The F3: Sharing the e-bike grin!

[amberwolf]

For protecting the motor against bottoming out the shock, you could install a limiter for the swingarm action. It could be as simple as a metal tube just above or below the motor that has one end against the opposite frame member from the swingarm, with a relatively thin plastic or rubber damper at each end, so that if it does bottom out it will not be *quite* such a WHAM.

It would probably be easiest to do this using the makerbot to make a stack of ABS sheets cut and shaped into a block that can go just below the motor, bolted either to the Recumpence drive plate or clamped to either the swingarm's front tube or the frame's seattube.

But I would personally want it to be where any load transfer goes into the places already beefed up to recieve it, like at the toptube/seattube junction where the shock already bolts to, or just under the motor to the seattube/maintube junction (assuming you can spread the force across that whole area of the seattube). I have crushed frames trying to invent suspension on them without first reinforcing the mounting points.

[MattyCiii]

Thanks Amberwolf!
For now I will just keep the shock pressurized 20-30% higher than where I've been running it - where I know it won't bottom out.

I took the plunge tonight on ordering a custom mount. Initially it'll be hose-clamped to fix it to the frame, but I have through holes in case I later want to bolt it. This time I decided to go to Big Blue Saw - a water jetting house.

The price for 5 parts is the same for 1 (based on a small sampling of designs I've uploaded to them). As a result, I designed my mount to use two identical pieces, stacked - and had six cut. So I'll have enough spare parts to do 2 more bikes (Anyone selling a 2010 Dahon JetStream?). Here's what the mount looks like:


The bottom is not flat - Each side has a rise of 0.5mm as you go from center-bottom to the outside edge. When installing, one side is socked down tight with one hose clamp. The other side will thus have a slim pie shaped wedge divergence from the flat, from the center cut to the edge. The V4 drive shaft collar is slipped into the 35mm center circle. Then the other side is socked down via hose clamp. By the time it is flat/flush with the bike frame's square tube, the 35mm center should be exerting pressure from all sides onto the shaft collar. I hope!

[MattyCiii]

Big Blue Saw has completed producing my mounts and submitted the package to UPS. Hope it arrives by mid next week... I'll be stalking brown box trucks until then

[crossbreak]

i'm waiting keen to see this, thx for posting

[MattyCiii]

looks like crazy power for this small bike. i like it. it plays in the league of the e-moulton miles build.

I found this cheap foldable bike at the bay and would like electrify it with a 500W hub motor (quick and simple):


I use bendable alloy sheets (Al Mg 3, 2.5 and 5mm thick) for my shaft mounts. It is also easy to weld and cut. And it is durable if the part is designed right.
The pieces which fit the frame can be made of plastic - I use 15mm thick PE plastic for it.

Two thoughts:
1) Not a lot of chain wrap on the pedal chainring. Maybe that can be solved with a chain tensioner between the motor and the pedal chainring. That will also give more chain wrap to the small motor sprocket
2) Unless the motor has really low KV, and is run with low voltage, you will need some reduction.

[MattyCiii]

Why don't you run the motor power through the NuVinci?

I'd love to, and some day I might. But for now, it's all about reliability. Powering through the NuVinci would mean both human and e-power through one chain. Complex arrangement at the drive sprocket. Extra stress to NuVi freewheel and internals. Too much risk of something breaking

In contrast, putting e-power on the left means I have two fully independent power sources to get me home. If "one side" should fail, I can detach the chain on that side at the master link, throw it in the bag, and get home on the other power source, no sweat.

[crossbreak]

Thx for your answers.

1) Not a lot of chain wrap on the pedal chainring. Maybe that can be solved with a chain tensioner between the motor and the pedal chainring.

That would violate rule #1 for the build of chain drives: never put any chain tensioner into the tight span of a chain drive
I hope the chain wrap will be ok the way I designed it already. A normal bike sprocket of a shift drive does not get more chain wrap,too and it still works. A chain guide which prevents the chain from falling off would be a possible solution.
The chain wrap of the crank chain ring is a concern. I just hope it will work with the chain tensioner right behind the chain ring.

2) Unless the motor has really low KV, and is run with low voltage, you will need some reduction.

I want to use a 36 front driving Q128 hub motor with 200rpm @ 36Volts. It has a 1:8 planetary reduction, so the inrunner should runs @ 1600rpm max.
The hubmotor gets a 16T sprocket, the 3-speed hub a 15T, the crank chain ring will have 44 teeth. I wanna start the project next month when I have the money for the folding bike.

I'd love to, and some day I might. But for now, it's all about reliability. Powering through the NuVinci would mean both human and e-power through one chain. Complex arrangement at the drive sprocket. Extra stress to NuVi freewheel and internals. Too much risk of something breaking

In contrast, putting e-power on the left means I have two fully independent power sources to get me home. If "one side" should fail, I can detach the chain on that side at the master link, throw it in the bag, and get home on the other power source, no sweat.

