SB Cruiser Mk II design ponderings

[amberwolf]

This may not remain titled the same, but for now, SB Cruiser Mk II will do to get the idea across.

So...I've been rebuilding the original SB Cruiser here:
https://endless-sphere.com/forums/viewtopic.php?f=2&t=67833&start=350#p1227053
to fix a bunch of "little things" and make it more useful.


But there's a lot of things I can't "fix" without starting from scratch, or doing so much to the old one that it'd be a lot easier to do it from scratch, anyway.


So this is going to be ideas on what exactly I'd do if I were to start over.

It needs to be able to handle quite a bit more cargo (or dog) and accelerate a lot quicker than SBC even with that cargo on there, *and* the trailer attached, also full of cargo (or dog). Preferably both the dogs, at least, in the cargo deck area, so I don 'thave to use a trailer to carry one, with the other on the deck.

Also needs a lot more range than the other one, preferably also while hauling the max cargo, but I don't expect I can manage that. The best I can do right now is both the A123 and the EIG pack at the same time, plus whatever that old Luna pack can put out when paralled with the others (by itself it'd probably just burn up at these loads).

First up is building the deck area frame more like my Mk IV flatbed trailer here:
https://endless-sphere.com/forums/viewtopic.php?f=2&t=76539
so it's lower for better stability in turns and such, especially when loaded down. The Raine Trike (on hold) would be built this way, too:
https://endless-sphere.com/forums/viewtopic.php?f=2&t=80951
but it's meant to be smaller than SBC, and SBC Mk II (SBC2) will be bigger--at least a longer cargo deck, and wider if I can manage it, because I don't need this one to go thru my front door. It'll be built to stay outside, albeit parked in the shed or something like that.



Motor drivetrain won't be hubmotors, but will be a central motor driving a differential that runs both wheels. I'll probably use large-diameter wheels, because they'll ride easier...I don't knwo if bicycle wheels will survive this, but if they dont' I'll have to see about moped/motorcycle wheels.

But they wont' be directly mounted to a transaxle, most likely, as live-axle wheels, probably they'll be driven by short chains from the transaxle ends. Otherwise I'll need to make some hubs to get the bike wheels bolted to the transaxle; I might be able to use some old powerchair hubs I have for that, if they fit teh axle, or if I can lathe them out to do so.


I dont' think I have a good diff, though, that could directly be used. I have an old powerchair with a brushed motor / transaxle combination (the chair itself was destroyed in the housefire, and the motor seems to be toast, but the diff is probably fine, just unlikely to be made to take the torque/power I need).

I might have to bulid one, and not being sure I coudl do that, I might have to buy one. :/ The peerless-type diff is what's been recommended to me a few times for the other trike projects, and this type:
http://www.staton-inc.com/store/index.php?p=product&id=179
http://www.northerntool.com/shop/tools/product_35768_35768
is typically around $140-$150 on various places online; if it seems to be the best option I'll put up a want-ad here on ES and see if anyone has one cheaper, cuz I dont' have that kind of money to spend.


The motor...I don't know yet. Probably the old powerchair BLDC motor I havent' yet gotten to use in a project, powered by an ebike controller. Might be something better; I've been advised a care package is being sent of some stuff; we'll see when it gets here if I can work with what's in there.


It will still be pedalable, albeit at an extremely low speed, just geared very low (like I just did to SBC) so I can accelerate it very slowly and keep going to get home in case of drivetrain failure...but I dont' know that I can put the pedasl thru the peerless diff; if i do and that's what fails, I'd still be screwed. Could make a separate pedal diff to input to the wheels, but..I dunno. Anybody else with any ideas?


I might also put the 1000w Fusin geared hub in the front wheel, but I dunno that it will be able to haul this thing very well for very far--it's just not geared for the super-low speeds it would probably have to be used at if I ever did have to use it as an emergency backup drive. So probably just a regular front wheel.

Basic layout, mostly like the SBC, though we'll see about a bit more elegance along with the functionality; depends on what I end up building it with, as that's the limitation I've got.


Will work some design ideas out and sketch them up to put here.

If anybody has ideas they're welcome to post those too.

