Open Source Build

[Chalz]

Open Source Build
I’ve seen a lot of sweet builds and learned a good deal. Now I want to build one, but there doesn’t seem to be a good set of plans around. You have to weed through hours of info and try to figure it all out one small piece at a time. I will always have more to learn, and be short on time, which leads me to wonder if anyone would be interested in helping out with this build? We could put together; instructions, bill of materials, blueprints, CAD files, and tooling files for this bike when all the details get worked out. I have been designing this so that a water jet cutter could cut all the pieces out of two flat sheets of 6061 Aluminum. You could also use a laser cutter, CNC, even just a grinder or I know some of the rough necks around here would rather just use their teeth. Even if you don’t know how to work metal, you probably have a friend that could help out and get you through this project. The pieces have been designed to self-align for the welder. It is built off a used Specialized Bighit frame as many good builds around here have been. Here is a short list of the bikes that inspired this design. These are a pre-requisite in understanding this build. Must read info to really get it.

http://www.stealthelectricbikesusa.com/fighter.html
http://endless-sphere.com/forums/viewtopic.php?f=6&t=38799&hilit=bighit
http://endless-sphere.com/forums/viewtopic.php?f=6&t=37489
I know a mid drive is a more powerful efficient build, but the problems seem too great right now. I really don’t like being locked into one motor, the extra noise, extra things to break, lack of stealth with all the drive mechanisms in clear view. So while this design will be less efficient, it will be simple and better looking in my humble opinion. Here are few things that make this build a little different
1. Aluminum frame should be lighter than steel “Fighter” frame.
2. Design is less blocky by distributing the batteries throughout bike “beams” instead of one huge “tank”. This has three small ones.
3. More stealth, as controller is not hanging outside the frame.
4. Internal frame cooling via head tube air scoop input, and seat post output. Controller is thermal pasted and bolted inside down tube. This is also great wire management potential.
5. Internal structure is not locked in to one type of battery. While it was designed to fit the best battery on the market in regard to Power per weight, it could easily take any other battery type. This increases the likelihood of the frame being useful to others. You could even run it with the same batteries but with four instead of eight. You’ll see how this achieved in pictures to come.
6. Motor is not locked in to one type of motor- like a mid-mount. This bike will accept a geared or direct drive hub that could be quickly swapped with two sets of rims and tires. I need this for commuting at higher speed with the Direct Drive and hill climbing with the geared motor when I just want to have fun. This is in line with the ability to use different batteries. I don’t want to lock the bike into a corner. It should be able to use a variety of batteries, motors, controllers or anything else that may develop in the future as things are always changing. This will make it more useful for anyone who would like to build it.
Check it out.



This is created in Solidworks. I started by using the vector drawings that come in the Big Hit manual and comparing that to a photo I took of the actual bike to get my measurements correct.



Below you can see how the original big hit frame was used to choose how the location of the batteries and controller.



And now, how the new frame boxes it in.



These two images show the front air scoop and rear exhaust.



There is a notch for the front shocks to recess into the frame for the proper turning radius. I have read a lot of complaints about this with a Stealth Bomber.



Here is how the batteries will enter the frame. This avoids having a giant panel on the side of the bike that detracts from the stealth of looking like it could possibly be a normal bike.



The batteries will be held in place with a wedged block method possibly made from nylon. I have only worked this out for the lower four batteries. It rests against an aluminum battery shield in the shape of a C and the frame leaving room for wire management. The block is in green and wedged shaped. This avoids having to permanently weld a battery holder in the frame which would restrict it to one type of battery. It will also tighten itself over bumps with the help of gravity. Easy to remove, alter, create and adapt. There will be an access panel on one side just big enough to stick a hand into, but not the batteries or controller. The frame is also stronger with this small access panel and therefore can be lighter.



Notice how the bottom four batteries are stacked front to back rather than side to side. This keeps the bike really thin by the cranks and gives you plenty of room for the chain ring.
I’ve also done a little Finite Element Analysis to see how strong it is, and take a close look at the weak spots. I have compared this to the original frame and the changes heat treating the aluminum make in my virtual world. I can get into the details of that later if anyone has interest, but I fear it might go on forever with details so I’ll just leave it at the following image which gives a ballpark idea of how it will handle stress.



