Oatnet's x5403/Norco A-line, and Front-Mount battery stuff

[oatnet]

Looking forward to seeing how these builds shape up. Love your work oatnet.

The bike pictured a couple of posts ago is already one of my favorite hub motor powered bikes on the forum. Keep up the good work.

Wow Kepler, thanks for the kind words! I love your work too, I have been watching the series of impressive developments you have been making with your line of friction drives. Stealth is important to me, and your latest stealth drive is so invisible, I had to do a 'where's waldo' on your picture to find it. I remember someone else posted they though also thought it was the 'before' picture.

-JD

[oatnet]

I got a few PMs asking about the battery box, so I thought I'd post details here. I've used two models of box so far, the Pelican 1300nf, and the Pelican/Hardigg im2075 storm case, both @$35 on ebay. Pelicans make great battery boxes because the are super-light, super-durable, and easy to dremel and drill.

I use 'weight clamps' or 'accessory clamps' to mount the Pelican boxes to the stanchions of RockShox Boxxer forks. Boxxer stanchions were 32mm/1.25" until 2010, when they went up to 35mm. The clamps are designed to mount lead weights on tube-frame race cars. They have holes for the .25" mounting bolt. The vendor for these particular clamps is Wehr's Machine Racing, here is the auction where you can buy them:

http://cgi.ebay.com/ebaymotors/ws/eBayI ... 0344689577

The entire assembly weighs only 4lbs, mounts securely, and offers the protection that soft-sided prisimatic cells need. The 1300nf will hold (20) a123 16ah Prisimatic cells (1kw), and the im2075 will hold (260 a123 Prisimatic 20ah cells (1.5kw). Since LiPo is 50% volume of the Life, you could fit twice as much capacity into the box; since it still weighs 85% of the LiFe, you would probably want to add more clamps for the extra weight.

Here is the post in the build thread that has lots of pictures. Note the (2) dead-simple but stealthy power switches, one has a resistor around it to pre-charge the controller:

viewtopic.php?f=6&t=24329&start=30#p470443

I did earlier builds with ammo boxes too, which are much heavier and more difficult to machine. I've also use larger clamps with .50" bolt holes, but they were much heavier so I would avoid them too.

With the weight over the front wheel, it always stays planted. When I turn my handlebars with one of these boxes, the battery mass is directly connected to them so steering input is instant. When I turn handlebars on a rear or triangle-mounted pack, that steering input has to translate through the frame to the battery mass, flexing and slowing responses. I first discovered this on my xtracycle, which has a 5304 and 30lbs of LiFe on the back, so steering inputs are more of a suggestion than an imperitive.

Suprisingly, it is pretty easy to lift the front end on jumps.

-JD

[veloman]

Oatnut: do you experience any downsides to have the battery up front there? I know it will make it feel odd if you ever want to rock the bike while standing to pedal hard, but that can be stopped if you teach yourself to not rock the bike - like a track sprinter.

[neptronix]

4 pounds just to get the battery up there?
That's kinda bad dude... I see the advantage of the front shock buffering the abuse on the batteries though so that's good..

I do like my mid-mount.. falconEV bag = less than 1lb..

[Kepler]

I really need to try a front battery mount setup. Makes sense to balance the bike weight with that battery position when using a hub motor. Biggest issue in my opinion is keeping the bike looking reasonably elegant. The Pelican case setup does the best job in keeping the build tidy I have seen so far.

[oatnet]

I really need to try a front battery mount setup. Makes sense to balance the bike weight with that battery position when using a hub motor. Biggest issue in my opinion is keeping the bike looking reasonably elegant. The Pelican case setup does the best job in keeping the build tidy I have seen so far.

So am guessing my early experimental models would NOT be on your xmas list? Here are a few pics to show you what you are "missing."

The initial "I'm just a beach blanket" model (below) opened my eyes to the potential, but the slop from the soft-mount added its own steering inputs.



The "ammo can" model (below) was bulletproof, but heavy. People loved or hated the industrial look, no middle ground. I'm planning to re-mount this on my x5tracycle - it's front wheel needs as much weight as possible to offset the heavy x5304 at the end of the long whip made up of the xtracycle and frame.

