Tadpole cargo trike based on Warrior

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Apr 18, 2020
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Last year I used an oxy-acetylene brazing rig and a flux core wire welder to cobble together a two-wheeled bakfiets cargo bike. It's been useful for hauling tools and materials for my work as remodeling contractor, and for hauling raw materials for my home "maker" hobbies. I've been thinking ever since I created my first cargo bike what I'd like to change when making a v2.0 design. I've owned several longtail cargo bikes and in the past I owned one two-wheeled recumbent (a Bacchetta Giro 20). Anyway, I've always like the potential stability of tadpole trikes, but never like how low they sit to the ground. I've been car-free for about 8 years now and I ride pretty much everywhere in Chicago. There's certainly cycling infrastructure, but my experience with riding a recumbent in city traffic left me a bit cold to the concept of having another one and having to ride in and among cars, even when you have bike lanes. At any rate, I was thinking about a new cargo "bike" build and decided that a trike would be the best layout for greater stability and weight carrying capacity. Also, the trike layout gives me the option of creating an awning for solar panels for charging e-bike batteries as well as providing off-grid power to recharge cordless tools. I decided ultimately to use the Bafang BBSHD mid-drive motor that is on my current cargo bike for the trike, and having it drive a single rear wheel was a far less complicated prospect than trying to drive two rear wheels like with any delta trike design.

One thing I took away from owning my Bacchetta was that I really disliked Over-the-seat-steering (OSS), and would greatly prefer under-seat-steering (USS) on any future recumbent I'd own. I looked at a bunch of the current commercially available trikes, especially looking at how the USS versions were set up, particularly how the wheels are mounted. Ultimately it seemed like the best starting point to keep reverse-engineering to a minimum was to start with the Warrior Trike plan since it incorporates USS and all the hard work is done in terms of figuring out how to construct the whole joint where the front wheel hubs meet up to the frame/steering mechanism. Now, where my plan differs from the Warrior layout is that I intend to make all three wheels be 26" diameter with the base wheelset being 26x3.0 WTB Ranger tires on WTB Scraper 40mm wide rims. The rear wheel part of the frame is going to be built around a 170mm wide axle so that I can have the option of running a Rohloff hub at some point, but the preliminary drivetrain is going to be based around some kind of wide range cassette - mountain bike type either 9, 10, or 11 speed.

Besides being for carrying cargo around on city streets, I wanted this trike to be handle to light off-road riding. Mind you, not shredding singletrack or anything, but I wanted it fully capable of handling rough roads, gravel, or semi-off-road double-track type stuff. Also, being to run full-fat 4.0 tires for winter/snow riding was also a plus. I plan on having this trike be not only a practical cargo hauler capable of hauling tools, building materials, etc, but also capable of carrying camping gear, as well as more esoteric things like my 8" Dobsonian telescope, or things like cargo modules for carrying refrigerated foods, or things like small kegs of beer as well as having custom beer tap/serving setup. There are a lot of things like this that I'd conceived of with the bakfiets, but there are issues with the stability of a two wheel setup when heavily loaded, not to mention my initial frame design is bit more flexy than I care for which is why I'd been planning a v2.0 pretty much as soon as v1.0 was done!

My design is going to have the cargo platform placed behind the driver's seat and just in front of the rear wheel. The plan is make the platform just big enough to accept a couple standard size cargo items such as a jobsite tablesaw, the current toolboxes I use, or a standard palletized shipping container. To increase the space available and the versatility of the cargo hauling I intend to have the bed feature extensions that can be deployed to allow carrying long items such as 2x4 lumber in varying lengths, raw steel tubing for welding projects, etc. The rear will also feature a hitch mechanism to allow me to tow my 6' long cargo trailer. Of course being as this will be e-assist I will also be incorporating storage under the bed area behind the seat for some larger capacity batteries than my current battery. My current battery does at least give me upwards of 60-80 miles range, and my current bike weighs about 90 lbs. I imagine this cargo trike is going to weigh significantly more than that though.

Another major reason for undertaking this new project besides improving on everything about my v1.0 cargo hauler, I see a trike as being a far more stable platform for cargo and the concept I have in mind lends itself FAR better to some of the other car-free/carbon-free/carbon-neutral concepts I want to explore with stuff like the solar charging, and just generally creating a human-powered vehicle that can be shown to be an adequate replacement for the average truck/van. Obviously not capable of being a completely 100% replacement, but more as an exploration of the concept and a test-bed for a lot of different technologies.