I understand your concerns. But driving the power through the Nuvinci would gain you a hill climb ability improvement of 360% with the same top speed in theory

[MattyCiii]

While I wait for parts (e.g., custom drive mount) I'm trying to get ahead of what I'll need next. Next up will be an enclosure for the belt drive. I'm enclosing it for the following reasons, in order of importance:
1) Protect me! I've placed the belt drive right next to shoe laces and pant legs. Though I tuck in the pants, there's still potential of me getting clothes in the spinning stuff and I don't want that
2) Stealth. The raw shiny aluminum is just too eye catching. The bike itself is distinctive, but I don't want to draw attention to it's e-bike nature.
3) Protect the drive. As a folding bike, there's high potential for parts to get banged up. As I type this the bike is laying on its side in the baggage space of a bus - things like this are beyond what a normal bike sees regularly and drive up the risk of damage. Gotta keep my e-drive running nice!
4) Reduce drive noise.

My plan right now is to get thin, rigid covers for the top and bottom of the drive pulleys, and print custom sides on the Makerbot. I only have 9mm total space, so things will be tight. I decided to go with 1.5mm thick carbon fiber panels from DragonPlate.com. CF should be strong and rigid. DragonPlate will custom cut panels, so I'm having them send me a quote. Below is a render of what will be the top piece:


It'll bolt to the Makerbot/ABS plastic all around, and to a custom piece between the pulleys/inside the belt line. Those ABS parts will bolt to the bottom piece, which will attach to the V4 drive.

[MattyCiii]

Continued from above.

The cost of the carbon fiber/CNC cut service is much like anything else - relate do the types and number of cuts, and related to the stock material used as an input. My two covers will fit on a standard 12" x 12" CF panel. As I laid it all out during design, I noticed there was a nice ~4" chunk left over, so I designed a cover for the freewheel side of the drive system. Only the outer cover of this piece will be CF - and only because there's "extra". The rest of that cover system will be printed on the MakerBot.

Of course, much like everything else like a build like this, there's a lot of waiting involved. Indeed this not a hobby for impatient people!

[crossbreak]

a protective cover should be indeed as light and durable as possible. CF ist a good material for this if you laminate it on a 3D model from foam.
The same is possible with Fiberglass but a bit less expensive.

Waiting for parts is booring. I like to build them myself.

I always
-print out my parts,
-cut the paper with a scissor and then
- glue it onto my alloy sheet.
-I cut it with a drill at certain points to have starting point for my fret saw. Then
-I drill the mounting holes
- the I counterbore my mounting holes for the conic screw heads

Then I might bend the sheet if it is a AlMg3 alloy sheet.

But the fibreglass is the best solution IMO. I learned this from a local amputation appliance maker, but it's also good for covers

[MattyCiii]

Quick update:
1) I got the power parts - servo tester, HV-160, and Astro 3210 - all working on the bench. Nice to know I can turn electrons to revolutions with parts I actually have in hand.
2) My custom brackets should arrive today! WOOT! With them in hand I can permanently install the reduction drive and build this thing up for real!

[MattyCiii]

I got my first taste of the EV grin today!

All the mechanicals are installed (Pictures to follow). The electrics... Let's just say packing tape and velcro was involved. I rode around on 6S LiPo a bit, this thing will be scary once I bump it up to 12S!

[crossbreak]

Thx for the update. I hope your HV160 will last with 12s battaries. Btw. Are you also thinking about a custom battery cases and mounts for your bikes? A carbon housing like the one you make for the belt-drive would be neat

[MattyCiii]

Are you also thinking about a custom battery cases and mounts for your bikes? A carbon housing like the one you make for the belt-drive would be neat

The long term plan includes something along those lines. It looks like I can mount two LiPo bricks above, and two below, the top tube between the steering stem and the folding hinge. I'll likely print up brackets on the MakerBot to hold the LiPo and wiring firmly in place. Then cover it all with a pair of CF panels left and right - they'll stiffen the MakerBot plastic brackets, plus provide a puncture-proof layer for when the bike falls down sideways.

This will all have to wait till after I get the CF enclosure for the drive parts done though... I just don't have the time to juggle all this stuff!

[MattyCiii]

Well, I'm disappointed...
The e-drive is great - it has some nice get up & go. What I definitely do not like is the large amount of extra drag I feel when riding on pedal power only. The left side chain and freewheel add a substantial amount of drag, not to mention noise. I have some ideas as to how to best mitigate this, I'll post something soon. In the mean time, I'll do some minor tweaks, such as exploring whether I can go back to the larger 16t freewheel and adapter, and loosen up the chain tensioner a bit...

[MattyCiii]

OK,
Thanks to the RC throttle interface build tutorial, I have a proper half-grip twist throttle, instead of reaching behind me and fiddling for the potentiometer on the servo tester. Much easier to stay on the bike with a proper throttle!