[veloman]

Slap a fairing on the front of the battery box. Say it's to keep the battery dry in the rain

[oatnet]

Slap a fairing on the front of the battery box. Say it's to keep the battery dry in the rain

I bought one of those zzipper mountain bike fairings a few years back, but didn't use it on the intended build, so I have in fact been considering using it on an A-Line build. Not sure it was built for these speeds though, and I have to see how unstealthy these builds turn out to be.

On another topic -

Jon Rob Holmes is a saint, guiding my dumb a$$ through the complexties of putting moped rims/tires on an ebike, PM'ing me to tell me he was OK with changing my rim size after the Cromotor went from 9.5kv to 13kv, and steering me away from impossible and dangerous configurations. I am so glad I have his expertise to guide me, I think if I had gone to a LBS they would have built exactly what I specified, which as it turns out is not what I wanted. Thanks JRH!

-JD

[markobetti]

thanks JON ROB HOLMES from me too , because i was the one to complicate oatnet situation
T H A N K S F O R B E I N G A N I C E G U Y

[gensem]

+1 for John Holmes he is really nice guy, always willing to help.

[liveforphysics]

I did a fork mounted 2kw-hr pack on a bike we built in a couple hours for a buddy to race at the last event.

High and forward does seem to be a great place to carry weight on a bicycle. However, I didn't like the heavy steering effects, which made it kinda awkward when you were really railing corners and needed to make a series of instant small steering input corrections to hold your line. If I could brace it from the frame alone, so it didn't turn with the forks, but keep the weight in the same place, I think I would really like it.

[Ypedal]

hmpf.... penismotor..

[oatnet]

I did a fork mounted 2kw-hr pack on a bike we built in a couple hours for a buddy to race at the last event.

High and forward does seem to be a great place to carry weight on a bicycle. However, I didn't like the heavy steering effects, which made it kinda awkward when you were really railing corners and needed to make a series of instant small steering input corrections to hold your line. If I could brace it from the frame alone, so it didn't turn with the forks, but keep the weight in the same place, I think I would really like it.

I remember that build well, I was really pleased to see you made it!

Anyhow, it took me a day or so to adapt to the new steering feel, and then maybe a week of progressively deeper leans/sharper turns to get a sense of how much better handling had gotten.

The steering felt twitchy at first, because having the mass up there made the bike lean over much faster than I was used to, it felt like I would lowside. Then I discovered that the lean is very predictable and controllable. No matter how hard or fast it goes into a lean, I can set my lean angle immediately, and with precision. It seems like the deeper I lean, the faster I can lock the angle. Thanks to that, I am taking corners much faster, with much deeper leans than I would have dared in the past.

I've spent a fair amount of time pondering why this works, and I have a two theories about it. First, when I lean into a turn, the bike is 'pushing' the battery mass sideways. Because the mass is mounted over the fork, the force vector from that 'push' runs directly through the fork, compressing it and planting the front wheel firmly. The steeper the lean, the harder the battery is 'pushed', and the firmer it plants. Second, my steering inputs aren't fighting a mass on the frame that wants to keep going straight, or the resulting occilations as the frame flexes between the battery mass and steering input.

Exiting turns, and Side-to-side transitions, are also faster for me, With just a little extra turn in, the battery mass snaps the bike back up much faster than I can pull it up myself. To me, it feels like a fighter jet.

I would have expected the gyroscopic effect of the spinning wheel would have been more difficult to overcome than the battery mass, so I am suprised to hear you report that the mass impeded your abiltiy to make fine corrections. However, I probably don't have even a fraction of your skills, experience or road feel, so maybe I'm just not refined enough to notice.

Was there any slop or flex to the battery box mounting, or the boxes contents? Slop felt all manner of odd, because it added its own unpredictible occilations and steering inputs. Hmm, I wonder if there was enough flex in the handlebars/stem to affect some slop, because as I think back to the 'I'm just a beach towel' mount, I tried a bunch of mechanisms to secure it to the handlebars, but no matter how tight I got the mount, it felt... wrong. It was only after I got the mass hard-mounted to the stanchions - and going absolutely going nowhere - that it felt stable.

