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Nuts & Volts
10 March 2011, 2137
Overall goals - I want a motorcycle that slightly exceeds or matches a 600cc sport motorcycle (on the street mind you). So quickness is somewhat of the defining factor here. Here are my performance goals

100mph top end
100miles at 35-45 mph
40miles at 70mph
0-60 in less than 4 sec
320lb motorcycle weight (max 350lbs)
Cost competitive with a Brammo Empulse 10 ($12k-$14k)


Planned Chassis - Nothing fancy here. Smaller, lighter, modern sportsbike.

Gen2 SV650
Gen1 SV650
125/250cc chassis (rare)


Batteries - These are the ideal specs that I need in a battery

95-106s LiPo OR 110s to 135s LiFePO4
15 to 25Ah
300A maximum
20-50A continuous
5.5 to 8 kWh
4 years OR 40,000 miles to 80% capacity retention (based on 45mph average)


Motor – Ideal specs

50 lbs max (lighter=better)
Minimum 2000RPM (no gearing up, 1:1 is ok)
20kW continuous (70 mph)
50kW+ peak (meets acceleration and top speed goals)
Smaller volume (no bigger than an AC15)
Liquid cooling


Controller – Ideal Specs

400-450V max input
300A max
25lbs max
Smaller volume
Liquid cooling


Charger and BMS – Under-Investigation
Will post my researched ideas later


Component Choices

Battery
1.)Turnigy LiPo

o 15 or 20Ah
o 20C meets all battery current needs
o 85-100lb packs
o 5.8 to 7.8kWh at 105s nominal (388.5V, 15 or 20Ah)
o Easily fits in any bike
o Complicated Wiring

2.)Headway

o 16 or 20Ah
o Need 15C max
o 133-266lb packs
o 6.1 to 7.7kWh at 120s nominal (384V, 16 or 20Ah)
o More series strings = more BMS $
o Volume Concerns


Motor
Enstroj EMRAX

a. 25kW cont
b. 60kW-80kW peak
c. 28lb
d. 3000-4000RPM max
e. 200-250Nm max


Controller
Still in the works, I have 4 to 6 viable options. Price, availability and weight are the main deciding factors



Yes my goals are big, but very realistic. I plan to take my time with this build. I hope to do a ton of engineering and planning up front. That way when i get to build I pretty much now my next step all along the way. I have been waiting to start a thread because it may be a very long time before any building occurs. This thread will be used to throw around ideas and to eliminate as many road blocks from the build process. I hope to talk about crazy ideas on here and to discuss how to make them work. I have some ideas up my sleeve that I may pull out when the time comes. I may try to update this first post or add information to the first couple of posts if this thread gets infinitely long. Thats enough for now. Dream Big

-Kyle, aka N&V

Nuts & Volts
10 March 2011, 2219
**All Calcs will be worst case (low battery temp, low SOC, large voltage drop, etc.)

Common Specs
Tire Radius=12.5in, Rolling Coef=.012, Cd=.065, Frontal Area = 615in^2, Wind Speed=4mph, motor eff=90%, contrl eff=97%, gearing=2.5

Power
Motor Max power = 60kW at 90%
Battery Power (3p105s) = 60/(.9)/(.97) = ~69kW
Battery Current max = 69,000/(105*3.4V) = 195A / 15 = 13C rate

Speed
At (105*3.4) 357V controller with FOC (Field Oriented Control) can provide motor voltage = Vdc*2/pi, thus about 227V. Motor data shows Kv ~14-15
So max Rpm at 357VDC should be 227V*14.5RPM/V = 3300 RPM. At 2.5:1 gearing that gives about 98mph. Also 20kW worst case at 100mph so no problem with power

Weight in lbs
Motor=28, Controller=22, Batteries=90, Rolling Chassis=150, Misc=50, Rider=180
Total Mass= 340 + rider = 520lb

Acceleration
220Nm motor max torque, base speed=3000RPM
Excel sheet Considering weight and motor torque only 0-60 = 3.66 sec
Excel sheet Considering weight, inefficiencies, motor torque, and aero drag 0-60=4.1 sec

Costs
Chassis = $1000
Motor = $4000
Controller= $4000
Batteries = $2500
Charger/BMS = $400 to $2000
Misc = $1000

Estimated Cost $12.9k to $14.9k

......