 

[docnjoj]

I would avoid the differential all together and use the power to the single rear axle and the other axle free like the Sun USX. It gives differential action but power only to one wheel. Ours has a front hub motor but you could add a mid drive also without too much trouble.
Just my two cents. Depending on whether you add the gearing to the axle without the pedal chain you coul have 3 wheel drive. The sun uses negative camber axles and wheels for stability.
otherDoc

 

[Drunkskunk]

you might try to find an ATV parts bike. The 4WD versions often had independent rear suspensions and a differential. I've seen them for $50 on craigslist. It's a step up from bicycle parts and that would take the power and weight of your cargo hauler.

fitting larger wheels is easy-ish. remove the tire from the ATV rim, drill the edge of the rim for spoke holes, and lace a normal large diameter rim. they do make a 21" motorcycle tire, which falls between a 24" and 26" bicycle tire in size.

 

[amberwolf]

I would avoid the differential all together and use the power to the single rear axle and the other axle free like the Sun USX.

I've already experienced how a one-drive-wheel trike handles, with SB Cruiser, for the pedal drivetrain. It's problematic in a number of ways, but mostly when trying to make lefthand turns--I basically can't make anything even close to a sharp turn, have to do a pretty wide curve (like that in an intersection from the left turn lane of say, southbound, to the lefthand lane of westbound). The closer to a tight turn it is, the more it feels like the left wheel is just jammed.

The same is true with the hubmotors in the wheels--if I only use one at a time, it only makes good turns in te direction opposite the side the motor being used is on (right motor, left turns; left motor, right turns).

So avoiding running power only thru one side is specifically why I want a diff of some sort, if I use a non-hubmotor solution.


Keep in mind that this is intended to be a cargo trike to carry up to a few hundred pounds (and itself will probably weigh 200-300lbs!) *and* pull a trailer with at least that much more on it, *and* still be able to acclerate from 0-20MPH in 3-4 seconds at most.

So while 3-wheel-drive might work, 1-wheel (especially just the front wheel) won't, most especially since my pedalling can't contribute even 1% of the power needed to do this.




I'm probably not going to take SB Cruiser apart for it's motor wheels/controllers, as it has it's own uses, and would still be a good backup trike even if this new one becomes my primary.



Regarding the camber, I might use a slight inward-at-the-top camber, like I do on SBC, but it can't be much because I need all the cargo area clear of wheels/tires, that I can get, and I have to put a fender frame/cover around the wheel too, so cargo (or doggie tails and ears!) doesn't touch the wheels.

you might try to find an ATV parts bike.

That's a thought. I'll have to poke around. One of the families in the neighborhood has one in their yard they don't use much, I could ask them if they know anyone selling a junked one.

fitting larger wheels is easy-ish. remove the tire from the ATV rim, drill the edge of the rim for spoke holes, and lace a normal large diameter rim.

I hadnt' thought about using the ATV rims *as hubs*, but I guess there's no reason it wouldn't work; just be heavier than is needed.

For now I probably cant' get any new MC tires/rims, but if I still have them (not sure) I could use the ones off the dirtbike frame mdd0127 gave me a few years back (a blue suzuki from the 1980s). They're knobbies, but at least I already have them (if I do) and would let me see if the idea would even work.

Then get new tires when I can afford them if these didnt' work well enough. The disadvantage is that I don't think they're the same width, since one is a front and the other a rear.

 

[amberwolf]

An update to this project:

I have a pair of MC wheels and tires that have street tires instead of knobbies, but they are different sizes (front and rear off teh same bike, probably 19" and 21" but I don't remember). They're also way too heavy; they're worse than my MXUS 3k hubmotor + wheel/tire. I suppose the fact that I could probably ride them completely flat and still roll down the road ok makes up for that....

It's still more likely I'd go with bicycle wheels and figure out better tires, or do multi-layer stuff, etc. However, I haven't seen any of the "fatter" tires in 26" that would give me good enough tire wear, or sufficient puncture resistance, without wasting the air volume inside with mulitple layers of other older tires and thick tubes and such.

So I could probably design in some form of suspension into the wheel hangers to the deck. I'm not sure how that would work yet. I have some vague ideas about plungers with springs under them, at one end of each hanger, with a pivot at the other.


There's an update over in the Raine Trike thread for it's design; it's not much like what I need for this one, but if interested it's here:
https://endless-sphere.com/forums/viewtopic.php?f=2&t=80951&p=1322366#p1322366

 

[amberwolf]

Four-years-plus into the redesign process, and I've begun collecting parts (well, I will once the places I've contacted get back to me with details so I can buy things).