I guess besides announcing the idea I wanted to get some input and see if anyone had any suggestions or cautions in regards to adapting the Warrior Trike design to what is essentially going to be a mid-fat/full-fat extended wheelbase tadpole trike. One thing I'm already thinking of is braking. Large rotors all round, probably 203mm for each wheel, and potentially TRP Hy/Rd cable-actuated hydraulic calipers for all wheels. I'd like to have a single brake lever actuate both front wheel brakes, but I don't know yet if anyone makes a lever that has adjustable pull. The TRP Hy/Rd use the short pull typical of road levers, while most of the dual-pull levers I've seen are for long-pull calipers like Avid BB7s or the TRP Spyke mechanicals. I had Spykes on a past bike but didn't like how much regular adjustment was necessary to keep the pads braking properly. The nice thing about hydros is that they continually adjust themselves so braking force stays constant throughout the life of the pads. Anyway, enough jabbering about my plans. I hope to begin construction in the next few weeks or month or two. How soon I get started is going to depend on my access to getting some steel tubing as I only have some limited materials right now most of the sizes of stuff I've got aren't suitable for this type of project. Anyway, I'd love to hear any thoughts or suggestions.
 
Joined
Oct 19, 2012
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Wakefield, UK
You're right about the weight going up. Fat wheels and tyres are very heavy. A pair of fat 20" on a 20mm axle weigh 6.5kg more than a pair of very skinny 20" on a 12mm axle. Remember that 26" fronts will either reduce the turning circle or you will need to make the trike wider to allow them to turn. Many people will not recommend anything over 20" for fear of bending them though that argument usually applies to regular width rims and fat rims are generally much stronger. No bike wheel is designed to take lateral forces though and the bigger the wheel the bigger the forces. Cargo weight is only going to add to those forces. Given the extended length of the main beam you'll have to up the spec of it from the original design.

As for a twin hydraulic lever you could try ebay for a motorcycle unit. I got a "universal" Chinese adjustable pull one that will mount twin lines via banjo bolts for about £20. Mine is pressing Yamaha R1/R6 callipers though.
 
Joined
Apr 18, 2020
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My original thoughts had been along the lines of recreating something like a Velove Armadillo (quad), but the complexity of the steering and delivering power to the rear wheels, not to mention screwy laws here in the states regarding what might be considered a "bicycle" or human-powered "cycle" means that something with e-assist and 4 wheels might start introducing legality issues, especially when trying to utilize existing cycling infrastructure. Anyway, the plans quickly went from delta trike to tadpole. My thoughts are basically to create something akin to the existing "fat" trikes made by companies like ICE or Utah Trikes, but extend the body between the seat and rear wheel to accommodate a cargo bed. The Armadillo is supposed to be able to carry up to 700 pounds, but that's WAY more than I can imagine I'd ever want to try moving, with e-assist. Instead, I can say I've safely carried up to around 200 pounds (not counting my weight - ~180 lbs), and found that much more than that on a two-wheeled bike is likely to be a major struggle. Of course three wheels makes a more stable platform and presumably could potentially carry a bit more weight than I'd be comfortable with on the two-wheeled bike. At any rate, this is more about having a platform that can handle bulky items that don't necessarily weigh an excessive amount. Carrying a couple heavy toolboxes, and a portable tablesaw is still likely to probably only tip the scales at 200 pounds at most. I'd think a max cargo weight of around 300 to 400 pounds is probably reasonable and is certainly doable if the weight is split between three wheels and the frame design is beefed up. I'm already thinking rather than the post-seat type of frame like you see on the Warrior, my frame is going to be a ladder type along the top with a lower single bar so that it looks like a triangle if viewed from the end. Struts joining all three of the long frame members will give it some additional strength in resisting flex and some side bars will extend out to provide structure for the platform. The rear portion around the rear wheel I'm going to design differently so that it resembles something similar to a traditional bike rear triangle. The whole thing will need to be wide enough to accommodate that max 170mm wide axle. My only width constraint for the 'cycle is that it be no wider than 34" so that it passes through doors that go back to the bike room of my apartment building. A max width of 34" also ensures that it's no wider than a standard bike lane so in the areas of my city where bi-directional bike lanes exist I'm not encroaching on the oncoming lane with my vehicle being too wide. Another thing - I do have a Surly Pugsley, so I know all about how heavy those fatbike wheels can be! However, surprisingly, if you set them up tubeless and use single-wall rims with cutouts like the Surly Rolling Darryl rims then you can keep the weight to a manageable level. They're obviously still WAY heavier than pretty much anything else, but WAY better than tubes. Tubes can add as much as an extra pound to the weight of the wheel. The plan will to be go tubeless on this bike for both wheelsets though. The main wheelset is going to be the 26x3.0 Rangers on the WTB Scraper rims. I found with 3.0 on my Yuba Mundo I used to have and the Kona Wo fatbike I had before my Pugsley, that 3.0 will roll over most anything and when set up tubeless goes a long way towards providing a kind of basic suspension. Our roads and paths around here are pretty shite with potholes and such.
 
