Full-Suspension Semi Recumbent Cargo Bike - NuVinci MidDrive

amberwolf

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This was originally buried in my other build thread, which had mutated into this bike from the one I had started with there. But in the interests of information finding, I've split off all the stuff from that thread from the point at which it changed to this new build. :)

This and the next post are reserved for some "plans" and updates, and the next pages of posts are all copied from the old thread.
 
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
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.
View attachment 1

DSC04042.JPG


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.
 
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...
 
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.
 
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
 
sami-b said:
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. :lol:

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:
http://endless-sphere.com/forums/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/viewtopic.php?f=2&t=15570&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.
 
I might get one of these from a friend:
2011-03-25 21.14.12.jpg
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
where the green is the leaf, red is the added rear triangle, and black is existing CB2.
 
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 ??
 
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. :?
 
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 ??? ???
 
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. ;)
 
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:
View attachment 4
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
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:
DSC04076.JPG

DSC04075.JPG

 
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

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. :lol: 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/viewtopic.php?f=2&t=21084&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. :oops:
 
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. 8)
 
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

CurvyBikeSketchFull1.JPG
 
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.
 
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:

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.
 
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