One key thing about this trike vs anything else I've done, is that I will use pre-made parts designed for the intended purpose, wherever possible, rather than having to make parts that may or may not work, may not be reliable, etc. The SB Cruiser has been a fun experiment the last almost seven years, but I have had a few serious problems with it mostly caused by my lack of ability to make things quite right. SBC will stick around as my backup trike, and testbed. But this new one will need to be as close to 100% reliable as possible, so whenever my budget allows, and a part exists, I'll be buying stuff for it (most of it will probably have to be used parts, since I *might* be able to scrounge a thousand dollars over the next several months out of my household budgets, including what I've already saved up to now--more if I'm lucky and get to keep working full time almost 40 hours a week; unpredictable with the whole plague thing frequently changing the world around me).

I *will* have to build the frame, which will be built of the same types of materials as SBC, so recycled cheap steel, mostly relativley thinwall square 1" tubing that used to be retail signage / fixtures. I'd rather buy new good steel, but that's way out of my budget. I'll likely use new wood (probably dogwood fence boards as they're light and cheap) for stuff like the cargo seatbox, and the cargo deck. It's worked well enough for the cargo area walls and roof on SBC; I don't have enough of the narrow whitepine(?) boards I used for SBC's box and deck, or a source for more. The similar stuff at local stores is thicker and heavier and too expensive, harder to cut and shape into what I need.



The hardest part has been deciding whether to go with a cargo area that can literally hold a pallet's worth of stuff (or a stack of empty pallets), or a much narrower cargo area that can still fit where most bicycles can go, like SB Cruiser itself has, and making a trailer to do the huge-cargo stuff for the rare occasions I need it.

Because a wider cargo area would also greatly increase the stability of the trike, as well as give much larger volume for batteries, suspension and drive parts, etc. (under the deck), as well as mean almost not having to use a trailer at all, maybe once every couple years, I really wanted to do that. But it takes up way way more space when parked (so I could no longer park inside at work, creating more risk of theft/vandalism as well as summer heat damage), and on the road, and could never be taken on most bike paths, lanes, etc. It simply wouldn't fit, being basically as wide as a car. That itself has an advantage in that I'd be much less likely to be forced off the road by a car, but since A) that doesn't happen with the SB Cruiser trike anyway, and B) that means I *can't* move over if a car/etc behind me decides not to change lanes and instead just go thru the left part of the lane I'm in, it's not really an advantage.


So, I'm going to stick with a total outside width just a little wider than SB Cruiser, probably around 3 feet max, which should give me around 2 feet total width inside the cargo area. I have to measure the distnace between things at some corners inside at work to see what the actual max width can be, vs the length of the trike and it's turning radius, as that is presently my real limiting factor.

The trike will be longer by about a foot, so close to 13 feet long, so that I can extend the cargo bed to carry objects about 4.5 feet long while flat, and still close and secure the back of it.

The secured cargo box under the seat will be wider and deeper front-to-back, and about the same height, but should end up nearly twice the usable volume because it wont' have chain/etc running thru the middle of it, and won't have a sloped front (vertical sides all around).

The top rack and front canopy and wooden cargo area that SBC uses will on this trike be replaced with a completely canvas white cover, double layer with insulation in between (to help keep the sun's heat out in the summer). The top will still be usable as a rack for long cargo (boards, pipes, etc) that I sometimes need to carry for projects. The cargo area's sides will have removable (from the inside, only, for as much security as cloth gives) covers, so it can be used as an open trike for better aero whenever I'm not carrying stuff, but be easily closed up for cargo or dogs. The top canopy will probably be fixed to the overhead rack frame, since that's useful year-round as a sunshade and rain canopy. A hard tailgate will also be an extendable ramp. A ball-hitch for pulling my heavy-duty trailers will be attachable to the rear frame (like SBC can do). It's unlikely, but possible, that I will make the entire frame above the level of the seat base removable, for nice weeks in the few winter months when no canopy / etc is needed. Is probalby too complicated to make it retractable instead.