Skeezmour
10 March 2011, 2255
The cost competitive part is not an easy one thats for sure. Most of the other goals look fairly dooable. Hope to see you with a bike your very happy with. Please keep us updated with your progress.

Gene

Nuts & Volts
10 March 2011, 2316
The cost competitive part is not an easy one thats for sure. Most of the other goals look fairly dooable. Hope to see you with a bike your very happy with. Please keep us updated with your progress.

Gene

Yep from my initial looking (2 months worth) I think the biggest problems will be with chassis (may buy working and use for awhile to utilize some value there) and controller. I have found options at the lower end of the controller and charging spectrums that will work. Motor and battery price is pretty much set.

ZoomSmith
10 March 2011, 2331
Is an SV650 chassis going to be wide enough to accommodate all that hardware? Might be better off with R6 or GSX-R 600 running gear.

Nuts & Volts
11 March 2011, 0003
Is an SV650 chassis going to be wide enough to accommodate all that hardware? Might be better off with R6 or GSX-R 600 running gear.

Thats actually why i want an sv650, its in between a 250 and a 600 frame. Here are some early renderings. I think this is 68 5s turnigy packs (~113s) and I dont even touch the tank or tail area :)

911912

PS- i didnt CAD the frame I found it online. maybe someday ill be that good!

EVcycle
11 March 2011, 0409
Interesting and lofty goals.

Are you keeping a Budget spread sheet?

Coninsan
11 March 2011, 0557
That's gonna be one hell of an SV i'll tell you that.
I'll be looking ofrward to see this progrss :)

Nuts & Volts
11 March 2011, 0811
Ed, yes I have it at $13,800 right now which includes a Elithion BMS that i dont really want to use. It also includes chains, insurance, plates, scrap metal, etc. I hope to bring the cost down to under 13 even, by adding my own labor cost and coming up with creative solutions. If I work over the summer part time I should be able to save up for the final bits for the project. I can also sell parts from bike 1 after this bike is complete to recoup some cost. (so GBS cells and an agni will be up for sale in about 3 years :))

Some might say I am putting a lot of mooollla into this build and yea its more than a sane person would spend, but when you got a passion there ain't nothing thats gonna stop you! If its fast enough maybe ill get someone to race it once or twice, maybe

podolefsky
11 March 2011, 0917
Some might say I am putting a lot of mooollla into this build and yea its more than a sane person would spend, but when you got a passion there ain't nothing thats gonna stop you! If its fast enough maybe ill get someone to race it once or twice, maybe

Sane? Maybe not... A great idea? Definitely.

If you can build an electric SV that competes with the Empulse IN YOUR GARAGE, then do it. As long as you're not digging yourself into debt, you can't put a price on passion.

You could be spending $50,000 for a chromed out West Coast Chopper. Oh wait, they're out of business because people figured out it was cooler to rattle can your paint job yourself then pay someone $50,000 to do it for you.

Nuts & Volts
11 March 2011, 0933
Sane? Maybe not... A great idea? Definitely.

If you can build an electric SV that competes with the Empulse IN YOUR GARAGE, then do it. As long as you're not digging yourself into debt, you can't put a price on passion.

You could be spending $50,000 for a chromed out West Coast Chopper. Oh wait, they're out of business because people figured out it was cooler to rattle can your paint job yourself then pay someone $50,000 to do it for you.

Thanks man, i appreciate the encouragement. Slowly, but surely Ill get this done. The only real problem for me will be if other responsibilities take my time or money! So time goal will be to have motorcycle street legal by mid-summer 2012. That will keep me moving forward

I am reading through the Tony Foale Motorcycle Handling and Chassis design book right now which should help some with the build. I'll write up a post about Wiring/BMS/Charger solutions later and learn your guy's thoughts.