And here is the Bill of Materials so far. This is going to be roughly a $3500 dollar bike.

Part, Price, Link or description

BB Shell $8.39 http://www.cycle-frames.com/bicycle-frame-tubing/7005-AL-BB-MTB-SHELL.html

HEAD TUBE $6.05 http://www.cycle-frames.com/bicycle-frame-tubing/41.4mm-x-4mm-x-200mm.html

High-Speed Drive $625.00 http://www.pbwbikes.com/product_info.php/cPath/26/products_id/57

Base Bike $650.00 Craigslist
batteries $864.00 http://www.hobbyking.com/hobbyking/store/__18210__Turnigy_nano_tech_8000mAh_6S_25_50C_Lipo_Pack.html

Motor Control $129.00 12 x 4110 MOSFET Extreme Modder Controller LYEN Edition
Frame Metal $200.00 ?
Hub Motor $250.00 Mac, Crystalite, or my top choice the BMC V4S Hub motor, which cost too much.
Computer $130.00 Cycle Analyst
Charger $239.95 http://www.usastore.revolectrix.com/Products_2/Cellpro-PowerLab-8-EC5-version_2/Cellpro-PowerLab-8_516

$3,102.39

As you can see I have put some time into this. I wish I had more time in the day, to finish it quickly. Maybe someone else out there would like to build something like this too and we can put our resources together?

Here are some things that need to be done, or I don’t have an answer for yet.
1. Is there a solution for fitting a torque sensor onto a Schlumpf High-Speed Drive? That would be so good. Looks like the Thun torque sensor is the only one that is highly reviewed, but there is no way that is going to work with the Schlumpf.

2. I have not worked out the charging plug. I need a parts list and design. I think it should be based off of this design and mount into the large opening under the seat post. http://endless-sphere.com/forums/viewtopic.php?f=2&t=39489

3. Speaking of Charging. Do I have the best balancer? Will it even do what I need? What about the charger itself. I have no idea what to use for that.

4. Should I thread the BB shell or just get a tapered shell for Schlumpf? Maybe I should use all the shell and suspension pivots that come with the Big Hit instead of re-creating something that comes with the used big hit starter bike?

5. What about range calculations? I guess this thing is a [2 x 6 Cell Pack (Paralell)X4] = (22.2v) 16 Ah] x 4 Series = 88.8 v and 64ah = 12s4p. It appears as if the stealth bomber uses 30W/m to get to the 50 mile range. So how do you predict range? I don’t have the time in my days to figure all this out.

6. I would love to organize the entire project. Maybe a wiki page type thing would work well? Something with Chapters and an Index? It’s nice to be able to have a group discussion about this in a forum, but I’m so tired of skimming through countless forums just to figure out every variable. I want to get riding quicker.

7. I’m missing something- If I knew what I would ask, but this is the best I can do without knowing

 

[Dlogic]

Great idea and a really good setup to begin with. ES should start a new topic of open source builds for the public. The clever way of raising interest towards electric bikes and more. With an easy to follow step by step instruction those who where still in doubt might just find the right layout to get started.

 

[amberwolf]

I'd recommend something that makes it impossible for the packs to vibrate/rub/move around at all inside the housing; unfortunatley this also makes it difficult to remove them after insertion thru one end. It is also hard to see if this is actually working when inserted via the end, rather than the side. You'd ahve to make sub-housings for them that contain them bound tightly inside, so the packs themselves cant' move within those housings, and then slide the housings into the main housing, with them also made so they can't vibrate around.

If you don't, you run the risk of rub-thru on teh heatshrink and cells or wires, and an eventual fire.



Range predictions: Hard to knwo for sure, but it depends on th speeds you want to go, primarily, then how much stop/start traffic you must deal with, then the terrain you're on. Around here, that's mostly flat, but there are some long/big hills here and there (which some people call "mountains" :lol. And both of those will depend on the power of your setup and whether you use WOT to get started--the higher the power capability, the higher your Wh usage is on non-flat terrain and non-constant riding. Then how much you pedal, and how hard.