To make the cargo area more usable, and practically wider by a significant amount, the wheel wells will go away, because the wheels will be entirely outside the trike frame, on single-ended axles, using 29" pedicab wheels. The front and rear wheels will all be the same size and type, so that I can carry a complete fourth wheel and simply swap out the first time I run into any tire/wheel/etc trouble on any trip. (the second flat would require using a patch kit or spare tube/etc, of course, but I rarely have the problem using the thicker MC/moped Shinko tires, so as long as I can use similar tread-thickness 29" tires I should be alright, and if not, I can use double or triple layer old-innertube-sheathing layers on the actual innertubes, etc., to achieve a similar level of protection (albeit probably less efficiently).

The front fork will probably be single-sided, to make it as easy in front to get the wheel on and off as it will be in back, if a pedicab-rated fork of this type is available (so far one seems to be).

The frame will have the axles well above the deck, so the deck and cargo and trike mass is as low to the ground as possible, like it is now but even lower if I can manage it (at least a few inches), just enough to clear speedbumps, curbs, etc.

The rear wheels will be motor-driven, in one of two ways. Haven't decided on which to use, but am leaning toward the second for several reasons.

The first has two variations, using a single motor (probably a broken-axled QS205 50h), depending on which transaxle I can find. The "best" variation would use a transaxle intended to be run from a vertical-shaft motor, because then I can use a pancake style motor, like ex-hub-motor, laying horizontally so it's rotation is around a vertical axis, mounted under the trike, driving the transaxle via belt or chain. The other variation would be the more typical pedicab-style that uses a sprocket parallel to the wheels, at the transaxle, and the motor would also thus be oriented like this, making a hubmotor less of an optimal choice to drive it as it would *have* to go inside the cargo/seatbox, wasting space (it can't go in the regular cargo area), or it would have to go in front of one of the wheels, outside the frame, and then have to be jackshafted over to the transaxle input. In either case, the transaxle will not directly be able to drive the wheels themselves, because as noted previously, their axles will be well above the deck, and the transaxle below it. So there will be sprockets on the transaxle ends driving chains to drive sprockets on the inboard side of the wheel hubs (which will also have disc brake rotors side by side with those, complicating things a bit).

The second way, most likely to be used, is to use independent hubmotors, not in the wheels, mounted forward and below the axles, in the frame, chain-driving sprockets on the inboard side of the wheels. THe motors would have only enough axle to clamp into a frame mount, and possibly not even that--I might instead use a side-by-side two-bolt system, holes tapped into the axle core on each end like APL's DIY axial motor thread shows, and bolt them between frame plates, to keep the system as narrow as possible.

I already have a number of broken-axle motors to choose from, from some 9C 280x's to the Mxus 450x's. I dont' need much power from the motors under cruising, perhaps 500-600w depending on the gearing chosen for peak speed vs motor max speed vs battery voltage, and any power peaks would typically be a few seconds long during acceleration from a stop. I would guess that a max peak power would be somewhere around 4kW per wheel, depending on gearing. The max speed I would probably gear for would be 30mph, to ensure that in the extremely unlikely event of having to go way faster than usual to get out of the way of traffic, I could do so. The normal, CA-limited, max speed would be 20MPH, as it is now. Battery voltage will probably be 28s, since I'm making the whole electrical system from scratch, and the controllers I'll probably use are the Lebowski-Honda-IMA hybrids I started building almost a year ago, but haven't gotten back to yet.


If the "small" 9C motors are unable to handle the peak power, I'll go to bigger ones. Haven't even tried simulating the system yet, so it's an open question what to use. If I had two of the QS205s, I'd just use those and have done with it, as I know they can handle whatever power I throw at them, but I only have one. It doesn't matter if they are the same winding or not, because I can simply use a different output sprocket on each motor so that the wheel speed for each ends up the same. If I had two of the old powerchair BLDC motors (thread about them somewhere here), I'd use those because they're even easier to mount on the frame; I would just have to bolt them to flat plates and be done with it (well, have to install normal triple hall sensors, as they're built with a SIN/COS encoder and I don't think the Lebowski brain can deal with those)--they even have solenoid-operated brake plates inside them that could be used as parking handbrakes with a bit of mechanical handiwork. But I only have one of those, too.