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Apr 18, 2020
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vk3ckc - certainly a valid idea. I've considered the idea of using a trailer only for when I need to haul things, but often as not I've been out on my regular bike or cargo bike and needed that capacity I'd get from a trailer and not had it. If it's at home or the shop then it does you no good when you need it. This build will include the ability to tow a big trailer for even more capacity if necessary, but the main thing is to build upon the capacity if have with my current cargo bike. The current bike has a platform that's just a bit too small. I chose to use some heavy duty cromoly tubes for the cargo area and they were only about 28" long which meant that the way I made the platform there is only about 25" usable length. I found out the hard way that there are almost no commercially available cargo totes that will fit onto my platform. Also, it's big enough to carry the table saw, but not all of the toolboxes I carry that are part of the stacking system I bought into. I need to have about 30" or so of cargo length. I guess the other thing that has me wanting to do this build is to use it as a test platform for off-grid e-assist cycling and such. Having the extra length of this cargo frame trike means I have much more space to build an awning to support solar panels. Do a Google search for "Sun Trip e-bikes" and you'll see a bunch of cool solar electric bikes, and that's part of the inspiration for this build.
 
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Apr 18, 2020
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vk3ckc - I was wondering about length myself. Some preliminary measurements were giving me a total length of around 9 1/2 feet, so I went down to the bike room to measure my bakfiets and sure enough - that bike is pretty much about the same length. I feel like about maybe 10' is not an unreasonable length for the 'cycle. I get what you're saying about making it modular, but I think that would simply introduce far too many things to engineer to accommodate. The chain would need to be shortened dramatically, the frame would have to be strong enough to support 300 pounds + while still being modular. This 'cycle/project is intended to be used mostly for hauling and as a test-bed for solar charging and car-free stuff so I think it'll be fine as-is.
 
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Apr 18, 2020
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Figured I'd post an update. I've further refined more of my design - bought the Viking plans as well to see if there was anything in them that would work better for my design. I decided partway through the brainstorming phase to make this serve as a tandem with the stoker's seat removable to accommodate the cargo platform. There are some supply issues with getting 26x3.0 tires and I didn't want to lock myself into a design where I would have difficulty getting replacements later. Just pivoted a bit and decided to make it full-fat with all three wheels being 26x4.0. Figuring out the stoker drivetrain and how to make the mid-drive motor place nice with all that was a challenge. A company called da Vinci that makes two-wheel tandems will be manufacturing a custom version of their stoker free-wheeling jackshaft setup that has been proven on their bikes to be able to handle captain, stoker, and a mid-drive motor. I'm waiting for various parts that weren't in my spares bins to come in. Reached out to a trials bike shop in the UK and will probably be getting some Magura "two-into-one" brakes for the front and salvaging another 4 piston Magura from my cargo bike as well. A nice guy on a recumbent forum reached out to me, and for the price of shipping I'm getting two complete mesh 'bent seats and mounting hardware as well as a bunch of steering gear and the like from a couple 20" wheel trikes he no longer uses. Took delivery of my frame steel a while ago and I expect to be building the frame and wheels and such within the next couple weeks or so I hope. When I get started I'll probably just create a new thread for the actual build. I'll also be filming it and putting it up on YouTube in installments as I'm working on it.
 
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I don't think this plan is a good idea ? or this idea is a good plan ?