Anyhow, when I drag these twins out to a future track day for 144v testing, maybe you'll be around to flog one for a few laps and see if you still feel the same way about fine inputs. Besides, at that voltage the CroMotor's no-load speed is 128mph, 80% of that is 102mph, which would require much bigger balls than I am dangling. You are probably one of the few that could take a 144v CroMotor build to its limits.

[oatnet]

JRH is building me a wheelset with a CroMotor in the back wheel, the front wheel will be on a 20mm through-axle DH hub. This is my first foray into using moped rims/tires on ebikes, so I learned a lot from JRH as he helped me sort out the configuration.

I was really glad for his expertise, because without it I would have asked for a really dangerous wheel build. The strongest spokes and strongest rim don't necessarily make the strongest wheel. After checking with him, I thought I'd post what I learned, in case anyone else knows as little as I did. This is in no way intended to be a guide - I have insufficient experience - but to highlight some of the issues involved. Pretty much everything below I picked up from John, except for anything that is wrong.

The front wheel bicycle hub is the weak point in the build. The RockShox Boxxer fork's 200mm front travel will help with hard bumps. However, John is still worried about the hub flange, so he wanted to use 13ga spokes "to encourage spoke breaking vs hub failure." The smaller spoke size also dictated a lighter steel rim, as the heavier alloy rim required 10ga/11ga spokes.

The rear rim is 17" to suit the 13kv of the CroMotor. Since the motor has more top end than I need, I wanted to go wih a small wheel to maximize accelleration, keep the motor cool, etc. I'll swap in 144v packs for testing/exhibitions (maybe even <gasp> LiPo ), but the rest of the time I'll probably keep them at 72v or 100v. I considered a 16" rim, but if I choose to run this at 72v nominal (roughly 79v for LifePO4) top speed would only be 46mph. Besides, I can run a Gazelle tire on the rear rim.

John likes the Michelin Gazelle M62 Moped Tires, I read a lot of good reports about them, and the are 'p' speed-rated to 93mph, so it seemed like a slam-dunk to use them on both wheels. However, I wanted my front wheel to be larger than the rear wheel - the Norco A-line comes with a 230mm fork, My Boxxer forks 'only' have 200mm, so I can use a little extra height to correct the rake angle. However, Gazelle moped tires are only made in 17"/18" diameters, so an 18" moped rim was the largest I could go.

That said, guess what? Good luck finding an 18" moped rim to fit that 18" moped tire, 16"/17"/19" are your choices - and a heavier 18" Motorcycle rim is too much weight for a bicycle front hub, plus as mentioned earlier it would need heavier spokes that would make the front hub flange fail first. When we thought the motor was 9.5kv, John bought a 19" rim and pair of 19"x2.5" Deestone tires/tubes at my request, So I decided to just go ahead and use that combo on the front wheel anyhow.

Which brings me to the mixed bag of nutty calculations used to describe tire diameters. Some tires are rated just as a diameter, I guess like bicycle tires. Other have ratings with 2 numbers, like automobile tires. Lets use 110/80 as an example - 110 is the width in mm. so the tire is 110mm wide. 80 describes the height of the tire, but it is a percentage of the width, not mm, so in this example 110mm*80%=88mm tall.

It is important to note that the width is measured across the widest part of the tread, which is not neccessarily the widest part of the tire, so if you buy a 110mm tire to fit a 120mm space, you still might find the tire rubs. In addition, I already knew from bikes that a wider the rim will also spread the tire wider. It seems that practical experience with the tire rim-combo at hand is the only way to be sure it will fit, so it seems like a good idea to leave some wiggle room when sizing the tires.

Most of the Moped tires seemed to be 2.25", 2.50", 2.75", and 3.0". The Boxxer forks have something like a 4.5" gap - room to fit any of them. However, the rear of the Norco A-line is about 3.5" where the treadline on a 16" or 17" rim meets the frame. I was concerned that 3" might be too tight a fit, especially since I might need even more wiggle room when shimming the Cromotor's 135mm axle into the Norco's 150mm dropouts, so I was more inclined to go with 2.75"/2.50". On the other hand, I wanted as much diameter as possible to cushion the heavy hub motor. On the other other hand, each extra .5" of tire width adds 1" of diameter, which decreases the accelleration I want, and increases top end I probably won't use. So while I would have liked to use a 16" rim with a 3.25 (22.5" diamter) wide tires for maximum padding, they might not have fit. The 17" rim with 2.75" tires is the same 22.5" diameter, plus I can use the Gazelle.