The pedal drivetrain will be entirely thru the front wheel, something like the way the TruckTrike does it, though I don't know exactly how it will work yet--that depends on what parts I can buy and what I have to make. I've looked at a few ways to do gearing changes, given that the wheel itself has to be a single-speed non-freewheeling sprocket, so that it can be swapped out easily like the rear wheels, all using the same design so a spare wheel can be put right on. So at least one IGH will be installed between the pedals and the front wheel, most likely a 7 speed SRAM I've got laying around here (that I need to find a shifter for). I've seen a Hammerschmidt 2-speed shiftable crank system over in the For Sale Used section here on ES, that would make shifting at the cranks easy (no derailer wanted, prefer a single-path completely coverable chainline), but it's $250 whcih is a quarter of my whole "budget", and I have other priorities that make that an unlikely addition. Using two series IGHs is a more likely end result, like a 3-speed SA or Sachs or Shimano I already have somewhere here.

The pedals need to be geared so that I can contribute at least a tiny amount of pressure on the pedals, enough to keep tension on them if I want to, so that I can exercise as much as possible while riding, even at 20MPH, and so that I can use a Cycle-analyst-read torque sensor for startup from a stop, and use cadence to control speed after that (the opposite way the CA3 usually works; presently it's all cadence on the SBC). But they also have to be geared so that if the mtoor system fails completely I can still pedal home, albeit very slowly (<1mph probably), a few hundred feet at a time with rests in between.



More thoughts later...my fingers are worn out.

 

[amberwolf]

A year and a half later, I'm beginning to consider continuing this project.

Some short time after the above post I was partly blocked on it because I was waiting for a pedicab company to get back with me on a deal for a bunch of drivetrain, wheel, and fork parts for it, but they just stopped communicating with me, and I didn't find any other source for some of the things I needed that didn't cost an arm, a leg, and two torsos. Some things I could've made for myself with a fair bit of work, but not as well as they would have been from the pedicab place. I'll probably end up having to do that anyway, since the prices of things have gone up and my pay has actually decreased for the same job.

I stopped even thinking about it a few months after the last post above, when Kirin died, and then Yogi not long after, because one of my main purposes for building it was to be able to more easily take Kirin and Yogi places without using the trailer, since the SB Cruiser was kinda built around Tiny's very small (for a Saint Bernard) size, and Kirin was very tall, and Yogi was just plain big. They could get into it, but neither was a comfortable fit (Kirin didn't care, because she got to be with me more, and that's all she really cared about, but...).

Now I only have JellyBean the Perfectly Normal Schmoo, who isn't all that much bigger than Tiny was, so if I have to take her somewhere in SB Cruiser, I can. And I don't really go anywhere much that I'd need to haul large cargo from with all the plague stuff going on, partly because of that and partly because many places I used to go either don't exist anymore, or don't have the things I would've carried in a bigger trike, etc.

But the SB Cruiser trike still has it's physical limitations, and it is aging, and it would be good to have a spare trike. If I'm going to make one, I might as well make a better one rather than just copy SB Cruiser (which would be relatively easy to do with stuff I already have).

So I am working out various design considerations for the new one again, and am looking for sources of pedicab-capable drivetrain, wheel, and fork parts, for their load-carrying capabilities, and the way the wheels typically mount (single-ended axles) which makes it much easier to do any form of tire or wheel repair.

 

[amberwolf]

Suspension:

I'd like to have at least some minimal rear suspension, but it is difficult to design something that will work well for both unloaded and heavily-loaded conditions, especially since the load itself should be able to be more than the entire trike & rider weight (which I expect to be about 400-500lbs total, depending on the motor system (battery, controller, motor) weight, including my own almost 200lbs).

Primarily the only load it will see is my own weight. Cargo carrying is mcuh rarer for me now than it used to be, so I only do heavy cargo about every 6-8 weeks or so with a big grocery trip of 150-250lbs, and a somewhat random-timing huge dogfood load of 200-300lbs a couple times a year or so when there is a big clearance sale of discontinued foods.

So it's more important that the suspension work well in unloaded or lightly-loaded conditions, but it'd be nice if it worked when heavily loaded at least enough to protect the wheels from pothole/etc damage in the rare but definite event of the unavoidable-for-various-reasons road damage or debris.

Whatever suspension system is used must move or pivot vertically entirely outside the cargo "box" area, it can be on a bearing roller inside a retaining track that's mounted to the side of that if necessary instead of freely swinging about a simple pivot, for instance. It just needs to leave the entire cargo area clear, and can't go under the trike as the bed and frame will be very low to the ground. It cannot "camber" the wheels in operation either, or else the tops of the tires would hit the side of the cargo box.