Nuts & Volts
12 March 2011, 1859
So after learning a bunch from our BMS thread. I have decided that I will most likely bottom balance my cells and be running a cell monitoring system that has an alarm for HVC and LVW(warning). I will test all cells before wiring everything up to make sure there are not duds. I will being use the alarm signal from the cell monitors to stop charging when HVC is reached by one cell. No balancing will be one board the bike because paying for, wiring and running a balancing board on 96 to 106 cells in series just sounds too expensive, complicated and tricky to me. This being said I will still have an RC charger/Balancer that I will use to balance out the pack every month or so if this is needed. This fits with my initial plans as well because I will simple have my HVC be about 4.15 to 4.17V and my LVW be about 3.6V. My controller LVC will be set at 3.4V* XXX cells in series. This allows for some voltage sag under load at low SOC riding, but ultimately I dont want to discharge cells below a resting voltage of 3.65V.

On the low SOC side of the pack I will use the controller to actually implement LVC at a pack voltage level. The LVW/voltage display of each cell will let me know if any cell is dieing on me. This may I can take it easy and get home without being stranded by a LVC that shuts down my whole bike. I have designed the ability of my pack to have one cell replace if an event like this should occur. I will also be running a 14/16 guage wire lead to every cell so that I can attach my cell monitors and also use these leads for low current balance charging if that is ever needed.

So I will purchase 17-18 of these http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9282. Still a lot of wiring but seems like a more reliable option to me.

I will also point out that max C rate on the cells in my bike will be about 13C, so I will not be stressing the cells very much which should help them stay in better balance on their own

Coninsan
13 March 2011, 0302
What your doing is really inspirational :)
I've been touring the same thoughts for a LiPo Cafe racer, buttom balancing and having a cell monitor log for LVW/HVC. Adding a RC charger/balancer to the mix for routine maintinance seems like a good seems like a wise choice.
One thought though, are you sure that the Cell-log can provide both a HVW and LVW? Hobbyking lists that Cell-log only has one programmable single cell alarm?

lugnut
13 March 2011, 0434
are you sure that the Cell-log can provide both a HVW and LVW? Hobbyking lists that Cell-log only has one programmable single cell alarm?

It only has one alarm, but it is triggered by 1) HV set point exceeded, or 2) LV set point reached, or 3) delta V setting exceeded between any 2 cells. So yes, it does provide both HV and LV warning.

Nuts & Volts
13 March 2011, 1035
What your doing is really inspirational :)

Well thanks.


It only has one alarm, but it is triggered by 1) HV set point exceeded, or 2) LV set point reached, or 3) delta V setting exceeded between any 2 cells. So yes, it does provide both HV and LV warning.
Cool, this is helpful info. It seems like I will need to create a circuit to interface with whatever charger I get to stop at HVC. Ill read up on that when I have some time. Maybe Ill also wire in a LED to blink on the dash when any of the warnings occur. This will be my LVW in case I do not here the buzzer on the alarm.

I was also thinking I might create some sort rotating/sliding display so that I only physically display 4 cell-logs at a time. Save some dash space.


Small update: I am not really in the market yet, but I may have found a chassis :D

teddillard
13 March 2011, 1039
Small update: I am not really in the market yet, but I may have found a chassis :D

..and that, my friend, is how it starts. :D

Coninsan
13 March 2011, 1105
Well thanks.


Well sorry if it sounds like I'm sucking up to you, but I figured that I had to say something nice before hijacking your thread ;)

Nuts & Volts
13 March 2011, 1118
Haha to both of you fools! I have hijacked plenty of threads in my day :)

BaldBruce
13 March 2011, 1602
Again I need to state the obvious so someone doesn't get burned. These cell log alarms are not isolated from each other. Your "interface" circuit MUST contain isolation in order to "or" the outputs together. Sorry if I sould like a broken record, but all it takes is one missaplication to melt some wires...........

lugnut
13 March 2011, 1637
These cell log alarms are not isolated from each other. Your "interface" circuit MUST contain isolation in order to "or" the outputs together..........

Yes, this is correct. I think the alarm output is an open collector circuit at the potential of the first cell in the string connected to the CellLog. So if you wire multiple alarm outputs together, you short 7 or 8 cells. Each alarm output needs to drive an isolation relay when using multiple CellLogs.

The USB port on the CellLog is also at cell potential (not isolated). So you can only use those one at a time. It is best to disconnect the cells from the CellLog before connecting the USB to a computer. The USB will then power up the CellLog.