My big bike is just under 30Wh/mile typically for 5-mile commute with a dozen or so full stops and starts each way. Longer rides on routes that don't force me to stop much can be as low as 22-26Wh/mile. That's all with no pedalling, WOT startups from a stop, cruising at a hair under 20MPH after having gotten there in 4-5 seconds, on an 80A peak setup at 16s (~66V hot), DD 9C 2807 hubmotor.

If I don't do WOT startups the Wh/mile goes down some, and if I could pedal much to help I could probably bring it down a bit more, and probably reach 15Wh/mile at least on the longer-less-stops trips.

I was over 30-35Wh/mile when I had ~120A peak setup and same other conditions (and the motor got pretty hot--it doesn't now).




Also, in reference to your "commuting at higher speed", just in case you didn't know, 20MPH is the max legal speed on roads here in AZ. Thankfully there is no power limit on electrics. I don't know how well it is enforced everywhere in Phoenix, but they certainly have been trying to do it in Tucson with the many gassers down there. Not a lot of assisted bikes here in Phoenix (I rarely see one), so I expect most of the time as long as traffic law is obeyed and riding is safe, the police ignore us.

To be on the safe side, since the tickets could be 4 digits and up, I stay at/below the limit (can't afford otherwise). But so far, other than once, the only times I've been stopped or talked to by officials at all have been to thank me for my lighting, or ask me about my "crazy ride". I suspect if I did ride a lot faster, I might draw unwanted attention, so I don't.

 

[amberwolf]

Balancing/charging: I dunno enough about RC chargers to say; I bulk charge mine and manually check balance (whcih so far has not been a problem, but I very rarely run the pack down all the way). I use a cheapy RC charger (accucel6) for my 12V EIG lighting pack. Both of my ammocan traction packs, one 16s1p 20Ah EIG and one 14s2p 10Ah RC LiPo are bulk charged, and I have Methods' HVC/LVC boards to keep me from overdischarge (I don't have the overcharge stuff hooked up yet, though I really should).

The simplest form of those just pulls down your throttle line when any cell drops too far down--but they are a last-line-of-defense kind of hting, and not an everyday HVC/LVC (you can use your CA for the pack-level LVC and current-limiting). More complex setups could trigger the V3 CA to switch modes to limp-home, or alert you visually or audibly, or actually cut power on the pack entirely, at LVC. And/or cut charging power if a cell goes too high. They're basically meant to keep you from destroying the pack (or having a fire) if something else goes wrong, like a bad cell going low way before the others, or shorting internally and allowing rest of pack to charge too high.

The charger/balancer you've linked to does both charging and balancing, can do them at the same time, AFAICS. (most RC chargers can, though some like the Venom I also have here are not very good; it is wildly inaccurate in various readings; can be over an amp off on what it says is flowing vs what is actually happening, and volts can be off a fair bit too, both the main and individual cells! Probably could lead to pack destruction if it was far enough off).

 

[amberwolf]

This might go against your "stealth" plans, but honestly I think it would make your commutes safer, day or night:

Lighting: if you're commuting on Phoenix streets, I HIGHLY recommend motorcycle-class (minimum) headlights and taillights and turn signals and markers. People will actually see you, even in daytime, much much better than without them. (not that I trust them to do so but it does make a big difference). Even though many (most?) drivers don't actually use their own turn signals, most of them do know what they mean and respond to them appropriately, whereas they haven't got a friggin' clue what hand signals mean (and neither do at least some of the police officers; I've been waved at before because they thought I was waving, when I was making a righthand turn signal!).


I recommend LED lighting; it's cheap enough now, and way bright, but youc an build your own. I am using MR16 LED spotlamps inside old Honda scooter turn signals and a brakelight bar off a junkyard car, and an old car headlight (usually on both low and highbeams) running off a 12V lighting pack, and a household CFL bulb off traction pack voltage plus an old laptop wall adapter. I'd like to get a complete HID 2-lamp setup off a car for the headlight, and a couple of large-size LED tailight units for the tail/brake lights as well as turn signals, but haven't run across any scrapped ones yet.