One consideration for what kind of suspension to use is the motor system, and how it will drive the wheel; see next post.

 

[amberwolf]

Motor Drivetrain, Wheel design, Braking

With the parts I have, the best drivetrain I can make is a hubmotor outside the wheel, driving it via a single-ratio chain/sprocket.

This also would be narrow, and better able to fit entirely outside the cargo area (without widening the trike too much to fit thru the doorways, etc that I have to go thru at work), leaving it uninterrupted unlike the SB Cruiser's which has a fair volume blocked by the wheel wells.

I'd use hubmotors in the wheels to simplify the drivetrain, but that would require a minimum of four identical motors, and machining a hollow axle-bearing mount to install in place of the existing axle on each, probably also making new side covers to accomodate larger bearings, etc. This would also make the wheels heavy, and probably less strong, and make the suspension work less well (or have to be designed around the extra weight, at least). Simpler to build and use plain wheels, because of weight, and to carry a spare, interchangeability, hand-manufacturing, etc.



As previously noted, I probably don't need much continuous power most of the time (outside of rare windy days), a few hundred watts, but I will need some hefty peak power for a few seconds of acceleration at every startup from a stop, especially when heavily loaded, potentially a few kW per wheel.

I have two QS205-50H stators, but only one rotor & side cover set. I am not sure if the MXUS 450x rotor and covers will fit; it's an experiment I will try at some point; I might need to make a couple of spacer rings to go on the cover edges and hold them away from the windings and fit the axle shoulders. If the magnets aren't as wide as the actual ones on the QS205-50H rotor, it won't make as much torque as it could, but it's still better than the MXUS motors themselves in that the QS are better made, and more likely to be able to handle high-peak-currents. Alternately if anyone happens to have a dead (cooked, etc) QS205-50H they'd be willing to send me the rotor and covers for....


I would not use a freewheel between the motor and wheel, so that I can still use the motors as variable-force electric brakes. I'd also have disc brakes, Avid BB7s, which would provide mechanical braking as well as parking brakes. Most likely I would use a large-diameter sprocket bolted to the motor's spoke flange, and a similarly-large sprocket on the wheel, probably inboard of the disc brake rotor (both would be on the inboard side of the wheel).


Because I want to be able to easily pull the wheel straight off the axle to do whole-wheel swapouts for flats (rather than roadside repair whenever possible), the rotor and sprocket mount would remain on the axle, on it's own bearing set, and engage the wheel via castellations or something similar; I haven't designed that even in my head yet; it just has to be easy for me to make (probably by hand), and easy to take the wheel off and put back on without a bunch of fiddliness, and strong enough to easily take the torque of rapidly accelerating and braking up to at least half a ton of mass in the 0-20MPH range.

The axle and it's mount must be able to support it's portion of that mass, so I am guessing 1" or thicker axles for this; I don't know what kind of movable mounting plate I can make that will do that without bending.

Axle height will be well above the cargo deck, so teh deck is maintained as close to the ground as practical. So far for my suspended-deck trailer, that has turned out to be about six to eight inches minimum clearance for speed bumps, curbs, etc.

Wheel size will be the largest diameter I can afford that I can also readily get a non-knobby street tire for. I would guess that 2.5-3" wide is probably good enough for the road-vibration absorption and traction required. I'd like 29" but 26" would probably work if it has to. The idea is that the larger the wheel diameter, the easier it rolls over debris and holes and whatnot. For instance, the 26" wheel on SB Cruiser's front rolls fine over a lot of stuff on the road that the 22"-ish rear wheels don't (they either bounce me up or bang into them and I can get rim damage, potentially pinch flats, etc). But even the 26" isn't large enough for some things, while a 29" might be.


Whichever size is used, all three wheels will be the same size, so that I can use any wheel on any position on the trike, and I can carry a spare wheel with tire/tube already mounted and inflated. (as well as the inevitable spare tube and air pump, just in case of a second flat on a trip).

 

[amberwolf]

A very basic sketch of the layout; I didn't try too hard to be proportional about things, i'ts just guesstimates by eye of relative size/spacing of things.

 

[amberwolf]

A series of new thougths and old, only a few of which have changed from the above:


The SB Cruiser MkII (until it gets a real name) is going to use "regular" spoked wheels, three identical ones, probably 29" for easier rolling over road problems (no suspension; it's too complicated for a trike that changes both overall weight and f/r ratio by as much as it's own weight dependign on what's loaded up).

The idea behind the wheels being identical and not internally powered is that they'll be swappable in "moments" with any wheel / tire problems.

They'll use hubs that slip on over axles built into the sides of the trike on the rear, and on a single-sided double-crown fork up front; I've seen this design functioning on pedicabs, so it should easily work for me. Bearings will be on the axles most likely, so I can have hubs with some form of spline or rib to accept the drive torque from a carrier that stays on the axle, and all the drive chains/etc would go to the carrier, as would the braking rotors. Makes changing wheels much easier, and tthey are lighter by however much, and I can more easily carry a spare wheel or two to swap out.

I expect the carriers to look vaguely like a washing-machine agitator.

The hubs I'd use a relatively large diameter flange, probably several inches, to give me plenty of room inside the spoke hole ring, and plenty of space between each hole for higher flange strength.

The wheels will probably use the tyipcal 14/15g butted or double-butted spokes, with eyeletted doublewall rims, as wide as practical for whatever the available 29" tires are. Tires have to be thick smooth road tread, but very grippy--not hard like typical bicycle tires, they have to be like the Shinko SR714 moped tires i'm using now. I would rather use bicycle tires if possible, but if there aren't any always-available ones that fit these needs, I'll use motorcycle tires and rims if I have to, to get the puncture resistance and grip required. Grip is extremely important for quick braking without skid with the highly variable mass, and also for cornering at intersections where idiots in traffic behind me don't allow me to slow down enough (rare, but it happens enough to worry about). The only tires I've ever had that had anywhere near the right grip were made by CST (cheng shin tire); all the common bicycle brands are just too hard and not grippy enough. The other catch is the tires can't be expensive, because if they're "thin" bicycle tires they're going to have to be replaced pretty often. MC tires are all so thick they'd probably last years, but I'd rather not use them.


I would use the same design of wheels / carriers on the MkVI trailer, based loosely on the MkV design that uses four wheels, in pairs of two side-by-side for weight distribution and redundancy. The difference is that the carriers on the trailer would be longer to accept two wheels on one longer axle, for a true "dually" wheel, whereas the MkV uses two bicycle wheels on independent axles slightly offset f/r for ease of access to their nuts, in the quickie few-hour-build-and-design-at-the-same-time I was able to do for it (built to pickup a piano that day or the next, I forget).

So the axle/hub/bearing size for both trike and trailer have to be able to handle the expected 1000lb+ load capacity for either one on it's own. As much extra load capacity as possible because there's no suspension, and there *will* be potholes/etc I won't be able to avoid or slowdown for from 20MPH while fully loaded because of other idiots on the road.



The fork is one-sided, double-crown, and I can use a dual-crown set from something else along with it's steerer, headset, bearings, and just cut off the right side that I wouldn't need, or use that to just clamp a partial tube in to bolt headlight or other accessories to.


The pedal drive...that's complicated, because I want to completley separate the pedal and motor drives. Since I want the motor drive to run both rear wheels (probably via separate motors on each wheel for redundancy, but possibly using a diff from a single motor), that leaves the front wheel for pedal drive. The best option I found for this is the Stites drive from TruckTrike or TrikeTruck website; the business shutdown but it's still up, and the owner said to contact with questions but has never replied to any of my inquiries about buying parts to make this, so I will have to build my own version from the few pictures there are of the drive.

The way this drive works is that the first chain goes up from the pedals along the frame to the headtube, then a form of universal joint connects that sprocket to the second chainline that goes down to the wheel. In his drive there is an IGH in the front wheel, but for mine the IGH has to be either at the headtube with the rest, or between the pedals and the first chainline, etc. I have a few possibilities for an IGH, including the Nuvinci and an SRAM 7speed, SA 3speed, etc. Mostly I just need a VERY low-speed high-torque gearing for the unlikely situation of complete motor system failure so i can still get home, but would also like to shift up to gearing high enough to let me pedal with *some* force along with the motors even at the max speed of 20mph. Aside from better exercise (for the little I can actually handle without exhaustion), that would also let me use a torque sensor for pedalling control of the motor system, not just cadence. (cadence works, so not required, but would be nice).


There's lots of other thoughts but I keep dozing so I'll post this and come bakc later when i can.