Nuts & Volts
13 March 2011, 1705
Again I need to state the obvious so someone doesn't get burned. These cell log alarms are not isolated from each other. Your "interface" circuit MUST contain isolation in order to "or" the outputs together. Sorry if I sould like a broken record, but all it takes is one missaplication to melt some wires...........

No not at all. I appreciate this.

So for every Cell log I have i need a relay driven by that cell log's alarm output. I then take all the relay output signals to run my charger off signal?

Thanks for pointing this out

BaldBruce
13 March 2011, 1820
Or an opto-isolator circuit that drives a single relay. Cheaper and easier than a gabillion relays......

Nuts & Volts
21 March 2011, 2035
Ok so here is one of the crazy ideas i have (or borrowed) for this build. Given the lightweight and mounting style of the motor (mounts on back face) I have sort of been throwing around the idea of doing a single-sided swingarm with the enstroj as a hub motor. The idea came to me when i remember seeing this post here (http://experimentalev.wordpress.com/2009/10/08/gsxr-update-3/).

So the idea would involve either design a custom single sided swingarm or modifying a current SSS to bolt to my motor. I would then make an adaptor plate to bolt to the front of my motor and then car rim like illustrated in the blog post linked above. I would also have the motor custom wound to run to about half the speed, but twice the torque at the same voltage and current ratings. This i see as the trickiest part of the deal, but i think the motor manufacturer may be able to do it for me. Yes the swingarm design would be tricky, but I think with somewhat simple force diagrams and calculations I can determine the material specs I need for lateral and torsional loading. Yes this may be hard so I want to try to get some opinions on here and from other resources about a design. More design discussions later to come.

Right now I just want to get a feel from people about the functionality and performance that I can get from this setup. The motor weighs about 28 lbs. I will be removing the rear brake. I will most likely be using some form of aftermarket 16" or 17" car rim like in the link which can be between 17 and 23 lbs. So we are looking at a 50 lb rear wheel while an '05 R6 rear wheel is about 34 lbs with tire, brake and sprocket. So I will add about 15 lbs or so of unsprung weight. Mind you I will actually reduce rotational weight by about ~7ish lbs bc the whole motor wont be spinning. I think I will have 400Nm max at the rear wheel, maybe more.

So the issues I see are
-can a car rim handle the lean of an electric motorcycle
-can a proper swingarm be created
-can I fit a motorcycle tire on a 6" or 7" wide rim
-can the motor be wound for lower speed operation
-can the motor case handle the loads in a wheel (motor mounts to a pole and handles the loads on a propeller)
-will the unsprung weight ill my handling

Benefits that I see are
-opens up frame space
-eliminate a chain (silent and grease free ride)
-super unique (except for the enertrac, gotta give mark some props too for design idea)
-awesome look of a SSS

So help me argue for and against a hub motor design like this (design fun later if applicable)???????

DaveAK
21 March 2011, 2101
Seems like a good idea on the face of it, but you're going to be asking a lot of it on the mechanical side of things I think. It would come down as to whether the design can be adapted to what you're asking of it. I'm not familiar with the design of a hub for a single sided arm, but in principal I imagine it can be done.

Would look pretty trick for sure. :)

Nuts & Volts
21 March 2011, 2116
Seems like a good idea on the face of it, but you're going to be asking a lot of it on the mechanical side of things I think. It would come down as to whether the design can be adapted to what you're asking of it. I'm not familiar with the design of a hub for a single sided arm, but in principal I imagine it can be done.

Would look pretty trick for sure. :)

Yea I understand the mechanical design will be extensive, but I'm not really doing anything that hasn't been done except the car rim part. I've been reading up on chassis design, but havent gotten to swingarm design yet. I'm hoping mark will chime in with a thought or two. Lot of work ahead of me nonetheless

I'm studying mechanical engineering right now anyways so why not live it! :) I am hoping to turn some heads with this ride. I want to illustrate how electrics can exploit the limitations I see with ICEs. Only real issue with a hub motor is it means no 2 speed tranny, but thats plan B :D hehehe

podolefsky
21 March 2011, 2148
Let me see if I understand. You want to fabricate a spindle that attaches to the motor shaft and bolts to the wheel. Then the motor body is attached to the SSS? That would be pretty trick...but...