More details I got from John: Wheel Diameter: bicycle rims are measured at the top of the tire, but Moto/Moped rims are measured at the top of the rim. Rim Width: Bicycle wheels are measured between the rim's outer surfaces, while the moped rim is measured to the inner surfaces.. Typical moped rims are 1.35", my ebike-preferred Alex DX-32 rims are 38mm(1.5"), but both are roughly the same size. In theory, my 19" front wheel with 2.5" moped tires should be the same size as a 24" (19"+2.5"+2.5") front bicycle using Alex DX-32's and 2.5" Maxxis hookworms.

Thanks to Saint JRH!

-JD

[dbaker]

Oat, just saw this thread. So cool you are going to build 2 of these high speed bikes. Luke is in Santa Cruz. I can't imagine he can't get some of his friends to join him for a a run down to LA to push your bikes to the 100 mph limit?? Sounds like a great week end You don't mind flames do you

What are your plans for the dropouts for the A-line frames? I finished a pair of dropouts last weekend that extended the A-line wheelbase 7 inches. I will try to get photos posted this weekend. I need a 800 pound spring for my rear shock

I commuted on a 17" Gazelle laced to a 9C mounted on a Giant Faith II for a year (24s2p Lipo, 18 fet ecrazyman). Tire was bullet proof compared to the multiple pinch flats I experienced on a 26" Hookworm over the same route.

Hope to get the wiring done and some CA data posted this weekend.

[oatnet]

I just got the plastic test parts for the replaceable dropouts, and I am simply stunned by the great quality. This is a complex part, especially where it mounts to the frame. It has one flat section that also curves against the frame at the bottom, one "wavy" section that the frame curves around at the top, and a step between them. These are meant to be the load bearing surfaces, so they must fit precisely, relative to each other. Their position is also relative to the three bolts that keep the dropouts in postion to these surfaces. The fit of the original parts is so tight I had to mallet the dropouts to get them off.

Our very own Magudaman CNC'd these beauties in short order, based only on a pair of the removable dropouts I sent him, and he reproduced them so EXACTLY that they are just as snug as the original dropouts, with tolerances I would say are at most +/- .001", and exceeding my wildest hopes.

While doing that, he also moved the bolt hole back 2", and moved the dropouts in 7.5mm so I could fit the 135mm CroMotor into the 150mm dropouts. Since these are removable, the dropouts are fully enclosed. And heck, I haven't even showed the lightening he did on the back side! Really Really impressive work, crazy good skills, I am beyond thrilled. Plus he has been great to work with, very responsive, shared expertise in metal selections, I'd give my highest recommendation on any parts you need made.

Given that is CNC, he can also make more, so I can buy a 3-4 sets, maybe build one for Mrs Oatnet too. With parts from Justin, even a clown like me can pick up one of those A-line frames currently selling on ebay and make an awesome, durable downhill ride, without mucking about with torque arms.

I only had time over lunch to bolt on one side, but tonight I'm going to put on a motor/brake/deralliur to confirm fitment, more pics to come.

'I'm dreaaaming of an A-Line, Christmas... Not like the hardtails I used to know...'
-JD

Note: the plastic block wasn't quite big enough to make the test parts, so you can see it is chopped off a bit at the rear axle mount. It will be fully rounded on the final piece.

[fractal]

wow, this just amazing work. this place is filled very talented people! i absolutely have to get those for mine! very impressive! count me in for a pair!!!

[Andje]

I'll be in for a pair as well. Please do let us know when you are ordering the final sets; I can send cash any time for such a thing.

[dbaker]

I also want a pair of those dropouts. So nicely done!

[sn0wchyld]

wow man, makes my work look like a dogs dinner!!

