electric push-trailer

[REdiculous]

Here's a couple pics. Sorry about the quality, I used the cheap camera...

For now I have the motor welded to the bike itself. Maybe you can see the blob in the pic. Of course I'll be putting the motor on the trailer but I'd like to get everything sorted first. The blocky thing that looks like it could be a battery is actually the 4" foam seat I made...the luggage rack was integral, so I hacked off the seat post and reinforced the welds. Oh, it's a folding bike which is why the handle bars look like they're out of whack...they're quick-release so it folds flatter.

The only problem with my bike is its carrying capacity. The front wheel is 20 x 1 & 3/8. The rear is 20 x 1.50. And the trailer wheel is also 20 x 1 & 3/8. When I was running the 1 & 3/8 wheels on the front and back this bike screamed. Unfortunately I've gained a little weight as I've gotten older and my back isn't too hot anymore either..hence the slightly larger back tire.

So, you're probably wondering why the trailer is upside down in the second pic. Well, I was thinking this might be the better way to attach it since I can get more of the weight on the trailer tire and less (or none) on the bike's rear wheel. It also decrease the length a bit too. Will it work that way?

Right now I have a 12v, 20ah SLA (13lbs), a MM23001C Minarik controller, a 2.5hp (1hp cont) treadmill motor (9lbs) and a 350w inverter. I went this way because I already had the motor and inverter. The plan is to get a better inverter (1200w?) and another 20ah battery. Should I get a 24v inverter or stick w/ 12v?

After much tweaking of the controller I finally got the motor running (no load) off the wimpy inverter. The motor is geared 1:1 w/ the back tire though. Does anyone know where to get large sprockets (compat w/ bike chain) for the back wheel? I know I can get a smaller sprocket for the motor too.

You should see it plugged into the wall though. OMG is it scary with everything maxed...ridiculous speed...all the lights flicker..

Thoughts, questions? All in good fun. thx

[fabricator]

My first call would be a bike shop, that does look like fun alright!

[REdiculous]

yeah, I'll ask at the local bike shop too, I was just hoping someone knows where to find some sprockets online.

I guess I'm stayin' w/ 12v since I can just run down to the truck stop and get an inverter. Unless there's some compelling reason to go 24v? thx

[willib]

I would say look in the trash bin for a rear bike wheel with a sprocket already on there , its amazing what people through out.

[REdiculous]

The problem is I think I need more teeth than a standard sprocket would have, otherwise I would've gone into town and bought one already. I'm thinking I need a rear sprocket with 48 teeth (or more). If I had a 48t on back and replaced the front sprocket (currently 16t) with 12t....

48:12 == 4:1

6750rpm (motor max) / 4 = 1687rpm

1200rpm / 4 = 300rpm

rpm x wheel circumference = distance traveled per minute

300rpm = 17.6 mph with my wheel.

[zap]

First off, I'm not an expert and I certainly applaud you wanting to make do with what you already have sitting around.

You're probably not going to get any weight off the rear wheel without somehow connecting the trailer in front of the rear wheel.  You could try and mount most of the trailer's weight behind it's axle but that will result in horrible stability, especially with only one wheel on the trailer.

Keeping the weight low usually helps the stability... because of that I'd recommend the setup shown in your first picture.

I'm wondering about how efficient it will be.  You're going from 12vdc to 110vac then back to 90-180vdc.  Every conversion adds inefficiency.

If you're prepared to go buy another inverter to increase your speed, I would suggest skipping your MM23001C all together and using a dc speed controller.

This place usually gets good reviews. http://tncscooters.com/view.php?page=Home

If you go with a dc controller and you want to get any kind of speed, you'll have to go with more than 12v.  Voltage=speed Amperage=torque

I don't know where you're located but you might try searching your local classifieds, craigslist, or eBay for used "kids" electric scooters.

Many people decide to get rid of these scooter after they find the cost of replacing batteries too high or they find the kid only used it a dozen times and moved on to the next toy.

I got a used scooter from craigslist and used it's controller on my pusher trailer.

http://www.fieldlines.com/story/2009/11/10/16828/297

Search this site... http://endless-sphere.com/forums/index.php  Chances are someone has done something similar to what you're attempting.  If you decide to join, there are a lot of helpful people there that will most likely try and assist with your endeavor.

Good luck.

[JamesJackson]

Cool!!! I like it that folks try something that is unique and different!

I am not sure if this will help you, but there is a company that I've dealt with in the past called 'All Electronics'. I noticed that they used to have electric bicycle bits and pieces. Not sure if they still do though, here is their web site...

http://www.allelectronics.com/index.php

Try looking under 'Motors' and 'Rotating Parts' for a start. You might also look in the 'Battery Chargers' section - that's where I got a battery charger for a friends' electric bicycle that works great!

Good Luck with your project!

Regards,

James Jackson

[REdiculous]

If I mount it upside down the trailer will only move up and down, not left and right. I can make the trailer shorter this way (I like compact) and it'll be easier to balance the weight over the wheel. Tire wear is my only concern.

I looked at DC controllers first but like you said, I'd need more voltage. To get 48v I'd need 3 more batteries...a 1000w inverter is half the price. Also the batts would weigh over 50lbs. It's a trade-off, for sure.

I found this page a couple weeks ago...

http://endless-sphere.com/forums/viewtopic.php?f=6&t=9855

After looking again, it looks like spinningmagnets found a solution to the gearing problem.