I'm not sure, but I agree with Dave that it would be putting a lot of stress on the motor. The motor bearings might hold up, but very likely it would bind. If it didn't self destruct, it would probably cause enough friction to seriously hurt your efficiency.

In the Emrax plane, the forces are mostly along the direction of the motor shaft. In what you are proposing, the forces will be mostly perpendicular to the shaft, supporting the weight of the bike. Not to mention very large vertical impact forces over bumps. Not to mention twisting forces when cornering.

Could be I don't understand what you're trying to do.

Nuts & Volts
21 March 2011, 2209
http://www.enstroj.si/images/stories/emrax_motors_d.jpg

The motor actually doesnt have a shaft extending out from the rotor. I would be surface mounting the motor to the wheel through a .5" to 1" adapter plate. Then the back side of the motor would be surface mounted to the swingarm. This make more sense with the motor picture

The motor is only about 3.5 inches long and the bearings in the picture are not that far apart. This all helps reduce the torque arm pivoting at the swingarm from the wheel loads helping to spread the load from the rim loads. Now what is also good is that the wheel is spinning so the static force diagram is actually effectively equally spread out on all the bolts and the full surface of the bearings.

The loss in efficiency would not be any more than is already lost in the wheel bearings of any swingarm and chaindrive setup, right? So as long as the motor bearings are spec'ed very similarlly to a motorcycles wheels bearings the motor could survive. The vibrations may be another story... but it seems to be all about the bearings which will be transferring the load on the shaft to the swingarm. Or I just drive on really smooth roads or really slow :)

Thanks for the thoughts Noah, hope i cleared some things up.

DaveAK
21 March 2011, 2235
Would all depend on those bearings I guess. I wouldn't know how to figure out what you need, and then it all depends on being able to retrofit something in to the motor design.

podolefsky
21 March 2011, 2246
The loss in efficiency would not be any more than is already lost in the wheel bearings of any swingarm and chaindrive setup, right? So as long as the motor bearings are spec'ed very similarlly to a motorcycles wheels bearings the motor could survive. The vibrations may be another story... but it seems to be all about the bearings which will be transferring the load on the shaft to the swingarm. Or I just drive on really smooth roads or really slow :)

Thanks for the thoughts Noah, hope i cleared some things up.

Ah right, I see. Man, that is a neat motor design.

I think you're right, if the bearings are speced the same you might be good to go. Although, I'd also worry a bit about the body that holds the bearings. Under normal conditions, the body doesn't experience much sideways load. So even if the bearings survive, you could deform or fracture the material around the bearings. Especially if it's cast iron, that stuff is strong but extremely brittle.

Still, I think it's a sweet idea...there's got to be a way to make it work.

podolefsky
21 March 2011, 2250
One more thought - is there a way you could get an axle through the hole in the motor center? If you could, then you could use actual wheel bearings to support the load outside of the motor itself. (I've only half thought this through - probably a reason it wouldn't work..)

Fab man
21 March 2011, 2308
Kelly supplies a 7kw version of what I think your referring to. Check under brushless motors in their motor section. It has a 5 stud pattern for a Buick wheel- I guess they're popular in China. It's already mounted with a brake disc.

Nuts & Volts
21 March 2011, 2313
One more thought - is there a way you could get an axle through the hole in the motor center? If you could, then you could use actual wheel bearings to support the load outside of the motor itself. (I've only half thought this through - probably a reason it wouldn't work..)

The motor encoder fits into that whole on the backside so unless I run sensorless then no. But I may be able to run a very large 120mm+ ID bearing on the outside of adapter plate that fits the motor face to the rim. This bearing would then help transfer load around the motor (I would create a simple motor "cage"). This would mean that not all of the wheel load has to be transferred through the motor. This may look funny but it would probably help a lot. I'll hopefully have some pictures tomorrow to illustrate my point. Ill also draw up some force diagrams too maybe.