I'd strongly recommend using a slot + a pinch bolt rather than an enclosed axle though, the small touch ups I needed to do to get my axle to fit tightly took hours, and taking the wheel off means taking the whole rear end apart, including breaks and derailleur. gets to be a pita after a while. it also relies allot on the precision of the axle your putting into it... if it varies even half a mm along its flat spots you'll know about it, and the axle wont sit tight /will develop some play unlike what'd happen with a pinch bolt.

try changing the 'slot' direction to being horizontal rather than verticle, so your axle can come out the back, and maybe beef up the top side above the axle a tad since it will be taking the full load of the wheel on its own. then you can run a pinch straight down into the lower section. alternatively you could work out a way to bring the slot out in front of the derailleur mount, perhaps giving less chain wrap but keeping it vertical...

as it is im still temped to get a set myself too... what final material are you using?




edit

I may even be interested in one with the standard axle hole, as ive got long term plans to put a mid drive on this bike! would be good to have an extended wheelbase for a normal rear end available!

[dbaker]

I agree with the pinch bolt drop out suggestion.

[Andje]

I have seen good success without torque arms on my norco 125; it has horizontal dropouts as you speak of without a pinch bolt. The bolt contact surface is knurled. With good torque on the bolts i have seen excellent lack of twisting. I wonder if good knurled surfaces would keep more peoples bolts tight under regen as long as the dropout is strong enough to resist the twisting.
Or the pinch bolt suggestion .

[oatnet]

I might ask for a pinch-bolt setup in the future, but the stubby little CroMotor axles limit the material I can get against the flats, and the enclosed axle hole is a stronger design. Plus it prevents the axle from sliding backwards, so the axle nuts will only need to hold the dropouts to the motor, not keep it from moving in the slot, so I can use thicker dropouts and engage less threads.

Besides, these removable dropouts are the only way I'd ever be able to try an enclosed axle hole. I'm aware that its going to be more work during fitment, but once installed I rarely have need to pull a motor back out.

I have asked that the diameter around the axle hole be 2" instead of 1" to have more metal aroound the hole. As Fractal pointed out to me in PM, I'll need to dremel out some materal to keep the wires from being pinched against the dropout.

Magudaman recommend 7075 T651 aluminum, 1/3 the weight and stronger than mild steel.

I was hesitant about ally at first, but after some research I came around. It is already annealed, and because the axle hole is fully enclosed, I am not expecting to see flex in the material. Here are the metal properties he found on a website and forwarded me.

7075 T651
Physical and Mechanical Properties Ultimate Tensile Strength, psi 71,000
Yield Strength, psi 58,200
Brinell Hardness 150
Rockwell Hardness B87
Chemistry Aluminum (Al) 87.1 - 91.4%
Zinc (Zn) 5.1 - 6.1% max
Copper (Cu) 1.2 - 2.0%
Chromium (Cr) 0.18 - 0.28%
Iron (Fe) 0.5 max
Magnesium (Mg) 2.1 - 2.9%
Manganese (Mn) 0.3% max


1018 Mild (low-carbon) steel
Minimum Properties Ultimate Tensile Strength, psi 63,800
Yield Strength, psi 53,700
Elongation 15.0%
Rockwell Hardness B71
Chemistry Iron (Fe) 98.81 - 99.26%
Carbon (C) 0.18%
Manganese (Mn) 0.6 - 0.9%
Phosphorus (P) 0.04% max
Sulfur (S) 0.05% max


Finally, on to the pron! I did a test fit with an 5305 (yes, I put it in backwards ) The rear shock isn't in yet, so the frame is where it would be with the rear shock fully compressed, and it looks a bit funny. I should be getting the correct driver for the press to install the FSA 1.5" to 1.125" reducer headset, that will allow me to install the Boxxer's, which also are at an odd angle. You can see how far back the wheel is, with the extra 2" on the dropouts.

Look how far back that wheel sits! I can't wait to strip those ugly red BOXXER decals off the forks, make them a nice generic white.

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You can see the windowing here.

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Here is the left side, from above.

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Here is the right side, from underneath.

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[fractal]

Nice! Is that a 26 inch wheel?

[oatnet]

Nice! Is that a 26 inch wheel?

Yep!