 

[Chalz]

Amberwolf,
I'm going to commute to work on railroad beds, canal paths, parks and power lines- no speed limit issues there.

The charging methods seems to work fine for Simon. I just want to follow what he did, but make it more powerful. Seems like a proven method. Good to know that balancer also charges. If that works good it should be perfect for the job. I wonder if anyone has experience with it.

~Chalz

 

[dh-paule]

What about a pinion 18 gear ? (except the price

http://pinion.eu/en/discover-pinion/pinion-p1-18/

 

[Chalz]

That gear box is pretty. But hopefully gears won't matter as much with electric power, as long as you have the ability to pedal at fairly high speeds. What is the price for that gear box? Is it way more than the Schlumpf?

 

[Dlogic]

You should include mounting points for a gearbox for those willing to spend that extra cash. An adaptor made out of steel sheets would be fixed here to provide a swivel point for the swingarm when building the bike without the gearbox. With this option you'd have a really versatile frame.

 

[iamsofunny]

The BB shell will warp after welding (oval) and the BB won't thread in
You'll have the thread the BB into the shell, then do a series of good clean tacks to make your weld. Don't let it get hot or the bearing will burn.
No bike company prethreads the BB shell. They mill it and then clean up the milled threads by hand after.
I don't want to discourage you, just I've built many bikes and the BB shell / head tube go oval after welding.

 

[Whiplash]

Can you buy a simple thread tap to thread the BB? I am getting ready for an aluminum frame build and I wonder how they doo this and keep it square? I wonder if I simply make a thick wall BB housing to help with distortion? I suppose I could have a junk BB to thread in during welding to keep it round...

 

[iamsofunny]

I have the unior thread tap but you can't really cut threads with it... well you can it 's just really hard.
You can use the cycle-frames BB shell, just screw the BB in before welding. If you weld the whole bead one pass, the BB will be stuck in there due to warping and it will never come out. So you have to tack it, let it completely cool, then do another tack. That's not a good welding technique but it would work minimizing ovaling.
Another technique I invented is to buy the bb shell and mount it in the frame by drilling a hole in a piece of square stock, drill and tap so that the BB shell is held in place by the force of the bolts rather than welding. then you can loosen the bolts and slide the whole bb shell out. But that's somewhat heavy and not good really.
Another technique is first get a press fit BB and cranks such as BMX. Then you can lathe the BB shell thick and then weld it with no warping. This is the best homeworkshop option IMO.

 

[Chalz]

It sounds like the schlumpf doesn't require threads, just a 45 degree taper that it jams itself into with huge torque. Shouldn't matter if it's not perfectly round if it's a interference fit. I don't have experience with this, so I can't speak with any authority- but that is what I thought, from reading this;

http://www.utahtrikes.com/ARTICLE-33.html

iamsofunny- How about if I use the existing BB shell but just cut some stock frame metal out with it to save it from getting hot enough to warp. Is that possible? How far away could you weld near the stock BB without it warping?

Dlogic- I could not even find a place to buy that gearbox that was pointed out, or a price so I didn't even try to find dimensions for it. But I would like to make the design as versatile as possible, and would be open to including it if I had anything to go on.

 

[iamsofunny]

If you left 1" of metal it should be fine because the tube is already welded to the BB shell and there would be minimal pulling forces from the new weld.

 

[Whiplash]

What about just using a tube the size of the OD of the bottom bracket, weld that in place, then press the BB into place and just tack it in two spots on either side so it does not move? It would only add a few oz. and look almost like it was threaded after welding! I think I'll try this method on my first frame!

 

[iamsofunny]

you can slide the BB in the hole and then use bolts to friction clamp it in. I was going to do this technique but have not tried yet. It has a high possibility of success. Tack welds may break although if you do some pretty cold welds on the edge you may be able to just carefully connect them without melting the threads but that is a tricky affair.

you can get a BB shell made at a cheap machine shop just get them to make the wall thickness, say 3/8" then it should not warp. I did force my BB shell into a cycle-frames totally warped shell post-welding but I had to put a 3 foot extension on my wrench to force it in. then I welded filler metal all over it to keep it in place because it didn't go all the way in. That's an other interesting technique.