Kelly supplies a 7kw version of what I think your referring to. Check under brushless motors in their motor section. It has a 5 stud pattern for a Buick wheel- I guess they're popular in China. It's already mounted with a brake disc.
Ill take a look at that motor, but I think those are all outrunner style, ie the shaft is fixed. The main concern with my design will be the loads that occur when lean'd over. The shaft of my motor will want to bend like a banana, but I have hopefully allow enough flex everywhere to keep my bearings from suffering. Risky business right here.

podolefsky
21 March 2011, 2340
ZEV (http://www.zelectricvehicle.com/4.html) has a 7 kW hub motor in it's scooters. Not that that's what you want, but they might have ideas about how to make this work. But 7 kW is only about 10 HP...I think you're going bigger than that.

DaveAK
22 March 2011, 0929
The motor encoder fits into that whole on the backside so unless I run sensorless then no. But I may be able to run a very large 120mm+ ID bearing on the outside of adapter plate that fits the motor face to the rim. This bearing would then help transfer load around the motor (I would create a simple motor "cage"). This would mean that not all of the wheel load has to be transferred through the motor. This may look funny but it would probably help a lot. I'll hopefully have some pictures tomorrow to illustrate my point. Ill also draw up some force diagrams too maybe.
This definitely sounds like it could work to help take some of the load off the motor. If you could get the motor "shaft" modified to take the bearing instead of using your wheel adapter it might help with bearing alignment. Alternatively I guess you could use the hole on the wheel side of the motor to align your adapter if the adapter had a suitable boss on it.

Nuts & Volts
22 March 2011, 1059
Here is a little drawing of two "cage" solutions with an additional bearing.925

This design may be awesome because it will be able to significantly reduce the load on the motor. The only issue I see is that added weight of this setup, maybe another 5lbs of unsprung weight. I like B because a bearing of this size will be lighter and easier to fit. I can live with some handling issues, I am not designing a super racer or anything. As long as the added unsprung weight doesnt create additional stresses elsewhere that will fail another component.

Other question; is a 6" wide tire too extreme? and do you think a car rim can handle the loads of a motorcycle?

THanks
Kyle

Harold in CR
22 March 2011, 1215
One example of car rims is, the front wheels, in a sharp turn, will flex enough to spit the full cover hub caps off, but, I can't imagine a car rim being less able to handle a motorcycle ??

Over on the DIYelectriccar site, a poster named "Fishguts" has modded a Honda Swingarm, under a VW Bug modified car frame, for a reverse Trike design. He adapted a car rim and tire, IF I remember correctly.

Edit:
I found the build thread I mentioned above. He had a wheel "Custom Built".
Here is a link to that thread, IF You might be interested.

http://www.diyelectriccar.com/forums/showthread.php/voltsrat-30353.html

larryrose11
22 March 2011, 1434
I like it! You are going to want to support the motor, as in your A or B design.
Perhaps a double row taper roller bearing:
http://www.skf.com/portal/skf/home/products?maincatalogue=1&lang=en&newlink=1_14_41
oo perhaos a new type of bearing, the Toridal roller:
http://www.skf.com/portal/skf/home/products?maincatalogue=1&lang=en&newlink=1_7_1
both are available in HUGE ID, like 600 mm

This way, the bearing takes all the torsional loads and transfers it to the swing arm. you are still going to have a torque arm for the motor to react against, but the unloading the motor bearing is important.

Nuts & Volts
22 March 2011, 1746
I like it! You are going to want to support the motor, as in your A or B design.
Perhaps a double row taper roller bearing:
http://www.skf.com/portal/skf/home/products?maincatalogue=1&lang=en&newlink=1_14_41
oo perhaos a new type of bearing, the Toridal roller:
http://www.skf.com/portal/skf/home/products?maincatalogue=1&lang=en&newlink=1_7_1
both are available in HUGE ID, like 600 mm

This way, the bearing takes all the torsional loads and transfers it to the swing arm. you are still going to have a torque arm for the motor to react against, but the unloading the motor bearing is important.

Support my motor with a bearing?? The motor will be mounted directly to the swingarm and the other side is bolted to the adapter which goes to the rim. This adapter revolves, but the case does not actually move. The motor has internal bearings if that is what you are referring to.

Maybe this helps. The left side of the motor is support by the swing arm. The right side is not supported, but the motor "shaft/adapter plate" is supported by the new bearing. This new bearing takes the load off of the internal motor bearings and thus the motor case. The new bearing deflects the load around the motor itself directly to the swingarm.

