Amberwolf's Bolt-Together Semi-Recumbent Cargo Bike

[amberwolf]

A little closer to getting this thing going today. I was on my way with a friend to a sci-fi social club meeting, and by chance we passed Build-A-Bike on the way there, so we stopped to check if they had anything useful on their used-parts shelf.

I found a cheapie dual-crown steel suspension fork for 26" wheels for $15, and a couple of really cheapie rear shocks/springs for $5 each.

DSC03484.JPG (46.03 KiB) Viewed 1039 times

More than I really wanted to pay, since sometimes I can find a whole bike for those prices--but not lately. A friend with me couldn't talk them down, either, but it'd probably cost that much to ship one even if someone had one to part with for nothing but shipping. But I decided I could afford it, since Google sent me a check for Adsense earnings, which I figured I would not have earned enough to get for a few more years--I guess the Youtube videos of my old motor tests it now also includes must be more popular than the blog, because it was only after those got included that I quickly earned enough to go over the boundary to get a check.

So now I have a front suspension fork that will take a hub motor if I need to do it that way (or want a backup motor).
I could see that it was the right diameter for the Trek frame, but I wasn't totally sure it would be tall enough. Fortunately, it is:

DSC03490.JPG (39.33 KiB) Viewed 1039 times

It is just a spring/elastomer shock, like the one on CrazyBike2 and DayGlo Avenger, but since it's for the front that should be fine for now. I've gotten by fine with just that kind with those two heavy bikes so far, in the front, so I may never need anything better than that even on this newer one (although I want better, it doesn't mean it's necessary ).

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It's called a "Hill Assault", "Pacific Professional Series".

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It had all the hardware with it, and has studs for the V-brake type of rim brakes. Doesnt ahve disc mounts but since it's steel I can fix that. Not lots of travel, but a bit more than DGA's, and definitely more than CB2's. Not sure if it's 60mm or 80mm, as I can't really compress it very well by hand (which is a good thing). A little heavier than the forks on DGA and CB2 but not by that much. Guess I'll find out how good it is after I build the rest of the bike.

One thought I had is that if I end up really needing a front adjustable shock *and* a powerful hubmotor, I could combine the Manitou fork and this one. Take this one's steel dropout tubes and slide them over the ends of the alloy Manitou fork (although I would have to cut off the Manitou's actual dropouts to do that, and the little disc-mount-plate stubs). I don't know for sure if they are even large enough for that, but they look like htey might be. Maybe. If not, I could slit the back or front of them, expand the diameter a bit, then slide them on and clamp them down with hose clamps, and weld a piece across the gap, then remove the clamps.

Rather not do that, but it's an option.



The rear shocks are complete as well, including the nylon bushings and bolts to mount them. One has an 850lbs/in spring,

DSC03488.JPG (19.49 KiB) Viewed 616 times

and the other a 750lbs/in spring.

DSC03487.JPG (19.14 KiB) Viewed 616 times

There was a third one there with a 550lb/in spring, but I figure if I am going to put heavy cargo in this bike, then if I use these on it (which I probably won't; I have another idea for them) then it's going to need high-rate springs.

I haven't taken the springs off to see if the dampers still work, but even if they dont' I can probably rebuild them easily enough.

They are "Lujan suspension" brand, model 400A (750lbs/in) and 400B (850lbs/in). I don't know if the A and B are for the spring rate or for something in the damper.

Anyhow, I am now a bit closer to getting this bike working, since I have a front fork with suspension that I can dedicate to it, that I dont' think will just come apart first time I hit a bump with it. And options on the rear suspension should my idea for the Manitou fail to work.

[amberwolf]

Been awhile since I had any updates for this project, as I have been trying to get the trike working (but am now stalled until I design and make a pivot for tilting), amongst other things like some fixes/updates to CB2 itself, and the Vpower pack project.

Not much to add just yet, but now I have a better seat that should take little work to implement:

DSC03889.JPG (53.23 KiB) Viewed 991 times

They're a tiny bit wider than the bleacher-back seats I picked up before (one of which is now the top of CB2's seat, and one of which you can see in the foreground right of the pic), and are complete seats rather than just backs. They are almost exactly the same size as the seat I already have on CB2, which I'm pretty comfortable with:

DSC03890.JPG (60.42 KiB) Viewed 991 times

To make them into seats for the bikes, I need to make an angled tubing piece that replaces the hinge pivots currently joining seat and back, so the seat frame becomes a solid piece and is stiffer. Then I'll need to make a T-piece that joins the seat frame to the front U bar underneath it so that it will be very stiff for a mounting point, and add a second U-bar at the rear of the seat frame.

I can't weld them on, though, because that would melt or set fire to the seat webbing itself. So I have some more pondering to do.


Also have a few other things, some of which may be useful for the middrive:
http://www.endless-sphere.com/forums/vi ... 07#p345907

DSC03891.JPG (55.06 KiB) Viewed 991 times

[amberwolf]

Another possible frame to use for the front of this bike, with the Trek as the rear; a Nishiki aluminum frame from LI-ghtcycle:

DSC03939.JPG (37.49 KiB) Viewed 541 times

Fred had to be the first to inspect it, the others hung back for some reason, and Nana was too lazy:

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Using my trusty super-accurate "Excelsior Improved Spring Balance scale, made by Sargent & Co. USA", I determined that the Nishiki frame only weighs a bit less than 4lbs, and that's including the axle and nuts holding the rear dropouts apart for shipping. The steel trek frame is more than 5lbs, closer to 6. I didn't weigh the fork but it feels almost as heavy as the Nishiki frame.

DSC03941.JPG (41.24 KiB) Viewed 541 times

The green trek frame is the same one I already had here in this thread before, just used for a comparison. The black forks are steel Trek forks LIghtcycle sent with the frame; they are nice and stiff and should work even with hubmotors. Using a FUsin geared motor I think I could go with no torque arms, though a 9C or similar would probably need them. Interestingly, the Nishiki frame will sit balanced as you see in the pic, but the Trek (and every other frame I have, AFAICR) will fall forward onto it's headset end if balanced like that.

There's not really a lot of size difference:

DSC03942.JPG (22.54 KiB) Viewed 541 times

The Nishiki is just tall enough that I could not use it as a replacement frame for DayGlo Avenger's aluminum frame (which I considered until I verified that); the top of the seattube would end up at the bottom of DGA's actual seat springs, so while I could use a standard seatpost on it, I couldn't use the suspension post I currently have on DGA (needed because of the hardtail).

But as long as I don't need to weld to it or cut anything on it, I can use it as the front of one of these cargo bikes similar to CrazyBike2. It's lighter than the front frame I used on CB2, even though it's larger and stiffer.

[amberwolf]

WHile waiting for my crazy sister to clear her stuff out today (multiple-months-extended-deadline in one minute and she is still not even trying), I worked out a few other possible combinations for the new bike, none of which I'm perfectly happy with, but the last of which might work.

DSC04044.JPG (58.18 KiB) Viewed 928 times

It's the Trek930 front frame, with an old BMX as the mid/rear, and the swingarm off a crappy steel FS Y-frame for rear suspension. Front suspension is the disc sus fork off a very heavy Murray crappy steel bike. Some ex-retail aisle-signholders for the cargopod top rack bar and side seat supports. "beach seat" for the new 'bent seat/chair.

Motor (Icecube57's GM/9C) goes in the Trek dropouts. Pedals on the Trek BB. Chainline not yet fully worked out, but should go from pedals to a jackshaft in the BMX, motor to same jackshaft, freewheel of jackshaft setup so motor doesn't spin pedals (ok if pedals spin motor). From jackshaft to rear hub, which is a 3-speed Sachs IGH with coaster brake. Jackshaft *might* include ability to shift gears for the motor more than just the 3 on the IGH.

Rear will be a 26" rather than 24" like it is now, probably, and if I can make it fit, 26" in front. Frame is significantly lower to the ground than CrazyBike2's, so this will put me and the bike back at about the same height off ground that CB2 is, which is about the same height as the average car driver would be at.

Since motor is at the rear of the triangle, there's still room for at least some battery in the rest of the triangle. More battery can go in the front triangle, but as much weight as possible I'd like to keep in the center and low, on the axle-line.

Everything is steel, so I can weld it all together.

Steering will still be remote, but I will likely go with a steering setup mostly copied from a trike design posted elsewhere on ES, where a headstock setup was bolted to a seatpost rather than how I welded stuff up on CB2's seatpost/headstock setup, whcih has proved problematic in a few ways since then (incluidng one complete failure earlier this year, which woudlnt' have happened if I'd had the other setup). Same handlebars as on CB2, but I'll have to build new controls as I don't have anymore scooter bar controls, and haven't run across any MC or scooter stuff in a long while.


Bike will be about 6-8" longer than CB2, almost 8' exactly from tire edge to tire edge. Positioning of things along the frrame is different, though, putting the seat a bit farther forward and the cargo pods a bit farther forward, too, so that they are as much completely forward of the rear axle as I can get them. That should let me put a rack over the rear wheel that is level with the tops of the pods, so I can use the entire top surface as an extra cargo rack for big stuff. Can't do that with CB2, as the pods are below the level of the rear tire top. I just have to figure out the swingarm clearances at full droop/bump.


Swingarm itself is held to the BMX dropouts by a scooter axle, using a long 1/2" drive socket instead of the original hollow bolt-together pins. Two more sockets on either side of it that are larger diameter than the long socket will keep the whole thing from sliding around on the axle, pinching it between the dropouts so it doesn't wiggle. Rear spring will need to be doubled-up, due to weight when laoded with cargo, and will be butted up against a bracket welded across the top of the BMX rear triange to seatpost.


Lots of things might change as I work this out. With luck, I'll have it finished and tested to bring to the DeathRace in just under a month, assuming everything works as planned.


Below are two of the other configurations I pondered. The Y-frame would be cut off at the point it overlaps the other frame, and welded to it there. That's pretty heavy, so I went with the BMX thing instead. Simpler and less frame-chopping, and weighs less. Should be as strong or stronger, too.

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I might yet use the red Nishiki frame from Li-ghtcycle as the front of the bike, as it gives a lot mroe triangle space. But it also chagnes some geometry and prevents me from doing any welding-together of the bike halves, forcing me to come up with bolt-together stuff that wont' come loose or wiggle under the power of the chain drive.

[liveforphysics]

Have you had a pooch acting badly my friend? I see what looks like a muzzle of some sort.

[amberwolf]

Have you had a pooch acting badly my friend? I see what looks like a muzzle of some sort.

Yeah, thanks to my crazy sister stirring them up, Nana (with the muzzle in taht pic) and Bonnie, who already didn't get along with each other cuz they both want to be in charge, began fighting.

There's a few posts here and there mentioning/describing some of the problems over the last year or so, maybe more, I think. Some of them also describe the injuries I got separating them (almost always from Bonnie, as she is usually so terrified of what's going on that she lashes out at anything/anyone even those trying to help).

Fred, the littlest black one, likes to take the side of whoever's "winning", so usually she will join in any fight. At first she attacked Nana, but now it's always Bonnie. So the first thing I always have to do is yank Fred off and lock her away from the rest, then get Nana and Bonnie apart. The other two don't show any inclination to join, thankfully.

But because of it, Nana had to wear a muzzle whenever she was around Bonnie or Fred. Earlier this year or end of last (can't remember), she decided that despite the muzzle she'd try for Bonnie, and managed to get hold of her scruff a little, starting the whole usual crap again.

Because of that, I can't even trust the muzzle will help, now, so I simply always keep them separated. I tried to do it by putting Nana in the back bedroom, but she destroyed the door (there's pics of that around here somewhere, if the server didn't eat them) and got out, even after armoring it and the wall around it with 3/4" plywood and some aluminum server case lids.

So now, Bonnie stays in my bedroom, where she is fine being by herself. Fred can't stay in there cuz she'll eat things, so she stays in the Kennel Trailer. Doesn't like it but doesnt' try to get out.

Loki, Nana, and Hachi all stayed in the rest of the house, where they generally stay out of trouble, until recently, again thanks to my crazy sister. She was doing something yesterday, screaming and yelling at the air, really nastily, and Loki and Nana suddenly got into it for no particular reason, while I was working on the bike above. They were very easy to separate and no one was hurt, but Loki now growls at Nana, which is the same thing Bonnie does that sets her off, so now I have to keep *them* apart, too.

So...I have another Kennel in my bedroom that's even bigger than the one on the Kennel Trailer, and it is where Nana sleeps when all the rest of us are in the bedroom. It keeps her from being depressed from not being able to be in the same room with me at night; she seems happy enough just being able to be in there even if she can't lay on the bed with us all like she used to (which I miss, too).

Now Loki stays in that kennel when I have to go to work/etc., (since he'll also destroy things in the bedroom, but wont' dig out of the kennel), with Bonnie just in the room. Fred still in the Kennel Trailer, and Hachi and Nana loose in the house.


I'd just put Nana in the kennel when I'm gone, but A) it wouldn't be fair to her to lock her up 90% of the time that way, and B) if she did get out for some reason she'd be locked in a room with Bonnie, and that could be very bad. I can't drag the kennel in and out of the room every day, so shuffling the dogs around works out better and easier.


All this is a big reason why I can't find anyone to trust to feed the dogs and let them out for potty break when I am gone for a day, making it tough to do the race thing. (although that might be worked out if timing is right on leaving and coming back; I'd just have some messes to clean up).


And that is the state of the disunity at the moment.

[grindz145]

angle aluminum and hose clamps are how I get around welding too:) I think with just a little bit of welding you could make that super lagitt though. Should be wicked fun. Wish I could suspend my xtracycle...

[amberwolf]

You could suspend it, but it will take some modification of the Xtracycle unit and/or a further extension of it to the rear.

I pondered how to suspend a wheel within a box frame for cargo pods on the sides and rack across top of them, more than a year ago I think. One of these threads ought to have some sketches of the various ideas I had, assuming they survived the attachment failure problem recently. Either this thread, the ARTOO thread, or CrazyBIke2, most likely.

If I remember where the sketches went (they're just pencil on paper) I can rescan them in, or if I have time I can redraw them better in Paint or something, so you can more clearly see the ideas.

The best of the ideas involves 4 vertical springs on front and rear of the axle on each side of the rear wheel. Each spring would just be a MTB rear shock, so not a lot of travel, but with four springs it should respond better to the kind of weight put on a cargo bike. IF the springs aren't sufficient, there are some powerchair suspension springs that are similar diameter and length but much higher loading, that can be used to replace the coil springs on the damper shocks.

The dropouts would be removed from the Xtracycle, and reinstalled onto the bottom end of the springs via a bar, probably square tubing in my case. It may require spreading the Xtracycle frame some, depending on the width of your rear wheel. If it is narrow enough (by removing spacers, etc), then the shocks and all will still fit. To prevent lateral movement or twisting, the bar would be mounted on a vertical post that it would slide up and down on like a freely moving piston; this bar would be part of the Xtracycle frame from then on.

I haven't yet tried this suspension, but it should work in theory.

Another idea essentially installs a swingarm below the Xtracycle frame, using the dropouts themselves as the top mounts for a pair of MTB shocks, verttically mounted, with new dropouts part of the swingarm, essentially raising the entire back end of the bike by however much the travel of the shocks would be (so that it does not allow the tire to hit the bottom of teh Xtracycle rack at full bump). The pivot would be wherever it is possible or convenient to do this, and/or wherever works best for the effectiveness of the shocks.

An advantage of this method is that it requires no permanent mod to the XC, as you can probably clamp on everything needed, inclding the pivots for the swingarm.

[sami-b]

I'v alway wondered what the point is whit that type of bike? :p are they comfortable? fast?
seams strange tho have the front tyre so far away
glhf

[amberwolf]

I'v alway wondered what the point is whit that type of bike? :p are they comfortable? fast?
seams strange tho have the front tyre so far away
glhf

The tire has to be far enough forward to not have "toe strike", meaning that when pedalling the toes sticking out forward don't hit the tire as you turn.

In my case it's actually got a few inches more than it needs, but that is because this bike was not completely custom built, but rather built from existing bikes that were "close enough" to give me the fit I was after, with minimal modification.

The main reason for this type of bike, for me, is it's comfort. Instead of having a hard saddle up my butt, vibrating with every lttle bump in the road, I have a comfy lawnchair-type seat suspending me above the bike, so that not a lot of the road vibration comes thru the seat itself. No more "numb-ass" after a long ride.

The second reason is that it's easier to deal with cargo on this bike than a taller, regular one, though ideally it needs to be a bit longer in the back, with suspension. That's where this bike project:
viewtopic.php?f=3&t=16920&start=0
comes in, to try to work out the problems with CrazyBike2 and make a replacement for it.

It's also definitely less power usage vs air resistance than an upright bike, partly because it's lower, but more because I'm leaning back rather than completely upright. Somewhere in this thread or in DayGlo Avenger
http://www.endless-sphere.com/forums/vi ... 70&start=0
I did a comparison; I dont' recall the exact results but CB2 takes less power at higher speed (20MPH) than DGA at the same speed. It takes more power to *get* to that speed because it's twice as heavy as DGA, but once at speed it takes less due to aero factors, as wind resistance really eats power the faster you go.


Another reason I like CB2 better is it's more fun to ride; without the cargo pods, I can lean it way farther over (significantly past 45 degrees based on pics of the Undead Race) than I could DGA or any other upright I have ridden, at much higher turn speeds, and not feel like I'm gonna skid out and crash. (or actually do so).

Plus, if I do crash or skid, I can walk away from it a lot easier than any upright bike. It's also not really possible under normal circumstances to do an endover on CB2 like you could on an upright, like say if you locked up the front wheel on an upright going fast enough, you'd go over the bars and faceplant. On CB2 it'd just skid instead, becuase it doesnt' have the leverage to flip the bike like that since it's so long and my wieght is so far back on it.

[amberwolf]

I might get one of these from a friend:

2011-03-25 21.14.12.jpg (45.56 KiB) Viewed 848 times

Out of the Harbor Freight clearance table, they're leaf springs off of (probably) one of their small trailer kits. One has three leaves and one has two, otherwise identical in appearance.

They appear in the pic to be about two feet long. If I can rig up a way to bolt the swingarm from a few posts above to CrazyBike2's rear dropouts as I am pondering doing to this one, I can test the leaf spring as a rear suspension on it instead of the dual-spring I was considering. If it works on CB2 then I can build this bike around that idea, which will require modification of the frame idea above, due to the length of the leaf spring.

Using CB2 to test it, it'd be something like this:

leaf spring idea1.PNG (6.18 KiB) Viewed 860 times

where the green is the leaf, red is the added rear triangle, and black is existing CB2.

[Harold in CR]

In your drawing, how do you figure the leaf springs will flex ?? One end has to slide as the leaf flexes. You have the leaf as moving in length instead of up-down ??

Its tough to go by a drawing, though ??

[amberwolf]

Well, based on the way the trailer kits I've seen these on appear to work, the L-shaped end is fixed via bracket to the frame so it doesnt' move, and the axle is attached via a pivot mountint point to the white pivot point on the other end of the leaf, with the "swingarm" pivot of the axle mounted somewhere between them on the frame. So it appears that it compresses/bends the leaves in order to absorb shock motion.

I am probably misunderstanding how they are originally mounted, and if so, then my pictured setup will not work, and I'll have to figure out how they *actually* are mounted, and do it that way if it's possible.

My pictured version would be just like it looks, with the L-shaped end under the seat, clamped via U-bolt/plate to the bottom of the square tubing there, butted against the seat tube so it can't move forward under compression. Then the white pivot point on the other end of the swingarm is mounted to the shock mounting point on the swingarm. The swingarm's pivot point is mounted to the dropouts of the main frame.

That would put the load from the wheel up in an arc into the leaf, compressing it against the frame, theoretically pushing the arc of the leaf down to bend under load/shock.

If that wont' work, I'm not sure how to utilize it.

[Harold in CR]

One end of a leaf spring has to move. The spring action is in the center of the spring.

With what you have, there is not a lot of travel in the swingarm. You would need to mount the leaves so that the swingarm pushed down on the ends.

As I said earlier, this is a drawing, and, the actual design MIGHT work, but, I can't see it doing anything the way it is drawn.

In one of MichaelPogues renderings, he uses Carbon Fibre leaves. You might look into his thread and see what I mean. IF you can do something similar, you would have a good suspension.

Maybe I am just not seeing what you are ??? ???

[amberwolf]

Apparently I need to learn more about leaf springs and how they work; I thought they worked by bowing in the middle, based on what I thought I remembered from trucks in shop class more than two decades ago, but that's not what happens based on your description (which is probably right, since I have never actually used leaf springs before).

I'll do some reading up and figure out how I *should* use them, and see if it'll fit.

[amberwolf]

I did some more fitting and pondering today, while moving and reorganizing stuff in the house so I can actually find things again.

I discovered that the original "good idea" isn't, really, as it would force the seat to be too high and too far forward:

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Note taht in the mockup, the motor ends up a couple of inches away from the middle downtube, but in reality it'd be a couple millimeters away, with the headtube/seatpost angle being matched instead of messed up.

So, since there's no way to join the headtube and seattube (for strength) without moving the blue frame down and forward, which then fills the space the motor would be in, it means the motor can't be in the dropouts, and I have to make dropouts for it. Either below the green triangle like this:

DSC04073.JPG (44.61 KiB) Viewed 577 times

or below the blue triangle.

Note that in the latter mockup, the headtube would align directly with the seatpost, so I'd basically cut off the blue frame's headtube and fishmouth the top/downtubes of the blue frame so that I could weld them directly to the back of the seatpost there. Actually just a bit higher, after cutting out the crossbar on teh top of the green triangle.

If I could manage it, I'd ideally like to align the toptube of the blue and green frames, to pass their line straight back and down under the seat, and have the seat mount directly to the top of them. That depends on ground clearances for the stuff along the bottom (pedals, motor, chain) at full bump of the suspension, at it's lowest point of travel (most compressed). Might not be able to, and end up with what you see in the mockup.

If I do manage it, the seat will be tilted back more (which I want), with it's base/back joint still in about the same place it is now. I may have to bend the front edge of the seat downward to clear my legs for pedalling, though.

The square silver rails would be to mount the cargo pods on, and also to provide support for the seat. I'd probably also have to add lower rails like CB2 has, to keep them from hitting the swingarm when loaded, but the lower rails won't have any rear-end support, and will have to extend beyond the rear wheel so I can put a cross-brace on all four rails to keep them spread apart back there under loads.

I also wish the rails could go higher, above the top of the tire, but they can't and still stay inline with the rest of the frame top (which I want), so the pods will not bolt straight across them, but at an angle across the top so the pod tops will clear the tire top thoroughly at full bump, so I can still have cargo up top.


Some pics of the rest of the room, which I've just barely started moving the bike stuff into:

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[amberwolf]

I found this page:
http://www.afcoracing.com/tech_pages/leaf.shtml
that gives me some better idea of my misconceptions, primarily thru the diagrams like these:

leaf_6.gif (14.99 KiB) Viewed 577 times

A few other quickly-googled sources essentially show that what I thought I wanted to do is just about exactly opposite of how leaf springs are supposed to be used.

I wanted to put the load on the ends and let the middle be compressed archways.

What really should happen is the load should be on one end and the center of the arch, pushing up in that center against the one end and forcing the arch to straighten out towards the other end (whcih should be free to slide, as Harold in CR said).

I still want to try it out like I diagrammed it, just to see how badly it doesn't work. Gotta wait till I get the spring, and then see if it will even fit in the space available.

EDIT: oh, and I also have this project idea thread:
http://www.endless-sphere.com/forums/vi ... 84&start=0
which Spinningmagnets posted that Michael Plogue idea pic to, as well, and people pointed out that the way I was doing it then was wrong, too. I just forgot. Oh, well.

[Harold in CR]

Your only misconception is, You are trying to use a Swing FRAME, not a swingARM. If you can envision cutting off the upper tubes of your swingFRAME, then you have lots of possibilities to use those leaves.

Your FRAME wants to move in a radius. This is why coils are used, for the push-pull effect, on the upper part of the swing frame. You need an up-down movement. You would have to beef up the lower tube section, and add uprights to attach the eyes in the leaves, to the swingARM you have now created. The further back, toward the wheel, the better y;our leaves will work. Removing the upper part of that swing frame, will allow room for more "Stuff", like Batteries.

You have a welder. Just make a swingARM and attach that to your BIKE FRAME. I don't see any problem making that work.

Sorry to rain on your parade. I'm in awe of your designs using gathered goodies.

[amberwolf]

OK, now that makes sense, I think. I'll have to draw up some ideas to see if I understand it right, but it sounds like the way I drew up a bike once before:

I might still be using them wrong in this application, but maybe it's closer to what you mean?

CurvyBikeSketchFull2.JPG (32.43 KiB) Viewed 569 times

CurvyBikeSketchFull1.JPG (41.34 KiB) Viewed 569 times

[Harold in CR]

Top sketch much better. Bottom sketch, I don't see any springs, unless they are very short. IF you shorten them, they get stiffer really quick.

[amberwolf]

Sorry, bottom sketch is just an angle view of the swingarm/etc, to show how it attaches to the BB/frame. Springs were left out so the rest would be visible; it all is the same as the top sketch.

I could do this swingarm one of two ways:
A) fixed bolt/pivot at each end of spring, doesnt' slide but only bows upward in center.
B) Fixed bolt at one end (front?) with slide pivot at other end (easiest at rear), not sure if that would even do anything in this design.
Which would probably work better?
If possible, I'd certainly prefer to build the swingarm/leaf one of the above ways, rather than the one below.

I came up with another method of using the leaf spring with the existing stuff previously sketched:

leaf spring idea 2a.jpg (31.8 KiB) Viewed 504 times

Would this one work, assuming my cargo pod frame (orange) is stiff enough?

Bike frame is all black, and would be welded as one piece. Cargo frame is orange, welded to bike frame along intersections with black frame visible.

Leaf spring is green, with it's pivot at rear of cargo frame, and the slide bracket (Ubolt of some type) onto the cargo frame.

Swingarm (swing frame) is red, and it pushes against the center of the leaf spring at it's axle, upwards. For now I'd leave it as the whole swing frame to test the idea, then build one just for this purpose if it works under the cargo loads I'd like this to haul (up to at least a couple hundred pounds in addtion to the bike's and my weight).

I guess one advantage of this way is that all the cargo weigth is directly transferred to the wheel, rather than via the bike frame. But it also means that the bike weight (and mine) has to go thru the cargo frame, and leverages against the cargoframe/bikeframe joins. Most of the time there won't be much on the cargo frame.

[Harold in CR]

Yes. That latest design would be fine. You will need to find out what weight you can put on the 2 springs, to see if it will be too stiff or too soft.

What about a shock to take the pogo effect out with more cargo weight ??

[amberwolf]

I have some dampers from powerchairs that may help with the latter.

The leaf springs I might be getting are from a trailer kit that has a bed that by itself probably weighs 50-100lbs, plus cargo capability of probably 500-1000lbs, maybe more. So with two leaf springs, it'd be too much. I'd like to figure out a way to use just one (which is why I wanted to use it forward of the swingframe, instead of beside it/above it).

I did think of a way, but it would add a lot of complication.

LEAF SPRING IDEA 3A.JPG (28.51 KiB) Viewed 494 times

Basically the leaf (ORANGE) would wind up upside down over the top of the tire, a bit above whereever the limit of swing would be. Then a rod (GREEN) comes up from either side of the axle (GRAY), pushing on the outer end of a lever (PURPLE) whose pivot point is mounted on the cargo frame (BLACK). The inner end of that lever pushes downward on the center of the leaf spring, effectively transferring the vertical upward load from the axle into a downward load onto the spring.

Does that make any sense?

I'm not sure that it would work, and given the extra complications it may not even be worth trying. But if I could make the levers compact enough and keep it all inside the frame (unlike in the drawing), it would help to leave all of my cargo frame free and flat on top for stuff.

Also, like MichaelPlogue's design, it would act as a fender to keep road crud off of me and my stuff.


I guess another way to use it would be pretty much like he did, with the normally sliding end fixed in place forward of the swing frame, angled upward and backward as if it were a fender, to arch over the tire. Then put the green rods I have in the above design from the axle to the pivot point on the leaf spring. It would then just bow back and forth, instead of the usual method.

LEAF SPRING IDEA 4A.JPG (10.98 KiB) Viewed 494 times

[Harold in CR]

The image 4A looks good. Flexing the spring from one end will give more action than flexing in the middle. Fasten the flat end and use the bushed end for the movement-swivel.

Myself, I like this last idea best. Just be sure to beef it all up solidly so no flexing of the swingframe.

I would still try to cut part of that frame off and beef up whats left, or, make a new swingarm, but, that's just me.

[amberwolf]

I'll eventually build one from scratch, but right now I just want to test the idea. Using existing parts with little or no modification is best for that, because if it doesnt work then I can just use them for something else. If I heavily modify them specifically for the test, they would probalby be unsuitable for a lot of other things they would've worked fine for before.


Plus, it's less work till I know I have to do it.


The hardest part about the last idea is fitting it all under the "rack" so I can still have low-mounted cargo across the tops of the pods, but I don't know exactly how high that top will be, yet, anyway. Gotta get the whole frame working first, with suspension, THEN figure out how low I can put the pods and still turn.

Before all that, though, I gotta get the leaf spring, so I can see how big it is exactly vs the other stuff I have.


Anyhow, in the next day or so I hope to have time in the daytime before work (cuz it's too late at night when I get home) to start cutting the blue frame so it fits up to the seattube of the green frame.

I need to make a decision before then as to whether I am going to cut the seatstays off teh green Trek930 frame, so I can fit it all together easier, and use them as support struts to extend the chainstays out and back and then inward, to make a triangulated center/bottom frame that connects to the BB of the blue frame, for battery platform/etc, and stiffen the whole frame.

If I leave the rear triangle of teh Trek alone, it is going to waste space and I'll still ahve to attach triangulation frame bits from it to the blue frame, but I could in theory still reuse the Trek frame for something else if I leave it alone. Most likely I will remove the seatstays, as that is the best way to accomplish my goal. (well, building an entirely custom frame would really be the best way, but I don't have all the right materials for that in long enough pieces, so this is the next best).