Pat

deacon · #1 06-23-2009, 02:12 PM

Lately I have been building a Pedal Assist Trailer. It is a one wheel push trailer which can support a lot of different motors. I have them with a 350 using a scooter wheel and fast scooter sprocket. I also have one using a 450 watt motor and a 16" bike wheel.

How to build a pat
How to build an inexpensive two speed emotor bike. The story begins with the search for a wheel.

Now I usually use a scooter rear wheel with the motor bracket attached. But for this build I am trying to go for the easy to find, anyone can do it, build instructions. So I have decided to use a wheel from a child's 16 inch bike. The thrift store had one for eight bucks but I wanted to see if I could find one for a better price.

Donar bike

step one
STEP ONE
strip donor bike

First you will probably need to remove the chain guard. Cheap plastic headed for the land fill. Mine was held on with a couple of Phillips screws.

Then you will need to loosen the bolts holding the rear wheel on. I found a couple of dropout locks as well. You might need to completely remove the bolts and any other hardware holding the rear wheel in place. Remove the brake lever clamp so that the wheel will move freely.

Move the wheel in the drop out slots until the chain is loose. Work the wheel out of the drop outs.

At this point it should look like this....

Next you should remove the brake lever... at that point you wheel will look like this..

Use your chain breaker to push out one of the rivets in the chain. I push mine ten half turns and then twist the chain. This should leave the rivet hanging so that you can use it to reuse that chain later.

At this point you can toss the rest of the bike if you want to. I however always junk it out as much as possible. For instance on twenty inch bikes and up the cranks are mostly interchangeable. Why would you want to? On a motor bike pedaling is secondary. The shorter pedal arms make it much more convenient for me. However on a sixteen inch bike they usually are not interchangeable so I didn't bother.

I pulled the handlebars and the goose neck from the bike. Those high rise handle bars are good to use if you need to sit low on the bike for balance and your knees hit on a regular handlebar. Mine always hit on a mountain bike it seems. I also pull the front wheel since the spare tire and tube are good to have around. It's easier to pull the whole thing than to remove the tire. I also pull the seat and post. The seat is too small for sure but the mounting hardware under the seat is pretty universal.

At this point I put the frame out for the metal junkers to pickup. If I still drove I might take it to the crusher myself. I expect doing that you can more than repay yourself for the purchase of a donar. For instance the rear wheel is about thirty bucks. The chain is over five... The front wheel is probably the same. You also have the equivalent of one new tire (between the front and rear ones) and a couple of good tubes if you are lucky. The seat hardware and handlebars are worth something down the road. In other words it was a good buy so far.

I shot this before I added the handlebars and goose neck to my stash.

__________________

**paul** · #2 06-23-2009, 02:18 PM

welcome deacon and people deacon is the master of innovation. i have seen a lot of his projects and they are awesome. glad to have you with us deacon

deacon · #3 06-23-2009, 02:31 PM

Step two is to buy a motor.

So most likely you will wind up with a scooter motor. The are almost perfect for building pusher bikes. They come in all kinds of power and mounting configurations. I will show you how to build with a currie motor scooter motor. It looks like this. NEW IZIP 500 24VOLT ELECTRIC SCOOTER MOTOR/ PARTS - eBay (item 320386087798 end time Jun-25-09 15:21:34 PDT)]I build exclusively with motors of this configuration. The come from 200 watts to 1200 watts. I have built with the 250 350 and 450. The more watts the more power. Also the more watts the more expensive. I also always build with 24 volts. I don't like the expense and weight of more batteries but that's just me.

Step three is a decision... the motor and the bike wheel have mismatched sprockets. You can put a bike sprocket on the motor or a scooter sprocket on the wheel. I chose to risk the $5 wheel rather than my $35 motor.

