Full suspension longtail bicycle (Folding)

[spinningmagnets]

This pic is from Dogmans suggestion that its useful for a bike to be able to fit on a bus rack (also helps for apartment or garage storage). Once folded with 26” wheels, its 35” from axle to axle (89cm), and 5-foot / 60” (152cm) overall from tire edge to tire edge.

FSLB_Folded.JPG (90.68 KiB) Viewed 423 times

This pic is inspired by Ypedal who is an advocate for a 20” wheel on the rear. Using the stock 26” suspension arm, there is room for a 4” / 100mm diameter motor. The large RC motor AussieJester uses is only 80mm in diameter, and it’s quite a powerful beast.

The derailleur hangs quite low, so if I end up going this route, I may use an internally-geared Nexus or a SRAM Dual-Drive with two broached ENO’s

FSLB_20_RC.JPG (94.88 KiB) Viewed 423 times

[John in CR]

...SpinningMags. I just noticed your initials would be SM. Hmmmmm............!
otherDoc

Doc,
If his username was Spinning&Magnets, then you'd be onto something.

[spinningmagnets]

Used the in-line skate wheel (smaller diameter) as an idler. The clothesline wheel already had a perfect groove in it, but the larger 4" diameter would have been more difficult to mount on this particular project. Wheel material (urethane, hard-rubber?) got soft when warm, had to let it cool on occasion to cut better.

I already had a coarse round-file and a sawzall blade handy, and they worked well. Wear a leather glove when holding the cutting tool, and have the spinning wheel pull the tool away from your crotch. Also point yourself and the job so that if the spinning wheel pulls the tool out of your hand, that it doesn't launch it across the room and stick into someone. Spread out an old sheet to collect all the little shavings and wear some type of glasses, even if they are sunglasses. Thanks for the suggestion Torker and Amberwolf.

White sleeve is the barrel I cut from a fat ink-pen, I used it as a bushing-rest when the all-thread was spinning. the idler-wheel shaft on the bike has jam-nuts spaced to allow the wheel to slide back and forth about 1-1/2 inches while shifting the chain across the rear gear-cluster.

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[zap]

Nice build spin.

That's exactly how I carved a roller blade wheel for an idler on my bent and also for a small pulley on my first pedgen.
I turned it with a drill also and was trying all kinds of stuff to lathe it. I finally ended up using a circular saw to quickly and cleanly remove the soft urethane to get a rough shape then clean it up with a rough file... it seemed to work the best.

[spinningmagnets]

I have an idea I could use some input on, to see if I'm missing something. I like how the bike folds up when I pull a pin from the rear shock. I'm likely to use a locking ball-pin on the rear-most shock joint.



Now that this beast has a chain I can start working out other issues.

When the bike folds, the bottom half of the chain droops a lot. Several ways to deal with this, but...I'm thinking I'd mount an ENO "Dos" to the suspension pivot. Run one chain (a half-link style) from a big single front chainring to the ENO joint, and then a second conventional chain runs to the rear gear-cluster and derailleur.

I "think" the trials crank from the resources sticky has freewheel threads on the right crank, in order to allow the front chainring to freewheel. I could just cut off the threaded section that has a square-tapered shank hole. Are trials cranks right-handed threads, or LH? Will the ENO Dos work like this (I may remove the pawls so it rotates in both directions...)...thoughts?

http://sickbikeparts.com/catalog/product_info.php?cPath=21&products_id=35



Edit: found a great post about ENO's on trials cranks with lots of pics concerning a tear-down:

http://observedtrials.net/vb/showpost.php?s=691c0e51b5e4944e3d543653e4899ec4&p=285967&postcount=7

ENOtrialsCrank.jpg (29.72 KiB) Viewed 372 times

[amberwolf]

So you mean, run the bottom chain *over* the joint instead of under it, riding on the ENO as an idler?

Assuming the ENO spins the right way or you take out the pawls, it should work, but:
--It won't allow the sideways movement across the cassette that the other idler does.
--I think it'll change the derailer tension differently (less?) than if it were spanning the bottom naturally, as the shock pivots.
--Won't you need another idler roller under the chainstay forward of it, to keep it off the frame as it goes down to the front chainrings, especially the smaller ones?

[grindz145]

I just got a Monty trials bike. If you REALLY need to know I can take it apart and figure it out

[spinningmagnets]

The idea is to tave two separate chains instead of one long chain. When the bike is rolling the chains will be near in-line, and when folded, they will be shaped like an upside down V, with the two-cog Dos as the joint. The derailleur on the rear provides some slack, so the rear chain could be a normal one.

The front chain would not neccessarily need a sprung idler wheel, so if using a half-link style chain, a chain could be made in the proper length to run from a large single chainring onto the Dos while being just the right length to fit the ENO joint into the drop-outs. Just a thought...

The trials crank is about $25 and the ENO Dos is $110 so I'm not going to rush into it. Certainly a small idler wheel on the bottom of my chain will work for now.