[REdiculous]

Thanks for the link..good stuff.

I forgot to mention that I've got a 12v charger. Which is another reason to stick w/ a 12v system, I guess.

I've been searching for weeks and it's looking like I'd have an easier time if I switched to #25 chain. I really don't wanna do that though. hrmm.

[HaroldCR]

 If you can slide the seat forward a few inches, you can make a mount for a Gooseneck hitch. Make it so the bar from the trailer rides on top of the seat frame. For instance, use a ball that sticks up, so the trailer bar slips over the ball. You might look into trailer supplies, or, at least get some ideas.

  I did the same type trailer, 53 years ago, using part of a tricycle frame, that was broken off the head post. Turned it upside down, and bent a piece of Galvanized water pipe, to fit inside the tricycle frame, and bent in an arc, to fit over the rear fender. Used a plate in the "V" section of the Bike frame, under the seat, with a long bolt jam nutted onto the plate. Let it stick up and used washers and a pin to keep the gooseneck from jumping off. Smash the pipe flat, so it will swivel in all directions.

  A hauled a lot of stuff for a few years, until I wore the semi-pneumatic tires through to the hollow center, and ended up with 4 sidewalls.

  What you want to do is really easy.

[REdiculous]

The problem is I've only got the single wheel. If it can swivel in any direction and most of the weight is up high then the trailer would want to fall over.

What do you think about mounting the trailer so it can only move up and down?

[JamesJackson]

...another place to look for what you are needing...

Electronic Goldmine... my wife knows that this is one of my weaknesses... shopping here... good mail order place...

http://www.goldmine-elec-products.com/products.asp?dept=1224

Look at this link - they seem to have some of what you are looking for.

Regards,

James Jackson

[HaroldCR]

 If it can't swing to the side, you are going to slide the tire, turning

[REdiculous]

Exactly right. The trailer tire will be pretty close to the bike's rear wheel as you can see in the pic...I'm hoping this will reduce that sliding to an acceptable level. Kind of like a tandem-axle horse trailer.

[David HK]

These URL's may give you some design ideas.

In the first URL look for the 8 man tricycle (scroll down)

http://www.dself.dsl.pipex.com/MUSEUM/TRANSPORT/tricycle/tricycle.htm

In the second, scroll down to the Bootbike

http://www.dself.dsl.pipex.com/MUSEUM/TRANSPORT/oddbike/oddbike.htm

In the third, this is for excitement only.

http://www.dself.dsl.pipex.com/MUSEUM/TRANSPORT/rocketbicycle/rocketbicycle.htm

David in HK

[REdiculous]

The boot bike has been one-upped. I think it was on Nitro Circus (maybe another show) where they used DC shoes on a motorcycle.

Oh how I love tricycles too. Man.

[Ungrounded Lightning Rod]

The only issue I see with flipping the trailer over is what this will do to its behavior when it hits a bump.  Is it supposed to let the fork pivot or flex and compress the braces or is it a rigid structure that's supposed to pivot as a unit on the hitch?

If the latter it should be fine upside-down (though the weight of the load may be an issue on really bad bumps).  If the former you may have a problem with an orientation that wasn't intended by the designer.

Note that when accelerating it will be taking weight OFF the hitch - in either configuration.  You might need the weight transfer of the standard configuration to keep the hitch loaded correctly and avoid sudden full or partial detachment of a powered piece of your vehicle, followed by havoc.

[REdiculous]

I'm not sure I understand the question..

The "hitch" would be a door hinge mounted horizontally. I'd weld the hinge to the trailer. The bike would have a plate welded to the rear so that the hinge/trailer can be bolted on. This way the trailer can track over bumps yet the two would be securely connected.

Cornering is what I'm worried about. However, new tires aren't that expensive and I doubt I'll be putting that many hours on it. Truth is, we'll probably use the trailer to light up my kid's treehouse far more often than it'll see pavement.

I live 1.5mi down a gravel road and I own a street bike. Maybe that's the real problem.

[Ungrounded Lightning Rod]

I was assuming a ball hitch, which likes to have some down force so you're working the ball against the socket rather than against the hold-on fork.

[REdiculous]

I hit up the second hand store at the edge of town and found a donor bike for $4. Score. I found some other cool stuff too, like a small 12v coffee pot I might have to go back for. Anyway..

Among other things, it had a crank with 3 sprockets, 48t on the outside. I cut off the pedals and ground the excess off so it won't wobble. I pulled a 16t sprocket from another project that I can weld to the left hand side of the crank. I can run the motor to the crank and from the crank to the wheel and get 3:1.

I welded the rear axle brackets to the rear of my bike - so it looks like you could almost mount a second wheel off the rear of the bike. You know those door latches that slide sideways and then rotate up/down to latch in place..? Anyway, I took the rod out and replaced it with a bolt. I welded the bracket to the trailer and connected it to the bike. Fits like a glove.

Unfortunately it got late and I didn't get a chance to get the tires aired up. I did coast around a couple times and it seems to be alright. The trailer does slide on sharp turns but it didn't look too bad. Unless you really turn it's hard to tell it's there, even with a mostly-flat tire.

Oh, I found some thin sheet that I can make a battery box out of and I can do some touch up on the welds when I get some more grinding wheels. I still need to get the motor off the bike too, and figure out how to mount the gears. And I need a sprocket for the trailer wheel which I'll have to get next month.

Maybe in the next few days I'll have it movin'...maybe not...