be as simple as a rear triangle from some other bike that's the same dropout width as your existing bike. You'd want to pick a bike that has a short stay-mount-tube, so you can use your scooter's steerer, upside down, thru the scooter's headtube and down into the rear triangle's stay-mount tube.

Common bob trailer for reference

randomnly chosen crappy magna frame bike with a short rear triangle swingnar,m that is removable, in a similar configuraton to a bob.


You'll progbably have to modify the triangle's dropouts to work wtiht the bob mounts. Also probaly ahve to cut off the end plate of the stay-mount tube of the triangle, so the ends are open so your scooter steerer will fit thru it.

The steerer might be too large a diamter to fit thru the triangle's tube. If it is, you'd have to use a smaller steerer, and then either add spacers around it to fit the ID of the existring scooter headtube bearings, or change those bearings to ones with the same OD they already have, and an ID that fits the smaller steerer.

It doesn't have tob e a "real" steerer, it just has to be a tube that fits the ID of the triangle's tube, and fits the ID of the bearings for the scooter headtube, and has "stops" that will keep it from sliding around in the bearings vertically. You can drill a hole htru the steerer and the triangls' tube and run a bolt thru that to secure those together.

If a steerer from a different bike ro scooter will fit, yhou can use that, cutting it off the fork it came from The magna's steerer, for the random bike I posted above, is a 1" threaded type, for example. (most of the crappy bikes you could use the traingle swingarm from are of this size and type).



Other methods include things like my old DayGlo Avenger's "chariot" trailer hitc h, later used with a different kind of trailer (which was not very successful). If you go with this type of mount, build it better than I did.

Amberwolf's DayGlo Avenger, MkII

First, a review in the first few posts about what this bike *WAS*, before I start on what it is now, and then what it is about to become. This bike has been through a lot, as almost all of my experiments were done on it before I built CrazyBike2. Right now it's unpowered, just my pedal-only...

endless-sphere.com

Some ipics from the thread showing the trilare and it's hitch and the bike end of things

the later trailer hitch design, trailer side (bike side didn't chainge)

Amberwolf's DayGlo Avenger, MkII

oh, definitely. :) the wu needs new wires on it; they're kinda short :P HAHA yeah soz about that, needed to reclaim my 8mm gold plated bullet connectors i didnt have any spares too hookz up the Turnigy, figured you would be pulling it apart anywayz so didnt really matter much :-) KiM p.s...

endless-sphere.com

 

[glennb]

Except you'd only be applying trailer power to assist on inclines. A 250w bike motor is fine for flats, no need for additional power. You could configure throttle controls such that the trailer lags the bike, but it'd be difficult with dissimilar motors, best not attempted I suspect.

Amberwolf, how'd you go with front castors? I couldn't get them to function that way, had to have them at the rear (on a DIY skateboard for being towed behind s bike).

 

[amberwolf]

Amberwolf, how'd you go with front castors? I couldn't get them to function that way, had to have them at the rear (on a DIY skateboard for being towed behind s bike).

They sucked; see the linked DayGlo Avenger thread for some of the various issues. I think they are also covered in the Mk I trailer thread, which is about that trailer specifically.

The reason I tried them then was to be able to load that trailer as heavily as required (especially with the wiggly cargo it was really meant for) without the bike tipping over during loading (either dumping the trailer too, or breaking the hitch or bike or trailer, etc). If I had made them retractable (like the front caster on a boat trailer) it would've been fine, but.... :/


The hitch itself worked well enough, given all the issues that any over-wheel hitch is going to have. I've learned quite a lot since then, and if I were to use that kind of hitch again, it'd probably be built a fair bit differently, though I could still use most of the same parts. But these days I just use automotive ball hitches; even the crappy harbor freight version is stil overengineered for my purposes.

However, I don't use the trailer to push me, just to haul things. If I ever do build a powered trailer, it'll be controlled such that it simply neutralizes the inertia of the trailer and it's load, via some sensor in the hitch itself that works a bit like the braking mechanics that are in some similar automotive hitches that automatically brake the trailer.

 

[glennb]

I see. Trailers are tricky with leaning vehicles. Ball hitches make sense for trikes and quads, not so much two wheelers.

I don't know if a complicated powered trailer is worthwhile, better to put the effort into designing a a vehicle capable of towing the required load. Different obviously for EU/AUS, where a powered trailer offers the potential to evade the 250W restriction.

 

[BicycleJoe]

Instead of a push trailer, have you considered mounting your scooter base above the bicycle rear wheel such that the scooter tire drives the bicycle wheel by simple friction? Others have done it and it seems compact and manageable.