Other good news. I have done some searching and found some 17" rims that are 12 to 13lbs!! Some awesome weight savings there with not too much more money. Anyone see any reasons to go to a 16" rim?

EDIT: so i reread your post larry, and i think you are simple agreeing with my design?? :) thanks

podolefsky
22 March 2011, 1925
Maybe this helps. The left side of the motor is support by the swing arm. The right side is not supported, but the motor "shaft/adapter plate" is supported by the new bearing. This new bearing takes the load off of the internal motor bearings and thus the motor case. The new bearing deflects the load around the motor itself directly to the swingarm.

Other good news. I have done some searching and found some 17" rims that are 12 to 13lbs!! Some awesome weight savings there with not too much more money. Anyone see any reasons to go to a 16" rim?

From my (non-engineer) point of view, this looks pretty good. One thing I realized is that if a car rim can handle massive sideways forces (i.e., parallel to the axle), it should be fine on a bike. On a motorcycle, the wheel never experiences the same sideways forces because you lean the bike through turns. So if you calculate the force components parallel and perpendicular to the axle, the parallel part will be smaller than you would have on a car. On top of that, motorcycles weigh significantly less than cars, so the force required to turn is much smaller.

In other words, I don't see why a car rim wouldn't work.

Oh, and the only reason to go with a 16" rim is that tires might be cheaper, and in general smaller rims weigh less. But if you found a super light 17" rim, then it's a wash.

DaveAK
22 March 2011, 1938
Just don't put spinners on it!

Nuts & Volts
22 March 2011, 2140
Thanks noah, I wanted someone to give me some encouragement there on using a car rim. Next is making sure the motor can be rewound. The motor guy is super busy testing so I might not hear from him for a couple of weeks.

More car rim research then ill start some more CADing

podolefsky
22 March 2011, 2211
Thanks noah, I wanted someone to give me some encouragement there on using a car rim. Next is making sure the motor can be rewound. The motor guy is super busy testing so I might not hear from him for a couple of weeks.

More car rim research then ill start some more CADing

I found this for ya:

http://vfrworld.com/forums/mechanics-garage/32450-car-wheel-conversion.html

Notice that his SSS actually cures in with the sprocket on the outside. If your SSS worked like this, you could just put the motor where the sprocket is on the outside. That would eliminate all these bearing issues and use a standard SSS motorcycle wheel. The thin Emrax motor would tuck right up in there, so it would still be super trick (IMO).

Don't forget that you need to fit a rear brake in there too. The motor/sprocket swap would also solve that problem.

http://www.asfphotos.com/upload/1252089033.jpg

Nuts & Volts
22 March 2011, 2253
I found this for ya:

http://vfrworld.com/forums/mechanics-garage/32450-car-wheel-conversion.html

Notice that his SSS actually cures in with the sprocket on the outside. If your SSS worked like this, you could just put the motor where the sprocket is on the outside. That would eliminate all these bearing issues and use a standard SSS motorcycle wheel. The thin Emrax motor would tuck right up in there, so it would still be super trick (IMO).

Don't forget that you need to fit a rear brake in there too. The motor/sprocket swap would also solve that problem.

http://www.asfphotos.com/upload/1252089033.jpg

This is definitely a viable and simpler option. The motor would still pop out say 5-6 inches due to the position sensor, the cooling tubes and the wire leads. If the bike ever goes down on the left side my motor would be toast (not just the case, the cooling and HV connectors and encoder would be f'ed). That is worst case, but in the frame or in the wheel may protect it more from any kind of low side. I do appreciate the brainstorming help. Do my concerns seem valid. see the picture below

http://www.enstroj.si/images/stories/emrax_motors_06.jpg

If I can't make my in wheel car rim setup work for some reason, I will be doing my best to have a 2 or 3 speed transmission. So I am going for "trick" on this build no matter what!! :)

podolefsky
23 March 2011, 0740
Yeah, that's a good point - motor will be protected much better inside the rim. And honestly, if you make that work it will be a lot cooler.

That link I posted also shows how to fit a car rim to a SSS, so might still be useful.