FSLBfoldedChain.JPG (87.59 KiB) Viewed 364 times

[amberwolf]

OH! I totally did not grasp that possibility when looking at it before.

[gogo]

I have an idea I could use some input on, to see if I'm missing something. I like how the bike folds up when I pull a pin from the rear shock. I'm likely to use a locking ball-pin on the rear-most shock joint.

When the bike folds, the bottom half of the chain droops a lot. Several ways to deal with this, but...I'm thinking I'd mount an ENO "Dos" to the suspension pivot. Run one chain (a half-link style) from a big single front chainring to the ENO joint, and then a second conventional chain runs to the rear gear-cluster and derailleur.


http://sickbikeparts.com/catalog/product_info.php?cPath=21&products_id=35

I don't think the dos allows two chains at the same time. Also, the lever action on the shock absorber link seems a potential problem. Can it compress far enough to "pop" into a reverse position? It looks like you really need a shock that will go all the way to your plate.

I've followed this thread since you started it and only this time caught doc's SM reference.

[docnjoj]

Not my fault, Gogo! John started it!
otherDoc

[docnjoj]

There are true dual frewheels that allow 2 chains at a time but the Eno is not one. I think Cyclone uses something like you (SM) want. As you said there are BMX types with different gears and reverse freewheels on opposite sides of the wheel. The folder is really brilliant!
otherDoc

[docnjoj]

Oh yeah! the Mongoose CX240 uses a 2 sided reverse freewheel so they may sell the part (hub) or wheel at reasonable cost. I made a double sided one from an old SA 3 speed hub for my grandkids CX240 and it worked fine. Close machine fit and JB weld held the freewheel on the left side. I may be able to find the prototype if any interest.
otherDoc

[vanilla ice]

I want a FS stokemonkey..

[John in CR]

SpinningMags,

Thanks for throwing that picture up of how it will fold. I hadn't thought about making sure I have clearance to make sure the rear will pivot all the way under and to the front, and I definitely want to copy that folding. With the front wheel off and that folding, my 2 wheel land rocket will be quite compact (for a big bike) for tossing in the car.

[spinningmagnets]

I now believe that the ENO "Dos" will allow a chain on one sprocket or the other, but not two chains at one time. Thanks for the warning, Gogo/docnjoj. You both just saved me about $135 (plus shipping) for a failed experiment. I may have gotten $50 for the used ENO-Dos, but the cut trials crank to make the mounting adapter would have been trash.

John-in-CR, I wasn't even thinking about folding it in the beginning, though I've always very much liked how my front disc wheel with quick-disconnect skewers pops off easily without tools (V-brakes choke fat tires when removing them). Dogmans posts about a bike being useful to fit on a bus rack got me thinking about it, and the first time I folded it up I got a big smile. I now feel this is an important feature.

If someone was interested in this, but found this particular lay-out a little too long/large/heavy...you can start with a 24" aluminum-frame mountain bike on the front and add a 20" suspension arm. If you are on a budget, it is quite easy to find trash-day BMX frames (some are even aluminum) and the back half of a BMX could easily be cut to become a smaller/lighter FSLB rear-suspension arm.

A 24"/20" FSLB would be longer and lower than a stock 26" hardtail, but shorter/lighter than this 26"/26" FSLB. If you can braze or know a welder, a shock mount could be made that looks more professional, my criteria for this shock mount was that...it had to be removable to restore the bike to original form if the experimant failed, and...it had to be adjustable once installed to compensate for unexpected issues concerning shocks and bike-handling. (DAMN, air-shocks are expensive!!)

[amberwolf]

I now believe that the ENO "Dos" will allow a chain on one sprocket or the other, but not two chains at one time.

I have an idea. Not thought out but just an "inspirational flash". So it might be worthless. But... take the other ENO that SBP has, with the 5-hole ring. Attach your desired jackshaft sprockets to adapter rings that will bolt to that ring, with the adapter rings on opposite sides of that ring, facing each other. Now there is clearance for even wide chains if you need it. Possibly the space you have available is too small to put all this in there, though.

DAMN, air-shocks are expensive!!

Yes, they are. The AirRide industrial types (firestone/bridgestone 4001) that were used for the Autospeed trikes ran around $150 each last time I tried to price them. That's one reason I never built the first trike I started designing, because it requires those to work, being based heavily on the Autospeed trikes.

If you have space for it, though, you can make your own airshocks of a sort.

Take a small diameter but wide tire, like some of the ones for dollys. Turn it inside out. Build a pair of (aluminum) clamping plates for each end, machined to be secured around the bead of the tire for an air seal. Use adhesives or sealants wherever necessary. Drill mounting holes in the end plates or bolt mounting hardware to them as needed. Drill a hole in an accessible spot on one end plate for an air valve. Install, and inflate to desired pressure.