There is a reason why 99% of cargo carrying tricycles are deltas , it is simple physics the heaviest object needs to be as close to the widest part of the trike and as close to the ground as possible else it will tip over.

regards Paul
 
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Apr 18, 2020
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I disagree. Cargo delta trikes are what they are simply because it's the easiest way to build something that is stable and hauls cargo using mostly standard bicycle components. The number of cargo courier messengers all round the world who ride two-wheeled cargo bikes of varying forms also show that lots of large bulky loads can be carried without the extra stability of three wheels. Although speaking from experience having owned and ridden a number of two-wheeled cargo bikes of varying styles, the one thing inherent to all of them is that when heavily loaded, low speed stability sucks and is usually when episodes of dumping cargo or tipping over the bike happens. What I'm building is primarily tandem first, cargo trike second. My original design would've had a shorter wheelbase, but now that it needs to accommodate a stoker and that stoker drivetrain, I believe it will actually be more stable than my original design would've been, mainly because of the longer wheelbase. Also, you might be envisioning me carrying heavier cargo than what I'll actually be carrying. This will mainly be for carrying things like 2x lumber, sections of long pieces of salvaged metal, bulky but fairly light items like boxes and such. Occasionally it will haul things like a jobsite tablesaw or something similar but again, we're not talking about things that are typically heavier than say 70 or 80 pounds even though they may be large.
 
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You're going to add a lot of extra weight with fat tyres. A fat 20" I've got is 3.3KG over a thin one. It'll be more for 26". I'd guess you're looking at 12kg over and above some thin ones.
 
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Carrying a couple heavy toolboxes, and a portable tablesaw is still likely to probably only tip the scales at 200 pounds at most. I'd think a max cargo weight of around 300 to 400 pounds is probably reasonable and is certainly doable if the weight is split between three wheels and the frame design is beefed up.
This does not sound to me much like ....

Occasionally it will haul things like a jobsite tablesaw or something similar but again, we're not talking about things that are typically heavier than say 70 or 80 pounds even though they may be large.
Anyway it is your build and you are riding it ......
 
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Apr 18, 2020
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I'm not sure what a cheap set of fat rims and tires weighs, but aluminum single wall rims I've had in hand, especially with cut-outs are hardly much more heavy than some of the wheelsets I've built with more traditional rims. I tend to err on the side of tough rather than lightweight, so some of the wheelsets I've built have for example been 26x2.5 Extraterrestrials on Alex DX32 trials/downhill rims. Stout wheels and not especially light. A set of fat tire wheels is of course going to be heavier than most traditional smaller tired wheels, but it's not like someone picks them up and will say, "Oh my gawd! That's so heavy! How the heck can you make that spin, it's so heavy!" Also, you'd be amazed at what going tubeless does for overall weight of any wheelset and what it does to improve ride quality. My tires are Schwalbe Jumbo Jim Exo Snakeskin Lite - basically the lightest, and lowest rolling resistance fat tires you can buy.

Also - between my posts I probably conflated some weights of cargo load and such. Cargo weight will seldom be much more than an average large adult will weigh. If you figure a pretty big adult is 200 pounds or maybe more, then cargo capacity can be that much, even more if the frame is built to take it. I think the way I'll build this it will easily be able to take 300 pounds of cargo but that would be a pretty massive load of just raw materials or tools or whatever. My two-wheeled cargo bike can take that kind of load but I've seldom carried more than about 150-200 pounds on it. If I ever need to haul more than weight capacity will allow or too bulky, I always have a big cargo trailer for that.
 
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Schwalbe Jumbo Jim Exo Snakeskin Lite
A long enough name for certain. They look like they'll be like riding over a cattle grid on the road. Have a look at the rolling resistance figures here:-


Looks like you're going to burn the thick end of 100W extra to make 3 of them roll over the best examples.
 
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Apr 18, 2020
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That website is the one I looked at when I was figuring out which tires to put on my Pugsley. I've always been a Schwalbe fan, so it warmed the cockles of my heart to see them lead the pack with the easiest-rolling fatty tires. My Pugsley is just "human-powered" and I regularly commuted on that on city streets and could ride at 18 mph without working up too much of a sweat. With e-assist and/or the stoker present I don't think it's much of an issue. I'm more concerned that the actual tandem frame is probably going to weigh nearly 80 or 90 pounds, probably even more once every component is installed.
 
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