I need as much hauling capacity and ability as possible without making the bike too big to handle; [ie: easy 18” low step through]. I had to compromise on the weight because it is not possible to reduce the weight from the cargo. And there is no way in hell that I will ever own a car again. A good little trailer is excellent to keeping the weight low enough. But I would like to build the bike so I don't need a trailer. So now I have two designs that should work for that. This utility bike would be even more stable if there were two front wheels with a tilting mechanism.
Children are wiggly so they really do need to sit lower than the axles. That is why the long box bikes of northern Europe will become popular even in Amerika, assuming we don't kill ourselves first from letting the Republicons defund all possibilities of reform.
Co-ops are the only way to take control of our financial future. But they do take money to start. That is one reason I am fanatically trying to design a way to build a heavy duty cycletruck without all the tools that a shop must have for production of traditional bicycle frames.
I am now going to have to build a bolt on rear end out of stainless steel rectangular tubes. Like work hardening 304 or 316 stainless steel. No painting needed.
I need to sell a couple of paintings to start building these bikes:
If you want to use a Motorcycle tire on the rear, you should look at the width of the Mid-drive kits; my kit has a very wide crank spindle because of the with of the motor. The left side should be at least as wide as the right side. The crank spindles that are on bikes are not wide enough for your foot to clear the rear tire unless the bicycle is made for a 3 or 4 inch wide tire. You can get them new at a reasonable price now. However most people do not understand the difference between a hub motor and a mid-drive. Hub motors are made for speed not for hill climbing with cargo. You will probably need two hub motors to do the job of one mid-drive kit to climb steep hills with 450lbs total combined weight.
I wish someone would build a bike with one of each kind of motor with the ability to switch between them. and using a CycleAnalyst meter you could make a video to show just exactly what the difference in power use is. But there is nothing better than a two speed gear system.
My Motor draws up to 1800 or 1900 watts for a very few moments climbing a steep hill. but it does not put out that much power. The controller allows it to suck 41 amps from the battery. But for hill climbing I use low gears so I can keep it under 1200watts coming from the battery. The battery is 52volt nominal so I am able to charge it up to 57 volts and a little more, this will keep the battery form destroying it's self.. I keep it under the maximum of 58 volts, and drain some off when the charge goes over 56volts unless I am about to use the power right away. 56Volts the night before is about 80% and I really need a much larger pack of cells that drain faster yet hold less electrons. [the Samsung 29E]. Higher voltage would help draw more amps with less heat, to climb steep hills.
But having more copper in the motor helps it deal with heat produced when climbing hills with out enough power.
High voltage = higher motor speed from more amps with less heat, so use lower gears [larger gear reduction]
[If you really want a hub motor it should have more copper and some vent holes, if you can think of a way to keep out the rain].
I put 750watts on my motor because there is no way to know exactly what it will output [short of testing on an expensive machine] and my gears are so low that I never go faster than 16mph unless I am riding down a steep hill without the motor on.
If you really want to use hub motors, it is so much better to use two of them just to have more copper and heat control: [see the motor graph]. Hub motors produce far more waste heat than Mid-Drive motors and do not let go of it well. I like the idea of using a large mid mounted motor set with a single speed reduction. I managed to build a two speed front crank that does not jump off the sprockets. And I always try to accelerate slowly enough to keep the chain from braking. This is another difference between a speed bike and a utility bike. Building a cargo bike for racing is an absurd concept.
Putting an extension on the rear will give some room behind the seat post to mount the motor, so I don't have to run the motor power through the crank set. Making the cranks sprockets last much longer. And I will be able to use a stronger chain from the motor to the drive sprockets.
The rear end that holds the drive wheel
Hub motors really need a suspension system for those large pot holes. But either way I think that 1/4” inch flat bar could work for a motor that is not pulling from one side. But rectangular tubing is far better: ¾” x 2” would be the best. Stainless steel is better if you can't afford to powder-coat paint the frame. It also does not need to be annealed after welding.
My drive hub allows for 3/16th inch thick dropouts, 1/4” is too thick. The walls of the rectangular tubing I got are .062” thick so I could use three walls thick for the dropouts. [3/16 in = 0.1875 in = 0.1875 × 25.4 mm = 4.8 mm]
If you need to weld on an extra bottom bracket tube get one at least as wide as the tire. My 2.25” motorcycle tire is actually 2.48” wide so a 3.5 to 4 inch wide tube is about right to make the rectangular tubes go straight back past the tire. But make sure to place the tube directly in the center of the frame, or the steering will be screwed up. My pedals are about 7.5 inches apart total but the left side is farther out than the right side. 3.5” on the crank side and 4inch on the left side. So the extra BB tube should be no wider than 6 inches with the ¼inch flat bars sticking out the front of the rectangular tubes [6.5”]. But keep in-mind that the hub is probably going to be wider so You will need to cut and weld the rear extension. [135 mm = 135 ÷ 25.4 in = 5.31496062992126 inch] a 4.83inch wide tube is just abut right. And it could be any tube that will hold a 3/4inh thick bolt. Like a 1”O.D. tube with .120inch wall [11 gauge] would be a nicely snug fit [you don't want the bolt to rattle around in the tube much] .120 in = .120 × 25.4 mm = 3 mm or 1.125” is 1/8th inch. A ¾” inch bolt is only .745” thick. A 170mm wide hub would be very good to allow more room for chain or belt drives. [170 mm = 170 ÷ 25.4 in = 6.692913385826772 inch]
- Head tube should be 2.5” Inch x.083 wall with 1.334” ID
- 1.125 inch steer tube. X .095” wall. With 955” ID [About 2ft long each]
- Handle bars 7/8th inch OD x .875” wall
- Extension holding tube 1” OD x 120” wall
- Fat bar for dropouts and rear extension connection can be only 3/16th inch x 1.5” or 2 inch.
- Rectangular tube 3/4th by 2 inch or 1” x 2”
- 1.25 inch square inch tubing for part of the frame is easy to find.
Custom Built Bike'$
If you go to a bicycle builder specializing in custom bikes, he would charge you about $1600 without the motor. That is why you should be glad to pay a backyard engineer 5 or 6 thousand dollars with the motor. Or do it yourself. And I do recommend DIY, it is so much more pleasurable to work for yourself.
If you had enough money you could have a Chinese factory build a ship container full of frames. But they would have to be a generic fit.
How ever most people are hopeless when it comes to building anything. So I hope to find someone in Mexico that start building this kind of cycle truck. The most important part is the balance, moving the seat forward from the usual place.
And the ability to handle so much cargo is essential. Why not buy a Surley long bike? Because the wheels are too large for motorizing. And 4 ply motorcycle tires are so much better than any kind of bicycle tire. Although Continental Ride Tour City/Trekking Bicycle Tires are three ply, even if they are still thin plies.
European's have experience in building heavy duty utility bicycles, but are not motorized nor are they built with a low enough seat to put your foot on the ground unless you have long legs. I just can't help but get the feeling that the bicycle industry is a hopeless case. But there are a few small utility bikes with 20 inch wheels: Factory Made Electric Cargo Bikes.
Eventually there will need to be many thousands of people building utility cycles just to help people stop burning gasoline. So why wait until there is a major panic, build your own now to get a head start on the rush.
And remember that when using a strong Mid-Drive you don't need more that 7 speeds. And stop leaning on the handle bars, it will wreck you spine.
More info about rear suspension extensions: