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  1. #1
    Transportation Cyclist turbo1889's Avatar
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    Designing an Urban Mule Cargo Bike with Electric Assist

    Okay, so long story short I’ve had “the itch” for a while to build myself an e-bike that fits the following criteria:

    1. ----- Fits on a bus bike rack without any issues beyond that of a regular bike.
    2. ----- Can be loaded down with cargo with cargo racks in both front and rear and can haul a lot of stuff. We are talking Costco runs without a trailer loads usually only possible with a dedicated cargo bike usually with a long wheelbase that won’t fit on a bike bus rack.
    3. ----- Has a 60-degree seat to BB angle so that I can easily put a foot down at a stop without having to slip forward off of the seated position for my foot to reach the ground while maintaining an upright riding position to maintain visibility both to see and to be seen.
    4. ----- Uses a quiet efficient direct drive brushless hub motor mounted up in the frame driving through the bikes gears like a stoker-monkey set-up. I have a cyclone mid-drive set-up and the noise is annoying but a quite direct drive hub-motor in the wheel doesn’t have the low end tongue for hauling cargo or climbing hills. In frame hub-motor driving through the gears is the only set-up I know of that combines the best of both worlds.
    5. ----- Uses a jack-shaft with dual freewheels to combine the motor and pedal input so that the pedals are not driven like an actual stoker-monkey set-up.
    6. ----- A standard 7 or 8 speed spool of gears with standard 3/16” width chain with a derailer on the rear. Minimum double possibly triple chain-wheels up front one large one for free running and smaller one(s) for cargo hauling.
    7. ----- Rear drop-outs should be forward hooked horizontal drop-outs to accommodate a forward up-angled rear derailer in a protective cage to keep it high and tight to prevent it being damaged or bent inwards in an act of vandalistic sabotage to grab the wheel spokes when shifting into low gear.
    8. ----- The additional weight of the battery pack and hub-motor in the frame should be kept as low as possible and as forward as possible for stability both on the road and in a bike rack on a bus.
    9. ----- Minimum 36V 20Ah battery capacity with the pack being constructed of high quality modular replaceable LiFePO4 prismatic cells.
    10. ----- Sturdy double kick-stand that does not get in the way.



    So far after a whole lot of fiddling around in CAD this is what I have come up with so far:




    The specifications and geometry of my current “bus bike” and myself are represented in the left side figure. A fairly common 26” wheel bike set-up with a wheel base that is slightly longer then 43 inches and fits on a bus rack just fine but cargo carrying is limited to a rear rack, front & rear panniers, and back-pack where the size of the rear panniers are limited due to heal strike issues and the front panniers cannot be too heavily loaded without severally effecting steering stability. In addition as you can see the represented green stick figure which represents my body proportions cannot put a foot down on the ground at a stop without slipping forward off of the seat.

    On the right is what I have come up with so far.

    Wheel base is 44” in length with smaller 20” wheels being used. Front fork geometry is more stable for more weight carrying capacity up front without effecting steering a large portion of which can be loaded on the over the wheel front cargo rack formed by a continuous large diameter tube running the full length of the bike and front wheel panniers in most cases will be unnecessary. The same full length large diameter tube that is the spine of the bike forms a generous rear rack as well and large rear panniers or rear basket racks may be attached without heal strike interference issues since the bottom bracket has been moved forward which also provides the ability to easily put a foot down at a stop while remaining seated.

    In blue color are the battery pack cells and the hub motor mounted in the frame behind the bottom bracket and forward of the rear wheel. The battery cells represented are high quality third generation LFP-G20 prismatic cells which are 20Ah capacity 3.2V LiFePO4 cells that I can pick up for $31 each plus shipping. They are 2.8” wide which should fit in single file within the frame width, 1.7” thick, and 6” tall not including their screw terminals on the top which should fit as shown in an in-frame double-decker rack forward of the bottom bracket with their weight down low, tight, and forward while still leaving me enough room to mount the motor controller circuit above them but still protected below the main spine beam of the frame.

    The gearing jack-shaft would be mounted high above the hub-motor further up the seat-post tube from the bottom bracket so as to accommodate a rear derailer that is tucked up tight and high protected by the right side bottom chain stay which slant downward to connect with the bottom of the battery box built into the frame.

    This is basically how the chain lines are worked out with the jack-shaft:




    It’s color coded. The light purple colored sprockets and chain lines are from the bottom bracket and pedals up to the jack shaft, a 48 tooth chain wheel turning a 16 tooth single speed freewheel on the right side of the jack shaft. The blue colored sprockets and chain lines are from the frame mounted hub-motor up the jack shaft. A 16 tooth sprocket is attached to the left side of the hub motor represented by the large blue circle via. the six bolt attachment made for a disk brake. This part is available off the shelf as an after market conversion part and is made for people who want a rear flip-wheel on their bikes with one side being a fixy (the sprocket attached to the disk brake mount spot) and a single speed freewheel on the other side for a bike that can be either a single speed or a fixy by just flipping the rear wheel around a process easily accomplished in about 30 seconds with a quick release on the rear. A chain runs up from such a sprocket attacked to the left side of the hub-motor to a left side 16 tooth single speed BMX freewheel on the left side of the jack shaft and thus the jack-shaft can be turned by either the pedals. or the hub-motor, or both. A set of fixed output sprockets are then attacked to the jack-shaft which serve as the main chain-rings for the main chain running back to the rear wheel represented in red with the 7 or 8 speed rear spool and derailer on that rear wheel so that all gears are available to the motor and pedals concurrently. Using a 21 tooth output sprocket on the stub-shaft with 16 tooth input freewheels will increase the gear ratio step-up to 20” rear wheel such that the gear steps are the same as if the bike used the larger 26” wheel size with a 48 tooth front chain-ring. So a 21 tooth would be the large output sprocket on the jack shaft and lower gearing would be accomplished with smaller output sprockets. I would probably put a 15 tooth, an 18 tooth, and a 21 tooth output sprocket on the stub-shaft and rig up a front derailer to move the chain in-between them just like a regular front triple chain ring set-up.

    A double kick stand will be mounted to the front of the battery rack part of the frame at the bottom where there is some clearance and will flip forward and up 200+ degrees.

    Also, both sides of the center section of the frame that houses the battery pack, hub-motor, motor control electronics, and jack shaft and gearing components to be covered by removable locking sheet metal covers to prevent vandalism or theft of those components. Basically keeping everything nicely boxed up in the frame and covered over on both sides with just the cranks with pedals showing on each side.

    Here is another diagram showing the slabbed over with sheet-metal sides and the kick-stand in place in the folded up position (slightly darker grey color just behind front wheel):





    Anyway, thought I would throw out what I’m trying to do and what I’ve got so far on this forum and see if any of you could point out anything I might have overlooked or anything like that.
    Last edited by turbo1889; 11-18-12 at 05:46 AM.

  2. #2
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    How about a Torker Cargo T and install a front wheel from Hill Topper
    http://www.torkerusa.com/uploaded/dy...-thumb_960.jpg

    http://www.electric-bike-kit.com/hill-topper.aspx
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  3. #3
    Senior Member badmother's Avatar
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    Quote Originally Posted by turbo1889 View Post
    Okay, so long story short I’ve had “the itch” for a while to build myself an e-bike that fits the following criteria:

    1. ----- Fits on a bus bike rack without any issues beyond that of a regular bike.
    2. ----- Can be loaded down with cargo with cargo racks in both front and rear and can haul a lot of stuff. We are talking Costco runs without a trailer loads usually only possible with a dedicated cargo bike usually with a long wheelbase that won’t fit on a bike bus rack.
    3. ----- Has a 60-degree seat to BB angle so that I can easily put a foot down at a stop without having to slip forward off of the seated position for my foot to reach the ground while maintaining an upright riding position to maintain visibility both to see and to be seen.
    4. ----- Uses a quiet efficient direct drive brushless hub motor mounted up in the frame driving through the bikes gears like a stoker-monkey set-up. I have a cyclone mid-drive set-up and the noise is annoying but a quite direct drive hub-motor in the wheel doesn’t have the low end tongue for hauling cargo or climbing hills. In frame hub-motor driving through the gears is the only set-up I know of that combines the best of both worlds.
    5. ----- Uses a jack-shaft with dual freewheels to combine the motor and pedal input so that the pedals are not driven like an actual stoker-monkey set-up.
    6. ----- A standard 7 or 8 speed spool of gears with standard 3/16” width chain with a derailer on the rear. Minimum double possibly triple chain-wheels up front one large one for free running and smaller one(s) for cargo hauling.
    7. ----- Rear drop-outs should be forward hooked horizontal drop-outs to accommodate a forward up-angled rear derailer in a protective cage to keep it high and tight to prevent it being damaged or bent inwards in an act of vandalistic sabotage to grab the wheel spokes when shifting into low gear.
    8. ----- The additional weight of the battery pack and hub-motor in the frame should be kept as low as possible and as forward as possible for stability both on the road and in a bike rack on a bus.
    9. ----- Minimum 36V 20Ah battery capacity with the pack being constructed of high quality modular replaceable LiFePO4 prismatic cells.
    10. ----- Sturdy double kick-stand that does not get in the way.



    So far after a whole lot of fiddling around in CAD this is what I have come up with so far:




    The specifications and geometry of my current “bus bike” and myself are represented in the left side figure. A fairly common 26” wheel bike set-up with a wheel base that is slightly longer then 43 inches and fits on a bus rack just fine but cargo carrying is limited to a rear rack, front & rear panniers, and back-pack where the size of the rear panniers are limited due to heal strike issues and the front panniers cannot be too heavily loaded without severally effecting steering stability. In addition as you can see the represented green stick figure which represents my body proportions cannot put a foot down on the ground at a stop without slipping forward off of the seat.

    On the right is what I have come up with so far.

    Wheel base is 44” in length with smaller 20” wheels being used. Front fork geometry is more stable for more weight carrying capacity up front without effecting steering a large portion of which can be loaded on the over the wheel front cargo rack formed by a continuous large diameter tube running the full length of the bike and front wheel panniers in most cases will be unnecessary. The same full length large diameter tube that is the spine of the bike forms a generous rear rack as well and large rear panniers or rear basket racks may be attached without heal strike interference issues since the bottom bracket has been moved forward which also provides the ability to easily put a foot down at a stop while remaining seated.

    In blue color are the battery pack cells and the hub motor mounted in the frame behind the bottom bracket and forward of the rear wheel. The battery cells represented are high quality third generation LFP-G20 prismatic cells which are 20Ah capacity 3.2V LiFePO4 cells that I can pick up for $31 each plus shipping. They are 2.8” wide which should fit in single file within the frame width, 1.7” thick, and 6” tall not including their screw terminals on the top which should fit as shown in an in-frame double-decker rack forward of the bottom bracket with their weight down low, tight, and forward while still leaving me enough room to mount the motor controller circuit above them but still protected below the main spine beam of the frame.

    The gearing jack-shaft would be mounted high above the hub-motor further up the seat-post tube from the bottom bracket so as to accommodate a rear derailer that is tucked up tight and high protected by the right side bottom chain stay which slant downward to connect with the bottom of the battery box built into the frame.

    This is basically how the chain lines are worked out with the jack-shaft:




    It’s color coded. The light purple colored sprockets and chain lines are from the bottom bracket and pedals up to the jack shaft, a 48 tooth chain wheel turning a 16 tooth single speed freewheel on the right side of the jack shaft. The blue colored sprockets and chain lines are from the frame mounted hub-motor up the jack shaft. A 16 tooth sprocket is attached to the left side of the hub motor represented by the large blue circle via. the six bolt attachment made for a disk brake. This part is available off the shelf as an after market conversion part and is made for people who want a rear flip-wheel on their bikes with one side being a fixy (the sprocket attached to the disk brake mount spot) and a single speed freewheel on the other side for a bike that can be either a single speed or a fixy by just flipping the rear wheel around a process easily accomplished in about 30 seconds with a quick release on the rear. A chain runs up from such a sprocket attacked to the left side of the hub-motor to a left side 16 tooth single speed BMX freewheel on the left side of the jack shaft and thus the jack-shaft can be turned by either the pedals. or the hub-motor, or both. A set of fixed output sprockets are then attacked to the jack-shaft which serve as the main chain-rings for the main chain running back to the rear wheel represented in red with the 7 or 8 speed rear spool and derailer on that rear wheel so that all gears are available to the motor and pedals concurrently. Using a 21 tooth output sprocket on the stub-shaft with 16 tooth input freewheels will increase the gear ratio step-up to 20” rear wheel such that the gear steps are the same as if the bike used the larger 26” wheel size with a 48 tooth front chain-ring. So a 21 tooth would be the large output sprocket on the jack shaft and lower gearing would be accomplished with smaller output sprockets. I would probably put a 15 tooth, an 18 tooth, and a 21 tooth output sprocket on the stub-shaft and rig up a front derailer to move the chain in-between them just like a regular front triple chain ring set-up.

    A double kick stand will be mounted to the front of the battery rack part of the frame at the bottom where there is some clearance and will flip forward and up 200+ degrees.

    Also, both sides of the center section of the frame that houses the battery pack, hub-motor, motor control electronics, and jack shaft and gearing components to be covered by removable locking sheet metal covers to prevent vandalism or theft of those components. Basically keeping everything nicely boxed up in the frame and covered over on both sides with just the cranks with pedals showing on each side.

    Here is another diagram showing the slabbed over with sheet-metal sides and the kick-stand in place in the folded up position (slightly darker grey color just behind front wheel):





    Anyway, thought I would throw out what I’m trying to do and what I’ve got so far on this forum and see if any of you could point out anything I might have overlooked or anything like that.
    Sure you want to build it? severalnice 20" heavy duty cargo bikes has been posted. Just search for them.

    Edit: https://www.google.no/search?q=20%22...a&channel=fflb
    Last edited by badmother; 11-19-12 at 04:41 PM.
    °Empty drums make a lot of noice... (Old Hungarian proverb).

  4. #4
    Transportation Cyclist turbo1889's Avatar
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    Quote Originally Posted by Dynocoaster View Post
    How about a Torker Cargo T and install a front wheel from Hill Topper
    http://www.torkerusa.com/uploaded/dy...-thumb_960.jpg

    http://www.electric-bike-kit.com/hill-topper.aspx
    The Torker Cargo T you linked too looks like its got a better angle between the seat and the bottom bracket then most factory bikes but I can't quite tell because it isn't a side profile photo. Still looks like heal strike issues with rear panniers and the over the front wheel rack looks pretty lame.

    As to the hill topper kit. If you have ever tried to pedal up a 30% grade hauling an extra 100+ lbs of cargo with an in the wheel hub-motor without the advantage of gearing between the motor and the wheel you will come to realize why I want the motor to drive through the gears of the bike. This is especially true if the hub motor is anything less then a 1000+watt set-up which I do want to use a lower wattage motor to extend range. It is amazing what a little 250 or 350 watt motor can do if it has the full range of gears available to it from the lowest granny gear to help climb the steepest hill with a heavy load or increase the cruising speed on the flat in the top end of the gears. Even more so if the RPMs of the motor and crank are carefully matched so that the electric and human power source work together with both the little electric motor and the pedals operating together at their ideal RPMs.

    Quote Originally Posted by badmother View Post
    Sure you want to build it? severalnice 20" heavy duty cargo bikes has been posted. Just search for them.
    I think the only way I'm going to get what I'm looking for is to either build it myself or have someone like "Cargo Tom" or "Haulin Colin" build it for me custom and pay accordingly for such custom services. The closest thing to what I'm looking for that I have found so far is James Black's "New Cycle Truck 001" (clickable hot link) which does have the kind of front and rear rack capacity that I am looking for and I admittedly borrowed some ideas from his design there. But it still has too steep of a seat to bottom bracket angle and I would still have problems easily putting a foot down while seated. Plus there isn't room in that frame for a stoker-monkey type set-up where a quiet hub-motor mounted up in the frame drives through the bikes gears. You could use a either a Cyclone or a GNG Electric or something similar along those lines but they all make a lot of noise and I would like something nice and quiet.