I have four old gokart tires I found in a small pile of trash in a Walmart parking lot, which I would like to someday test this theory with. I also have two small powerchair tires about the same 10" diameter but only 3" wide that would probably work as well for lesser displacement, after I pull them off the "airless" tubes inside them.

[John in CR]

Yeah stuff for bikes like $150 shocks and $80 freewheels pisses me off to no end.

[vanilla ice]

That pivoting idea is great. Less storage space than a standard bike! I'm trying to imagine a swing arm design that would allow me to pivot on a hub motor axle.. or maybe modify an xmart swinger and your dropouts do it.

[John in CR]

That pivoting idea is great. Less storage space than a standard bike! I'm trying to imagine a swing arm design that would allow me to pivot on a hub motor axle.. or maybe modify an xmart swinger and your dropouts do it.

I'm in the process of that. My swingarm will have dropouts on both ends. At the pivoting motor end, they'll be clamping dropouts 1/2" thick steel on each side. The attachment to the frame that holds the outer race of the bearings will have to bolt to the frame, since the axle pivoting point is fixed instead of sliding out like motorcycle pivots. The axles on mine are 20mm thick. I'm not sure the skinny axles of typical hub motors are up to the task if you go with mono-shock, because the forces on the pivot are quite leveraged.

[spinningmagnets]

Amberwolf, this one (the 22T-ENO) ?



I think that would work, I could easily attach a second sprocket (in a more desirable tooth-count too) to stand off enough to allow two chains at the same time. Cheaper than the "Dos" also. Great idea, might do that later...I noticed having a small chainring allows me to have good curb-jumping clearance, while the jackshaft gear-up would still allow me to pedal at higher motor-speeds (Instead of adapting a 52T chainring)

Rodney Dangerfield: "I tell ya, I get no respect!...I was talkin to my wife on the phone, and she happened to mention she wanted to try some S&M today...I started to get a little excited, so I left work early. But when I got home and opened the bedroom door, I found out she meant Salesmen & Mechanics" (cue rimshot)

[TylerDurden]

DAMN, air-shocks are expensive!!

Yes, they are. The AirRide industrial types (firestone/bridgestone 4001) that were used for the Autospeed trikes ran around $150 each last time I tried to price them. That's one reason I never built the first trike I started designing, because it requires those to work, being based heavily on the Autospeed trikes.

Depending on your installation, you might be able to fit a small auto airshock. Airshocks for Super-Beetles are still available for about $80/pair.

[amberwolf]

Actually this one:
http://sickbikeparts.com/catalog/produc ... ucts_id=62

I guess it's by White made only for SBP.

They also have this one:
http://www.sickbikeparts.com/Products/Freewheel.html
http://sickbikeparts.com/catalog/produc ... ucts_id=34


But the one you're looking at would work too.

[Grinhill]

Hi Spinning, some great ideas happening on this build.

I have a feeling you will have many more challenges ahead once you start looking at the drive side of things as well .

[spinningmagnets]

I made a "fast and ugly" idler wheel on the chains bottom-run from a bolt with two wide washers as side-plates, and several plastic washers as the roller. I will likely buy a more professional-looking idler sometime later.

I wanted the bike to roll easily when folded up, and the rear tire was rubbing up against the BB. Also, when loading/unloading from my truck or bringing it indoors, the rear flopped around. So, I made a fold-up pin-latch out of organic composite fiber (wood).

I dug through my pile of bike parts, and the kick-stand I liked most was tubular aluminum from a 24" bike (too short). So I cut it in half, bought a $5 tap to cut ID threads and added a section of all-thread-rod and two locknuts.

All the mechanics at Big Poppi bikes were very helpful and encouraging. They sold me derailleur cable housing at $1/foot (any length) and threw in some aluminum housing-tips for free so I could experiment. They would have crimped two cables together for free, but I ordered a 10-ft continuous cable from a recumbent site (coiled up in picture at the derailleur). So now I have 6 gears on the rear, and I didn't really need the front derailleur for the BB as its pretty flat terrain here.

I really like having my feet flat on the ground at stops. There's a lot of potholes and rough sidewalk in Junction City so the fat tires and full-suspension are well worth the effort for me. The red seat tube is from a trash-day steel BMX, and soon both the seat tube and shock mount will be completely changed into something that looks more professional. I'm envisioning a four-legged spider for both seat/shock that frees up the space under the seat between the stays, with the shock being horizontal.

The left/right edges of the flat aluminum shock mounting plate occasionally brush against my ankles when pedaling, so if I was in a hurry to do this again, I would use an aluminum squared C-channel section attached between the seat stays, with the four U-clamps coming in from the sides. The most pressing need right now is a cup-holder and music.

Ft Riley, Kansas was home to George "I aint afraid of no Indians" Custer, and Patton. The stone pillar in the pic is one of the many 130-year old hitching posts here. Originally for horses, they are now used for decoration.

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