I bought a small scooter sprocket from TNC scooter store. I got a 55 tooth sprocket but you can get others. I welded mine to the sprocket on the bike. If you don't have access to a welder, or a friend with one, you can always find a shop to do it or you can drill and bolt the new sprocket on. If you just use your imagination you will have a rear wheel that looks like this....

this next one is a not so good picture of the rear of the sprocket which is where I welded it. Oh yeah be sure it is centered..

STEP FOUR

You can use a the bike bracket from TNC scooters to mount the motor onto the wheel axle. I had a mount bracket that I was already using on the bike so I kept it. Mounting th motor should not be a problem.

Use your imagination and it shouldn't be much of a job to make a unit with motor and wheel on the axle.

deacon · #4 06-23-2009, 02:33 PM

STEP FIVE

To manage step five you have to build a trailer frame. Again welding is better but you certainly can bold this frame together. The pusher wheel is actually a bob tail trailer.

so to build one you need to make two side rails. One end attaches to the bike and one to the axle of your rear wheel. The rails are best left without a connection between them. It is easier to remove the wheel if you can just remove the whole rail. So this is what you need to build.

You need two of those.... You can build exactly like that or better depending on what you have laying around the shop.

FAQ..

How long should it be.... as long as necessary. It needs to be at least (half the size of there rear bike wheel + half the size of the pusher wheel+ two inches) that is bike axle to pusher axle hole. You probably want some excess tail. (No crude remarks please)

What should I use for the sides. I used square tubing for the one you see but I have also used the solid L channel pieces from Home depot.

How do I attach it to the bike. However you can. There are usually some holes around the rear axle of the bike to use for attaching. I usually attach most metal to the bike so that I can work with it separately from the trailer.

What are those L brackets on top of the frame. If you look at the picture of my pusher you will see that I put the batteries right onto the pusher. The L brackets are what I use to hold them.

Now at this point you should have the pusher attached to the bike. Congrats you are almost finished.

deacon · #5 06-23-2009, 02:35 PM

step six

the last thing to do is to wire the bike up. I use an on off on switch it give me a two speed helper motor. One that steps right out there.

the diagram is easy to follow you have the negative wire of the motor going to the negative terminal of one battery. The positive wire from the motor goes to the center terminal of the switch.

One wire goes from each of the end terminals on the switch to one of the positive battery terminals. Then the last wire goes from the unused negative battery terminal to the positive terminal on the OTHER battery. If you get it right your switch will provide half power for starting from a stop to full power to running.

Be sure to wire in a fuse. A 40a will not melt the wires and give you some protection... You can try a thirty but it might blow.

Good luck you are ready to roll.... Please be careful it takes a little getting used to, but it is a nice, easy, little DIY ebike.

deacon · #6 06-23-2009, 03:09 PM

Lest you think I am a total nutcase, I also own a bike with a 250watt hub motor. It cost me three times as much, at least, it has less power and is less fun. No one can tell that it is a motorized bike. A lot of the fun for me is the "Look what I can do" factor.

deacon · #7 08-07-2009, 02:12 AM

Today I took apart the last of the pat bikes. I had a lot of fun with them and they did everything I asked them to do, but there were not the kind of bike a DIY novice could put together. So I have move back to friction drive. This time it seems to be working somewhat.

myocardia · #8 08-07-2009, 05:30 AM

Who gives up an electric bike for a tire shredder?

Nice build, though.

deacon · #9 08-13-2009, 11:40 PM

ah Well I like friction drive. The latest of the incarnations uses a scooter wheel on top of the rear bike wheel. No shredding at all. It does however have a bit of an ugly problem. But there form follows function.

since the picture I have changed the tires and wheels.

myocardia · #10 08-14-2009, 12:04 AM

Hmm, a scooter wheel atop the rear wheel. That's not a bad idea, although I'd personally put it on the front wheel. It looks very dangerous (to me) where its located now, because of its proximity to the rider. Great idea, though. That way you don't go through tires every hundred/few hundred miles, like with the majority of friction drives. On a different note, I'm willing to bet you could easily go into business selling PAT's just like the one in the OP, if you ever had the notion.