    Long story short if someone made what I'm looking for I'd be interested but non-one seems to come close enough with factory stuff so custom looks to be the only way and with custom it is either pay through the nose or do it yourself. I can weld and I've already built some tandem bikes by cutting and welding old steel frame bikes together so I think I could do it. I know there are some on this forum who have built their own cargo bikes to suit their needs and I was hoping to catch a few of them for advise/pointers while I'm still in the planning stage since once you actually start welding things together making changes isn't quite as easy as just changing a few lines in CAD and getting it as right as possible on the drawing board. It's that old measure multiple times and double and triple check everything so you only have to cut once thing.

  5. #5
    Senior Member badmother's Avatar
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    I understand how you think. Problem is there is a lot of info floating around out there but to find it all can take a long time.

    I found several looking trough the old posts last night but one had racks that was too wide for a bus rack (maybe that could have been changed),
    and several do not have the seat set back as far as you want.

    Personaly I do not like the forward BB style becouse I feel i have no strenght for hills riding in that position.

    When I start on a project of heavily modifying stuff (like making a homemade longtail) I often make a rough sketch first- Make something that does not involve much work but can give me a feeling of what the finished product would be: What about starting off with something 20" (like a R20 or similar) and fit a BMX setback seatpost? That could give you a feeling of how much setback (seat vs BB) you want, and can also give you an idea of using a "shopper type frame" w setback seatpost is an option at all.

    I remember several yrs ago a bike was posted several times in the forums: A BMX (right size and strenght) with two long pipes clamped to the frame, one on each side. Gave exactely the same effect as the one you linked to but with two pipes instead of one. Made a stable front and rear rack to clamp platform or box to. Could be welded and made more neat looking. An extra toptube added to a nonfolding R20 or a steel minivelo (a lot of them being discussed in the BF foldingbike forum) both options with a setback seatpost could be a start (like a sketch) or could be good enough if you are lucky.

    Did you see sixty`s old R20 converted to a touring bike with longer wheelbase? I think he chopped off the seat and chainstays of it and welded (or brazed) the rear part of a full size bike to the R20. This way he got a longer wheelbase and less heel strike when using a "normal" rear bikerack and full size panniers. In your case I was mostly thinking of the better balance this would bring to the bike with a setback seatpost.

    We need a sticky with links to good looking 20" cargo bikes so that they are easyer to find!

    I think your project is interesting but it is a bit advanged for the regular utilityrider and is a mix of stuff you`ll also find in the foldingbike forum, the Alt bike forum and the framebuilders forum.

    Keep us updated!
    °Empty drums make a lot of noice... (Old Hungarian proverb).

  6. #6
    Senior Member badmother's Avatar
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    Last edited by badmother; 11-21-12 at 02:49 PM.
    °Empty drums make a lot of noice... (Old Hungarian proverb).

  7. #7
    Transportation Cyclist turbo1889's Avatar
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    Thanks for the links, some good stuff to look at there. As far as the available pedaling force with a more forward bottom bracket to seat angle and not being able to push down as hard into the pedals. I've ridden a few cruiser and chopper type bicycles with the bottom bracket even more forward then the 60-degrees set-up I drew up and find that those with a seat back rest that you can push back into while seated really helps to maintain full pedal force:


  8. #8
    coprolite fietsbob's Avatar
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    IDK if a patented, design, but, a hub motor out of the wheel, driving a crossover crank, normal Tandem Bike component,
    as that jack shaft, gives you the rest of the gear ratio range, of the drivetrain
    to apply that motor assist , with the rest of the drivetrain..
    but there needs to be space for the motor, Stoke Monkey used a Xtracycle longtail stretch to do that
    with a smaller motor and smaller 20" wheels there may be room created but still keeping a 1M wheelbase.

    Of course on a SWB Recumbent , you have the whole area to load up behind the seat,
    and that flat footed stop of a crank forward upright bike you desire.
    Last edited by fietsbob; 11-23-12 at 11:39 AM.

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