[MattyCiii]

Here's a few pictures of the last stage of the build. Sorry I didn't take more pix - but I had critical parts for both bikes delivered on the same day and so I was chasing daylight.

Here is the custom bracket I designed and had water jetted at bigbluesaw.com. The standard mount supplied with the Recumpense V4 drive is simply too tall to work where I wanted to place the drive. The mount is 2 times 0.625" wide, making it just about exactly the same depth as the square tube it will bolt to


Notice the small relief cut at the bottom. As I tighten the hose clamps, the mount will squeeze down around the shaft collar and hold it nice and firm


Here it is mounted. Notice I have the shaft collar inset into the mount. The inboard half of freewheel adapter will fit inside the bracket, which I have to do in order that the FW teeth have a good chain line. Everything has to fit like clockwork here, in some places I have only 1mm of clearance.

[MattyCiii]

Here's the working bike:


A closer shot of the drive system. Note the gratuitous use of hose clamps, e.g., for the chain tensioner


One more shot (guest photographer: Mr. Blurrycam)

[crossbreak]

thx for posting the pics. the chain drag could be met by adding a freewheel at the rear shaft. But it's hard to find one that fits

[MattyCiii]

The chain drag could be met by adding a freewheel at the rear shaft. But it's hard to find one that fits

I have a couple of fixes in mind:

Near Term:
1) I oiled the chain and adjusted the chain tensioner. Drag has been reduced, but again this chain moves much faster than a standard bike chain, and it has a tight bend at the FW that basically slings excess oil right up my left leg.
2) I will change the FW from the 13t I'm using now to a 16t, which will lower drag a bit and give me more teeth of engagement.
3) I should be receiving my carbon fiber panels soon. Enclosing that FW will help with the noise and the oil, and keep loose clothes/wires/etc out of that chain

Long Term: I plan to design and build a left hand freewheeling mount for the NuVinci/110mm BCD chainring. I'll make (outsource) 10-12, to get the per-unit cost down (the total cost is near fixed whether I make 3 or 12, so why not have extras?) I'll be able to use one on this bike and another on my A-Line, then keep a spare or two and hope I can sell the rest.

This bike is turning out real nice so far, I have half a mind to pick up another Dahon Jetstream and build a spare (I actually already have another Dahon Jetstream, but it's a 2007 model and is just slightly different enough that I'd need different mounts, etc.)

[MattyCiii]

Two related updates:
1) Even with just 6s, this thing has some excellent low-end torque. I'll certainly have to get my V3 CA installed ASAP to have some throttle mapping take some umph off the top! I gave it too much throttle on my first long ride, it wheelied and threw me straight to the ground!
2) My rear brake is a Magura HS33 (hydraulic rim brake). Having ordered/received a bleed kit, I found the time today to install a pressure based brake e-brake cutoff switch. Again, I need to install that V3 CA to make it functional. I have a kit on the way from bikes.ca full of JST connectors that will allow me to wire the CA up nice.

[MattyCiii]

OK, made a small change today that has made quite a big diference!
I swapped out the 13t drive freewheel for the 16t. That dropped my secondary drive reduction from 4.07:1 to 3.31:1 (13t / 53t is now 16t / 53t). This has had several impacts:
1) Loss of torque. This is a good thing, there's less wheelie danger. This is a commuter bike, not built for thrills.
2) Higher top end speed. Nice. This is subjective, I don't have a speedometer installed yet.
3) Less friction. I can feel a noticeable reduction in drag when pedal only performance.
4) Less noise in the freewheeling chain. I like that.

Also, moving from an odd number of FW teeth to even means loss of 1/2 link of chain. That's a good thing, the chain line is almost tight enough to run without a tensioner at all. I'm leaving the tensioner in the loop for now, when I'm in a better position to do testing I'll try without the tensioner.

Here the two FWs look the same


But this picture shows the reality - there's definitely a difference.

[crossbreak]

The fact that you dont need a tensioner is great

I almost wanted to ask you if you would like to add a different kind of tnesioner, one that varies distance between the shafts.

I just like using them

[MattyCiii]

The fact that you dont need a tensioner is great

I almost wanted to ask you if you would like to add a different kind of tnesioner, one that varies distance between the shafts.

I just like using them

Wow I'll do some looking into them, they look like they can definitely solve problems, perhaps on my other bike.

[MattyCiii]

Also have a look at bended alloy ... it's too easy, cheap and helpful to miss

I definitely want to pursue this now. My hose clamp was not strong enough and it snapped. One of those two pictured there:


In a heartbeat, the FW went out of line and threw the drive chain. In about 1 rotation of the rear wheel, the chain wrapped tight and stopped the rear wheel to zero RPM. Good thing I was at the very top of a hill, slowing to stop at a stop sign - I could be covered with road rash if this happened at speed.

So, I've removed the entire drive system until I fab up and install respectable drive mounts. Back to pedal-power only for me for a while!!